Preparation of a Nonenzymatic Potentiometric Lactic Acid Biosensor Modified by g-C₃N₄/ZnS Composite Materials on a SnO₂-Coated Flexible Printed Circuit Board

In this study, to enhance sensor performance a non-enzymatic lactic acid sensor based on SnO2 was developed and modified via g-C3N4/ZnS composite material to enhance its sensing performance. The modified sensor generates a voltage through the reaction between lactic acid and the material, and its performance is characterized using a voltage-time measurement system. Specific evaluation criteria include average sensitivity, linearity, repeatability, response time, selectivity, drift effect, and limit of detection. Experimental evidence shows that, compared to the unmodified SnO2 variant, the g-C3N4/ZnS modified sensor exhibits superior performance in lactic acid concentrations ranging from 1 to 9 mM, with an average sensitivity of 8.02 ± 0.12 mV/mM and with a linearity of 0.999. This modification significantly enhances sensor performance.