Engineers at the University of California, San Diego, have developed an innovative electronic finger wrap that can continuously monitor vital chemical levels, including glucose, vitamin C, and medications. The wrap is powered by the wearer’s fingertip sweat. This groundbreaking technology could make personalized health monitoring as simple as wearing a Band-Aid.
The device, which fits snugly around the finger, consists of multiple electronic components printed onto a thin, flexible, stretchable polymer material. Its design allows it to conform comfortably to the finger while being durable enough to withstand repeated bending, stretching, and movement. Professor Joseph Wang, who led the research team, described it as “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.”
Fuel cells positioned where they contact the fingertip are at the core of the device’s functionality. These specially engineered cells efficiently collect and convert chemicals in sweat into electrical power, which is then stored in two stretchable silver chloride-zinc batteries. This energy powers four sensors, each tasked with monitoring a specific biomarker: glucose, vitamin C, lactate, and levodopa (a medication used to treat Parkinson’s disease).
The fingertip wearable relies on several key engineering concepts:
Biofuel Cells: The device uses biofuel cells to harvest energy from sweat. These electrochemical cells convert chemical energy from sweat into electrical energy through redox reactions. The cells likely use enzymes or microbes as catalysts to facilitate these reactions with the specific compounds in sweat.
Microfluidics: Tiny paper-based microfluidic channels wick the sweat from the skin to the sensors. Microfluidics is the science of manipulating and controlling fluids in channels with dimensions from tens to hundreds of micrometres. Capillary action moves the sweat through the paper without the need for pumps.
Biosensors: Each sensor is an electrochemical biosensor that detects a specific biomarker. Biosensors combine a biological recognition element, like an enzyme, with a physicochemical transducer to generate a measurable signal proportional to the concentration of the target analyte. The enzymes likely undergo redox reactions with the biomarkers, producing an electrical current.
Flexible Electronics: The electronic components are printed on a stretchable polymer substrate, enabling the device to conform to the finger. Unlike rigid silicon-based electronics, flexible electronics utilize materials like conductive inks and polymers that can bend and stretch without damage.
Wireless Communication: A small chip processes the sensor signals and wirelessly transmits the data via Bluetooth low energy (BLE) to a smartphone app. BLE is a power-efficient short-range wireless communication protocol commonly used in wearables.
In real-world tests, a subject wore the device to track glucose levels during meals, lactate during desk work and exercise, vitamin C while drinking orange juice, and levodopa after eating fava beans. The researchers say the device can be customized to monitor different health markers based on individual needs.
Looking ahead, the team is working towards a closed-loop system that could both monitor biomarkers and deliver treatments. For example, a diabetes device could continuously track glucose and automatically administer insulin when needed, then assess the treatment’s effectiveness. Co-first author Shichao Ding described the ultimate goal as “autonomous power, sensing and treatment all in one device.”
This sweat-powered fingertip wearable represents a significant step towards making continuous health monitoring effortless and personalized. If successful, this technology could transform how we manage chronic conditions and enable earlier detection of health issues, improving outcomes and quality of life for many.
TLDR:
- UCSD engineers developed a sweat-powered electronic finger wrap that continuously monitors glucose, vitamins, and medications
- The device uses biofuel cells to harvest energy from sweat and power sensors for each biomarker.
- Potential future applications include a closed-loop system for detecting and treating health conditions like diabetes.
- This technology could make personalized, continuous health monitoring as easy as wearing a Band-Aid.
