Contactless power couplers for respiratory devices

This paper presents the design and implementation of contactless power couplers for transferring power to heat up the breathing tube and sensors of respiratory devices produced by Fisher & Paykel Healthcare Ltd, NZ. The respiratory device supplies humidified air to the patient through an air delivery tube. The air needs to be heated along the tube to prevent condensation and a sensor has to be placed at the mask to measure the temperature. The tube heating power, or the temperature of the air, should be adjustable according to user preferences while the 5V/250 mW sensor has to be operating all the time. Medical devices have to be frequently cleaned, any direct metal contacts pose safety and reliability issues so that their presence is undesirable. Inductive and capacitive power transfer technologies were proposed and successfully developed in this research as a contactless power transfer solution. The prototype can successfully supply a constant power of 250 mW to the sensor while enabling heating control in the specified range.