The key facts

  • The wearable patch prototype was made on a substrate of hanji paper from mulberry fibers
  • The microneedles were printed using light-based 3D printing; about 56% of the model substance was released over 80 hours
  • The uric acid sensor operated in the range of 0.01–8 µmol/L and agreed with mass spectrometry

A paper base for a wearable patch

Researchers at Jeonbuk National University in South Korea have developed a prototype of a breathable patch based on traditional Korean hanji paper, reports Gazeta.Ru. The device combines microneedles for potential drug delivery with an electrochemical sensor for uric acid in sweat; the work was published in the journal Chemical Engineering Journal.

Why hanji

Conventional substrates for wearable devices can trap moisture and interfere with sweat evaporation. The network of plant fibers in mulberry paper, by contrast, lets moisture pass through, which is why it was chosen as the base for the prototype.

Test results

The microneedles were fabricated on the paper substrate using light-based 3D printing without an additional adhesive layer. Modifying their geometry made it possible to increase the payload of a model substance: over 80 hours, about 56% of the loaded model dye was released. On isolated rat skin, the needles penetrated approximately 954 micrometers while retaining their structure.

Sweat sensor

Separately, the researchers tested the uric acid sensor: it operated in the range of 0.01 to 8 micromoles per liter, and the analysis of sweat samples agreed with laboratory mass spectrometry. A wireless module allowed the sensor readings to be transmitted. All reported results were obtained on a prototype under laboratory conditions; no clinical trials are mentioned in the publication. Earlier, according to the same outlet, a transparent scaffold for corneal regeneration was created in Russia.