Structurally Engineered All-Polymeric Microneedle Sensor for Highly Sensitive and Real-Time Monitoring of Glucose in Interstitial Fluids

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia with multiple clinical manifestations and complications, such as cardiovascular disease, kidney dysfunction, retinal impairment, and peripheral neuropathy. Continuous and minimally invasive glucose monitoring is essential for effective DM management. Microneedles (MNs)-based sensing platforms offer a promising solution; however, conventional polymeric MNs suffer from limited electrochemical sensitivity due to their insufficient electroactive surface area and inefficient loading of catalytic and enzymatic components. Herein, we present a fully polymeric, high-sensitive glucose sensor based on structurally engineered mushroom-shaped MNs. The MNs were fabricated from a biocompatible composite of triethylene glycol dimethacrylate (TEGDMA) and diurethane dimethacrylate (DUDMA) and further functionalized with poly(3,4-ethylenedioxythiophene)/tosylate (PEDOT/Tos) to enhance electron transport capabilities. A capillary-driven dip-coating process led to the deposition of Pt nanoparticles (Pt NPs)/PEDOT:PSS composite ink into the neck region of the MNs, resulting in localized loading of electrocatalytic material and a significant increase in electrochemical activity. Consequently, the mushroom-shaped MNs exhibited a 12.6-fold enhancement in current response to glucose compared to conical MNs, while maintaining a linear dynamic range between 2 and 20 mM. Furthermore, in vivo validation demonstrated real-time glucose tracking with strong agreement to commercial glucometer readings, and Clarke error grid analysis verified clinical accuracy. Collectively, these results underscore the utility of structural engineering in polymeric MNs to achieve reliable, continuous glucose monitoring for next-generation diabetes care.