Researchers at Penn State have developed a wearable sensor that can withstand the rigors of continuous monitoring of the body’s glucose levels in sweat.
Advanced sensing features are coming to wearables beginning in 2025 and Penn State’s device, made with laser-modified graphene nanocomposite material, will allow for the detection of specific glucose levels in sweat for three weeks while also monitoring body temperature and pH levels simultaneously.
“Sweat is ideal for real-time, continuous and noninvasive biomarker detection,” said Huanyu “Larry” Cheng, the James L. Henderson, Jr. Memorial associate professor of Engineering Science and Mechanics (ESM) at Penn State and principal investigator in the report. “But low biomarker concentration levels in sweat and variability of other factors such as pH, salinity and temperature have pushed previous sweat biosensors past the limits of their detection and accuracy. This device is able to account for this variability while measuring glucose with needed specificity for weeks at a time.”
How they did it
Researchers used a simple laser treatment to create a stable 3D network of gold and silver metal alloys and carbon-based nanocomposite materials on the porous LIG electrode. These metals are not just highly conductive but are also resistant to oxidation, Cheng said.
Heating the gold and silver alloy nanocomposite materials with the laser treatment allows it to resist agglomeration, a phenomenon where the nanoparticles coalesce into clusters, limiting the materials surface area.
“Glucose on the surface of the modified LIG electrode oxidizes at lower potential,” said Farnaz Lorestani, ESM postdoctoral scholar and researcher on the project. “This oxidation generates a measurable current or potential change that is directly proportional to the overall glucose concentration in the solution. We also see far greater stability over time, with the laser-treated sensor losing only 9% of its sensitivity over three weeks compared to 20% sensitivity loss for a sensor without laser treatment.”
Fabrication
To fabricate the wearable, the researchers combined the dual glucose and pH sensor with another LIG-based temperature sensor and a stretchable layer with coil-shaped microfluidic channels to continuously collect and route sweat for sampling.
The device allows for the calibration of glucose measurements based on fluctuations in sweat pH and body temperature from activities such as exercise or eating, Cheng said.
It would be deployed as a patch roughly about the size of a postage stamp and affixed to the skin with adhesive tape. It can wirelessly communicate with a computer or mobile device for real-time monitoring and analyzing data.
“The result of our work is a sensor with the notable sensitivity and stability to monitor glucose levels over multiple weeks,” Cheng said. “It is a low-cost platform offering convenient, accurate and continual analysis of sweat in diverse conditions, which has great potential for individual and population health, personalized medicine and precision nutrition.”
The full research can be found in the journal Wiley Advanced.
