By Josh Perry, Editor
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Researchers at Rutgers University (New Brunswick, N.J.) and Oregon State University (Corvallis, Ore.) have developed a cost-effective method that uses intense pulses of light to fuse silver wires with polyester to fabricate thin heating patches that run on coin batteries and are 70 percent more effective than previous attempts.

This image shows how to make a personal heating patch from polyester fabric fused with tiny silver wires, using pulses of intense light from a xenon lamp.
(Hyun-Jun Hwang and Rajiv Malhotra/Rutgers University-New Brunswick)

According to an article from Rutgers, these patches can help reduce the energy costs from heating a building because individuals can activate the patches to manage individual warmth.

“The Rutgers and Oregon State engineers created highly efficient, flexible, durable and inexpensive heating patches by using ‘intense pulsed-light sintering’ to fuse silver nanowires – thousands of times thinner than a human hair – to polyester fibers, using pulses of high-energy light,” the article explained. “The process takes 300 millionths of a second.”

Experiments showed that the patches produce more heat per area and are more durable after bending, washing, and exposure to different environments than previous attempts to design personal thermal management solutions.

The research was recently published in Scientific Reports. The abstract read:

“Fabric-based personal heating patches have small geometric profiles and can be attached to selected areas of garments for personal thermal management to enable significant energy savings in built environments. Scalable fabrication of such patches with high thermal performance at low applied voltage, high durability and low materials cost is critical to the widespread implementation of these energy savings.

“This work investigates a scalable Intense Pulsed Light (IPL) sintering process for fabricating silver nanowire on woven polyester heating patches. Just 300 microseconds of IPL sintering results in 30% lesser electrical resistance, 70% higher thermal performance, greater durability (under bending up to 2 mm radius of curvature, washing, humidity and high temperature), with only 50% the added nanowire mass compared to state-of-the-art.

“Computational modeling combining electromagnetic and thermal simulations is performed to uncover the nanoscale temperature gradients during IPL sintering, and the underlying reason for greater durability of the nanowire-fabric after sintering.

“This large-area, high speed, and ambient-condition IPL sintering process represents an attractive strategy for scalably fabricating personal heating fabric-patches with greater thermal performance, higher durability and reduced costs.”