Reviewed by Lexie CornerSep 4 2024
Engineers at the University of California, San Diego, have developed an electronic finger wrap that monitors key chemical levels in fingertip sweat, including vitamins, glucose, and medications, all while being powered by the same sweat. This innovation could make personalized, continuous health monitoring as easy as wearing a Band-Aid. The study was published in Nature Electronics.
This finger wrap is powered by the wearer's fingertip sweat—and also monitors levels of glucose, lactate, vitamin C, and levodopa in that same sweat. Image Credit: Shichao Ding
The research team led by Joseph Wang, a professor in the Aiiso Yufeng Li Family Department of Chemical and Nano Engineering at UC San Diego, was involved in the study.
The gadget, which fits snugly around the finger, harnesses power from the sweat produced by the fingertip. Fingertips, despite their small size, contain over a thousand sweat glands, making them one of the body's most active sweat producers. Even at rest, they can generate 100 to 1,000 times more sweat than most other parts of the body, providing a reliable energy source to power the device without requiring physical activity or external stimuli.
The device consists of multiple electronic components printed onto a thin, flexible, and stretchable polymer material. It comfortably conforms to the shape of the finger, while its durable design withstands repeated bending, stretching, and movement.
It is 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.
Joseph Wang, Professor, Aiiso Yufeng Li Family Department of Chemical and Nano Engineering, University of California, San Diego
At the core of the device's functionality are biofuel cells located where the gadget contacts the fingertip. These specially designed cells effectively gather the chemicals found in perspiration and transform them into electrical power. Two stretchable silver chloride-zinc batteries store this electricity, which powers four different sensors: glucose, lactate, vitamin C, and levodopa (a medication used to treat Parkinson's disease). Each sensor is responsible for monitoring a different biomarker.
The device generates energy from the sweat it samples while simultaneously analyzing biomarker levels. As sweat flows through tiny paper-based microfluidic channels to the sensors, the sensors process the biomarker data. A small chip within the device then processes the sensor signals and wirelessly transmits the information to a smartphone or laptop via a specially developed Bluetooth low-energy application.
This is automatic health monitoring at your fingertips. The wearer can be resting or asleep, and the device can still harvest energy and track biomarker levels.
Shichao Ding, Study Co-First Author and Postdoctoral Researcher, Jacobs School of Engineering, University of California, San Diego
The device was tested throughout the day to monitor various bodily functions, such as glucose levels during meals, lactate levels during exercise and desk work, vitamin C levels after drinking orange juice, and levodopa levels following the consumption of fava beans (a natural source of the compound)
According to Ding and co-first author Tamoghna Saha, by detecting distinct sets of biomarkers, the device can be tailored to meet the needs of individual patients. In addition to monitoring biomarkers, the researchers are working on creating a closed-loop system that will treat patients based on the information gathered. In the event of diabetes, for example, the device could automatically administer insulin when necessary and continuously monitor blood glucose levels. It could also measure the biomarker levels to determine how well the treatment worked.
Autonomous power, sensing, and treatment all in one device—that’s the ultimate goal.
Shichao Ding, Study Co-First Author and Postdoctoral Researcher, Jacobs School of Engineering, University of California, San Diego
Journal Reference:
Ding, S., et al. (2024) A fingertip-wearable microgrid system for autonomous energy management and metabolic monitoring. Nature Electronics. doi.org/10.1038/s41928-024-01236-7.