Wearable self-powered electrochemical sensor with MXene/PU composite and advanced electrodes for non-invasive lactate detection during physical activity

Here, we report the design of a flexible, self-powered biosensor for lactate detection based on MXene-integrated hydrogels and enzyme-modified carbon cloth electrodes. MXene was synthesized via selective etching of Ti₃AlC₂ in HF and subsequently incorporated into a polypyrrole/polyurethane hydrogel to enhance conductivity and flexibility. The anode and cathode were fabricated by immobilizing lactate oxidase (LOD) and bilirubin oxidase (BOD) on reduced graphene oxide (rGO)-coated activated carbon cloth (ACC). Electrochemical impedance spectroscopy revealed reduced charge transfer resistance, while cyclic voltammetry confirmed strong bioelectrocatalytic activity. The sensor demonstrated a maximum power density of ∼3 μW.cm⁻² at 100 mM lactate and exhibited a linear current response across physiologically relevant concentrations. Integration with the MXene-based hydrogel enabled a 15-fold increase in current output due to improved electron mobility and ionic conductivity. Mechanical testing showed stable resistivity and structure under 500 bending cycles, validating its suitability for wearable use.