Printed flexible thermoelectric generators for use on low levels of waste heat

This work focuses on the design, fabrication and testing of thermoelectric generator (TEG) devices using dispenser printer. A series-parallel prototype of 50 couples, with 3.5 mm × 600 μm × 100 μm printed element dimensions, is fabricated on a custom designed polyimide substrate. Se doped mechanically alloyed (MA) Bi2Te3 was used as the n-type material whereas Te doped MA Bi0.5Sb1.5Te3 was used as p-type material. The prototype TEG device produces a power output of 33 × 10−6 W at 0.75 × 10−3 A and 43 × 10−3 V for a temperature difference of 20 K resulting in a device areal power density of 2.8 W m−2. To achieve a similar power output in a practical situation, such as from pipes carrying hot fluid an experimental study in forced and natural convection is performed. In forced convection, 33 × 10−6 W power output is achieved when the pipe surface temperature is about 373 K. While, in natural convection, maximum power up to 8 × 10−6 W power is obtained at 373 K pipe surface temperature. Forced convection is desired for the system to generate sufficiently high power. In the case of natural convection, we achieved much lower power compared to forced convection. The prototype presented in this work demonstrates the feasibility of deploying a printable and “perpetual” power solution for practical wireless sensor network (WSN) applications.