Most effective exercise programs include a stretching component. During the past few years, developments in stretchable sensors and batteries indicate that stretching is a good feature for wearable medical and health technology as well. We’ve written about stretchable sensors that monitor pH, enhance rehabilitation, sense touch with on-skin displays, and much more.

Engineers in the Penn State Department of Engineering Science and Mechanics published a report on stretchable, wearable sensors that detect human biomarkers and toxic gases. The report published in Trends in Analytical Chemistry summarizes advancements in the materials, materials, applications, performance, challenges, and future prospects of stretchable gas sensors.

Stretchable gas sensors employ gas-sensitive nanomaterials applied to stretchable structures in the form of nanoparticles or nanowires. The Penn State team leader Professor Huanyu Cheng points out that human skin perspiration and exhaled breath can contain about 2,600 different biomarkers in gas form. Researchers can leverage the data from these gaseous biomarkers to develop diagnostics for a wide range of diseases and conditions. The same sensors can also detect toxic gases that might be present in the environment, such as methane in coal mines.

The metal-oxide gas sensors that are commonly used in current gas sensors operate at high temperatures; this rules them out for wearables, according to Cheng. The Penn State team is developing a platform that uses laser-induced graphene (LIG) with laser scripting. LIG can integrate with carbon-based or metal oxide nanomaterials that are highly sensitive to gas. The resulting film transferred to a soft substrate with a conductive coating reduces resistance, creating a gas-sensing platform that operates at much lower temperatures.

Cheng’s team continues to study how various shapes of composite materials affect their ability to sense environmental gases. Development goals include finding gas-sensing nanomaterials with high sensitivity, distinct selectivity, fast response, and wide detection limits.