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Silver nanowire sensors could be the flexible foundation for new wearables

Silver nanowire sensors could be the flexible foundation for new wearables

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A clear, bandage-like sensor could eventually make everything from fabrics to our fingers smart. Dr. Yong Zhu and a team of North Carolina State University researchers created an ultra-thin, flexible sensor that could be used in clothing, on the body, any in other ordinary objects to track things like strain, pressure, human touch, and bioelectronic signals.

The endeavor began in 2012 when Zhu developed elastic conductors made from carbon nanotubes. The technique he used was fairly simple: silver nanowires are placed on a silicon plate, and then a liquid polymer is poured over them and heated, converting it from a liquid to an elastic solid. The entire form is peeled off the silicon, now with the nanowires inside of it. That's the technology Zhu uses in this new sensor, which can be stretched 150 percent or more of its original length without losing functionality.

The sensor can stretch to 150 percent or more than its original length

In essence, it's a sensor that can store and monitor electric charges, or capacitance, in a super thin and stretchy form. An insulating material placed between two nanowire conductors gives the sensor capacitive abilities, and it can also measure capacitive differences caused by pushing, pulling, or touching the conductors. Capacitive sensors are already used in many devices including smart utensils and styluses, but they do not have much flexibility as they are just one part of a rigid, structured gadget. By stripping away the external device, Zhu is trying to bring flexibility back to these sensors, much like recently developed ultra-thin electronic tattoos, and open up a range of new uses for them.

Zhu and his researchers have already tested the sensors by putting them on thumbs to control robotic devices, and on knees to monitor running, walking, and jumping. There's still some time before they could be embedded into things like clothing or even skin, but that is the ultimate goal, and it's coming quickly.