1f capacitor

Last update: August 25, 2019

Entering the 7th season of NBC Sports/DRIVE,

with

Followers,

It is a leading authority in all fields of automobile.

Scott Roper

Review team

Products Show

hour

expert

comment

How do we decide

If you purchase a product through one of our links, its partners may earn commissions.

.

Published on August 25, 2019

A noisy car audio system is great, but it also obstructs other parts of the vehicle. An overpowered amplifier may drain battery juice, dim the car's lights or fatigue the alternator. To mitigate any problems or potential damage, you should connect a high-quality capacitor. It works like a smaller version of a battery and stores energy for use in other electronic components, such as amplifiers. This is the best car audio capacitor you consider riding.

This is a 2 farad capacitor that can be charged in just a few seconds. It has a red three-digit voltage display, which is easy to read even in the dark.

A warning tone will sound to warn you of low voltage, over voltage or reverse polarity. With remote terminal screws, it is easy to connect to charge or connect to car audio amplifier.

Its small and compact shape can store less energy. May be insufficient for more powerful amplifiers. The screws are a bit fragile and will be damaged if you tighten them too tightly.

Author

Published

Boss Audio’s Planet Audio cover comes with a variety of accessories to power your audio system. It has a powerful capacitance of 10,000,000, a power supply of 16 VDC and a surge voltage of 24 VDC. This makes it one of the most durable capacitors on our list, and it will keep your headlights bright no matter how loud the music sounds.

One of the best features of this machine is its audible alarm tone, which can be used as a reverse polarity warning. It will also inform you of possible voltage overload or low battery power. Including your own voltmeter can also measure the level. It is also equipped with a three-digit bright blue LED voltmeter, allowing you to easily read the internal layout of the capacitor. 

The downside is that if you use line 0, it is not compatible with the capacitor. The shell around the cover is also not strong and will spread out during installation, but will not damage the actual components. You may also hear annoying beeps from the cap every time you start the vehicle.

Boss Audio Systems capacitors are light and compact and can be placed in the smallest places. Because it has a high-level input voltage of 24 volts, it can keep up with high-power audio systems. In addition, its capacitance value is two farads, which means it only takes a few seconds to charge and then you can power your car audio amplifier.

Whenever there is a failure (including overvoltage, low voltage or reverse voltage conditions), the device will sound an audible alarm. You can also record the capacitor voltage on the easy-to-read red digital voltage display. Moreover, the device has a long service life due to its corrosion-resistant and weatherproof housing.

The compact shape allows it to seamlessly integrate with the vehicle's interior, but compared to larger capacitors, it stores less energy and must be charged more frequently. For the same reason, it may not be able to power certain higher-power amplifiers. In addition, the terminal screw is very fragile, and if it is tightened too tightly, it may break.

Although Sound Storm’s capacitors are only rated at 3.5 farads, they can withstand certain more powerful capacitors. Its operating voltage range is 16 VDC, and the surge voltage is also 24 VDC. The tolerance percentage of small capacitors is +/- 10%, which provides great flexibility for the sound quality and lighting of your vehicle.

It is equipped with a small red text display to let you know the exact measurement of the charge and voltage in the tank. In terms of durability, the bottle cap is designed as a chrome-plated post with hardware and mounting brackets to simplify installation. In short, capacitors are also very light. It weighs less than 4 pounds and can also be used as a two-farad power capacitor.

Although it looks small, it is actually larger than expected. This may make things more difficult during the installation process, but it will not affect the process much. It may also take a minute to charge the capacitor. You only need to spend longer than this to worry about it. Another disadvantage is that you need to buy wires to connect properly.

Why trust us

All our reviews are based on market research, expert opinions or practical experience of most of the products we contain. In this way, we provide a true and accurate guide to help you find the best option.

The main difference between the types of car audio capacitors is their ability to hold charge. Electrolytic batteries usually have a faster charging speed, but their reserve power is less. Normally, electrolytic capacitors will also be packed in circular tanks and use one farad (the amount of electricity the capacitor can hold) per 1000 watts of power.

Carbon car capacitors are the opposite of electrolytic capacitors. Although they can reserve more power to transfer back to the amplifier and the entire audio system, they will not be able to charge as quickly as possible. Generally, they will use the same number of farads as electrolytic capacitors.

You can also find a mixture of electrolysis models and carbon models, but they can be more expensive and larger. They look like smaller versions of car amplifiers, and 5 farads per 1000 watts of power are recommended. If you need a second battery, consider using a hybrid audio capacitor. 

Boss Audio, based in Oxnard, California, has been in business for more than 30 years. It is responsible for manufacturing a large number of car audio equipment, such as amplifiers, subwoofers, tweets and capacitors. One of its most popular car audio capacitors is

Rockford Fosgate was founded in 1973 and is part of Rockford Corporation in Tempe, Arizona. It produces audio products used in automobiles, ships, motorcycles and other applications. One of its best-selling capacitors is

NY Rockville’s main business headquarters is located in Inwood, dedicated to the production of high-quality car audio components. The company also manufactures speakers, amplifiers and receivers for boats and other off-road vehicles. One of its top automotive capacitor designs is

Stinger has been in the car audio business for the past 30 years. The company provides the best car audio accessories, wiring kits, batteries, submarines, etc. to enhance the music in your vehicle. Stinger is headquartered in Clearwater, Florida and is responsible for

The value ratio of the capacitor is one of the most important factors for this component. It measures how much power can be retained in it by using a Farad device. The range can vary from two farads to more. The more powerful your amplifier, the more farads you need.

The second most important thing about a capacitor is its rated voltage and surge voltage value. You will want to make sure that the DC voltage of the capacitor is higher than the DC voltage of the alternator and battery. However, you will need to be careful when looking for the correct voltage rate; capacitors that exceed the surge level may be damaged beyond repair, and low voltage may cause it to short-circuit. 

The more terminals a capacitor has, the more components you can connect. Generally, a smaller terminal will have two terminals, and a larger terminal will have more terminals. If you need to use it as a distributor block, additional terminals are also useful, which will make hardware installation easier.

To accurately calculate the number of farads required to run the audio system, first check the car amplifier. People who consume less than 2,000 watts only need about one to two farads to successfully power the system. The more power you have, the more farads you need.

Additional terminals may be used for voltmeter display. If it is turned on for a long time, it may drain the battery. The terminal can be used as a remote open and close switch to prevent drainage.

You can measure the energy inside the capacitor by performing the test frequency using 1kHZ or 120Hz.

For one of the most powerful and durable car audio capacitors, it will keep your lights bright, please consider using

. 

You can choose a more budget-friendly option and keep the bass

other

Comments you might like:

Sign up for our newsletter

Technology, performance and design have been delivered to your inbox.

©

all rights reserved.

We are a participant in the Amazon Services LLC employee program, an affiliate advertising program designed to link to

And affiliate sites.

◎High power and low density (low ESR)

◎More than 500,000 cycles of cycle life (semi-permanent)

◎Suitable for UPS, AGV, renewable energy applications

◎Comply with RoHS / WEEE / REACH

VINATech's supercapacitors have been used in energy, automotive and industrial fields. VINATech's energy and industrial technologies include a variety of solutions from supercapacitors and fuel cells to efficiently use energy.

Snap In supercapacitors range from 100 farad capacitors in a 22 mm x 45 mm (D x L) tank to 500 farad capacitors in a 35 mm x 82 mm (D x L) tank, and will be mass-produced in multiple locations ; VINATech will provide services to many customers with the best customer service and reasonable delivery time.

Compared with lithium ion secondary batteries, Hy-Cap supercapacitors have higher power density, higher charge/discharge efficiency, wide operating temperature range and longer service life. Hy-Cap supercapacitors can store a large amount of electrical energy by physically adsorbing and desorbing the charge on the surface of activated carbon, and then provide a large current immediately or continuously. VINATech supercapacitors are environmentally friendly energy storage devices with high power density and long life. Hy-Cap will be an ideal choice for responding to instantaneous power failures of uninterruptible power supplies (UPS) and compensating for peak power to compensate for the pitch of wind turbines. .

Since 2010, VINATech has launched a 3.0V electric double layer capacitor (EDLC) for the first time in mass production in the industry. Compared with 2.7V EDLC, the energy density has increased by 23%. VINATech’s Pulse Capacitor (VPC) was recently launched with an operating voltage range of 2.5V to 3.8V. Especially in the field of radial supercapacitors 1F to 1,000F supercapacitors, we are equipped with world-class smart factory production technology.

Custom-designed super capacitor module of VINATech R&D department

Hy-Cap, Snap In series supercapacitors provide a capacitance range of 100 farads to 500 farads, and rated voltages of 2.7V and 3.0V. VINATech R&D laboratory and module team provide custom-designed series or parallel supercapacitor modules.

◎Learn more about the 3v Snap Incapacitor data sheet on our website

◎Learn more about the 2.7v snapshot supercapacitor data sheet on our website

VINATech's embedded supercapacitors can provide more than 500,000 cycles of cycle life (semi-permanent), high power density, and low ESR. The Snap In supercapacitor data sheet is available on our website, and contact us to customize the design or detailed information about the supercapacitor module. Most companies involved in the global supply chain and multi-site manufacturing companies, therefore, the Vietnam VINATech factory, Jeonju R&D laboratory and Jeonju production line will provide quality services to valued customers around the world.

About VINATech

Founded in 1999, VINATech has developed and produced electric double layer capacitors (EDLC, such as supercapacitors or supercapacitors) and fuel cell membrane electrode assemblies. The equipment is equipped with smart factory-based production facilities with the highest level of automation to ensure the world First-class quality level in range. Call +82 31 448 3066 or contact us for supercapacitor solutions, please visit our website for more information.

Share the article on social media or email:

View articles in the following ways:

All press releases list the contact information and available social follow information at the top right.

Or interested in learning more about our news service?

1-866-640-6397

© Copyright 1997-2015, Vocus PRW Holdings, LLC. Vocus, PRWeb and Publicity Wire are Vocus, Inc. or Vocus PRW Holdings, LLC. Trademark or registered trademark.

These authors contributed equally to this work.

Ferroelectric memory has been intensively studied for decades, because compared with conventional flash memory, ferroelectric memory has higher speed, lower power consumption and longer service life. Although great efforts have been made to develop ferroelectric memory based on perovskite oxide on silicon, the formation of an undesirable interface layer substantially impairs the performance of the ferroelectric memory. In addition, due to the high processing temperature, non-CMOS compatibility, difficulty in scaling and the complex composition of perovskite oxides, three-dimensional (3D) integration is unimaginable. Here, we show a unique strategy that can solve key problems by applying oxide-based ferroelectrics and oxide semiconductors. Therefore, the formation of an interface layer can be avoided, which ultimately allows ferroelectric memory to achieve unprecedented silicon-free 3D integration. The storage performance produced by this strategy cannot be achieved by conventional flash memory or previous perovskite ferroelectric memory. Device simulation confirmed that this strategy can achieve ultra-high density 3D memory integration.

Flash memory devices currently used in mass data storage for mobile devices and servers are based on floating gate or charge trap storage transistors that use electron tunneling through tunneling oxide (

,

). Since the electron tunneling process requires high-amplitude and long-duration voltage pulses, current flash memory devices usually require a high operating voltage of ~20 V and a slow speed of ~10

And show a limited endurance of about 10

cycle(

-

). In addition, it requires higher deposition temperature (>600°C) and/or annealing temperature (>900°C) to form the channel layer and oxide layer (

). In order to overcome these limitations, many types of emerging storage devices have been evaluated, but there are no substitutes for current flash memory (

). Ferroelectric memory transistors can replace current flash memory because it has the potential to run quickly at low power consumption (

). In a ferroelectric memory transistor, the charge in the channel layer can be directly controlled by the polarization of the ferroelectric layer, which is incorporated into the gate stack of the ferroelectric transistor (

). Although previous studies using ferroelectric perovskite oxide deposited on Si wafers have shown its feasibility as high-performance flash memory applications, the formation of an interface layer with Si channels will limit the storage window, durability and data retention characteristics (

). In addition, the complex composition of perovskite oxide limits the applicability of ferroelectric memory as next-generation flash memory devices (

). In addition, the three-dimensional (3D) integration of such ferroelectric memories is a key requirement for commercialization, but since depositing perovskite oxides and precious metals in a 3D structure is a difficult task, and these materials are very difficult to etch, this Is unachievable (

).

F-based ferroelectric materials have gained research interest due to their complementary metal oxide semiconductor (CMOS) compatibility, low power consumption and fast switching speed (

). In addition, recent studies have shown that while maintaining ferroelectricity, f-based ferroelectrics can be reduced to <1 nm (

). Due to these advantages, ha-based ferroelectric materials have been used in ferroelectric memory transistors, negative capacitance field effect transistors (FET), ferroelectric tunnel junctions and artificial synapses (

). F-based ferroelectric materials can be deposited conformally on vertical structures using atomic layer deposition (ALD), so ferroelectric transistors using them are considered useful for 3D memory (such as 3D NAND (

). However, it is still necessary to solve the device performance problem caused by the formation of the interface layer with Si channel (

Here, we propose a unique integration strategy to overcome the above-mentioned key problems in ferroelectric memory transistors by introducing indium zinc oxide (InZnO).

) As the semiconductor layer and zirconium-doped oxide ha (HfZrO

) As a ferroelectric layer. One, SiO

The use of InZnO can effectively prevent the interface layer inherent in traditional perovskite oxide or ferroelectric memory based on f oxide

As a semiconductor, while maintaining the necessary material quality (or material quality equivalent to Si) to obtain high-performance memory. This can increase the operating speed hundreds of times (<10

s), and the operating voltage (<5 V) is the current flash memory (

). In addition, since there is no interface layer, it has excellent durability (> 10

Ferroelectric transistor compared to two charge trap flash memory (~10 cycles)

) And ferroelectric transistors with Si channels (~10)

) (

). Since all processes can be completed at temperatures below 400°C, the integrated ferroelectric memory device is compatible with CMOS, so we can confirm that our process can achieve commercialization milestones, including demonstrations of NAND flash memory arrays and 3D vertical structures . Our nano-level 3D vertical flash memory has excellent performance and is expected to achieve ultra-high density 3D flash memory in the future. The 3D device displays a large storage window of 2.5 V and has 10 stable switching characteristics

cycle. Device simulation confirmed the operation mechanism and possibility of ultra-high-density 3D memory integration. These results prove the rationality of ALD-based ferroelectric memory as future 3D non-volatile storage devices (such as 3D vertical NAND).

Confirm the ferroelectric properties of HfZrO

, We made a capacitor with TiN/HfZrO

/ TiN structure and measure the polarization electric field (

-

) Characteristics of 24 nm thick HfZrO

(Figure S1A). Zirconia

Show positive residual polarization+

= 15.1μC/cm

And-the negative residual polarization-

= -13.8μC/cm

. Coercive electric field of HfZrO

It is ~1.2 MV/cm; it is larger than ferroelectric perovskite oxide (~0.05 MV/cm), and may be advantageous in ferroelectric transistors because a large coercive electric field leads to a large storage window (

). Therefore, using thin HfZrO can achieve a sufficient storage window

Compared with perovskite oxide. Ferroelectric of HfZrO

Piezoelectric force microscopy (PFM) and capacitance-voltage (

) Measurement. After applying -6 V to the outer square area of ​​the sample and then +6 V to the inner square area of ​​the sample, the PFM amplitude and phase image were measured. The obvious contrast difference indicates that the polarization state of HfZrO is different

In the PFM amplitude (Figure S1B) and phase image (Figure S1C). of

The ferroelectric properties of HfZrO cause the curve to show a butterfly lag

(Figure S1D). These results confirm the ferroelectric properties of HfZrO.

the film. Durability and polarization conversion characteristics of HfZrO

Be characterized. In order to obtain lasting characteristics, a repetitive voltage pulse with an amplitude of ±6 V and a width of 5 μs was applied (Figure S1E). Ferroelectric HfZrO

Demonstrates stable 10 switching characteristics

cycle. Polarization conversion characteristics of HfZrO

The light absorption rate was evaluated by measuring the switching and non-switching polarization characteristics under applied voltage pulses with an amplitude of 7.2 V (ie 3 MV/cm) and different widths (Figure S1F). As the pulse width increases from 30 ns to 700 ns, the switching polarization of HfZrO

increase.

In order to study the feasibility of our integration strategy, a ferroelectric thin film transistor (FeTFT) with bottom contact structure was fabricated by combining ALD-based HfZrO

And InZnO

(

). Quantify its electrical characteristics by scanning the gate voltage

Between -5 and 5 V at source-drain voltage

They are 0.1, 0.05 and 0.01V respectively. FeTFT shows counterclockwise hysteresis, which is caused by the iron polarization switching in HfZrO

). Linear field effect mobility of InZnO

The channel in FeTFT is about 1.9 cm

V

s

Lower than InZnO

On SiO

Layer (~7.8 cm

). This difference seems to be due to the high dielectric constant of HfZrO

Layer, which can cause long-range scattering of phonons (

). By using a gate electrode layer with a high electron density, the remote scattering of such phonons can be reduced (

). In addition, the mobility of InZnO

By optimizing process parameters, such as doping and growth temperature, the channel can be further increased (

). In order to quantify the storage window of FeTFT, the device is programmed and erased by applying positive voltage (5 V, 10 ms) and negative voltage (-5 V, 10 ms)

pulse. After applying each pulse,

Sweep from 0 V to -5 V to verify the state of the device. Threshold voltage

Use linear extrapolation to extract programming state and erase state

). Memory window, this is

The number of programmed and erased states in FeTFT (> 2 V) is greater than previously reported FeTFT (0.5 to 1 V) with f-based ferroelectric materials and oxide semiconductors (

). Determining the switching characteristics of FeTFT based on HfZrO

,

Pulses with different amplitudes and widths were applied. Before measurement, erase FeTFT by applying negative voltage

Pulse (-5 V, 10 ms). Then, apply a pulse with a width of 1 μs and an amplitude of 3 to 5 V in 0.2 V increments. As the pulse amplitude increases,

The equipment has been changed (

). Using a pulse with an amplitude of 5 V can reach a storage window of ~2 V, which is approximately four times the pulse amplitude required by conventional flash memory (

).

A change was also observed when the pulse width was increased from 100 ns to 1 μs with an amplitude of 5 V (

). These switching characteristics may be the result of partial polarization switching of HfZrO

The layer can be controlled by applying pulse conditions (

). With a voltage pulse width of 500 ns, a storage window of ~1 V can be reached, which is about hundreds of times faster than the erasing operation of conventional flash memory with the same storage window (

). The storage window of the flash memory depends on the storage operation, such as multi-level data storage, and when a smaller storage window is required, the flash memory can be operated faster (

). However, compared with the ferroelectric memory introduced in this study, a higher program/erase voltage (

). Confirm the reliability of FeTFT based on HfZrO

, We studied the endurance performance using devices with different storage windows of 0.5 and 1.5 V. By applying triangular pulses (5 V, -7 V) and (6 V, -8 V) to obtain 0.5 and 1.5 V storage windows (

And figure. S2). Pulse widths of 500 ns and 1 μs are used for programming and erasing operations, respectively. After applying continuous programming and erasing pulses, confirm the device status by scanning

From 0 to -5V. When the memory window is 0.5 V, FeTFT uses ALD-based HfZrO

cycle. The robustness of FeTFT based on ALD seems to be derived from its metal-ferroelectric semiconductor structure without interface layer (

). When the silicon layer is used as a channel, SiO

An interface layer can be formed between the channel and the ferroelectric layer, so a ferroelectric transistor with a Si channel has a metal-ferroelectric insulator-semiconductor (MFIS) structure (

). When

If it is applied to MFIS structure, a lot of applied electric fields can be induced in SiO

The interface layer has a low dielectric constant compared with the ferroelectric layer. High electric field in SiO

The interface layer can cause the charge to tunnel across SiO

Interfacial layer and cause charge trapping in the ferroelectric layer; it reduces endurance characteristics (

). In our FeTFT, the formation of the interface layer can be suppressed by using oxide semiconductor channels. No interface layer will produce stable endurance characteristics. In addition, a comparison was made between this work and previous storage devices (such as charge trap storage, perovskite oxide-based ferroelectric transistors and oxide-based ferroelectric transistors) (Table S1) (

). Use of HfZrO

Compared with traditional charge trap memory and perovskite oxide-based ferroelectric transistors, its operating voltage is lower, its operating speed is faster, and its processing temperature is lower. In addition, by avoiding the formation of SiO

The interface layer has strong durability compared with charge trap memory and ferroelectric transistors.

(

) Schematic diagram of FeTFT using HfZrO

. (

) FeTFT transfer curve

= 0.1, 0.05 and 0.01V. (

)

The curve of FeTFT in erased and programmed state. Threshold voltage

Extract using linear extrapolation. Memory window is the difference between erased and programmed

FeTFT.

FeTFT is based on (

) Amplitude and (

) The width of the programming pulse. In operations with different pulse amplitudes, the pulse amplitude is increased from 3 V to 5 V, and the width is fixed at 1 μs. In operations with different pulse widths, the pulse width is increased from 100 ns to 1 μs, and the amplitude is fixed at 5 V. (

The endurance characteristic of FeTFT is 10

Use positive (5 V, 500 ns) and negative (-7 V, 1 μs) triangular pulses for programming and erasing operations.

The structure of a ferroelectric NAND (FeNAND) flash memory array is similar to that of a NAND flash memory device (Figure S3A). The difference lies in the type of storage unit. FeNAND uses ferroelectric transistors, while NAND flash memory uses conventional flash memory. In FeNAND, the page consists of ferroelectric transistor memory cells that share a word line (WL). The FeNAND string includes ferroelectric transistor memory cells connected in series. All FeNAND strings share one source line (SL). Each NAND string is connected to the bit line (BL) (

). We fabricate 4×4 FeNAND arrays by integrating FeTFT with ferroelectric HfZrO

Layer and InZnO

Channel layer (Figure S3B). The manufacturing process of FeNAND is compatible with CMOS and can be performed below 400°C. First, deposit TiN on SiO for WL

/ Si substrate and HfZrO

The deposited layer is used for the ferroelectric layer. Deposition of Mo layer and InZnO for BL/SL

Deposit the layer of the channel layer. ALD is used to deposit HfZrO

Floor. Annealing process of induced ferroelectric phase in HfZrO

InZnO is deposited at 400°C for coating

Floor. The processing temperature of FeNAND is lower than that of ferroelectric devices based on perovskite oxide (> 700°C) (

). Finally, an etching process is performed to open the contacts for WL. The 4×4 FeNAND array is made up of four WL (WL

;

= 0, 1, 2 and 3) and four NAND strings (

). Each NAND string is connected to BL (BL

= 0, 1, 2 and 3). All NAND strings are connected to the same SL. In this 4×4 FeNAND array, each of the 16 memory cells

Located at the intersection of WL

And the NAND string on BL

. This array is used to demonstrate the program operation of FeNAND. In the NAND structure, undesired programming may occur in the memory cell that shares the WL with the selected memory cell during the program operation; therefore, unnecessary programming may occur in the memory cell. This phenomenon is called program interference (

). In order to avoid program interference, a method of prohibiting program operation is used. for example,

with

Selected as programmed and programmed suppressor cells respectively. Before the programming operation, the FeTFT memory cells in the FeNAND array are erased by applying an erase pulse with an amplitude of.

= −5 V, and the width of WL is 10 ms

, While applying 0 V to BL and SL (

). Then, program

, The amplitude is

= 5 V and apply a width of 10 ms to the selected WL

And apply 0 V to BL

. Prohibited program

Shared WL

versus

，Prohibited programming pulse with amplitude

= 2.5 V, with a width of 30 ms applied to BL

And SL (

). The passing amplitude is

= 2.5 V and a width of 30 ms is applied to the unselected WL.

It will also interfere with the state of the storage unit. Therefore, the effect

Study traffic interference by increasing the amplitude

From 0.5 to 4V. in

> 3 V, passing interference occurs, so

A voltage with an amplitude of 2.5 V is used for program prohibition operation (Figure S4). After erasing and programming operations, confirm the state of the memory cell by applying WL voltage

Scan (0→-5 V) to the selected WL

. During these operations, only the storage unit

Can be programmed by the voltage difference between the gate and the channel layer (

). Otherwise, the program may be prohibited by the prohibited program operation in the prohibited program unit

. and

Applied to BL

And SL, the channel potential can be increased; the voltage difference between the gate and the channel can be reduced to

-

). program

Prevent by using the program to prohibit the operation method

= 2.5 V because of the polarization switching of HfZrO

Layer in

Be obstructed (

). These results show that the voltage difference between the gate and the channel is small enough to avoid incorrect gate programming.

. In order to study how the program prohibition pulse affects the program prohibition unit, the program prohibition pulses with different amplitudes are used to execute the program operation (Figure S5). The amplitude of the programming prohibition pulse is increased from 0 V to 2.5 V in 0.5V increments. Prohibition of programming behavior depends on the magnitude.

. in

<1 V, program not needed for storage unit

(Unwanted cell) happened. As amplitude

Added, storage unit program

Was suppressed (

). Prohibit program running

= 2.5 V can successfully prevent harmful programs; repeated programs and program prohibition operations confirm this (Figure S6). These results show that through the application

.

) Optical image of a 4×4 FeNAND flash memory array (left) and a NAND string containing programmed cells in the FeNAND flash memory array (

) And the cell (

) (Correct). (

) Equivalent circuit of FeNAND flash memory array and erase/program operation.

with

Represents programming, erasing, pass and prohibit voltage respectively. (

Curve

Storage unit and

Memory cell after erasing and programming operations. program

The program prohibits the operation to prevent the storage unit. Prohibited programming pulse with amplitude

= 2.5 V is used to prohibit the program from running. During the prohibition period,

The storage unit can be upgraded to

All 16 memory cells in the FeNAND array are operating normally. Confirm the state of the storage unit by measurement

Curve of programming state and erase state (

). Memory cells in

Curve after programming and erasing operations. The status of the device can be confirmed non-destructively by measuring the string current when reading the voltage

Apply to selected cells. For lossless read operations, the amplitude is

The Δε is selected within a range that does not cause the switching of the polarization state in the ferroelectric layer. During application

When the amplitude is -2 V, the state of the memory cell does not change. Therefore, to read the state of the selected memory cell,

= −2 V is applied to the selected WL, and the BL reads the voltage

Sweep from 0 to 0.5 V. Read current by measuring

In the structure of the memory cell, the polarization state of the ferroelectric layer in the selected memory cell was confirmed.

10 out of 16 memory cells in the 4×4 FeNAND array were measured in the programmed and erased states (Figure S7).

According to the memory status shows obvious differences (

). Demonstrated string-level and page-level NAND operations using FeNAND devices. Three different cases of NAND strings are used (all programmed cells, one erased cell and all other programmed cells and all erased cells) (

The length of the string is

= -2 V is applied to all WLs. When all memory cells are programmed, the NAND string is in the on state. However, when the string contains at least one erased cell, the NAND string is in the off state because all memory cells in a string are connected in series (

). These results confirm that NAND storage operations can be performed using FeTFT arrays.

16 memory cells in programming and erasing states. (

) Statistical distribution of read current

The number of 16 memory cells in programmed (blue) and erased (red) states. (

) NAND operation: all programmed cells (case 1), one erased cell and all other programmed cells (case 2) and all erased cells (case 3). (

In cases 1, 2 and 3, the number of NAND strings is one. When even a cell is erased, the off state is obtained.

In order to study the wafer-level uniformity of the device, we fabricated FeNAND arrays on 4-inch SiO

/ Si wafer (Figure S8A). The programming and erasing operations of nine memory cells from different locations on the wafer were measured (Figure S8B). The memory cell in the programming and erasing state

(Figure S8C). These results indicate that FeNAND manufactured using ALD can exhibit uniform electrical characteristics in wafer size. Use programming pulses with different amplitudes

Demonstrated the tuning characteristics of the memory cell in FeNAND (Figure S9A). First, erase the memory cell by applying an erase pulse (-5 V, 10 ms). Then, programming pulses with amplitudes of 3.3, 3.8, and 5 V are applied. As the programming pulse amplitude increases,

The curve moves in the negative direction. Memory cell display in FeNAND

Use programming pulses with different amplitudes to repeat cycles for four different states (Figure S9B).

In order to confirm the feasibility of FeTFT as a 3D storage device, we fabricated a vertical FeTFT array by sequentially depositing SiO2 with a thickness of 50 nm

Insulator and 100 nm thick TiN gate electrode (

). As HfZrO

Layer is deposited using ALD, both layers are conformally deposited (

). Here, we define FeTFT with the middle TiN gate electrode located between SiO

Intermediate TFT (m-TFT). The effective channel area of ​​m-TFT is 10μm

(Channel length/width, 100 nm / 100μm). Research the electrical characteristics of m-TFT through application

Scan to m-TFT gate

When applied = 1 V

The voltage to the unselected gate (ie top and bottom TiN) electrodes is 1 V

). Observed n-type transfer characteristics with counterclockwise hysteresis

A scan of -5→5→-5V is applied to the m-TFT gate electrode. The storage window of the vertical FeTFT is about 2.5V. This result shows that FeTFT can operate in a vertical stack structure with a channel length of 100 nm. Verify the switching characteristics of m-TFT by applying voltage pulses with different pulse widths and amplitudes (

). The pulse width required for the programming operation decreases as the voltage pulse amplitude increases. In order to confirm the reliability of m-TFT, the endurance performance was studied by applying positive (6 V, 1μs) and negative (-7 V, 1μs) triangular pulses as programming pulses and erase pulses (

). After applying continuous programming and erasing pulses, confirm the device status by scanning

From 0 to -3 Vm-TFT exhibits a stable switching characteristic of 10

cycle. In addition, similar anti-clockwise hysteresis transmission characteristics were observed in m-TFT devices with an effective channel area of ​​0.2 μm.

(Length/Width, 20 nm / 10μm). These results indicate that the manufacturing process using our integrated strategy is compatible with 3D structured devices with large storage windows and excellent durability characteristics.

) Manufacturing process flow of vertical FeTFT array. (

) Optical image of vertical FeTFT device array. S and D represent the source and drain respectively. (

) Scanning electron microscope image (false color) of the cross-section of the vertical FeTFT array. (

) The transmission curve of m-TFT has a counterclockwise hysteresis. To characterize,

Scanning is applied to the m-TFT gate electrode, and

Apply = 1V to unselected gate electrodes. (

The m-TFT device changes according to the program pulse amplitude and width. (

) The durability of m-TFT device is 10

Use positive (6 V, 1μs) and negative (−7 V, 1μs) triangle pulses for programming and erasing operations, respectively.

We use technical computer-aided design (TCAD) tools to simulate the vertical FeTFT array (

). Before performing FeTFT simulation, we first perform simulation

Characteristics of 24 nm thick HfZrO ferroelectric capacitor

And compare with the experimental results (Figure S10) (

). TiN is used for the top and bottom electrodes; saturation polarization, residual polarization, coercive electric field and Landau-Khalatnikov parameters of HfZrO

Is extracted from experimental data (

). Simulated

The hysteresis is similar to the experimental results, which shows that the TCAD tool can be used to correctly simulate the ferroelectric properties. Refer to the experimental results to determine the material and its thickness (

). Apply a positive pulse (5 V, 100μs) and a negative pulse (-5 V, 100μs) to the m-TFT gate electrode (that is, the selected cell) for programming and erasing operations, while applying

= 1 V to unselected gate electrode. Polarization in HfZrO

After programming and erasing operations, this layer has changed significantly (

). continued,

After programming and erasing operations, a scan voltage of −3.5 to 2 V is applied to the fabricated and simulated vertical FeTFT array (

). The experimental and simulation results show similar programming and erasing characteristics. The results confirm that the electrical characteristics and operation of FeTFT can be correctly simulated using TCAD tools.

) Simulate the device structure of a vertical FeTFT array (

) The material used for the simulation and its thickness. (

) Enlarged image of vertical FeTFT array. (

Simulation of polarization in HfZrO

The layer is in the programmed and erased state. For programming and erasing operations, voltage pulses (5 V, 100 μs) and (-5 V, 100 μs) are applied to the m-TFT gate respectively. Polarization in HfZrO

After programming and erasing operations, the layer can obviously be changed. (

) Experiments and simulations

The curve of m-TFT in programming and erasing state.

Evaluate the feasibility of FeTFT based on HfZrO

In the future 3D FeNAND, we simulated a single string containing 16 WL, a string selection line and a ground selection line (

). The single string of 3D FeNAND is manufactured using a gate last process, which is similar to a terabit cell array transistor (Figure S11) (

). First, the nitride and oxide layers are sequentially deposited on a p-type (100) Si substrate, in which the n-well, p-well and source are formed by implanting 10 phosphorus

cm

Boron 10

And 10 arsenic

, Respectively. Etch a channel hole with a radius of 80nm; deposit an oxide semiconductor channel with a thickness of 10 nm, and fill the channel hole with SiO

(Ie filling material). Etch the nitride layer and HfZrO with a thickness of 24 nm

Be deposited. Finally, TiN WL and Mo BL were deposited. In our proposed 3D FeNAND, TiN with a thickness of 30 nm and HfZrO with a thickness of 24 nm

InZnO 10nm thick

, And Mo are respectively used as WL, ferroelectric gate insulator, oxide semiconductor channel and BL, and the thickness of SiO

The spacer between adjacent WLs is 30 nm. In order to observe the operating characteristics of 3D FeNAND, block erase and program operations (

). First, by applying a voltage pulse (10 V, 10 μs) to the substrate, block erase all WLs. Then, WL

And WL

The cells are programmed sequentially by applying voltage pulses (4 V, 1 μs) to the selected WL. After WL programming

Cell, WL

Use the same method to program the cell. Polarization in HfZrO

After block erase and program operation, the layer has changed significantly. In addition, the polarization state in WL

No change after WL programming

; This result shows that adjacent cells did not cause significant interference. continued,

Scan voltage from -3 to 1 V completes WL

After block erase and program operation (

). of

Features of WL

After programming adjacent cells (ie WL

), and has obviously switched to the programming state after WL programming

. In addition, a 3D FeNAND with more stacked cells was simulated using TCAD tools. The number of stacked batteries is 32, 64, and 128 (Figure S12). The electrical characteristics of the 3D FeNAND were characterized using the same procedure and block erase operation method discussed above. Using the above voltage pulse, all 3D FeNAND has been successfully programmed and erased, and the storage window is not significantly affected by the number of stacked cells, which confirms that 3D FeNAND can operate in a highly stacked structure. These results show that the proposed 3D FeNAND composed of low-power and fast-running FeTFT can replace 3D NAND flash memory.

) Simulate 3D FeNAND device structure. The simulation contains a single string of 16 WL, ground selection line (GSL) and string selection line (SSL). 30nm thick TiN, 24nm thick HfZrO

And 10 nm thick InZnO

Respectively used as WL, ferroelectric gate insulator and oxide semiconductor channel. Silica

Used as oxide filling material. SiO thickness

The interval between adjacent WLs is 30 nm. (

The second layer after block erase and programming operations. First, erase all WLs through a block erase operation. Then, WL

The cell is programmed. Finally, WL

The cell has been programmed. Polarization in HfZrO

After the block erase and program operations, the layer can obviously be changed. (

) Polarization changes after block erase and program operations. au, arbitrary unit. (

Curve in WL

After cell erase and programming operations.

We showed the combination of ferroelectric HfZrO

The oxide semiconductor channel is a unique integration strategy to solve the key problems in ferroelectric memory transistors. The device is manufactured using a CMOS compatible process at a lower processing temperature (400°C) and has a faster operating speed (<10

s), low operating voltage (<5 V) and excellent durability (> 10

Cycle), which is achieved through the synergy of ferroelectric HfZrO

Oxide semiconductor. We also studied the potential of ferroelectric memory as an alternative to conventional flash memory using integrated FeNAND and vertical FeTFT arrays. In FeNAND, program interference can be minimized by using the method of prohibiting program operation. In the prohibiting programming operation, the polarization switching of the ferroelectric layer is prevented by reducing the voltage difference between the gate and the channel. The state of the memory cells in the NAND string is successfully confirmed by a non-destructive read operation. of

The Pb of the FeTFT memory cell used for erasing and programming shows distinguishable programming and erasing states. In addition, a FeNAND array was used to demonstrate string-level and page-level NAND operations. Only the stored character string with all programmed cells is displayed in the on state; when even one cell is erased, the character string is displayed in the off state. A vertical FeTFT array is made by vertically stacking TiN gate electrodes and SiO2

Insulating layer to study its feasibility for 3D FeNAND. We verified that FeTFTs can operate in a vertical structure, and confirmed the operating mechanism through device simulation. Finally, by simulating programs and block erase operations in 3D FeNAND cells, the possibility of ultra-high density 3D memory integration was confirmed. These results indicate that FeTFT based on ALD has potential in future high-density 3D memory applications.

Hf [N(C

H

CH

]

[Tetra(ethylmethylamino) ha(TEMAH)] and Zr [N(C

[Tetra(ethylmethylamino)zirconium (TEMAZ)] was purchased from Korea UP Chemical. C

National Bureau of Statistics

in

[Bis(trimethylsilyl)amiyl diethyl indium (INCA-1)] and Zn(C

)

[Diethyl Zinc (DEZ)] was purchased from iChems, Korea. Si wafer with 100 nm thick thermally grown SiO

Used as a base.

Device fabricated on SiO

/ Si substrate. Use a mask aligner (MA6, Suss MicroTec) for photolithography. The FeNAND array is manufactured by integrating FeTFT. First, use DC sputtering to deposit TiN on SiO

The Si substrate is used as the gate electrode of FeTFT and as the WL of FeNAND. The TiN layer is patterned using a lift-off method. Then, use HfZrO with a thickness of 24 nm

Film is deposited on TiN/SiO

/ Si through alternating HfO ALD cycles

ZrO

Use TEMAH, TEMAZ and O at 280°C

Respectively as Hf precursor, Zr precursor and oxygen source. Electron beam evaporation is used to deposit Mo, as the source/drain electrodes of FeTFT and SL/BL of FeNAND. The Mo layer was patterned using a lift-off method. 20nm thick InZnO layer

Use INCA-1, DEZ and O to deposit films at 150°C

Respectively as indium precursor, zinc precursor and oxygen source. Zinc oxide

The layer is patterned using a combination of photolithography and wet etching. The channel length and width are 10 and 50 μm, respectively. Then, the device was thermally annealed under N at 400°C for 10 minutes

surroundings. The etching process is completed to open the contacts of the WL. For vertical FeTFT arrays, TiN with a thickness of 100 nm and SiO with a thickness of 50 nm

The layers are deposited sequentially using sputtering and plasma enhanced chemical vapor deposition, respectively. Titanium Nitride/Silica

/Titanium Nitride/Silica

Etching/TiN layer by dry etching (NE-7800, ULVAC) using sulfur hexafluoride (SF)

)plasma. 24 nm thick HfZrO

Layer, InZnO with a thickness of 20 nm

The channel layer and Mo source/drain electrodes were deposited using the same method as described above.

All electrical properties are measured under ambient conditions and room temperature. A semiconductor parameter analyzer (4200A-SCS, Keithley Instruments) was used to obtain electrical characteristics. Measure the ferroelectric properties after 10 applications

The period of rectangular bipolar pulse (±7.2 V, 5μs) is used to wake up HfZrO

(Figure S1). of

Use a pulse measurement unit (4225-PMU, Keithley Instruments) to measure the curve. A scanning probe microscope system (NX10, Park Systems) was used to obtain PFM images. To perform PFM measurements, a cantilever with a Pt-coated conductive tip was used to apply voltage to the sample and ground the bottom electrode. Polarize an area of ​​2.5 μm by 2.5 μm (outer square area) by applying -6 V at a scan rate of 0.5 Hz; then, apply a voltage of 6 V at a scan rate of 0.5 Hz to 1.5 μm × 1.5 μm (inner square area) ) To scan. After that, a reading process was performed on an area of ​​3 μm by 3 μm to verify the polarization state. of

Use impedance analyzer (4194A, HP) to measure the curve. Use an optical microscope (LV100ND, Nikon) to capture the optical image of the device. A high-resolution field emission scanning electron microscope (JSM-7800F PRIME, JEOL) was used to obtain a cross-sectional image of the device. The simulation was carried out using Sentaurus TCAD (Synopsys Inc.) software.

For supplementary materials for this article, please visit:

This is an open access article distributed under the following terms

, It allows use, distribution and reproduction in any medium, as long as the final use is

For commercial interest, and provide the original works appropriately cited.

Volume 7 Number 3

January 13, 2021

Thank you for your interest in promoting the term "scientific progress".

Note: We only ask you to provide your email address so that the person you recommend to the page knows that you want them to see the email and that it is not spam. We will not capture any email addresses.

This question is used to test whether you are a visitor and prevent automatic spam submission.

Please log in to add an alert to this article.

by

: Eabe1341

It provides a unique three-dimensional integration strategy for high-performance, ultra-high-density ferroelectric memory.

Volume 371, Issue 6526

©2021

. all rights reserved. The American Association for the Advancement of Science is 

, 

 with 

ISSN 2375-2548.

These authors contributed equally to this work.

Wireless wearable sweat biosensors have received great attention due to their potential for non-invasive health monitoring. Since high energy consumption is a key challenge in this field, the effective collection of energy from human movement represents an attractive way to sustainably power future wearable devices. Despite a lot of research activities, most wearable energy harvesters still have the disadvantages of complex manufacturing process, poor robustness and low power density, so they are not suitable for continuous biosensing. Here, we propose a highly durable, mass-produced wearable platform that does not require batteries. This platform can effectively remove the body from human movement through a free-standing frictional electric nanogenerator (FTENG) based on flexible printed circuit boards (FPCB) Get energy. The carefully designed FTENG shows a high power output of approximately 416 mW m

. Through seamless system integration and effective power management, we demonstrated a battery-free friction electric drive system that can provide multiple powers for human sweat biosensors, and wirelessly transmit data to the user interface through Bluetooth during human human testing .

A large number of studies on the development of wearable bioelectronics technology have greatly expanded the vision of personalized health monitoring (

-

). Wireless wearable devices provide a non-invasive means to extract real-time physiological parameters that indicate health conditions and transmit continuous data to user equipment. Wearable devices capable of detecting various vital signs (such as pulse, respiratory rate, and temperature) have been widely commercialized and integrated into daily life (

). Sweat is another attractive medium, which contains a variety of molecular biomarkers, including electrolytes, metabolites, amino acids, hormones, and drugs that can be analyzed by wearable sensors (

). Continuous monitoring of these biomarkers may supplement laboratory-based blood tests, thereby realizing real-time monitoring of daily health conditions and early disease detection and management (

).

In the past few years, extensive interest and efforts have focused on developing novel sensors and improving the wearability of these platforms (

,

). So far, most wearable sensor prototypes have relied on bulky rigid battery packs to power electronic circuits for data collection, processing, and transmission. Some people suggest using flexible batteries to make skin conformal contact (

), combined with low-power electronic devices, which greatly reduces the power requirements of wearable devices and allows the use of small button batteries. Despite these efforts, batteries still face limitations because they need to be charged and replaced frequently. In addition, although unlikely, lithium-ion batteries are prone to explosion, causing safety hazards. Reported on battery-less systems powered by Near Field Communication (NFC) (

), but the operating distance is short. As an alternative, energy can be harvested from renewable, portable and sustainable energy sources (such as solar energy, biological fluids and human movement) to power future wireless wearable electronic devices (

The triboelectric nanogenerator (TENG) converts the mechanical energy generated by human motion into electrical energy through the coupling of induction and triboelectric effect (

), provides an attractive energy harvesting strategy for powering wearable sweat sensors in intensive physical exercise, because their operation is independent of uncontrolled external sources, such as sunlight or wireless power transmitters. Despite the advantages, most existing TENG-based devices still have the problems of low power intensity, low power management efficiency, and insufficient power continuity and life. Therefore, there are no reports of using TENG to continue to power fully integrated wireless wearable molecular sensor systems (

Here, we propose a battery-free, fully self-powered wearable system, which consists of a high-efficiency wearable stand-alone TENG (FTENG), low-power wireless sensor circuit and a microfluidic sweat sensor patch, located in a single A flexible printed circuit board (FPCB) platform that can dynamically monitor key sweat biomarkers (for example, pH and Na

) (

). This wearable sweat sensor system (FWS) driven by FTENG

) The design and manufacture are compatible with the traditional FPCB manufacturing process, which can realize mass production and high reliability. Our FPCB-based independent design combined with effective power management can efficiently collect energy from human skin, and is particularly suitable for powering wearable devices in contact with the skin. With waterproof medical tape, FWS

Can be stacked conformally on the side torso to maximize energy collection (

). The integrated Bluetooth Low Energy (BLE) module can easily transmit sensor data to the mobile interface to track the health status during exercise. This is the first demonstration of a fully integrated battery-free friction electric drive wearable system for hyperhidrosis sensing.

(

) Schematic diagram illustrating FWS

The product integrates human movement energy collection, signal processing, microfluidic sweat biosensing and Bluetooth-based wireless data transmission into the mobile user interface for real-time health tracking. (

with

) Optical image of FWS based on FPCB

Can be worn on the side of the human body. Scale bar, 4 cm. (

) Schematic diagram of FPCB-based FTENG with grating slider and fork designator. (

) Schematic diagram of FWS

Shows a microfluidic-based sweat sensor patch connected to a flexible circuit. (

) System-level block diagram showing the power management, signal conversion, processing and wireless transmission of FWS

From FTENG to biosensor to user interface. Image courtesy: Yu Song, California Institute of Technology.

FTENG consists of an interdigitated stator and a sliding block with grating pattern (

). In order to obtain a strong charging effect, polytetrafluoroethylene (PTFE) and copper are used as friction pairs in the flexible FTENG. FTENG is manufactured through commercial FPCB technology (as shown in Figure S1), and the detailed size parameters are shown in Figure 5. S2. The distance between electrodes was optimized by FTENG's transfer charge density study (Figure S3). The stator and the slider are respectively patterned into periodic complementary interdigital structures and grating structures by photolithography. After electroless nickel/immersion gold (ENIG) surface treatment is performed on the electrode area, the stator is further laminated with PTFE. The reusable flexible circuit and the disposable micro-sweat sensor patch can continuously perform electrochemical measurements of key biomarkers in sweat (

). During the movement, the power generated by FTENG is stored and released from the capacitor under the control of the power management integrated circuit (PMIC).

). After being fully charged, the storage capacitor releases its stored energy, which is adjusted to a stable voltage to power the BLE system-on-chip (PSoC) module and instrumentation amplifier to collect and transmit potential measurements through BLE.

The working mechanism of FTENG can be explained as the coupling effect of contact charging and in-plane sliding induced charge transfer, as shown in Figure 1.

. Since the triboelectricity of copper is higher than that of PTFE, electrons will accumulate on PTFE during sliding. In the initial state, the grating slider completely overlaps a stator electrode, and due to the electrostatic balance, no charge flow occurs between the designated sub-electrodes of the fork. The one-way sliding process causes a charge flow between the stator electrodes until the grating slider completely overlaps the second stator electrode with the opposite polarity. The numerical simulation using COMSOL Multiphysics further verified the working process (Figure S4). The detailed model of FTENG under open circuit and short circuit conditions is illustrated in Figure 5. S5 and notes S1 and S2. Our optical microscopic image of FTENG based on FPCB and typical short-circuit current (

) Cross-sectional view of FTENG at different operating frequencies

. FTENG operates continuously at varying frequencies of 0.5, 1.25, and 3.3 Hz to obtain maximum

They are 8.39, 19.11 and 42.25μA respectively. Open circuit voltage (

The frequency obtained at a frequency of 0.5 Hz is shown in FIG. 5. S6A, the signal polarity of the envelope waveform oscillates rapidly along the sliding process. To evaluate the use of our FPCB-based FTENG as a power source, voltage and power were measured under a series of different load resistances (

), its operating frequency is 1.5 Hz. An increase in resistance exceeding 1 megohm will cause a rapid increase in voltage. The load resistance of FTENG is 4.7 megohms and the maximum output power is 0.94 mW (equivalent to 416 mW m

) Schematic diagram of FTENG's working mechanism and charge distribution. (

) Microscopic images and optical images of FPCB-based interdigital stators, which have ENIG surface finish on the patterned electrode area. The scale bars are 200 μm and 5 mm. (

) Current output of FTENG at different operating frequencies. (

) The peak voltage and corresponding average power of FTENG under different external load resistances (

= 5). The working frequency is 1.5 Hz. (

) After 20,000 test cycles, the durability of M-PDMS–, W-PDMS– and PTFE stators.

Indicates the maximum open circuit voltage after and before the endurance test. Illustration after 20,000 test cycles, SEM images of M-PDMS, W-PDMS and PTFE. The scale bars are 5, 50 and 50 μm. (

) A schematic diagram of a flexible FTENG with different stator layouts (one parallel, three or six panels) and corresponding slider layouts. (

) Compare the voltage of capacitors from 10 to 1000 μF, and charge 30 cycles with one, three and six panel FTENG. (

) The long-term stability of the three-panel FTENG charging a 47μF capacitor for 2 hours at a working frequency of 1.5 Hz.

After 20,000 working cycles, FPCB-based FTENG's PTFE exhibited superior durability to traditional miniature pyramidal polydimethylsiloxane (M-PDMS) and wrinkled PDMS (W-PDMS) (

),

As shown in Figure 2, the attenuation is minimal. S6B. Scanning electron microscope (SEM) image

And figure. S7 revealed the shape of different friction materials before and after the durability test: PTFE showed excellent mechanical strength without scratches, while M-PDMS and W-PDMS both suffered obvious surface damage. During normal use, the influence of normal force and shear force (reflected by sliding frequency) on the performance of FTENG is shown in Figure 1. S8: The peak output voltage increases with the increase of the normal force, and then reaches saturation. For a given normal force, the output voltage remains stable under the changing sliding frequency. FTENG is mechanically robust and shows similar electrical output even at a high normal force of 100 N. The response of FTENG is stable after 1000 bending cycles (with a radius of curvature of 5 cm) (Figure S9) and at varying physiological temperatures (Figure 9). S10). In addition, FTENG can maintain high performance after 100 washing cycles, which shows that it has superior wearable performance compared with traditional TENG (Figure S11 and Table S1). When designing future TENG power supply equipment, it is important to consider factors such as cost, materials, mechanical properties and power density. The cost of TENG prepared by fabric weaving and polymer coating process is very low, but it is subject to lower manufacturing resolution and repeatability. In contrast, FPCB-based FTENG provides a high-resolution, cost-effective and mechanically robust energy harvesting solution.

In order to meet the high energy demand of wearable sensors, one, three and six panels of FTENG were designed by considering the size of the human torso, and further evaluated by capacitor charging (

). The output of FTENG is rectified with a full-wave rectifier. These different FTENG layouts are all driven for 30 working cycles to match 10 to 1000 μF (

). For a 1000μF capacitor, one, three and six plates can obtain voltages of 0.03, 0.12, and 0.19 V, respectively, showing a strong charging ability. At a working frequency of 3.3 Hz, the six-panel FTENG shows the largest transfer charge (σ

) Reach 15.73μC in one work cycle (Figure S12A). At the same time, figure. S12B depicts the charging and discharging curves of different capacitors charged to 2 V at a working frequency of 2 Hz using a three-panel FTENG. The three-panel FTENG starts at a working frequency of 1.5 Hz and can recharge a 47μF capacitor within 2 hours from 0 to 2 V (

), indicating that the long-term cycle stability is very high. FTENGs can also be used to charge various capacitors with different cycle lengths (Figure S13). Depending on the specific application, connecting multiple FTENGs in parallel may be a practical and attractive strategy that can greatly increase power output.

A schematic diagram of a dual biosensor array based on ion-selective electrodes (ISE) for sweat analyte analysis is depicted. The laser-engraved microfluidic channels are assembled on the sensor patch. The detailed manufacturing procedures are listed in Materials and Methods and Figure 2. S14. The Ag/AgCl reference electrode is coated with polyvinyl butyral (PVB). Regardless of the ionic strength of the solution, it can maintain a stable potential in the potential measurement of various electrolytes in sweat. Deprotonation of H when used for pH analysis

Measure the atoms on the surface of electrodeposited polyaniline (PANI) layer as H indicator

concentration. Na

Ion selective membranes containing Na facilitate concentration measurement

The ionophore X and the poly(3,4-ethylenedioxythiophene (PEDOT): poly(4-styrene sulfonate) (PSS) layer) between the gold electrode layer and the sodium ion selective membrane serve as ion electrons The converter can minimize potential drift as shown in the figure.

, PH and Na

In the physiologically relevant pH value (4 to 8) and Na, the sensor showed a sensitivity of near nerve energy of 56.28 and 58.63 mV for every ten times the concentration.

Concentration (12.5 to 200 mM). Both sensors have excellent selectivity, repeatability and long-term stability (Figure S15 to S17), and their response remains stable under different physiological temperatures (Figure S18), making them suitable for continuous wearable monitoring .

) Schematic diagram of a flexible biosensor array containing pH sensors and Na

The sensor is patterned on a flexible PET substrate. (

) Open circuit potential response of the pH sensor in standard Mcllvaine buffer solution (B) and Na

Sensor in NaCl solution (C). The illustration shows the corresponding calibration chart for each sensor. Error bars represent SD from six independent tests. (

) Schematic diagram of microfluidic design for dynamic sweat sampling. M tape, medical tape. (

Dynamic response of Na

Sensors at different flow rates when switching solution concentration. (

Repeatability of Na dynamic response

The sensor is realized by continuously switching the inflow solution at a flow rate of 2μlmin

. (

) A schematic diagram of a microfluidic sensor patch attached to human skin. The inset is an optical image of the microfluidic sensor patch under mechanical deformation. Scale bar, 5 mm. (

Na reaction

PH sensor array after 0, 200, and 400 cycles of bending (H) and during bending state (I) (radius of curvature of 2 cm). Data logging pauses for 30 seconds to change conditions and settings. Image courtesy: Yu Song, California Institute of Technology.

The laser-patterned microfluidic layer is connected to a polyethylene terephthalate (PET) sensor substrate in a sandwich structure (medical tape/PDMS/medical tape) for controlled and automatic in-body sweat sampling (

And figure. S19). In order to verify the performance of the microfluidic system, dynamic biosensing was carried out during the continuous flow injection of Na

Physiologically relevant sweat rate (1, 2 and 4μl min

). Donna

The concentration was switched from 50 mM to 200 mM at a flow rate of 2μlmin

,that

It takes about 2 minutes for the sensor to reach a new stable reading. The high time resolution is repeatable in multiple concentration change cycles (

). The flexible microfluidic sensor patch can conformally adhere to human skin (

), and have passed a rigorous bending test (curvature radius of 2 cm) showing excellent mechanical stability, indicating their potential for wearable applications in various sports activities (

As mentioned earlier, FWS

It consists of an interdigital FENG stator, a PMIC, a low-dropout regulator, two low-power instrumentation amplifiers and a BLE PSoC module seamlessly integrated into a polyimide-based FPCB. In addition, the complete platform requires a grating patterned FTENG slider and microfluidic sensor patch. For design compatibility and flexibility, FTENG and electronic circuits are designed on a single PCB design software. The detailed parts list and circuit diagram of the flexible circuit are shown in Figures 1 and 2. S20 and S21 respectively. The block diagram shows the electrical connections between the modules

. In order to achieve the best power management, commercial energy harvesting PMICs are used to manage the power generated by FTENG, while minimizing power waste. With the aid of a bridge rectifier, the rectifier converts the high-voltage AC signal generated by FTENG into a DC signal, and the PMIC stores the power generated by FTENG in two parallel capacitors (220 and 22μF). Three SET_

The resistor sets a programmable threshold and hysteresis voltage to release the stored power through the built-in switch control logic only when absolutely necessary. When the voltage of the storage capacitor (

) Reaches 3.5 V, then the capacitor to the load/output (

) Until

Drop to 2.2V. At 2.2 V, the control unit of the PMIC disconnects the storage capacitor from the load/output until the storage capacitor is charged back to 3.5V. When powered by the storage capacitor, the load/output voltage is adjusted to 2.2 V through the regulator to provide a stable voltage for the precision measurement circuit.

) Schematic diagram of FWS without battery

It consists of FTENG module, biosensor interface, instrumentation amplifier, energy harvesting PMIC, voltage regulator and BLE PSoC module. (

) FWS operation process

Perform signal processing and data transmission. (

) Power consumption of FWS

During the operation. (

) Real-time potential of capacitor during FWS continuous operation (242μF)

Use three-panel FTENG under different operating frequencies. (

) Verify data transmission from FWS

) Long-term stability of capacitor charging process during FWS

It operates at a working frequency of 1.5 Hz. (

Sensor response in human sweat samples collected by FWS

It operates at a working frequency of 1.5 Hz.

Efficient power management matches the low-power measurement performed by a low-power instrumentation amplifier with shutdown mode, and low-power data transmission through connectionless BLE advertising, thus realizing FTENG-powered wearable and wireless sweat analysis. Every time the storage capacitor is charged to 3.5 V, the BLE PSoC module will start a ~510-ms work cycle, as shown in the flowchart (

). After the main processor starts, PSoC pulls the general-purpose input/output (GPIO) pin high to wake up the two instrumentation amplifiers from the shutdown state. After initializing the instrumentation amplifier, PSoC's embedded 12-bit ADC (analog-to-digital converter) samples and averages 32 potential measurements obtained through the instrumentation amplifier. After ADC measurement, the instrumentation amplifier will be turned off to minimize power consumption. PSoC's BLE sub-module requires a 32 kHz watch crystal oscillator (WCO) to operate accurately, and its maximum startup time specification is 500 ms. Therefore, after the ADC measurement, the PSoC main processor starts the WCO, enters a 500 ms deep sleep state, and consumes about 2μA current. Then, the BLE stack is initialized, and the ADC measurement result is notified to nearby BLE observer user equipment. The detailed power consumption breakdown of the circuit including the regulator, BLE PSoC module and two instrumentation amplifiers is shown in the following figure:

. When a 2.2 V power supply is provided, the circuit consumes an average of 330 μA in ~510 ms (168 μC).

Some studies were conducted to verify the robustness of the fully integrated system. The three-panel FTENG is activated by sliding motion at a frequency of 2 to 1 Hz to simulate human arm swing during exercise (

). The final charge and discharge cycle of the storage capacitor is shown in the figure.

. In addition, in order to verify the operation of the low-power wireless sensor circuit, a voltage of 100 to 300 mV (charged every 300 s) was applied to the reference electrode and working electrode pin by using a DC power supply to simulate potential input.

). These analog sensor inputs are accurately measured and transmitted by the FPCB platform, and are powered by the three-panel FTENG, which is activated at different operating frequencies. Long-term stability of the entire FWS

Demonstrate the system by using FTENG to power the FPCB for more than 4 hours, during which pH and Na

Measure the concentration of human sweat collected within one hour (

). In addition, by comparing the ability of FPCB-based FTENG to power the entire platform one month after its first use, its long-term durability was tested (Figure S22). By further improving the power density and efficiency of FTENG, wireless data transmission can be improved in terms of transmission interval.

Common cardiovascular exercises such as running, rowing, and elliptical training can cause sliding between the side of the torso and the inner arm. Using this mechanical movement, the stator of FTENG can be fixed on the side trunk, and the slider of FTENG can be installed inside the arm. For human evaluation, FWS based on six-plate stator FTENG is used

Used to increase power output (as shown in Figure S23). FTENG power output waveforms during various exercises are shown in the figure

. Choose a treadmill as an exercise, and conduct a human body verification experiment on the entire system. During the 60-minute constant speed operation, the FPCB storage capacitor charging and discharging curve shows that up to 18 operating cycles can be achieved (

). The length of the charge/discharge cycle ranges from 2.1 to 3.7 minutes (

). It should be noted that when the stator and slider physically rub against each other, the system generates power. Whenever there is frictional movement, the charge in the capacitor will accumulate without discharging. When the capacitor is charged to the threshold voltage, the capacitor will discharge and power a single measurement event. Although the duration of the capacitor charging/discharging cycle varies due to changes in friction area, force and frequency, FWS

The system proves that it can function normally during normal physical exercise (Figure S24). Human performance of the entire FWS

Healthy subjects were evaluated by a treadmill at a constant speed of 9 km/h

. Two wearable systems charged by FTENG and batteries are placed on the subject's back. The physiological information collected by the two systems is wirelessly transmitted to the user interface via BLE for further analysis (

). Five measurements have been recorded from FWS

During 30 minutes of exercise; stable pH and increased Na

Observe the level from both systems (

), confirm the accuracy of FWS without battery

Used for human body induction. Noise contribution of subjects wearing FWS during various exercises

It is insignificant compared to the sensor signal of interest (Figure S25). These data prove the potential of the self-powered wearable platform to continuously monitor various physiological biomarkers in sweat during exercise.

) The output waveform of FTENG based on six-panel FPCB in various exercises. (

) When the subject runs for 1 hour at a constant speed of 9 km/h on a treadmill, the real-time potential of the capacitor charged by FTENG (B) and the average charging time per package transmission (C)

. The ratio in (C) represents the percentage of charging cycles in all charging cycles (charging duration within a given time range). When the potential reaches 3.3 V, the capacitor discharges due to BLE data transmission. (

) Optical image of an object on a treadmill wearing FWS

And a cell phone. (

Real-time sweat pH and Na

Electricity obtained wirelessly from a wearable system during constant speed operation, which is charged by a lithium battery and FTENG. Image courtesy: Yu Song, California Institute of Technology.

Emerging wearable technology has achieved numerous personalized medical applications. Wearable sweat analysis may achieve non-invasive and continuous monitoring of personal health at the molecular level. Due to multi-function and multi-tasking requirements, wearable sweat biosensors usually have high power consumption. Batteries are the main power source for most wireless electronic skin systems, but they are usually limited by availability, especially when power supplies are limited. Given that the main application of sweat sensing is health and fitness tracking during strenuous exercise, harvesting energy from the human body is a promising method for powering future wearable sweat sensors, especially for moving organisms A sensor that converts mechanical energy into electrical energy.

The emergence of TENG technology has caused great excitement due to its potential application in self-powered systems (especially wearable and implantable electronic products). As an emerging energy conversion technology, TENG faces major challenges that need to be resolved in practical applications. First, the TENG signal is essentially a high-voltage pulse, which is not enough to meet the real-time energy consumption of wearable electronic devices. Second, for continuous use of wearables, due to the stability limitations of organic polymer materials used in device manufacturing, the life span of TENG needs to be increased. Last but not least, the system integration of TENG in wearable devices and the demonstration of their usability in practical applications are far from enough.

Here, we propose a highly durable, mass-produced, fully self-powered battery-less wearable system to meet these challenges. The system can effectively and reliably move from the human body during strenuous exercise through FPCB-enabled FTENG Collect energy in. Compared with traditional TENG, FTENG manufactured using commercial FPCB manufacturing procedures has excellent mechanical and electrical stability even after severe mechanical deformation and repeated cleaning cycles. Through seamless system integration and effective power management, this fully flexible system can provide power for human sweat biosensors and wirelessly send data to the user interface via Bluetooth during human testing. Compared with the previously reported non-wearable wireless sensor system based on TENG (Table S2), the wireless sensor system is either not wearable or requires an extra long charging time to perform the measurement. In contrast, FWS

It represents a breakthrough in the practicality of wearable applications. We envision that with further development, this technology will become a very attractive method for self-powered wireless personalized health monitoring in people's daily activities. It will also find many applications in the environment and defense fields.

EDOT, PSS, ionophore X, bis(2-ethylethylhexyl) sebacate (DOS), PVB, polyvinyl chloride (PVC), tetra[3,5-bis(trifluoromethyl)phenyl ] Sodium borate (Na-TFPB), aniline, sodium thiosulfate pentahydrate (Na

small

Ø

), sodium bisulfite (NaHSO

), calcium chloride dihydrate (CaCl

·2 hours

O), block polymer PEO-PPO-PEO (F127), multi-walled carbon nanotubes (MWCNT), iron (III) chloride (FeCl)

), potassium hydroxide (KOH) and citric acid were purchased from Sigma-Aldrich. Sodium chloride (NaCl), ammonium chloride (NH

Cl), methanol, ethanol, acetone, tetrahydrofuran (THF), hydrochloric acid (HCl), tetrachloroauric acid (HAuCl

) And disodium hydrogen phosphate (Na

high pressure

) Purchased from Thermo Fisher Scientific. PDMS (SYLGARD 184) was purchased from Dow Corning Corporation. Silver Nitrate (AgNO

) Was purchased from Alfa Aesar. Waterproof double-sided medical tape (75μm thick) was purchased from Adhesives Research. The conductive silver paint was purchased from Structure Probe Inc. (SPI) consumables. Moisture-proof PET film (100μm thick) was purchased from McMaster-Carr. PTFE (50μm thick) was purchased from JIAET.

The FPCB module of FTENG and electronic circuit is designed using Eagle CAD (Autodesk). The BLE PSoC module is programmed in the PSoC Creator integrated design environment (Cypress Semiconductor). Figure 2 provides a complete list of components used in circuit design. S20 includes power management unit (MB10S-13, Diodes Incorporated; S6AE101A, Cypress Semiconductor; TPS7A05, Texas Instruments), BLE PSoC module (CYBLE-022001-00, Cypress Semiconductor), potential detection unit (AD8235, Analog Devices) and passive element. Figure 2 shows a detailed circuit diagram. S21.

The flexible circuit and FTENG are manufactured by commercial FPCB manufacturers (the detailed manufacturing process is shown in Figure S1). Two commercial flexible copper clad laminates (120μm thick; Jinghuang Electronics Co., Ltd.) composed of a flexible polyimide substrate and a copper film sandwiched a layer of epoxy adhesive. Pattern the copper film by photolithography and etch with FeCl

The solution is to manufacture the circuit elements and interdigital electrodes of the stator, as well as the complementary grating structure of the slider. The ENIG layer is deposited to protect the stator electrodes. Finally, a layer of PTFE is laminated on the interdigital electrodes of the stator to induce electrification. The total size of FTENG's single-plate stator is 22.6 cm

(Length 5.78 cm; width 3.78 cm). The weight of FTENG's single-plate stator is 0.586 (without PTFE coating) and 0.782 g (with PTFE coating). The total size and weight of FTENG's single-panel slider is 18.22 cm

(Length 4.36 cm; width 4.18 cm) and 0.396 grams.

In order to improve the output performance of FTENG, a digital oscilloscope (Agilent DSO-X 2014A) was used to test the open circuit voltage with a 100 MΩ probe. The short-circuit current is amplified by the SR570 low-noise current amplifier of Stanford Research Systems. COMSOL software is used to simulate and verify the electrostatic stimulation during sliding.

Microstructured PDMS (M-PDMS and W-PDMS) participated in the durability test as a triboelectric material in the contact separation mode. First, mix the PDMS elastomer and crosslinking agent with a ratio of 10:1. For M-PDMS, the vacuum degassed solution is spin-coated on a Si wafer with an inverted pyramid structure (manufactured by photolithography and KOH wet etching). After PDMS is partially cured, a FPCB-based stator (3×4 cm

Coated with ENIG electrodes). After curing at 80°C for 2 hours, the stator was peeled off with the prepared M-PDMS. For W-PDMS, the cured PDMS is pre-stretched at a strain of 30% and subjected to ultraviolet ozone treatment with a commercial ultraviolet lamp (Hangzhou Yaguang Lighting). After the release process, W-PDMS is applied and applied to another FPCB-based stator. During the durability test, the maximum gap between PDMS and another friction material (copper) was fixed at 3 mm at a working frequency of 2 Hz.

For the washing test, first rinse the FPCB-based FTENG with deionized (DI) water (25°C), and then perform bath sonication for 10 minutes. Then, FTENG was fully dried at 60°C for 10 minutes for later use.

For the long-term stability study of FTENG (Figure S22), the test was conducted under the same conditions 1 month before and after. During the 1 month interruption, FTENG was stored in a plastic box in a regular office drawer at room temperature.

An optical microscope (Carl Zeiss AXIO) was used to characterize the morphological microscopic image of the interdigitated stator electrode. The SEM images of PTFE, M-PDMS and W-PDMS were obtained by field emission environment SEM (FEI Quanta 600F).

The fabrication of the electrode array is shown in FIG. 2. S14. After pretreatment of the PET substrate, 20 nm Cr was deposited on the PET substrate using electron beam evaporation, and then 100 nm Au was deposited to form a gold electrode with a diameter of 3 mm. The electrode array is also coated with 1μm Parylene C (ParaTech LabTop 3000 parylene coating machine) and patterned by photolithography. Array made by further etching with O

Reactive ion etching (Oxford III-V System 100 ICP / RIE) removes the parylene layer in the plasma. Then, modify the electrode and deposit different functional materials to form Na

pH electrode and shared Ag/AgCl reference electrode. Carbon monoxide

A laser cutter is used to pattern the microfluidic layer. First, a waterproof double-sided medical tape layer with a cavity of 3mm diameter is pasted on the PET sensor substrate. Then, a container with a diameter of 3 mm, an inlet, an outlet, and a PDMS layer (thickness of 100 μm) with fluid connections were pasted on the medical tape. Finally, another layer of medical tape with an entrance pattern is attached to the PDMS layer.

Electrochemical workstation (CHI 860, CH Instruments) is used for electrochemical deposition and sensor characterization. For Ag/AgCl reference electrode, use Ag deposition solution (0.25 M AgNO

, 0.75 M Na

And 0.43 M NaHSO

) Is used to deposit Ag on Ag electrodes by constant voltage electrodeposition (-0.25 V for 600 s). Next, 0.1 M FeCl

It was drop cast on Ag for 30 seconds to form Ag/AgCl. A total of 6.6 μl of PVB reference mixture (79.1 mg PVB, 50 mg NaCl, 1 mg F127 and 0.2 mg MWCNT in 1 ml methanol) was drip-cast on the Ag/AgCl electrode to dry. First by depositing Au (50 mM HAuCl

Then dissolve in 50 mM HCl at 0 V for 30 s, and then perform 50 cycles of cyclic voltammetry (-0.2 to 1 V at 50 scan rate) on Au electrodes (0.1 M aniline and 0.1 M HCl) in a bath Electropolymerization of PANI. Millivolt second

). For Na

ISE performs constant current electrodeposition (14μA, duration 740 s) in a solution containing 0.01 M EDOT and 0.1 M NaPSS to deposit PEDOT:PSS on an Au electrode. Then, take 15μl Na

The selective membrane mixture was dropped onto the PEDOT:PSS layer and dried overnight. In order to prepare a cocktail, a mixture of 100 mg is required, which contains Na ionophore X (1%, w/w), Na-TFPB (0.55%, w/w), PVC (33%, w/w) and DOS (65.45) %), w/w) dissolved in 660μl of THF.

In order to obtain the best performance for long-term continuous measurement, cover the biosensor with a solution containing 0.1 M NaCl for 1 hour before the measurement to minimize potential drift. For in vitro characterization, unless otherwise specified, NaCl solutions of 12.5, 25, 50, 100, and 200 mM in deionized water and Mcllvaine buffer with a pH of 4 to 8 were used. Considering the difference in the absolute potential value of the ion-selective sensor in the same solution, it is important to perform a single-point calibration in the standard solution. Here, the biosensor was calibrated using a 25 mM NaCl solution before being used in all tests.

The batch biosensor is characterized by changing the solution to verify its repeatability and repeatability. Interference study by continuously adding chloride solution containing 50 mM NH

, 50 mm

And 50 mM Ca

. When changing the solution, all measurements are suspended for 30 s. Long-term stability of pH and Na

The sensor is first continuously tested in a 100 mM NaCl solution for 3 hours, and then evaluated for more than 6 weeks to check the sensitivity change.

Previous work concluded that the pH in sweat remains relatively stable during exercise. Therefore, the sampling ability of the microfluidic sensor patch focuses on the dynamic tracking of Na

. Use a syringe pump to inject different Na solutions

The concentration (50 and 200 mM) was changed at different flow rates through the inlet of the microfluidic channel. The mechanical reliability of the sensor patch was evaluated by repeatedly bending 800 cycles on a three-dimensional printed mold (radius of curvature, 2 cm). The sensor measurement value is obtained every 200 cycles. In another study, continuous sensor measurements were recorded during the active deformation of the sensor.

For the long-term sensor stability test (Figure S17), the biosensor array is tested under the same conditions every week. Before weekly measurements, cover the sensor array with a 0.1 M NaCl solution for 1 hour to minimize potential drift. Store the ion-selective sensor under ambient conditions at room temperature (25°C) for a period of 6 weeks.

Verification and evaluation of FWS

Human subjects were tested in the gymnasium and all ethics requirements under the protocol (ID 19-0892) approved by the California Institute of Technology Institutional Review Board were complied with. Healthy subjects aged 20 to 35 years were recruited from California Institute of Technology. Before participating in the study, all subjects gave written informed consent.

The subjects performed cardiovascular exercises using treadmills (Aeon), elliptical machines (Precor) and rowing machines (Stamina). Before exercise, wipe and clean the subjects’ upper back with alcohol swabs and gauze. Then, use waterproof double-sided medical tape to paste FWS

On the subject. The system containing the FTENG stator is adhered to the side torso and the FTENG slider is fixed to the inner arm. To ensure the accuracy of the data, a new microfluidic sensor patch was used in each human test. To evaluate the power output of FTENG during exercise, connect the output of FTENG or the voltage across the storage capacitor to an oscilloscope. When evaluating the entire system including the microfluidic sensor patch, the subject was asked to run on a treadmill at a constant speed of 9 km

30 minutes (obtain sensor data regularly every few minutes); BLE data is retrieved from mobile phones or personal computers. In addition, sweat samples were collected from the subjects’ foreheads on a regular basis, and then pipetted into a centrifuge tube and centrifuged at 6000 rpm for 15 minutes. The sweat samples were then frozen at -20°C for further testing.

For supplementary materials for this article, please visit:

.

This is an open access article distributed under the following terms

, It allows use, distribution and reproduction in any medium, as long as the final use is

For commercial interest, and provide the original works appropriately cited.

Volume 6, Number 40

September 30, 2020

Thank you for your interest in promoting the term "scientific progress".

Note: We only ask you to provide your email address so that the person you recommend to the page knows that you want them to see the email and that it is not spam. We will not capture any email addresses.

This question is used to test whether you are a visitor and prevent automatic spam submission.

Please log in to add an alert to this article.

by

: Eaay9842

The wireless battery-free wearable sensor driven by human motion can analyze sweat biomarkers to achieve personalized medical care.

Volume 371, Issue 6526

©2021

. all rights reserved. The American Association for the Advancement of Science is 

, 

 with 

ISSN 2375-2548.

In many fields, including electrochemistry and colloidal science, the electrified solid/liquid interface is the key to many physical and chemical processes. With great efforts dedicated to this topic, unexpectedly, there is still a lack of understanding of the molecular level of the electric double layer. It is particularly confusing why the dense Helmholtz layer often shows a bell-shaped differential capacitance on the metal electrode, because this would imply that the capacitance in some layers of the interface water is negative. Here, we report a state-of-the-art ab initio molecular dynamics simulation of a charged Pt(111)/water interface, aiming to reveal the structure and capacitive behavior of the interface water. Our calculations reproduce the bell-shaped Helmholtz differential capacitance and show that when the electrode potential is changed, the interface water follows the Frumkin adsorption isotherm, resulting in a special negative capacitance response. Our work provides valuable insights into the structure and capacitance of interface water, which can help you understand the important processes of electrocatalysis and energy storage in supercapacitors.

The electric double layer (EDL) formed on the charged interface can provide a potential change of several volts in a very thin layer of 3 to 5 Å (

-

), which is equivalent to a very large electric field, and its intensity is similar to that in a particle accelerator. Naturally, people will want to know how solvent molecules such as water or any other reactive molecules inside the EDL will behave in response to such a strong electric field. Answering this question is not only of fundamental significance, but also of technical importance in a wide range of scientific and technological research fields, to name a few, namely, energy storage in supercapacitors (

,

), electrocatalysis related to energy and environmental applications (

), self-assembly of colloidal particles (

), the transport of ions across biological membranes (

), and the mineralization process in earth science (

). Despite its important significance, due to its complexity and difficulty in exploring EDL, the understanding of EDL at the molecular level has been greatly lacked. Due to advanced experimental methods (such as synchrotron-based technology and Raman spectroscopy) and computational methods (such as ab initio molecular dynamics (AIMD),

)], only recently began to reveal the microstructure of EDL.

One of the key characteristics of EDL is that its capacitance can measure the ratio of surface charge change to potential change, which can be obtained by conventional electrochemical techniques (such as voltammetry and impedance spectroscopy). The potential dependence of the capacitance, the differential capacitance, led to the development of the well-known EDL Gouy-Chapman-Stern (GCS) model, where the EDL is composed of a Helmholtz (compact) layer and a Gouy-Chapman (diffusion) layer, used as two series connected Capacitor (see

). The GCS theory proposed about 100 years ago successfully predicted the Gouy-Chapman minimum value in the differential capacitance curve at the limit of dilution (

), and is still the main conceptual model of EDL. Among other things, a long-standing problem is how to understand the bell-shaped differential capacitance curve of the Helmholtz layer (

). If the Helmholtz layer is expressed as a series capacitor, then negative capacitance will inevitably be introduced to some layers (

). Although this is not ruled out in principle, it is not satisfactory due to the lack of physical foundation. Trasatti first noticed in the 1970s that simple Helmholtz capacitors

Metal is related to its electron density (

). Since then, several theoretical models have been proposed to try to link this special phenomenon with the electronic effects of metal electrodes (

). For example, applying the jellium model to

Metal, Schmickler (

) Is the negative capacitance caused by the surface potential change caused by the overflow of electrons in response to the surface charge. Halle, Price and colleagues (

) Use the first principles method to calculate the capacitance curve of the copper-water interface.

(

) Schematic diagram of EDL's GCS model. EDL is composed of Helmholtz layer and Gouy-Chapman (diffusion) layer, and the interface potential distribution is represented by the red curve. (

) EDL capacitance can be represented by capacitors corresponding to two layers (ie,

with

) Concatenation. (

) Pt(111)/water interface model of PZC. There is a significant redistribution of interface electrons along the surface normal

Due to the chemical adsorption of water, as shown by the blue curve. (

) Water density distribution (ρ

) Along the surface normal

In different potentials. The position of the water molecule is indicated by the position of the oxygen atom, where zero means

The coordinates indicate the position of the top nucleus of Pt(111). All potentials refer to PZC of Pt (111). (

) Typical snapshots of the charged Pt(111)/water interface relative to PZC at −0.93 and 0.84 V. Pt, Na, F, O and H atoms are colored in gray, blue, purple, red, and white, respectively. Compared with the bat model, the bat model highlights the chemically adsorbed water.

Although very insightful, these early attempts either completely ignored the metal lattice structure (

) Or impractically represent the electronic structure of the metal, such as using only copper pseudo-potential treatment

Valence electron (

), so the electronic interaction between the metal and the electrolyte solution cannot be described correctly. Since about thirty years ago, new surface science technologies, such as scanning tunneling microscope (STM) and modern density functional theory (DFT), have been used in ultra-high vacuum conditions to conduct in-depth research on molecular chemical adsorption. For example, Michaelides and colleagues (

) The detailed microstructures of water monomers, clusters and layers adsorbed on metal surfaces (such as Pt) have been studied by combining STM and DFT calculations. Recently, the most advanced AIMD simulation has been applied to the metal/water interface to calculate the interface structure and potential (

). It is worth noting that colleague Zheng He (

) Accurately calculated the zero charge (PZC) potential of several transition metals, and found that the charge redistribution caused by the chemical adsorption of water (see

) A large number of interface dipole potentials can be induced under PZC conditions, for example, about ~1 V on Pt (

). Then a question arises: When a bias voltage is applied, will water chemically adsorbed on the metal surface contribute to the capacitive response of the EDL?

In order to reveal the molecular origin of Helmholtz capacitance, in this work, we performed extensive AIMD simulations on the charged Pt(111)/water interface and calculated electrodes using the recently developed calculation standard hydrogen electrode (cSHE) method Potential, calculate the surface charge density. We reproduced the bell-shaped differential capacitance curve and performed a detailed analysis. The results showed that the surface coverage of chemisorbed water may vary with the applied potential. Our calculations show that the adsorption/desorption process of surface water with different potentials will cause the negative component of Helmholtz capacitance. We further proposed a theoretical model based on Frumkin adsorption isotherm, which can describe our calculation results well. Our work emphasizes the importance of EDL molecular-level pictures and electronic structure for understanding the capacitive behavior of interface water.

as the picture shows. S1, a series of charged Pt(111)/water interface models are established under different surface charge densities (σ), in which the surface charge is compensated by the counter ion, namely Na

Or F

, Located on the outer Helmholtz plane. Please note that our EDL model does not consider the Gouy-Chapman layer and therefore corresponds to high concentration conditions.

The analog cell maintains charge neutrality, and the surface charge density is controlled by the number of counterions added to the cell. For a detailed description of these models, see the "Materials and Methods" section, as well as the charge distribution diagram in Figure 6. S2 shows the location of the charge at the electrical interface. Use AIMD to simulate these models first, then perform data balancing, and then use the cSHE method to obtain the corresponding electrode potential and SHE relationship from these AIMD trajectories [see Supplementary Materials and (

) For a detailed description of the method]. We have successfully applied the same method to the Au(111)/water interface to clarify the molecular structure of water in the Helmholtz layer under negative bias (

).

The PZC of these models relative to Pt(111) covers a potential window range of -0.93 to 0.84 V [ie, 0.2 to 0.3 V relative to SHE (

)], which allows us to study the water structure and capacitance of the Helmholtz layer on Pt(111). It is worth mentioning that in this work, we ignored the specific adsorption of H and OH. When the specific adsorption is insignificant, this is equivalent to pH conditions. The experimental capacitance we compared was removed by the pseudo capacitance due to specific adsorption (

A detailed analysis of the AIMD trajectory shows that the density and direction of the interfacial water largely depend on the applied potential and the distribution of water density (ρ

) And direction distribution, represented by the angle φ between the bisector of water and the surface normal and the angle θ between the O−H bond of water and the surface normal

, Respectively. Note from the density distribution map that there are two different interface water peaks in the Helmholtz layer (

<~4Å, where

Is the distance to the surface); at a peak

= 2.3Å corresponds to water chemically adsorbed directly on the surface, the other corresponds to

= 3.3Å represents the unchemically adsorbed water in the Helmholtz layer. The discovery of water at the two-layer interface is also in line with the understanding of Fei Liu and his colleagues (

) On Pt(111). At a very negative potential of -0.93 V, there is no water chemically adsorbed on the surface due to Coulomb repulsion, so the first peak is

= 2.3Å disappears. All water molecules in the Helmholtz layer are in a "one hydrogen down" configuration, with one hydrogen atom pointing towards the metal surface (see

), the hydrogen bond analysis is shown in the figure

It means that one hydrogen forms a hydrogen bond with another hydrogen in the water and nearby water, which is similar to the hydrogen bond observed on Au (111) under negative bias (

). This type of water is characterized by the φ peak in the orientation distribution curve of φ at ~135° and the θ peak at ~90° and ~165°.

. As the potential increases, the interface water begins to adsorb on the surface, causing the intensity of the first peak to gradually increase, while the intensity of the second peak

= 3.3Å in the water density curve

. Under a positive potential of 0.84 V, almost all water molecules in the Helmholtz layer are chemically adsorbed on the surface, reaching a saturation coverage of about 0.5 monolayer (ML). as the picture shows

, The chemically adsorbed water is located on the top of Pt(111), its molecular plane is almost parallel to the surface, and the two hydrogen atoms are slightly inclined upward, the φ peak of orientation is at ~60°, and the two θ are both at ~75°. And, from

Under a very positive potential, each chemically adsorbed water accepts about one hydrogen bond from the adjacent chemically adsorbed water, indicating that a two-dimensional (2D) hydrogen bond network is formed on Pt(111). The 2D hydrogen bond network benefits from the hydrogen bond matching between the chemisorbed water and the underlying Pt lattice (both 2.8 A), which helps stabilize the structure of the chemisorbed water at a positive potential.

Angle φ (

Between the bisector of water and the surface normal and the angle θ)

) The distance between the OH bond of water and the surface normal of the interface water under different applied potentials). The illustration shows two angles, the interface water is within 4 angstroms of the metal surface. The potential refers to PZC of Pt (111). (

) The relationship between the number of hydrogen bond donors (pink circles) and acceptors (green diamonds) of the interface water molecules and the potential. When the OO distance is less than 3.5Å and the OOH angle is less than 35°, it is defined as a hydrogen bond. The illustration shows the structural model of interface water at very negative and positive potentials. au, arbitrary unit.

As mentioned above, a small part of the chemically adsorbed water of PZC can generate a significant interface potential (~1 V) on Pt (

). Therefore, it can be considered that the observed potential dependence of the surface coverage of chemisorbed water may directly affect the capacitance response of the interface water. A simple model

Can be proposed to prove this effect. The interface potential change (Δψ) of the entire Helmholtz layer can be decomposed into two parts, that is, the usual potential change (Δψ) caused by surface charges

) And water chemical adsorption (Δψ

). At PZC, the surface charge is zero, so Δψ

=0. And Δψ still has a remaining contribution

Due to the chemical adsorption of water (see

) (

). Since the electron density is transferred from water to Pt, Δψ

Will cause a negative shift in electrode potential. Potential is much worse than PZC (

), all chemically adsorbed water will desorb from the surface, indicating that Δψ

= 0 and only Δψ

Contribute to the total Δψ. Has a more positive potential than PZC (

), both Δψ

And Δψ

Is limited, but the signs are opposite, so they can compensate each other to get a smaller overall Δψ. Qualitative analysis shows that Δψ is involved

The "long-term" term due to chemically adsorbed water may produce smaller changes in potential, thereby increasing capacitance. When the surface charge changes from negative to positive, more water is adsorbed on the surface, and Δψ

Move to a larger negative number (as opposed to Δψ)

), thereby implying negative capacitance.

The potential distribution at the Pt(111)/water interface under different applied potentials (

)

) PZC and (

)> PZC. The Pt electrode and the aqueous solution are the areas colored by gray and light blue, respectively. The red, white, blue and purple balls represent oxygen atoms, hydrogen atoms, cations and anions respectively. The interface potential change ∆ψ (blue) is composed of the usual potential change ∆ψ

Induced by surface charge (green) and electric potential Δψ

Caused by water chemisorption (red). The potential in the bulk solution is set to zero.

Respectively indicate the distance separation of the dipole caused by the chemically adsorbed water and the Helmholtz layer.

In order to further show the quantitative image, we plot the surface charge density σ and the coverage θ of chemisorbed water

Function of electrode potential

,as the picture shows

. Obviously, σ-

The graph is non-linear and shows an S-shaped relationship, which means that the bell-shaped differential capacitor

Helmholtz layer. θ

The curve is also S-shaped, which is familiar to adsorption isotherms. Since chemically adsorbed water will cause interface dipoles, they must repel each other, so the water adsorption/desorption process after charging will follow the Frumkin adsorption isotherm (

). Therefore, we use isotherms to formulate the capacitance behavior of the Helmholtz layer on Pt, and derive the relationship of σ in detail,

And θ

Given in the supplementary material. In formalism, we assume that the electronic dipole of chemically adsorbed water has nothing to do with the electrode potential, but please note that the chemically induced dipole should usually be polarized in the presence of an electric field (

). However, in our case, the effect of the polarizability is very small, and due to the lateral dipole-dipole interaction between the chemically adsorbed water, the electric field caused by the surface charge is compensated (see section S4) .

Surface charge density σ(

) And the surface coverage of chemically adsorbed water θ

(

) As a function of electrode potential

. The solid points with error bars represent the calculated data of AIMD simulation, and the black curve is the corresponding fit using the proposed theoretical model. Computational convergence

Corresponding θ

Can be found in figs. S3 and S7. The illustrations in (A) show the representative configurations of chemically adsorbed water on Pt(111) at -0.93 V, PZC and 0.84 V, respectively. The dotted lines in (B) indicate their respective θ

At PZC and ~0.1 V. The potential is PZC (

As can be seen

And figure. S8, the fitted curve (black) can describe the calculated data well. According to the fitted curve, we find

Maximum display is ~100μF/cm

The potential is slightly higher than PZC (~0.1 V), then attenuates to ~20μF/cm

When the electrode potential is removed from PZC. Most features

(Blue curve

) Very similar to the experimental differential capacitance curve (

). It is worth mentioning that the comparison is more useful in the vicinity of the double-layer region, for example, outside this region, the significant ratio of H adsorption may cause the narrowing of H.

peak(

Decomposition of differential Helmholtz capacitance

(Blue) as a function of electrode potential

Divided into two components, solvent capacitor

(Green) and capacitance

(Red) Due to chemical adsorption of water. The illustration shows

Connected in series. The potential window (~0.2 V) of the double-layer region of the Pt(111)/water interface at pH 4 is light blue (

We also derived a theoretical model consisting of two capacitors connected in series to represent Helmholtz capacitance (

). In this model, use

, Corresponding to the usual dielectric response of the solvent in the Helmholtz layer, the fitted value is ~20μF/cm

, Very similar to Helmholtz capacitors on inert metals such as mercury. Other ingredients

Explain the role of water chemical adsorption. Obtained value

Is negative, the maximum value is near PZC, as shown in the figure

. Connect two capacitors (

) Can produce bell-shaped contours

. From the formula

(Ie equation S16), we notice

When θ reaches its maximum

It is equal to half of the maximum coverage of chemically adsorbed water on Pt(111), which is 0.25 ML. as the picture shows

, Relative to PZC, the corresponding potential is ~0.1 V, θ

Approximately 0.16 ML in PZC. This explains why the potential corresponds to

The maximum value is slightly positive than PZC on Pt (

Our calculations and the proposed model clearly show that the peak value of the differential capacitance

Caused by the chemical adsorption of water, leading to negative capacitance

. The size of the latter depends to a large extent on the dipole that chemically adsorbs water on the metal surface (see equation S10) and therefore also depends on the binding strength of water. This may help rationalize other transition metals such as Au and Ag(

) And sd metal [for example, mercury (

)]; For example, max

The content of platinum is higher than that of gold and mercury. In addition, our results indicate that the incorporation of solvent chemical adsorption on the electrodes can provide a new strategy for enhancing the energy storage double-layer capacitance in supercapacitors. Our new model also reveals detailed changes in the solvation environment at the interface at different potentials, which are closely related to electrocatalytic reactions such as hydrogen release, oxygen reduction and carbon monoxide.

Reduction) occurs inside the Helmholtz layer.

In summary, we used AIMD calculations to study the Helmholtz layer at the Pt(111)/water interface under different potential conditions. The focus is to reveal the molecular structure of the interface water and the response to the electric field in the Helmholtz layer. We found that when the potential is shifted from negative to positive, the surface coverage of chemisorbed water increases. Since the chemically adsorbed water can induce a significant interface dipole potential, the change in its coverage will result in a change in the potential, leading to a negative capacitance response. Combined with the normal dielectric response of the solvent, we can obtain the experimentally observed Helmholtz layer's bell-shaped differential capacitance. Our work proves the importance of the chemical adsorption of water on the metal electrode to the capacitance of the EDL, thus providing a new idea for the relationship between the molecular structure of the interface water and the capacitance behavior. In addition, our findings lay the foundation for future exploration of adjusting the electronic interaction between electrodes and electrolyte solutions to optimize the performance of energy materials in electrocatalysis and supercapacitors.

Pt (111) surface

(4×4) Periodic slab of four atomic layers. The vacuum space between the plate and its periodic image is 21 Å and is filled with water molecules. The battery contains 64 Pt atoms and 68 water molecules, with a size of 11.246Å×11.246Å×27.887Å. The metal work function and PZC of the model, such as (

), close to the experimental value (

). Charged Pt(111)/H

The O interface is modeled by inserting Na

Ions near the surface of Pt(111). Pay attention to that

And F

Ions are not specifically adsorbed on Pt(111), so the outer Helmholtz plane is formed, and on the AIMD time scale, these ions will not diffuse into a large amount of water. All models are charge-neutral, and the electronic structure of the interface is optimized to generate double layers with ions and charged surfaces with opposite signs. The charge of the ions in the model is proved by the calculated expected state density, as shown in Figure 2. S5. The amount of Na changes

The "α" in this model is equal to controlling the surface charge density, thereby controlling the electrode potential. Using this method, six charged Pt(111)/water interfaces were constructed with surface charge densities of -43.8, -29.2, 14.6, 29.2, 43.8 and 58.4μC/cm

. The bulk water density in these models remains close to 1 g/cm

. These models contain two symmetrical interfaces, so the net dipoles of these models are cancelled out, as shown in the average electrostatic potential curve in Figure 2. S4. Use the cSHE method to calculate the electrode potential of the charged interface model (

). Please note that the Gouy-Chapman layer is not included in the interface model. Therefore, our EDL model corresponds to the high concentration limit under which the surface charge in the Helmholtz layer is effectively shielded. In our model, Co ions are also omitted, which may not affect our research on the water structure and capacitance of the Helmholtz layer, because our EDL model has the correct charge excess. It is worth mentioning that the same model setup has been successfully used to clarify Au (

AIMD simulation uses the freely available CP2K/Quickstep software package (

). The DFT implemented in CP2K is based on a mixed Gaussian plane wave scheme. The orbit is described by the Gaussian basis set with the atom as the center, and the auxiliary plane wave basis set is used to expand the electron density in the reciprocal space. The 2s and 2p electrons of O; the 2s, 2p and 3s electrons of Na; the 2s and 2p electrons of F; the 5d and 6s electrons of Pt are regarded as valences, and the remaining core electrons are determined by the Goedecker-Teter-Hutter pseudopotential (

). The Gaussian set is double ζ, with a set of polarization functions (

), the energy cut-off value is set to 400 Redberg. We used the Perdew-Burke-Ernzerhof function (

) To describe exchange-related effects, and the Grimme D3 method is used in all calculations for dispersion correction (

). Because the size of the pixel is very large, only the Γ point in the reciprocal space is used in our calculation. The second generation of Car-Parrinello Molecular Dynamics (SGCPMD) (

) Is used as the structural sample of the interface model, and the target temperature is set to 330 K. The correction step is obtained by five iterations of optimization of the orbit transformation (

), the integration time of each step is 0.5 fs. Langevin friction coefficient (γ

) Is set to 0.001 fs

, And the inherent friction coefficient (γ

) Is different, ie 5×10

fs

For Pt and 2.2×10

For H

O and ions. For more detailed information about SGCPMD settings, see (

). For each AIMD simulation, the initial molecular dynamics trajectory of about 5 ps (about 10,000 steps) is used to balance the system, and then a production cycle of 15 ps or more is generated.

For supplementary materials for this article, please visit:

This is an open access article distributed under the following terms

, It allows use, distribution and reproduction in any medium, as long as the final use is

For commercial interest, and provide the original works appropriately cited.

Volume 6, Number 41

October 7, 2020

Thank you for your interest in promoting the term "scientific progress".

Note: We only ask you to provide your email address so that the person you recommend to the page knows that you want them to see the email and that it is not spam. We will not capture any email addresses.

This question is used to test whether you are a visitor and prevent automatic spam submission.

Please log in to add an alert to this article.

by

: Eabb1219

Water chemisorption in response to changes in electrode potential results in negative capacitance of the electric double layer.

Volume 371, Issue 6526

©2021

. all rights reserved. The American Association for the Advancement of Science is 

, 

 with 

.

ISSN 2375-2548.