Abstract
Continuous metabolic monitoring plays a pivotal role in managing chronic conditions such as diabetes mellitus and evaluating physiological responses to physical exertion or metabolic stress. Traditional venous and capillary blood sampling methods are invasive, episodic, and poorly suited for dynamic, real-time physiological tracking. Here, we report the development and systematic evaluation of a wearable, flexible nanosensing platform based on laser-induced graphene (LIG) integrated with a minimally invasive hollow microneedle array for simultaneous, multiplexed monitoring of glucose and lactate in dermal interstitial fluid (ISF). The working electrodes were engineered via CO2 laser scribing on polyimide, followed by the electrodeposition of platinum nanoparticles (PtNPs) to provide a high-surface-area catalytic interface. Specificity was achieved by immobilizing glucose oxidase (GOx) and lactate oxidase (LOx) onto distinct sensing channels, shielded by a permselective Nafion/chitosan composite membrane to mitigate biofouling and electroactive interference. The resulting biosensor demonstrated high sensitivities of 24.8 µA·mM⁻¹·cm⁻² for glucose and 18.2 µA·mM⁻¹·cm⁻² for lactate, broad linear dynamic ranges encompassing physiological ISF concentrations (0.1–25.0 mM and 0.5–20.0 mM, respectively), low limits of detection (15 µM and 40 µM), and rapid response times of under 5 seconds. Ex vivo transdermal validation using porcine skin confirmed robust fluid extraction and stable sensor response under continuous mechanical deformation. This integrated nanoplatform presents a versatile paradigm for decentralized, non-invasive metabolic profiling and personalized health monitoring.
