Semi-flexible bimetal-based thermal energy harvesters

TL;DR

This paper presents a semi-flexible, low-cost thermal energy harvester using a curved bimetal and electret converter, achieving practical power outputs suitable for powering wireless sensors.

Contribution

Introduces a novel semi-flexible bimetal-based thermal energy harvester with integrated electrostatic conversion for scalable, low-cost energy harvesting applications.

Findings

Raw power output of 13.46μW per device at 60°C

Achieved 10μW of usable power with three devices

Demonstrated compatibility with wireless sensor powering

Abstract

This paper introduces a new semi-flexible device able to turn thermal gradients into electricity by using a curved bimetal coupled to an electret-based converter. In fact, a two-steps conversion is carried out: (i) a curved bimetal turns the thermal gradient into a mechanical oscillation that is then (ii) converted into electricity thanks to an electrostatic converter using electrets in Teflon (r). The semi-flexible and low cost design of these new energy converters pave the way to mass production over large areas of thermal energy harvesters. Raw output powers up to 13.46uW per device were reached on a hot source at 60{\deg}C and forced convection. Then, a DC-to-DC flyback converter has been sized to turn the energy harvesters' raw output powers into a viable supply source for an electronic circuit (DC-3V). At the end, 10uW of directly usable output power were reached with 3 devices, which is compatible with Wireless Sensor Networks powering applications. Please cite as : S Boisseau et al 2013 Smart Mater. Struct. 22 025021 Available online at: http://iopscience.iop.org/0964-1726/22/2/025021/