In a bid to charge the wearable gadgets, scientists have developed a fabric that can harvest body heat to power small wearable electronic devices such as activity trackers.
According to Trisha Andrew from the University of Massachusetts Amherst, many wearable biosensors, data transmitters and similar tech advances for personalised health monitoring have been ‘creatively miniaturised.’
However, they require a lot of energy, and power sources can be bulky and heavy, Andrew said.
The research, published in the journal Advanced Materials Technologies, describes that in theory, body heat can produce power by taking advantage of the difference between body temperature and ambient cooler air, a “thermoelectric” effect.
Materials with high electrical conductivity and low thermal conductivity can move electrical charge from a warm region towards a cooler one in this way.
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Some studies have shown that small amounts of power can be harvested from a human body over an eight-hour workday, but the special materials needed at present are either very expensive, toxic or inefficient, researchers said.
“What we have developed is a way to inexpensively vapour-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,” Andrew said.
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.
The device converts heat to electrical energy even over long periods of continuous wear, researchers said.
This is a practical consideration to ensure that the conductive material is going to be electrically, mechanically and thermally stable over time, they said.