A highly sensitive, wearable gas sensor for environmental and human health monitoring may soon become commercially available, according to researchers at Penn State and Northeastern University.
The sensor device is an improvement on existing wearable sensors because it uses a self-heating mechanism that enhances sensitivity. It allows for quick recovery and reuse of the device. Other devises of this type require an external heater. In addition, other wearable sensors require an expensive and time-consuming lithography process under cleanroom conditions.
Hand and arm showing sensor applied to inner write with moble phone sized read beside it.
“People like to use nanomaterials for sensing because their large surface-to-volume ratio makes them highly sensitive,” said Huanyu Cheng, assistant professor of engineering science and mechanics and materials science and engineering, Penn State. “The problem is the nanomaterial is not something we can easily hook up to with wires to receive the signal, necessitating the need for something called interdigitated electrodes, which are like the digits on your hand.”
Cheng and his team use a laser to pattern a highly porous single line of nanomaterial similar to graphene for sensors that detect gas, biomolecules, and in the future, chemicals. In the non-sensing portion of the device platform, the team creates a series of serpentine lines that they coat with silver. When they apply an electrical current to the silver, the gas sensing region will locally heat up due to significantly larger electrical resistance, eliminating the need for a separate heater. The serpentine lines allow the device to stretch, like springs, to adjust to the flexing of the body for wearable sensors.
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