Resistor design considerations - Today's Medical Developments

Safe and reliable resistors can expand surge protection and provide green performance in medical contact equipment.

Medical designers are faced with the complex fields of various applications and performance environments of the devices they develop. The aging population, more healthcare facilities, and the increasing demand for smarter and more convenient devices keep designers in a dilemma because they are faced with faster, smarter, unparalleled performance and precision devices. Continued competitive pressure.

These complex devices must also work closely with the human body, fusing complex digital components with the reality of the simulated patient. Therefore, resistors-passive components that resist the flow of current-play a vital role in medical design. In medical device design, each active integrated circuit (IC) requires up to 20 resistors. Off-the-shelf resistors are often insufficient, prompting designers to use specialized components specially manufactured to deal with various medical challenges, such as high voltage and electromagnetic interference.

Understanding the choice is critical, because various medical applications have different requirements for resistor performance. For example, in imaging, X-ray systems require ultra-high voltage resistors. Magnetic resonance imaging (MRI) scanners require non-magnetic resistors; ultrasound equipment requires integrated resistor arrays. In instrumentation and analysis, accuracy and stability are the key. In addition, some of the most challenging resistor applications have been found in contact devices. These contact devices are directly connected to the human body and are usually responsible for safely delivering high-energy pulses or detecting and monitoring biological signals.

Automated external defibrillators (AED) are widely used life-saving tools today, but their success is based on the ability to provide electrical pulses to ensure patient safety. Connected medical devices (such as electrocardiogram (ECG) monitors) also require the same security. Protection resistors with high rated energy support this application. This can be achieved using pulse-resistant thick-film components and a double-sided chip design, which can provide twice the energy of traditional components in the same footprint. The most important thing is that the defibrillation energy must reach the patient's body, which is usually achieved by designing a pulse resistance resistance directly in the lead set of the monitor's input circuit. The proportion of the defibrillation surge energy dissipated by the protective resistor decreases as the ohm value increases, which means that the designer must select the maximum value that is consistent with the functional requirements of the monitor. The designer must also consider the parameters of the test circuit itself, and consider the number of leads in a lead set based on electromagnetic compatibility (EMC) standards (such as IEC601).

In this case, the protective resistor (applying an appropriate surge to the patient and protecting the connected monitor from electrical damage) must reduce the rated energy from 25.00J at 1kO to 0.25J at 100kO. Although this has traditionally relied on synthetic technology, thick film solutions are being developed. Professional resistors complying with IEC 60601/61000 standards are also provided to minimize risks and speed up product development.

Consider that the total energy in the defibrillation pulse may be as high as 350J. The protection resistor is designed on the printed circuit board (PCB) in the display cable group or in the display itself to absorb part of the energy to prevent the defibrillation energy from entering the display. For small electronic components, even 1% of energy is important.

Other options that have been proven in industrial applications are also adding new value to medical design. Pulse tolerant chip (PWC) and high pulse tolerant chip (HPWC) provide higher energy capacity; for example, as an untrimmed resistor with 5% tolerance, HPWC can provide a capacity of about 1J during the duration of a defibrillation surge .

of

) Is an advancement of the high-density signal carrier (HDSC) option. It is an unfinished double-sided version that doubles the surge capability through thick film materials on both sides of the chip. This compact option is optimized for monitor input to ensure the pulse tolerance of the defibrillator. Surge protection can be maximized in two ways: against intentional surges (such as from a defibrillator) and against random surges (such as surges caused by electrostatic discharge (ESD)). DPCR has been pre-qualified to achieve maximum energy and voltage performance. DPCR is pre-certified IEC 60601-2-27 for defibrillation surge and IEC 61000-4-2 level 4 for ESD certification. It provides powerful design options to reduce risk and quickly bring the design to market.

Green options are also increasing, which can help designers meet the environmental requirements of medical devices. The use of lead-free resistors can meet the non-exempt standards for lead-free designs-with the continuous improvement of lead-free design requirements, the design has a longer service life and reduces the need to replace components.

Special resistors play an important role in medical design. These pre-qualified options have value far beyond mass-produced commercial components, providing features such as high electrical ratings, small size, high surge performance, and environmental value, enabling medical designers to provide safe and stable equipment To save lives.

About the author: Stephen Oxley is a senior application and marketing engineer at TT Electronics plc. He can be contacted by

After the US election and the COVID-19 vaccine – what will happen in the future?

When preparing for 2021, do we dare to reflect on 2020? Considering COVID-19 and political drama, we are not willing! There will be books and movies telling the story of 2020, so we will hold Hollywood in charge.

instead,

In the United States and around the world.

Some expectations in 2021:

– As of this writing, Pfizer, Moderna and AstraZeneca have all reported positive results of their vaccine clinical trials. Let us hope that the final result will continue to produce very positive results-other vaccines will also be released with similar results.

– We don’t want but now we want to get your attention. Let’s see what the Biden administration thinks about the reorganized Obamacare and what they choose to pay for.

– Combining the COVID-19 experience with the revised NAFTA (now known as USMCA) should yield positive results in reproduction/near-production activities in North America. COVID-19 tells us that certain medical supplies should be considered vital to the United States, so there should be a certain percentage of these key supplies manufactured in the United States, Canada or Mexico. This should be an important move, and USMCA should make this goal easier to achieve.

– China’s supply chain may become more stable and more competitive for two reasons: (1) China seems to have recovered from COVID-19; (2) the new US government may abandon the trade of the previous government war. Although there will be some withdrawal/approaching measures, China will remain a strong and reliable part of the global supply chain. (Note: We do recognize that some manufacturing industries in China are moving to Vietnam, Thailand and other places, but this development will not be as fast as some people think. For example, if a company wants to sell products in China, it Will still need to be made in China, otherwise it may lose market share.)

-We hope it will stay here. Since the Centers for Medicare and Medicaid Services (CMS) and insurance companies finally become logical for modern healthcare during COVID-19, it is difficult to predict this topic. Let us hope that they now understand that telemedicine is safer (in most cases) and very efficient.

We cannot guarantee this, but we hope. Although we are very happy to see you online, we also like to meet you in person.

I wish you all safety, prosperity and success in 2021! During this period, happy holidays, please be safe!

About the author: CEO Florence Joffroy-Black is MedTech's long-term M&A and marketing expert. You can contact her in the following ways

. Managing Director Dave Sheppard (Dave Sheppard) is a former medical OEM Fortune 500 company executive and an experienced MedTech M&A expert. He can be contacted by

Researchers have developed clinical-grade wireless implants that can operate without batteries.

A kind

Epilepsy, Parkinson's disease, chronic pain and other diseases may soon be treated. The miniature device is powered by magnetic energy and generates the same high-frequency signal as a clinically approved battery-powered implant.

Developed by

, The implant is about the size of a grain of rice.

The implant is a layer of magnetoelectric material that converts magnetic energy into voltage. This method avoids the shortcomings of radio waves, ultrasonic waves, light and electromagnetic coils, all of which have shown interference to living tissue or harmful heat.

Although battery-powered implants are often used to treat epilepsy and Parkinson’s disease, studies have shown that nerve stimulation can be used to treat depression, obsessive-compulsive disorder (OCD) and chronic, intractable pain, which can cause anxiety, depression and Opioid addiction.

Manufacturing wireless devices that are easy to implant and do not require batteries can make neurostimulation therapy more widely used. The researchers' equipment is small enough that it can be implanted almost anywhere in the body through minimally invasive surgery, similar to the type of implant surgery that places a stent in a blocked artery.

In order to prove the feasibility of magnetoelectric technology, the researchers implanted the device in rodents. During the test, rodents can roam freely in the enclosure. Studies have found that rodents prefer to be placed in a part of their shell, and the magnetic field will activate the stimulator, thereby providing a smaller voltage to the reward center of the brain.

Jacob Robinson, a member of the Rice Neural Engineering Initiative, said: "This proof-of-principle demonstration is important because it is a huge technological leap from a desktop demonstration to a treatment that can be used to treat people.

Amanda Singer, an applied physics student at Robinson Lab, solved the problem of wirelessly powering devices by joining layers of two different materials in a single film. The first layer is a magnetostrictive foil of iron, boron, silicon and carbon, which vibrates at the molecular level when placed in a magnetic field. The second is a piezoelectric crystal, which directly converts mechanical stress into voltage.

Singh said: "The magnetic field creates stress in the magnetostrictive material." "This material generates sound waves, some of which are at resonant frequencies, creating an acoustic resonance mode."

Acoustic reverberation activates the piezoelectric part of the film. Magnetoelectric membrane can obtain a lot of energy, but its working frequency is too high to affect brain cells.

Robinson said: "One of the main projects Amanda solved was to create circuits to regulate cell activity at a lower frequency." "It is similar to an AM radio-you have very high frequency waves, but they are so you can listen to them. Low frequency modulated."

It is a challenge to produce biphasic signals that can stimulate neurons without compromising the modulation of neurons, and so is miniaturization.

"When you need to develop something that can be implanted into small animals subcutaneously, your design constraints will change a lot," said Caleb Kemere, a member of the Neural Engineering Initiative. "Let it work on rodents in an unconstrained environment, forcing us to minimize size and volume."

Robinson and Kemere are associate professors of electrical and computer engineering and bioengineering. The research was supported by the National Science Foundation and the National Institutes of Health.

Flexibility and scalability allow electronic products to be added to a wider range of applications and products.

• Reach US$8.3 billion by 2030

• Market for healthcare products including flexible electronics

– A medical technology start-up company based in Evanston, Illinois has developed a wearable device for non-invasive monitoring of the ventricular shunt function of patients with hydrocephalus – was named the winner of the 2020 global competition at the Virtual Medtech Conference and won 35 Ten thousand dollar jackpot.

From discrete monitoring during treatment to continuous monitoring, it can improve diagnostic capabilities, preventive medical services, and provide:

MT3 can perform grinding, milling, turning, drilling and tapping operations on the workpiece with one setting.

MT3 can perform grinding, milling, turning, drilling and tapping operations on the workpiece with one setting. Vertical cylindrical grinder, supplement

, MT3 comes standard with 42-inch diameter T-slot table and precision grinding spindle with HSK-50A connection. The machine tool spindle can be interchanged through the HBK-200 clamping system, so that the spindle can be adapted to specific applications.

The machine can be expanded from a vertical grinder to a single-machine processing machine tool system, combining various spindles and tools into an optional unit, which is automatically replaced by the Fanuc R-2000 robot and Bourn & Koch's Alien Claw arm end tool, which can be quickly replaced Most tools and spindles. The unit is equipped with a spindle gear plate type tool changer, which can manage various tools and spindles.

Programming is done by using Bouuc & Koch's Grinding Human Machine Interface (HMI) and Fanuc manual guide-i, and is controlled by Fanuc 0i CNC. The virtual Y axis allows the machine to perform standard milling functions. The MT3 spindle has a Fanuc Beta-il 160M motor, which can generate 30kW of power from 2,000rpm to 10,000rpm, providing sufficient power and range for various grinding, milling, drilling and tapping applications.

The cast iron table frame is reinforced with polymer concrete to dampen vibration, thereby providing extra strength; heavy linear guides run on the X axis

Large diameter ball screw with heavy linear guide; supports grinding head and spindle on Z axis; optional scale feedback

Servo cylinder assembly, used for precise movement, X-axis positioning for feeding; protection from chips, chips, and contaminants; optional scale feedback

Fanuc servo motor, right angle gear box, mounted on the top of the machine column, driving the Z-axis ball screw

Direct-drive work spindle can realize high-speed machining, worktable positioning; 100rpm standard; 250rpm optional