Paper-Based Patch Integrates Sweat Sensors and Drug-Delivery Microneedles

Poor breathability can trap sweat and cause skin discomfort. It can also reduce the reliability of sweat collection for biochemical monitoring. To help address this challenge, researchers have developed a breathable paper-based patch that combines sensing and potential drug delivery.

Researchers at Jeonbuk National University (Jeonju, South Korea) developed a breathable theranostic patch using traditional Korean mulberry paper, or hanji. The platform combines light-based 3D-printed microneedles with printed electrodes for wireless uric acid sensing. The study was published in the Chemical Engineering Journal.

The porous plant-fiber structure of the mulberry paper supports moisture transport across the patch surface. In experiments, the paper showed rapid wetting, with its water contact angle decreasing from 72.19° to 7.96° within six seconds. This property could help direct sweat toward the sensing electrodes while reducing moisture accumulation beneath the patch.

The microneedles were fabricated directly onto the mulberry paper substrate without requiring an additional adhesive layer. Following geometric modification, the optimized microneedles achieved a drug-loading capacity of 25.36%, compared with 12.6% for unmodified microneedles. They released 56.41% of a loaded model dye over 80 hours and penetrated approximately 954 micrometers into excised rat skin without structural deformation.

The printed electrochemical sensor detected uric acid across concentrations ranging from 0.01 to 8 micromolar, with a detection limit of 9.3 nanomolar. Testing in buffer and sweat produced recoveries of 98.1% to 101.3%, consistent with liquid chromatography–mass spectrometry analysis. The sensor dried within 13 seconds after use, produced consistent readings over three consecutive uses, and transmitted data through a wireless board drawing approximately 15 mW at peak.

Because uric acid is a marker associated with gout and hyperuricemia, the sweat-based patch could eventually support at-home monitoring without repeated blood draws. The researchers next plan to test clinically relevant uric acid-lowering drugs, conduct skin-safety studies, and evaluate the platform for real-time on-body monitoring.

“Conventional wearable patches often struggle to balance skin comfort with reliable sweat collection. By using breathable mulberry paper, we aimed to develop a platform that supports moisture transport while accommodating both microneedles and printed sensing electrodes,” said Professor Sooman Lim of Jeonbuk National University.

“Our findings demonstrate the potential of combining microneedle-based delivery and wireless sweat sensing on a single breathable substrate. Although we evaluated these functions separately, the results provide a foundation for future devices that could integrate treatment and real-time health monitoring,” added Professor Lim.

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Jeonbuk National University