Researchers at University of Massachusetts, Amherst have developed a smart fabric that can harvest the wearer's body heat to power wearable devices and microelecronics. The fabric does this by taking advantage of the thermoelectric effect between a person's warm body temperature and the cooler temperature of the ambient air.
“What we have developed is a way to inexpensively vapor-print biocompatible, flexible and lightweight polymer films made of everyday, abundant materials onto cotton fabrics that have high enough thermoelectric properties to yield fairly high thermal voltage, enough to power a small device," says Trisha Andrew, materials chemist at the University of Massachusetts Amherst.
From the University of Massachusetts, Amherst article: "For this work, the researchers took advantage of the naturally low heat transport properties of wool and cotton to create thermoelectric garments that can maintain a temperature gradient across an electronic device known as a thermopile, which converts heat to electrical energy even over long periods of continuous wear. This is a practical consideration to insure that the conductive material is going to be electrically, mechanically and thermally stable over time, Andrew notes.
'Essentially, we capitalized on the basic insulating property of fabrics to solve a long-standing problem in the device community,” she and Allison summarize. “We believe this work will be interesting to device engineers who seek to explore new energy sources for wearable electronics and designers interested in creating smart garments.'
Specifically, they created their all-fabric thermopile by vapor-printing a conducing polymer known as persistently p-doped poly(3,4-ethylenedioxythiophene) (PEDOT-Cl) onto one tight-weave and one medium-weave form of commercial cotton fabric. They then integrated this thermopile into a specially designed, wearable band that generates thermo-voltages greater than 20 milliVolts when worn on the hand."
Read more about powering smart garments with body heat at the University of Massachusetts, Amherst.