Abstract
Lactic acid is one of the most important metabolites in clinical analysis and the food industry. Its detection is an important clinical assay for the diagnosis of numerous human disease conditions. As a result, the analysis of lactic acid and its related lactate ion was widely studied and detection methods based on the lactate oxidase (LOx) enzyme were finally proposed. For its monitoring, the development of smart lactate-biosensors based amperometric and potentiometric ElecFET (Electrochemical field effect transistor) at the microscale is required. Lactate and pyruvate concentration profiles within the sensor were obtained by solving reaction coupled mass conservation equations using a finite element analysis (FEA) software called COMSOL Multiphysics and the currents were calculated from the hydrogen peroxide flux at the electrode surface. In presence of lactate ions, it is responsible for the production of hydrogen peroxide H2O2 that is oxidized on the electrochemical microelectrode, leading to the production of proton H+ and finally for a local pH decrease. The proposed model points out the role of the ElecFET design, i.e. the number of enzymatic units per volume unit n(enz), the L-lactate oxidase Michaelis constant K-M and the lactate concentration [S-1]. The ElecFET concept is extended to the detection of lactate [1-6 mM] concentration range. The sensitivitie is 13 mV/mM.