Supercapacitor-powered wearable biosensor for continuous lactate monitoring from sweat

The development of wearable sensing platforms for continuous monitoring of sweat biomarkers has gained significant attention, particularly for lactate detection. This study presents the design and fabrication of a novel wearable lactate biosensor that integrates a flexible supercapacitor power supply with an advanced lactate sensing platform. The sensing platform features NiCo nanosheets electrodeposited onto nanocages of bimetallic CoFe Prussian Blue analogue (PBA), providing an optimal microenvironment for the immobilization of lactate oxidase (LOx) enzymes. The CoFe PBA nanocages act as efficient electrocatalysts for the reduction of hydrogen peroxide, enhancing the sensor's performance. The electrode exhibits a sensitivity of 262 μA mM^-1cm^-2 and demonstrates a short response time (<5 s), making it suitable for real-time monitoring applications. Additionally, the energy supply unit is constructed using a wearable conductive carbon textile (CCT) substrate modified with NiCoS through electrochemical deposition, achieving the necessary electrical conductivity. A flexible asymmetric supercapacitor (ASC) is then developed utilizing NiCoS@CCT and FeS@CNT@CCT as the positive and negative electrodes, respectively. This ASC exhibits remarkable electrochemical properties, including a high specific capacitance of 205 F g⁻¹, notable energy density at elevated power densities, and excellent rate capability. Integrating these components with a custom-designed electronic circuit board results in a lightweight wearable sensor capable of continuous lactate monitoring in perspiration. This innovative approach demonstrates significant potential for advancing point-of-care health monitoring technologies.