Micro Needles Used for Paper Patch Glucose Tests are Found Painless and Biocompatible

University of Tokyo has advanced a patch of microneedles connected to a paper sensor for diagnosing conditions such as prediabetes. These needles are too short to reach other neurons or cause pain.

Researchers have been trying to advance a way to use micro needles less than 1mm in length for daily medical monitoring. These needles are too short to reach other neurons or cause pain. These needles are developed in such a way that along with drawing the blood, they also draw certain fluids in the skin constituting few important biomarkers that are essential for blood tests. //

There are various types of micro needles but developing a practical device that analyzes the fluid rapidly has proved evasive. "We have overcome this problem by developing a way to combine porous micro needles with paper-based sensors, the result is low-cost, disposable, and does not require any additional instruments.", says Kim.

‘Paper patch test that uses micro needles is found painless, biodegradable, biocompatible and user friendly.’

Initially, the researchers poured a melted mixture of a biodegradable polymer and salt into the cone-shaped cavities of a micro-mold by applying heat to develop the micro needles. Then the mold and needles were flipped upside down and were placed on top of a piece of paper while applying pressure from above.

Due to high pressure, the mixture was forced into the pores of the paper, securing the attachment and allowing fluid drawn through the needles to pass effortlessly into the paper. After removing it from the mold, the needles were then cooled in a solution that removed out all the salt, leaving behind enormous pores.

Several salt concentrations were checked to examine the pores of the micro needles. They used double-sided tape to attach a paper glucose sensor onto the paper base of the needle array and completed the patch.

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Finally, the patch was tested on an agarose gel in which glucose had been dissolved. They observed that the fluid from the gel flowed into the pores of the micro needles and from there into the paper and ultimately to the sensor layer. As the color changed in the paper, the glucose concentration was recorded.

"Of course, prediabetes testing is just one application of this technology, the paper-based sensor can vary depending on the biomarker you wish to monitor.", says first author Hakjae Lee.

These patches are disposable, biodegradable, and can also be used without any medical expertise. They are not problematic even if they remain inside the skin since they are biocompatible.

Source-Medindia