Pressure sensors gaining durability

Researchers in Singapore have done what most materials scientists can only dream about: They ran their project over with a car. But this act wasn’t born of frustration. Rather, it demonstrated the durability of pressure sensors made from eutectic gallium indium, or eGaIn, a metal that’s liquid at room temperature (ACS Sens. 2016, DOI: 10.1021/acssensors.6b00115). To create their device, researchers at the National University of Singapore dispense electrically conductive eGaIn into a cavity they have patterned within a silicone elastomer. They then seal the device with a flexible polyethylene terephthalate film that also supports two electrodes made from screen-printed silver. Squishing a device redistributes the liquid metal and alters the resistance between the electrodes, converting pressure changes to electrical signals. The sensor is durable enough to stomp on, but soft and flexible enough to wear inside a shoe, the researchers report. They could even discern whether it was worn inside a sneaker or a high heel. Such sensors have many potential applications, team leader Chwee Teck Lim tells C&EN, including artificial skins to enable prosthetics capable of delivering tactile sensations.