GaN Technology — Contributing
to Medicine in No Small Way

In past issues of Fast Just Got Faster, the disruptive nature of gallium nitride semiconductor technology, especially eGaN^® power transistors, was discussed…now with significantly higher performance at an equivalent cost, the inevitability of GaN displacing the aging power MOSFET is becoming clearer.

This issue of Fast Just Got Faster highlights a specific end-use application that affects all of us – the contribution that GaN technology is making in medical applications with enhanced patient mobility using wirelessly powered devices and improved diagnostics with higher resolution equipment.

Medical Applications: Introduction and Overview

Being untethered to the power cord not only makes life easier for patients and health workers, but also increases safety and allows health care to be administered faster and more efficiently. Imagine medical teams never having to plug in a power cart while rushing to save a life in an emergency room or having to worry about the tangle of wires that can interfere with the delivery of IV fluids.

From a patient’s point of view, think about eliminating the need to have infection-prone wires extending from the body to recharge the batteries for a heart pump. And, in the world of diagnostic procedures, just think about the impact of significantly increasing the resolution of scanning equipment such as sonograms and MRI, or the ability to swallow miniaturized X-Ray machine imbedded in a pill to perform a colonoscopy.

These improvements to the world of medicine are being enabled by gallium nitride technology. Let’s take a closer look.

At the Hospital – Untethered Emergency Carts, Unplugged Bedside Monitoring Instruments, and Untethered Patients

We are all familiar with the chaotic environment in which emergency medical personnel navigate at life-saving speed and can thus appreciate the advantage of having the equipment readily available without the need to “find power outlets” (see figure 1).

Even at a patient’s bedside, not having power cords will be welcomed – for ease of moving instruments, avoiding accidental unplugging of critical equipment, reducing the risk of electrical shock, and reducing the potential to breed bacteria. The emerging availability of wireless power transfer is making wireless medical carts and bedside stands a reality.

The advancement of wireless power transfer is an electronics industry-wide movement. Industry leaders including Hewlett Packard, Intel, Texas Instruments, Samsung, and Witricity have established a consortium (A4WP) for consumer and computing equipment. This technology is applicable to hospital environments, which is using frequencies at both 6.78 and 13.56 MHz. In addition to the convenience, wireless power will increase safety and reduce price by removing cable clutter around the patient.

On the Patient – Heart Pumps, Pacemakers, Muscle and Nerve Stimulators, and Electric Wheelchair Recharging

In addition to untethering the instrument carts in the emergency room, having wireless power available enables patients to be more comfortable while bedridden and increases their freedom of movement when ambulatory.

Likewise, if a patient is bound to an electric wheelchair, the need to recharge batteries can be accomplished with a “drive over” mat that will charge the battery without the need to plug in. As with electric vehicles, electric wheelchairs can recharge simply by rolling over a wirelessly coupled mat. This vehicle recharging technology is in operation today with drive-over chargers for electric cars and buses.

There are also numerous direct patient applications for wireless power transfer enabled by GaN technology. Figure 2 illustrates some of the high-impact applications under development and in clinical trials. These applications involve heart monitors and nerve stimulators that do not require that wires – wires that are prone to infection – protrude from the body in order to “plug in” for power. Wireless charging is not only more convenient, it is safer for the patient.

Diagnostics – MRI, Colonoscopy

Resolution is a critical attribute of all medical scanning devices, such as sonograms, CAT scans, and MRI imaging (see figure 3). Equipment manufacturers are very excited about using eGaN^® FETs to increase the speed and precision with which they can conduct scanning measurements. In the case of MRI systems, eGaN^® FETs are used in the transmit functions, which require extremely high RF power for both the power supply and power amplifier being constrained by heat. The small size and efficiency of eGaN^® FETs allow the transmit function to be placed closer to the patient allowing effective higher power capability for faster imaging. This faster imaging can be taken as either more image slices in the same time for higher resolution, or shorter scan time for more efficient equipment usage.

The receive coils are placed in direct contact with the patient and are limited by heat. Replacing silicon-based components with eGaN^® FETs to detune these coils for the transmit phase and tune them for the receive phase yields a drastic reduction in power dissipation, allowing a higher density receive matrix. This provides more information in the same space for higher resolution images. Thus, medical professionals will have more accurate images and a patient’s care will benefit with improved diagnosis.

Perhaps the most innovative medical application enabled by the extremely small size of the eGaN^® FETs is the “colonoscopy pill” (see figure 4). This pill contains a miniature X-ray machine that, after ingestion (no pre-purging needed!), creates a 3-D image of the intestinal track as it passes through the patient’s digestive system.

The scanned images are transmitted wirelessly to a receiving unit placed on the patient. Once the pill has passed through the patient’s system, physicians can analyze the digital information stored on the receiving unit. Imagine, no more discomforting overnight preparation for the traditional colonoscopy! This “pill” and procedure is the result of EPC’s customer Check Cap, and is currently undergoing European agency trials and is on track for final evaluation by 2016.

In no small way, eGaN^® FETs are contributing to changing the cost curve of medicine.

Summary: GaN Technology for Medical Applications

The world of semiconductors is undergoing a technological disruption and medical applications that take advantage of high performance eGaN^® power transistors and integrated circuits are emerging rapidly. In this issue of Fast Just Got Faster, applications improving the quality of medical care were presented:

• Untethering the all-important “medical cart” containing emergency instruments to make movement of the cart less of a contributor to bacterial infestations, as well as faster and easier to address patients.
• Removal of the necessity to have infection-prone “wires” protruding from a patient’s body because they are needed to power heart pumps, or nerve stimulators.
• Increase in the resolution of body scanning devices, such as MRI equipment, giving more accurate information about the condition of patients at a lower cost.
• Introduction of new diagnostic procedures, such as the “colonoscopy pill,” giving doctors more precise critical information, while easing medical procedures for the patient and reducing costs.

In conclusion, GaN technology is contributing to significant improvements in medicine.