The field of wearable health monitoring is in need of innovative solutions that can overcome the current limitations related to energy supply, sensing capabilities, circuitry regulations, and form factors.
Imagine a world where continuous, personalized health monitoring is as effortless as wearing a Band-Aid. The University of California, San Diego, is developing a sweat-powered wearable that will make this vision a reality.
Engineers have designed an electronic finger wrap that not only derives its energy from fingertip sweat but also monitors vital chemical levels, including glucose, vitamins, and even drugs. This breakthrough has the potential to revolutionize health monitoring and empower individuals to take control of their well-being effortlessly.
Harnessing the mysterious power of our own fingertips, this innovative device wraps snugly around the finger and draws energy from an unexpected source—the natural sweat produced by our bodies. Despite their small size, our fingertips are among the most proficient sweat generators in the human body, with over a thousand sweat glands packed into each one.
What’s more, these tiny powerhouses can produce 100 to 1000 times more sweat than most other areas of the body, even during periods of rest. This continuous flow of natural perspiration provides a consistent and reliable energy source, powering the device even during periods of inactivity or sleep.
The device itself is a marvel of engineering, constructed from cutting-edge electronic components printed onto a thin, flexible, and stretchable polymer material. Its innovative design allows it to conform comfortably to the finger while remaining durable enough to withstand 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,” said Wang.
At the heart of its functionality are cutting-edge biofuel cells strategically positioned where the device comes into contact with the fingertip. These specially engineered cells effectively gather and convert sweat chemicals into electricity. This generated electricity is then stored in a pair of flexible, silver chloride-zinc batteries, which power a suite of four sensors.
Each sensor is dedicated to monitoring a specific biomarker: glucose, vitamin C, lactate, and levodopa, a crucial drug for Parkinson’s disease treatment.
As sweat is drawn through tiny paper microfluidic channels to these sensors, the device evaluates the biomarker levels while harnessing the necessary energy from the very sweat it’s analyzing. A compact chip processes signals from the sensors and wirelessly transmits the data via Bluetooth low energy to a custom-designed smartphone or laptop application.
“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.”
During the tests, a participant wore the cutting-edge device all day, enabling real-time monitoring of glucose levels during meals, lactate levels during both sedentary and active periods, vitamin C levels while consuming orange juice, and levodopa levels after ingesting fava beans, a natural source of the compound.
Ding and co-first author Tamoghna Saha emphasize the device’s ability to be personalized for individual health needs by detecting various sets of biomarkers. Moreover, the researchers are diligently working on creating a closed-loop system that not only monitors biomarkers but also delivers treatments based on the gathered data.
For instance, in the context of diabetes, such a device could continually monitor glucose levels and automatically administer insulin as required, followed by evaluating the treatment’s effectiveness through continued biomarker level monitoring.
Journal reference:
- Shichao Ding, Tamoghna Saha, Lu Yin, Ruixiao Liu, Muhammad Inam Khan, An-Yi Chang, Hyungjin Lee, Han Zhao, Yuanzhe Liu, Ariane Sina Nazemi, Jiachi Zhou, Chuanrui Chen, Zhengxing Li, Chenyang Zhang, Sara Earney, Selene Tang, Omeed Djassemi, Xiangjun Chen, Muyang Lin, Samar S. Sandhu, Jong-Min Moon, Chochanon Moonla, Ponnusamy Nandhakumar, Youngmin Park, Kuldeep Mahato, Sheng Xu & Joseph Wang. A fingertip-wearable microgrid system for autonomous energy management and metabolic monitoring. Nature Electronics, 2024; DOI: 10.1038/s41928-024-01236-7