The system is a disposable, double-sided electrochemical sensing film that attaches to the underside of a smartwatch. It looks for chemical indicators found in sweat to give a real-time snapshot of what's happening inside the body.
While current smartwatches are able to monitor some health indicators, say the researchers, they are unable to monitor body chemistry. For that, they need to track biomarker molecules found in body fluids that are highly specific indicators of health - such as glucose and lactate - that tell how well body metabolism is working.
To address that need, the researchers designed the electrochemical sensing film to detect molecules such as metabolites and certain nutrients that are present in body sweat in very tiny amounts. The researchers also built a custom smartwatch and an accompanying app to record data.
"The inspiration for this work came from recognizing that we already have more than 100 million smartwatches and other wearable tech sold worldwide that have powerful data-collection, computation and transmission capabilities," says study leader Sam Emaminejad, an assistant professor of electrical and computer engineering at the UCLA Samueli School of Engineering. "Now we have come up with a solution to upgrade these wearables into health monitoring platforms, enabling them to measure molecular-level information so that they give us a much deeper understanding of what's happening inside our body in real time."
The skin-touching side of the adhesive film collects and analyzes the chemical makeup of droplets of sweat while the watch-facing side interfaces with circuitry that converts the chemical signals into electrical ones that can be read, processed, and then displayed on the smartwatch. The film incorporates enzymatic-sensing layers that specifically target glucose and lactate, which indicate body metabolism levels, and nutrients such as choline.
"By making our sensors on a double-sided adhesive and vertically conductive film, we eliminated the need for the external connectors," says graduate student Yichao Zhao, a co-lead author of a paper