Study shows that a highly sensitive, wearable gas sensor like an ”electronic nose” for environmental and human health monitoring may soon become commercially available.
The study was conducted by the 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. The study was published in the Journal of Materials Chemistry A. While other devices of this type require an external heater, this device allows for quick recovery and reuse of the device. According to the study, other wearable sensors require an expensive and time-consuming lithography process under cleanroom conditions, the study said.
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.”
For the results, the research 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, according to the study. The serpentine lines allow the device to stretch, like springs, to adjust to the flexing of the body for wearable sensors.
The nanomaterials used in this work are reduced graphene oxide and molybdenum disulfide, or a combination of the two; or a metal oxide composite consisting of a core of zinc oxide and a shell of copper oxide, representing the two classes of widely used gas sensor materials — low-dimensional and metal oxide nanomaterials.
“Using a CO2 laser, often found in machine shops, we can easily make multiple sensors on our platform,” Cheng said. “We plan to have tens to a hundred sensors, each selective to a different molecule, like an electronic nose, to decode multiple components in a complex mixture.”

Source: Outlook India, ANI news, Phys.org

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