Glucose Microbiosensor Based on MnO₂ and Glucose Oxidase Modified Carbon Fiber Microelectrode

A glucose microbiosensor has been developed using electrochemical codeposition of glucose oxidase (GOx) along with MnO 2 as mediator, onto a single carbon fiber microelectrode. A two‐step deposition of only MnO 2 initially and then of MnO 2 in the presence of GOx has been introduced to ensure appropriate activity of the mediator. Several parameters such as deposition potential and time, concentration levels etc. have been characterized and optimized. A thin Nafion film was applied as an immobilization/encapsulation and interference‐free protective layer. The proposed microbiosensor was employed as an amperometric glucose detector at pH 7.5 at an operating potential of +0.58 V (vs. Ag/AgCl). The microbiosensor is characterized by a well‐reproducible amperometric response, linear signal‐to‐glucose concentration range from 1.5 mmol L −1 to 15 mmol L −1 , and a limit of detection ( S/N =3) of 0.8 mmol L −1 . The microbiosensor exhibits good stability over more than ten hours of continuous measurement.