Potential exposure to dangerous chemicals is a reality for many people working in mining and manufacturing, as well as medicine. While spills of liquids are easily detected, many gases are not. Sensitive wearable gas sensors stuck to the skin would be useful for gas exposure detection, but these devices have to be flexible, need a heating mechanism, and require an integrated electric power source to function. A team of collaborators from Penn State and Northeastern University brought their expertise together to create an inexpensive way to produce flexible and self-heating devices that can detect a variety of dangerous gases. The platform allows for a selection of chemicals to detect and devices made using this approach can be reused repeatedly. The technology relies on producing a highly porous laser-induced graphene (LIG) pattern in a metal that acts as a sensing component, but which also naturally heats up because of electric resistance when current moves through it. The electricity is supplied via a flexible connection with wavy silver wires within it, which can bend along with the skin to which the device is attached. This way the power source, which may be too bulky and uncomfortable for skin, can reside somewhere else nearby, such as within clothing. Manufacturing these kinds of sensors doesn’t require a cleanroom nor an expensive lithography process. Instead, cheap CO2 lasers are employed to create a variety of sensor types. The team is already able to detect sulfur dioxide and nitrogen dioxide, for example, using their platform and promise they can make dozens of other sensors this way. “Using a CO2 laser, often found in machine shops, we can easily make multiple sensors on our platform,” said Huanyu Cheng, assistant professor of engineering science and mechanics and materials science and engineering, Penn State, and one of the study leads. “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. Study in Journal of Materials Chemistry A: Novel gas sensing platform based on a stretchable laser-induced graphene pattern with self-heating capabilities Source
