Self-Powered Microneedle Patch Collects Biomarker Samples Without Drawing Blood

Conventional testing usually requires blood samples, which are unpleasant for patients and challenging for healthcare providers due to the need to separate platelets and red blood cells before analysis. Now, researchers have developed a wearable patch capable of collecting cleaner samples from the skin within minutes, without blood draws or external power.

The self-powered microneedle patch created by researchers from North Carolina State University (Raleigh, NC, USA) is a fully passive system that does not rely on batteries or external energy sources. The patch contains four layers: a polymer housing, a gel, a layer of paper, and microneedles. When applied, the microneedles swell as they absorb interstitial fluid (ISF), which wicks through to the paper layer. Osmotic pressure created by glycerol in the gel then draws more ISF until the paper is saturated, storing the sample for later testing.

In proof-of-concept testing, the patch was applied to synthetic skin models to evaluate its sampling ability. Researchers demonstrated its capability by monitoring cortisol, a stress biomarker that fluctuates throughout the day. The findings, published in Lab on a Chip, show that the device successfully collected measurable biomarker samples in as little as 15 minutes and preserved them for up to 24 hours.

The patch offers a low-cost and minimally invasive alternative to blood tests, as it avoids needles, vials, and phlebotomists. Made from widely available materials, the main cost lies in microneedle manufacturing, but overall expenses are expected to remain competitive with traditional methods. Human trials are already underway, and researchers have also developed electronic readers to measure biomarkers such as cortisol directly from the patch’s paper strip.

This new technology could allow patients to monitor biomarkers like cortisol multiple times a day without repeated blood draws. Its design may extend to a wide range of biomarkers found in interstitial fluid, supporting both clinical diagnostics and at-home monitoring. Researchers are now seeking industry partners to expand diagnostic applications and scale up production for broader clinical use.

“The highest cost of the patches would be manufacturing the microneedles, but we think the price would be competitive with the costs associated with blood testing,” said Professor Michael Daniele, corresponding author of the study. “Drawing blood requires vials, needles and – usually – a phlebotomist. The patch doesn’t require any of those things.”

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North Carolina State University