Hydrogel-based electrochemical microneedles biosensor for sensitive monitoring of lactic acid in interstitial fluid

Lactic acid is a critical biomarker for pathology and physiological status in health and sports. Current monitoring relies on invasive blood tests performed by professionals in clinical settings, limiting accessibility, frequency, and real-time insight. This creates a significant barrier to personalized health and performance management. There is a clear need for a painless, portable, user-operable method to enable continuous lactic acid monitoring outside the lab.

We present a portable hydrogel microneedle (MN) biosensor for rapid, continuous, and painless lactic acid detection in interstitial fluid (ISF). The device features a detachable electrode integrated into a MN patch, enabling both in-home and mobile use. It achieves real-time data transmission for user health management. Key performance metrics include a wide linear detection range up to 2 mM, high sensitivity of 19.45 μA mM^-1 cm^-2, and a low limit of detection of 3.6 μM, demonstrating its capability for accurate physiological monitoring.

This work provides a minimally invasive, cost-effective alternative to blood-based lactic acid testing, significantly improving patient compliance and accessibility. Its portability and real-time data capabilities empower individuals to proactively manage health and athletic performance. This technology represents a paradigm shift towards user-friendly point-of-care monitoring, with transformative potential for personalized healthcare and sports science applications.