High Power Resistors for Medical Industry

Designing medical electronics equipment is a greater challenge than designing for other industry applications. Because a precious human life is involved, the products and components used in various medical equipment must be absolutely reliable and safe beyond doubt. Even the compliance and safety standards set by various international bodies are more stringent when it comes to the healthcare industry, and rightly so.

Passive electrical components have an important role to play in ensuring the safe working of medical equipment, thereby protecting expensive devices from damage and also safeguarding human life. This study is about the critical role played by power resistors in the medical electronics industry.

What are the emerging trends in the medical electronics industry for equipment manufacturers? What are the main problems that may occur in the use of medical instruments, which effective use of resistors can solve? What are the special considerations that engineers must keep in mind while designing electronic devices for medical applications? What are the product offerings from KWK Resistors that specially cater to medical applications? You will find answers to these queries and more in this study.

Emerging trends in the Medical Electronics Industry

Technology assisted medical practices are constantly on the rise. Whether it is sophisticated equipment used in surgical processes or high precision diagnostic devices, doctors and hospitals are relying more and more on technology to aid their efforts.

Another important trend in the medical industry is the transition from hospital care to home-based health care. This new development has created a greater demand for compact, self-use electronic devices for patients such as BP monitors, blood sugar test kits, physiotherapy devices.

The present CoronaVirus pandemic has brought the healthcare industry and indigenous medical equipment manufacturing into sharp focus. The global medical electronics market was estimated to be around USD 94 billion in 2015 and was projected to grow at a CAGR of 7.9% over the next nine years. However, the pandemic has accelerated the growth exponentially – especially with increasing demand for diagnostic and imaging systems, emergency care systems, ICU equipment.

Role of Resistor Components in Medical Devices

All human body parameters are measured as analog values – such as blood pressure, heart rate, temperature and so on. Passive components play a role in regulating the electrical contact which the various devices have with the human body. Every IC used in any medical equipment contains at least a dozen passive components.

The primary sources of malfunction in these devices that can be prevented using appropriate power resistors are – power surges, high supply voltage and voltage fluctuation.

When there is a large differential in input energy due to sudden surges or fluctuation, the equipment is exposed to excessive power for a short duration of time. This could damage its components, which may be very expensive and difficult to replace. It could also cause incorrect functioning and frequent maintenance. Such sudden power surges may be part of the routine functioning of the equipment in some cases – such as in AED (Automated External Defibrillator).

The purpose of using power resistors is two-fold – To protect the patients from fluctuations in the medical equipment circuitry and to prevent damage in the medical equipment due to voltage and power surges.

Power Resistors are designed to withstand and dissipate large amounts of power in a short amount of time. In order to achieve this goal, these resistors are made from materials that have very high thermal conductivity. Depending on applications, these resistors could also include both internal and external heat sinks that can absorb large amounts of heat.

High power resistors from KWK for the Medical Applications

KWK Resistors offers a wide range of resistive components for use in various medical devices. Our power resistors are the perfect choice to protect high value medical equipment from power surge and high voltage stress.

Our power resistors come with CE marking, and are used by major medical industry OEMs, both in India and across the world. All our resistor components are RoHS (Restriction of the Use of certain Hazardous Substances in Electrical and Electronic Equipment) compliant.

Some of the KWK resistor product series suitable for different application areas in the medical industry are listed below:

1. Human contact devices

Devices that make physical contact with the human body include defibrillators, ECG/EEG machines, surgical devices Resistors used in such devices must be capable of handling power surges during short duration pulses. Especially in AEDs, if the surge energy is diverted away from the patient, it may propagate back into the defibrillator and damage sensitive monitoring inputs.

Pulse-withstanding resistors – They are usually built-in to the monitor input circuit. During transient or overload conditions, these high energy resistors safeguard the equipment from energy surges (up to thousands of Joules) for short durations.

Carbon composition resistors, Wire Wound Resistors or Thick film Resistors from KWK are commonly used due to their surge handling capabilities. Materials with low inductance are more suitable. The medical application must also be able to tolerate a wide range of resistance shifts due to temperature, humidity, or even drift over time.

KWK’s Anti–surge resistors offer benefits of non-inductive performance and high-power density. As an added feature, they provide impulse energy capability normally associated with wire-wound or composition resistors. KWK anti–surge resistors can handle voltages of up to 1200V and do not need any additional protective measures.

High Ohmic Value Resistors

These resistors are used where it is required in sensitive first stages to amplify small signals. These are rated by their resistance value in Ohms (Ω) and the electrical power in Watts (W) that they can safely dissipate depending upon their size. Their power rating may range from a few Watts to several kiloWatts. These resistors are widely used as high gain amplifiers in ECG.

There are various types of High Power Resistors – Braking resistors, Radial Type, Aluminium Housed, Silicon Coated, Vitreous Enamelled Resistors. High Power resistors come in customised designs and materials to suit the product where they are applied.

2. Lab equipment and instrumentation

Accurate and stable instrumentation in the medical field requires the ability to detect very small signals without producing false readings. Compact sizing is another important consideration to minimise the space requirement.

For instance, the input stage of an instrument with a resistive sensor (such as a thermistor) in a precision temperature-monitoring circuit consists of a bridge of resistors which must be closely matched in value.

3. Imaging and Diagnostics

Imaging applications are scanning devices such as X-ray, ultrasound, and MRI systems. Each of these sophisticated devices have specialised resistance requirements. For instance, X-ray machines require high voltage supply for X-ray generation. MRI scanners generate strong magnetic fields, so the resistors used have stringent restrictions for non-magnetic material to be used.

High-voltage resistors from KWK – Used in X-ray head supply dividers.

Thin-film resistors from KWK – Used in Ultrasound transducers.

Metal Foil or Thin film precision resistors from KWK – Used for high stability in IVD analysis equipment.

Why KWK Resistors?

KWK Resistors has years of experience with design and manufacture of resistive components used both inside the medical equipment as well as the resistive load banks used to test power supplies and batteries of these equipment.

From the slimmest, 10mm thick metal encased resistor for MR systems to extreme high impulse capable resistors for X-Ray tube discharge, we have a wide range of resistor solutions for every specific requirement. We support OEMs, design houses and contract manufacturers end to end – from Design to Production.

Talk to our experts to get a free technical consultation for custom resistors requirement or select desired ranges from our existing product catalogs.

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