Power Wearable Medical Device Components Via Thermoelectric Circuit Integration

Abstract

Previous wearable thermoelectric energy harvester design strategies seek to enhance thermoelectric power generation through skin-generator contact resistance reduction. Flexible generator fabrication may achieve this end. Unfortunately, previous flexible generator fabrication techniques (1) lack methodology on how to couple the generator with an efficient heat dissipation system and (2) are time consuming to fabricate and largely inaccessible. Alternative approaches exist that match rigid off-the-shelf thermoelectric generators, which addresses the second concern, to heat sinks, which addresses the first concern, to enhance power generation. Even so, thermoelectric generators produce a millivolt voltage, too small to apply across circuit components, which necessitates amplification. Previous amplification techniques focus on maximum power point tracking to amplify the voltage at a maximum power point. Yet, maximum power point tracking requires additional switching components and a microcontroller to execute the maximum power point algorithm. Alternatively, it is possible to match a thermoelectric generator array to the input impedance of a DC-DC step-up converter to amplify the voltage without maximum power point tracking. In our previous work, we described a method to design a thermoelectric circuit by matching the input impedance of an array of off-the-shelf thermoelectric generators to the input impedance requirement of a DC-DC step-up converter. We applied this methodology to fabricate a wearable thermoelectric circuit and operate a lower power microcontroller. During the tests, the thermoelectric generator array provided an average power output of 20.3 μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . This was enough power to operate the microcontroller in a low power state as it listened for external input. Upon external input, the microcontroller lit an LED, which visually demonstrated wearable thermoelectric circuit function.