Washable electrical power connections open up wearable applications

Technology News |
By Nick Flaherty

“We’re working on taking any garment you give us and turning it into a solar cell so that as you are walking around the sunlight that hits your clothes can be stored in a battery or be plugged in to power a small electronic device,” said Trisha Andrew, director of wearable electronics at the Center for Personalized Health Monitoring in UMass Amherst’s Institute of Applied Life Sciences (IALS).

One of the major problems with wearable electronics is distributing power through a material that is constantly flexing and often being washed.

“We aim to build up the materials science so you can give us any garment you want, any fabric, any weave type, and turn it into a conductor,” said Andrew. “These conducting textiles can then be built up into sophisticated electronics. One such application is to harvest body motion energy and convert it into electricity in such a way that every time you move, it generates power. By sandwiching layers of differently materials between two conducting electrodes, a few microwatts of power can be generated when we move,” she said.

The team used chemical vapour deposition (CVD) to coat fabrics with a 500nm layer of conducting polymer, poly(3,4-ethylenedioxytiophene), also known as PEDOT. These woven conducting fabrics that are resistant to stretching and wear and remain stable after washing and ironing.

They tested 14 different fabrics, including five cottons with different weaves, linen and silk. “We show them to be stable to washing, rubbing, human sweat and a lot of wear and tear,” said Andrews. The PEDOT coating did not change the feel of any fabric as determined by touch with bare hands before and after coating and did not increase fabric weight by more than 2%.

“There is strong motivation to use something that is already familiar, such as cotton/silk thread, fabrics and clothes, and imperceptibly adapting it to a new technological application,” she said. “This is a huge leap for consumer products, if you don’t have to convince people to wear something different than what they are already wearing.”

The lab has also made a wearable heart rate monitor with an off-the-shelf fitness bra to which they added eight monitoring electrodes connected using these fabric links.

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