Motors for Portable Medical Devices

Different motor technologies offer different motion solutions with distinct advantages for different types of portable medical devices. These motion solutions are contributing to new portable medical devices that are smaller, lighter, more powerful, and often cheaper than ever before -- and designed for global distribution.

New slotless, brushless motors
A new slotless, brushless motor design from Portescap called the ECS Series is targeting applications in respiratory therapy ranging from hospital invasive ventilators to home care bi-level respiratory machines, where high-speed motor operation and highly dynamic control are required to quickly adjust the pressure output of the ventilation system.

Jonathan Martha, North American medical segment manager for Portescap, told Design News:

One customer is using these slotless motors to design a new ventilator which will potentially eliminate the need for the motor cooling system and fan electronics altogether. The motor's improved efficiency has reduced the temperature rise enough to remove the cooling mechanism. Eliminating the cooling system would reduce the cost, size, and weight of the end device.

Since power considerations are important and higher efficiencies require less current input to achieve the same output, applications are able to achieve a higher power output. This allows design engineers to make some trade-offs, and potentially lower the power source to lower costs. With a battery-operated mobile device, battery technology continues to improve, but it is still one of the limiting factors of most portable medical devices. By drawing less current and putting less stress on that battery, that is definitely a benefit.

Dave Beckstoffer, project manager for Portescap, told us:

Other applications for slotless motors include infusion-type diabetic pumps where there has been a migration from coreless motors to using brushless operation due to overall improvements in the price to performance of brushless motors. The major differentiator for brushless motors is that applications are able to achieve much higher speeds and longer life. Typical brushless speeds range from -10,000 to 50,000 RPM, and can reach up to 100,000 RPM, compared to brush motors speeds that are typically 12,000 RPM or lower.