Flexible charge-storage developed for clothing

Materials scientists from the US have developed a method for making a charge-storing system that is easily integrated into clothing.

A major factor holding back development of wearable biosensors for health monitoring is the lack of a lightweight, long-lasting power supply. Now a team at the University of Massachusetts Amherst have developed a method for making a charge-storing system for embroidering a charge-storing pattern onto any garment.

Materials chemist Trisha L. Andrew said: "Batteries or other kinds of charge storage are still the limiting components for most portable, wearable, ingestible or flexible technologies. The devices tend to be some combination of too large, too heavy and not flexible."

Their new method uses a micro-supercapacitor and combines vapour-coated conductive threads with a polymer film, plus a special sewing technique to create a flexible mesh of aligned electrodes on a textile backing. The resulting solid-state device has a high ability to store charge for its size, and other characteristics that allow it to power wearable biosensors.

Andrew adds that while researchers have remarkably miniaturized many different electronic circuit components, until now the same could not be said for charge-storing devices. "We show that we can literally embroider a charge-storing pattern onto any garment using the vapour-coated threads that our lab makes. This opens the door for simply sewing circuits on self-powered smart garments."

The team show that their vapour coating process creates porous conducting polymer films on densely-twisted yarns, which can be easily swelled with electrolyte ions and maintain high charge storage capacity per unit length as compared to prior work with dyed or extruded fibers. Andrew, who directs the Wearable Electronics Lab at UMass Amherst, notes that textile scientists have tended not to use vapour deposition because of technical difficulties and high costs, but more recently, research has shown that the technology can be scaled up and remain cost-effective.

She and her team are currently working with others at the UMass Amherst Institute for Applied Life Sciences' Personalized Health Monitoring Center on incorporating the new embroidered charge-storage arrays with e-textile sensors and low-power microprocessors to build smart garments.