Many people with diabetes endure multiple, painful finger pricks each day to measure their blood glucose. To prevent this, the device takes readings from a person’s sweat with the touch of a fingertip, and then a personalised algorithm provides an accurate estimate of blood glucose levels.
According to the American Diabetes Association, over 34 million children and adults in the US have diabetes. Although self-monitoring of blood glucose is a critical part of diabetes management, the pain and inconvenience caused by finger-prick blood sampling can keep people from testing as often as they should.
Scientists have developed ways to measure glucose in sweat, but because levels of sugar are much lower than in blood, they can vary with a person’s sweat rate and skin properties. As a result, the glucose level in sweat usually doesn’t accurately reflect the value in blood.
So to obtain a more reliable estimate of blood sugar from sweat, Joseph Wang from the Department of Nanoengineering at the University of California, San Diego, and his colleagues wanted to devise a system that could collect sweat from a fingertip, measure glucose, and then correct for individual variability.
A hand-held device combined with a touch sweat sensor (strip at right) measures glucose in sweat, while a personalised algorithm converts that data into a blood glucose level. Credit: Adapted from ACS Sensors 2021, DOI: 10.1021/acssensors.1c00139
Image credit: Adapted from ACS Sensors 2021, DOI: 10.1021/acssensors.1c00139
The researchers made a touch-based sweat glucose sensor with a polyvinyl alcohol hydrogel on top of an electrochemical sensor, which was screen-printed onto a flexible plastic strip. When a volunteer placed their fingertip on the sensor surface for one minute, the hydrogel absorbed tiny amounts of sweat. Inside the sensor, glucose in the sweat underwent an enzymatic reaction that resulted in a small electrical current that was detected by a hand-held device.
The researchers also measured the volunteers’ blood sugar with a standard finger-prick test, and they developed a personalised algorithm that could translate each person’s sweat glucose to their blood glucose levels. In tests, the algorithm was over 95 per cent accurate in predicting blood glucose levels before and after meals, the researchers reported.
According to the researchers, to calibrate the device, a person with diabetes would need a finger prick only once or twice per month. But they added that before the sweat diagnostic can help manage diabetes, experts must conduct a large-scale study on the device.
The study ‘Touch-Based Fingertip Blood-Free Reliable Glucose Monitoring: Personalised Data Processing for Predicting Blood Glucose Concentrations’ is published in ACS Sensors.