This wearable runs on sweat and can tell how healthy you are

Sweating could soon mean personalized health monitoring, thanks to a finger wrap gadget.

Though small, fingers have many sweat glands – over a thousand each. They produce 100 to 1000 times more sweat than most other body parts, even when you’re at rest.

This knowledge inspired engineers at the University of California, San Diego, to create an electronic finger wrap that monitors vital chemical levels in your body. By using fingertip sweat, the gadget can not only fuel its own battery but also determine the levels of glucose, vitamins, and drugs.

“It’s based on a remarkable integration of energy harvesting and storage components, with multiple biosensors in a fluidic microchannel, along with the corresponding electronic controller, all at the fingertip,” said Joseph Wang, the research lead.

To wrap up around the fingertip firmly and allow movement, the gadget is made out of stretchable polymer material with electronic components printed onto it.

Biofuel cells are positioned where the device contacts the fingertip. These cells have been specially engineered to efficiently collect and convert the chemicals in sweat into electricity, which is stored in a pair of stretchable silver chloride-zinc batteries.

The device has four sensors that track specific biomarkers: glucose, vitamin C, lactate, and levodopa (a Parkinson's drug).

Sweat moves through tiny paper channels to these sensors, which analyze the levels of these biomarkers. The device uses the sweat for power and sends the data to a smartphone or laptop app via Bluetooth.

During trials, the testers wore the device throughout the day. The device monitored glucose levels during meals, lactate levels during both desk work and exercise, vitamin C levels while drinking orange juice, and levodopa levels after eating fava beans, a natural source of the compound.

“This is automatic health monitoring at your fingertips,” said study co-first author Shichao Ding, a postdoctoral researcher in Wang’s research group at the UC San Diego Jacobs School of Engineering. “The wearer can be resting or asleep, and the device can still harvest energy and track biomarker levels.”

Researchers believe that the device can be tailored to meet individual health needs by detecting various biomarkers. The researchers are working on developing a system that could also administer treatments based on the collected data.

For instance, it would be useful for people with diabetes, as a device could continuously monitor glucose levels and automatically deliver insulin as needed.

“Autonomous power, sensing, and treatment all in one device – that’s the ultimate goal,” concludes Ding.

The research paper was published in Nature Electronics on September 3rd.