Highly Sensitive Lactic Acid Biosensors Based on Photoresist Derived Carbon

Abstract

In this study, a highly sensitive electrochemical capacitive lactic acid enzymatic sensor based on a carbon-microelectromechanical system (C-MEMS) is developed. The sensing platform of the biosensor, which is photoresist-derived carbon (PDC) microelectrode, was synthesized by pyrolysis of photo-patterned photoresist polymer in oxygen-free and high-temperature conditions. The surfaces of the microelectrodes were functionalized by the oxygen-plasma pretreatment technique to form –COOH functional groups. The lactate oxidase enzyme was immobilized on the carboxylic group covered surfaces of the microelectrodes. The sensor demonstrated the detection of lactic acid over a wide dynamic range of 0.1- $5000~\mu \text{M}$ with a low detection limit of $1.45~\mu \text{M}$ (S/N=3). The sensitivity found to be 33.48 mF.cm−2. (Log (M))−1. This mediator-free lactic acid sensor exhibited 80.07% accuracy in the presence of uric and ascorbic acid and only a 2.35% decrease of measured capacitance in 20 days, which implies good selectivity and high stability. The presented results show that the C-MEMS based lactic acid biosensor is a promising contender for the highly demanding point of care health monitoring applications.