Scientists have created a sensor that overcomes current problems requiring external heaters where the newly developed one is a highly sensitive, wearable gas sensor capable of tracking the environment and human health conditions.

FREMONT, CA: Researchers at Penn State and Northeastern University have developed a sensor overcoming the challenges of existing ones that require an external heater. The newly developed one is a highly sensitive, wearable gas sensor that can monitor the environment and human health conditions. The sensor incorporates a self-heating mechanism that enhances sensitivity. It is advantageous over others as it does not require an expensive and time-consuming lithography process under cleanroom conditions. Also, it allows for quick recovery and reuse of the device.

Most people stick to using nanomaterials for sensing owing to their large surface-to-volume ratio that is responsible for their high sensitivity. However, it is not easy to hook up to nanomaterials with wires to receive the signal as it requires interdigitated electrodes.

Here, the research team uses 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. Also, the team creates a series of serpentine lines and coats it with silver in the non-sensing portion of the device platform. On applying an electrical current to the silver, the gas sensing region gets heated up owing to the larger electrical resistance. The serpentine lines incorporate the ability to stretch the device like springs, thereby adjusting to the flexing of the body for wearable sensors.

The researchers have utilized the two classes of widely used gas sensor materials—low-dimensional and metal oxide nanomaterials. It includes 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. They are further planning 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.

According to the researchers, the U.S. Defense Threat Reduction Agency is showing an inclination towards this wearable sensor to o detect chemical and biological agents that can potentially damage the nerves or lungs. One of the medical device companies is working with the team to maximize production for patient health monitoring, including gaseous biomarker detection from the human body and environmental detection of pollutants that can affect the lungs.

The team is looking forward to creating high-density arrays while trying ideas that can improve the signal and make the sensors more selective using machine learning to identify the distinct signals of individual molecules on the platform.

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