Abstract: Enzyme-free electrochemical sensing avoids the stability issues and complex immobilization associated with natural enzymes. Here, a ternary Pt-Cu@PDA-rGO composite was prepared, in which polydopamine (PDA) reduces graphene oxide (GO) and anchors Pt-Cu alloy nanoparticles, suppressing agglomeration and enhancing electron transfer. The resulting electrode shows a linear response to glucose from 0.1 to 25 mM (R2 > 0.99), a sensitivity of 2.39 μA·mM?1·cm?2, a detection limit of 0.21 mM, and storage stability over six weeks. A 15 × 15 porous poly(glycidyl methacrylate) (PGMA) microneedle array was fabricated by micromolding, with a force of 0.17 N per needle at 300 μm displacement, sufficient for skin penetration. Applying 1.5 V reverse iontophoresis enhanced interstitial fluid (ISF) extraction, reaching 92.4 mg within 15 min. The microneedle array, reservoir chamber, Pt-Cu@PDA-rGO electrode, and a custom PCB were integrated into a single device. The extracted ISF is retained in the reservoir, where glucose is detected in situ. The signal is processed and transmitted via Bluetooth, and a universal port allows electrode replacement. In vivo studies in rats over 4.5 h and 12 h showed that the device tracked glucose fluctuations in agreement with a commercial glucometer, with a mean absolute relative difference (MARD) below 10% and all data points within zone A of the Clarke error grid. After 12 h of wear, TUNEL staining and IL-6 immunohistochemistry revealed no significant increase in apoptosis or inflammation. Overall, this integrated platform provides a minimally invasive and enzyme-free route to in situ glucose monitoring, showing promise for further development.

Keywords: Pt?Cu@PDA?rGO, enzyme-free glucose sensor, porous microneedle, reverse iontophoresis, interstitial fluid