Flexible Amperometric Biosensor for Sweat Lactate Detection

A flexible amperometric biosensor using silver nanoparticle-based conductive electrode was fabricated for sweat lactate measurement. The developed sensor was composed of three-electrode configuration for the demonstration of electro-chemical sensing with silver nanoparticles as a single electrode material. Thin-film electrodes with cross-serpentine pattern have been demonstrated to be highly flexible without significant change in their electrical behavior. Fabricated electrodes were annealed for higher conductivity and modified for electrochemical analysis of lactate. The permselective membrane on working electrode was used to enhance selectivity of the sensor against common interfering electroactive anions such as ascorbate. Enzyme was immobilized on the sensor surface for lactate oxidization to produce hydrogen peroxide. The optimum potential (0.65 V) was determined employing cyclic voltammetry and applied for different in-vitro experiments to generate current flow- proportional to lactate concentration. Bleach-assisted-modified in-sensor pseudo reference electrode evinces its long term potential stability against standard commercial reference electrode. The catalytic response of the sensor shows excellent linear behavior between 0~25 mM of lactate. This noninvasive electrochemical lactate sensor also demonstrates excellent behavior to reject anionic interference, resiliency against mechanical deformation and temperature fluctuation which leads to the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Finally, the wireless data transmission using near-field-communication unit is demonstrated for the realization of a practical sensor application to be able to measure sweat lactate portably using human perspiration.