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Graphene sensor patch measures glucose levels in sweat and provides treatment

A graphene sensor patch has been developed that can measure blood glucose levels and also deliver treatment in response.
The patch was created at the Centre for Nanoparticle Research at South Korea’s Institute for Basic Science (IBS), and could remove the need for people with diabetes to prick their fingers, which many have to do up to multiple times per day.
The stretchable patch sits on the skin and analyses the glucose levels in sweat. An equivalent value for blood glucose is then provided.

Because grapheme is soft, think and flexible the patch can stretch and contract with the skin, ensuring it remains connected. This is important because the glucose level in sweat is known to rise and fall proportionally to the glucose level in blood, so the patch needs to constantly be able to provide treatment.
If blood glucose levels rise beyond a programmed amount, the patch triggers heaters embedded in the patch to dissolve the coating of medication loaded microneedles. This enables an appropriate amount of medication to be delivered.
The patch contains several sensors that detect other properties of sweat, such as humidity, pH and temperature. These sensors help eliminate the effect they have on sweat, and ensure the blood glucose readings are reliable.
In a new study, published in the journal Nature Nanotechnology, Professor Dae-Hyeong Kim of Seoul National University and colleagues showed that when the patch is heat-activated it delivered metformin through the skin of diabetic mouse models. The mice experienced a significant lowering of blood glucose levels compared to mice that weren’t connected to the patch.
Kim explained: “One can easily replace the used microneedles with new ones. Treatment with metformin through the skin is more efficient than that through the digestive system because the drug is directly introduced into metabolic circulation through the skin.
“It takes an average of 15 minutes for the sweat-uptake layer of the patch to collect sweat and reach a RH over 80 per cent at which time glucose and pH measurements are initiated.”
The patch has also been tested on two male participants, and the reliability of the figures was assessed against results from commercial glucose tests.
This research is at a very early prototype stage, but could prevent people from finger pricking multiple times a day, which remains the most common method of testing blood sugar levels. Moreover, the patch could lessen the need for people with diabetes to inject insulin or take other medication.
This month also saw the development of another patch: a synthetic insulin patch that contains live insulin-producing cells. This technology can control rising blood glucose levels for up to 10 hours at a time, and could signal the end of insulin injections.

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