Structure-optimized flexible thermoelectric device and its applications to wearable electronics

Abstract

A flexible thermoelectric device (f-TED) attachable to heat sources having arbitrary shape can greatly expand the application range of a commercially available non-flexible thermoelectric device. As a f-TED that is structurally flexible has been reported despite the use of inorganic thermoelectric materials having high thermoelectric performance, the possibility of realizing practical applications of the f-TED has been opened. However, the power generation and cooling applications of the f-TED are still limited because the optimization of the f-TED which is in an initial development stage has not been achieved sufficient performance to drive the applications. This Ph. D. dissertation proposes a new application field for wearable electronics utilizing the power generation and temperature control functions of a f-TED whose efficiency is greatly improved by optimizing the structure and by developing novel heatsinks. To achieve these goals, first, a comprehensive model that can predict the performance of the flexible thermoelectric power generator from body heat, and an optimized structure is proposed based on the model. Next, we introduce the results of remarkably improved power generation of the f-TED using flexible polymer heatsinks, and the results of implementing a self-powered wearable electrocardiography sensor with the f-TED. In addition, the scope of application is extended to a new field, which is a variable stiffness system, by using the f-TED as an active temperature controller. Finally, the results of implementing multi-functional electronics with the variable stiffness module including the f-TED is discussed.