People with diabetes need to closely monitor their blood glucose levels multiple times every day, usually using a device that pricks their finger for a blood test to assess whether they need insulin shots or other drugs. Since blood collection and shots can be painful, not all patients do it as regularly as they need to—which can lead to dangerous fluctuations in their blood glucose levels.
Disposable sweat patch is currently being developed by Eccrine Systems that could calculate the amount of glucose in the blood.
For people with diabetes, this could represent an end to finger pricking in order to obtain a drop of blood when measuring blood glucose levels.
Advanced sweat sensors for medicine, industry and sport. Eccrine Systems and other researchers are currently developing sweat patch that can calculate the amount of glucose in the blood.
Eccrine Systems® is developing non-invasive, electronic wearable systems that measure and transmit real-time data about human sweat.
The ability to monitor sweat biomarkers with chronological accuracy is the key to attaining market-enabling improvements in the predictive value of non-invasive wearables data – across a wide spectrum of applications for medicine, industry, and sport.
How does the patch work?
Eccrine Systems’ multiple layer patch design manages the flow of sweat so data, known as “biomarkers”, can be collected about how the body behaves. This information includes glucose, hormones, proteins and other molecules that are produced during metabolism.
Co-founder Jason Heikenfeld, PhD, is working on a sweat patch that can monitor a person’s health from their sweat after detecting these biomarkers.
Similarly researchers in Korea have just developed a wearable, and potentially disposable, glucose monitoring and drug-delivery system that uses sweat, not blood, to determine glucose levels.
The results, published today in Science Advances, suggest it’s a major upgrade. There are several differences between the artificial pancreas and the sweat-based monitoring system, according to lead author Hyunjae Lee, of Seoul National University in the Republic of Korea. While both devices can check blood glucose in real time and deliver necessary drugs, the artificial pancreas’s drug-delivery needles are permanently embedded subcutaneously, and the device itself is made of rigid plastic, which “might cause discomfort,” Lee tells mental_floss.
The sweat-based system, on the other hand, is transfer-printed onto a thin silicone skin patch. It’s made of flexible and stretchable electronics, a series of stretchable graphene sensors—humidity, glucose, pH, and temperature—packed as closely as possible. The sensors’ electrodes are made from porous gold nanoparticles, whose structure helps create an electrochemically active surface area in order to analyze what’s in your sweat. Above a heating strip, which helps create humidity and generate sweat more quickly, is a film strip of drug-loaded microneedles, 0.6 inches by 0.8 inches. These are loaded with metformin, a drug used to control glucose in Type 2 diabetes. (At present, the sweat-based patch has not been tested on insulin, whose molecules are too big for delivery through the microneedles, though Lee hopes to work on designing one that can work with insulin in the future.)
Sweat accumulates in the porous sweat-uptake layer of the patch, which also helps screen out negatively charged molecules, including drugs that may interfere with the glucose sensing. A waterproof band helps prevent the patch from peeling away from the skin. When the sweat covers the glucose and pH sensors, the measurements begin. “When blood glucose is high, [the] therapeutic part activates microneedle-based drug delivery,” automatically, Lee explains.
Researchers adhered the patch to five healthy human subjects, ages 20 to 60. It takes 10–15 minutes for the device to generate enough sweat to measure glucose levels, though exercise could speed that process up. However, Lee says they took into account that for some people with diabetes, “sweat generation through exercise could be a burden.” He adds, “Considering [that] point, we miniaturized sensor design that allows for reliable sweat analysis even with an infinitesimal amount of sweat.”
The participants’ blood glucose levels were tested using a commercial glucose meter one hour before and after a meal as a comparison. The researchers found that the sweat-glucose sensor measurements were comparable to those of a commercial blood glucose assay kit.
Human clinical trials are not yet scheduled for the drug-delivery process, so to test this part of the system, Lee’s team turned to mice. They took 16 diabetic mice, 8 to 12 weeks old, and fasted them overnight before the experiment. They attached drug-loaded microneedles to their shaved abdomens, which had been stained with a special blue dye. Then, they used an embedded heating element to activate the microneedles, since the mice can’t produce enough sweat to do so. The microneedles’ successful penetration of the skin was made visible by the blue dye.