Diabetics' wearable sensor seeks sugar in sweat

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A prototype of the biosensor, with a US quarter for scale(Credit: University of Texas at Dallas)

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In order to monitor their blood glucose levels, diabetics typically have to perform finger-prick blood tests as often as several times a day. Thanks to research being conducted by scientists from the University of Texas at Dallas, however, a non-invasive alternative may be on the way. Led by Dr. Shalini Prasad, a team at the university is creating an electrochemical biosensor that continuously measures glucose in the wearer's sweat.

The flexible device incorporates stacked metal/metal-oxide thin films within a porous polymer-based textile, and utilizes the same basic chemistry and enzymatic reaction found in blood glucose testing strips. That said, instead of being able to analyze a full drop of blood, the sensor will have to make do with the small amount of sweat that would be present on the skin underneath an adhesive patch, or perhaps beneath a health-tracking watch.

Dr. Shalini Prasad (right) and doctoral student Rujuta Munje, who helped design the sensor(Credit: University of Texas at Dallas)

To address this challenge, the scientists designed the sensor in such a way that a very small amount of sweat can spread evenly across its underside, making full contact with the integrated electrodes. Additionally, the surface topography of the polymer has been altered in such a way that it traps glucose oxidase molecules, essentially amplifying their signal.

The sensor also compensates for the fact that throughout the day, the chemical composition of a person's sweat can change. More specifically, the pH can go up or down, plus exercise or stress can cause increases in compounds such as cortisol and lactic acid.

All told, in order to get an accurate reading, less than a microliter of sweat is required – that's about as much liquid as "would fit in a cube the size of a salt crystal."

Although the prototype has already been successfully tested on human sweat samples, a consumer version is likely still a few years away. In the meantime, diabetics might also want to keep an eye on similar sweat-analyzing technologies being developed by the University of Cincinnati, Korea's Institute for Basic Science and Fraunhofer.

The research was described in a paper recently published in the journal Sensors and Actuators B: Chemical.

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