A wireless, battery-free microneedle patch with light-cured swellable hydrogel for minimally-invasive glucose detection

The escalating global prevalence of diabetes necessitates the development of advanced diagnostic methodologies that are both minimally invasive and devoid of discomfort. This study introduces a wireless battery-free passive microneedle patch with CMC-pHEA GelMA-GOx (CMC: sodium carboxymethyl cellulose; pHEA: polyethylene glycol diacrylate, 2-hydroxyethyl acrylate; GelMA: gelatin methacryloyl; GOx: glucose oxidase) light-cured swellable hydrogel for minimally-invasive glucose detection. The core of this technology combines microneedle with Radio-Frequency (RF) coupling detection, achieving extraction capacity; the microneedle lies in the use of composite hydrogel composed of a freeze-dried CMC-pHEA nanogel and GelMA-GOx, specifically fabricated to be selectively glucose-responsive through cross-linking with glucose oxidase. Upon exposure to interstitial fluid, the hydrogel microneedles swell in proportion to the glucose concentration, enabling glucose binding and facilitating the detection process. A flexible antenna, which is integral to the microneedle substrate as a passive sensing component, detects changes in the swelling of the hydrogel; these are reflected in the RF parameters (frequency, magnitude) variations, which are directly correlated with glucose levels. Furthermore, the results are near field wirelessly detected through a reading coil, simplifying sensing patch configurations. This method not only integrates the glucose monitoring process by combining extraction and detection into a single step but also enhances patient comfort. The platform's sensitivity, specificity, and minimal invasiveness make it a promising tool for diabetes management and continuous glucose monitoring. By demonstrating the successful application of RF technology in wireless sensing applications, this study paves the way for advanced, user-friendly glucose monitoring solutions.