Paper-Based Biodegradable Microneedle Patches Take the Pain Out of Blood-Glucose Testing

Simply pressing the patch against your skin would be enough to get an accurate blood-glucose reading, without the need for a finger-prick.

Researchers from the Institute of Industrial Science at the University of Tokyo may have found a way to take all the little pricks out of blood-sugar monitoring, thanks to a paper patch based on microneedles which they say offers a "painless" test — and has the benefit of being fully biodegradable.

Traditional blood-glucose monitoring, key in managing diabetes, involves taking a sample of blood — usually by pricking the patient's finger. By contrast, the patch developed by a team led by Beomjoon Kim is simply pressed against the skin — and uses microneedles, too small to be felt by the wearer, to draw liquid up into a disposable, biodegradable paper sensor.

The patches are constructed by melting a polymer, mixing it with salt, and pouring in into a heated "micro-mold" which shapes the tiny needles. The entire assembly is then flipped over and pressed onto paper, which forces the polymer mixture into the paper and secures it in place ready for a process which rapidly cools the device and removes the salt — leaving behind tiny pores through which fluid can flow. Finally, the paper microneedle patch is attached to an off-the-shelf paper glucose sensor.

The paper-based patch has not yet been tested on humans. (📹: University of Tokyo)

The team has yet to test the technology on humans, but in experimentation with an agarose gel containing dissolved glucose the paper sensors reacted exactly as expected — changing colour to reflect the concentration of glucose. A similar technology, though based on silk with colour-changing bioink, for detecting food spoilage through packaging, was unveiled by the Massachusetts Institute of Technology (MIT) earlier this month.

Glucose testing is only one potential use-case for the paper patches, too: ""Of course, pre-diabetes testing is just one application of the technology," explains first author Hakjae Lee. "The paper-based sensor can vary depending on the biomarker you wish to monitor."

The team's work has been published under closed-access terms in the journal Medical Devices & Sensors.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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