Beyond allowing ventilation or draining away sweat, future athletic wear might actually respond to sweat by opening vents or relaxing constrictions.
The invention is based on the different ways fabrics can respond to wetting. Postdoctoral researcher Yahui Yang of the Micro-Nano Innovations Laboratory at the University of California, Davis, bonded patterns of waterproof fabric to a piece of cotton fabric.
When cotton gets wet, it expands in volume, but the non-wettable fabric does not expand when exposed to water. Yang found that by sticking the two together, he could create shapes that curl up when they get wet and relax again as they dry out.
Many materials expand or contract in response to heat or humidity. Stick two metals together that expand at different rates in response to heat, and you’ve made a simple thermostat. But this is the first time this principle of mechanical expansion has been applied to do something useful with fabrics, or with water-driven rather than thermal expansion, says Tingrui Pan, the head of the MiNi lab.
“By opening up these vents in the fabric as you exercise, you can bring in more air flow,” Pan says.
Yang experimented with different patterns and sizes of cuts in the wettable fabric. He found that with smaller cuts, he could get the stiffer fabric to act as a cantilever, concentrating force in a particular area.
“Just a few percent of expansion can give you a lot of movement,” he says.
The university has filed a provisional patent, and Pan says that they are already in discussions with companies about the technology.
The National Science Foundation and the National Institutes of Health supported the work.
Source: UC Davis