Novel electrochemical device for the detection of cholesterol or glucose

A thin-layer twin-electrode electrochemical cell in which the working and auxiliary electrodes are facing each other and which contains the appropriate enzyme and a mediator was used for the determination of cholesterol or glucose. A steady-state diffusion-controlled response was obtained for cholesterol whereas for glucose the response was limited by diffusion and kinetics. Simulation of the system showed that a steady-state response is obtained, in the absence of kinetic complications, after a time of 0.01 d²/D s, where d is the distance between the two electrodes and D is the diffusion coefficient of the mediator. Linear plots of steady-state current versus concentration were obtained for cholesterol and glucose. The results were compared with those expected theoretically and a thin-layer capillary fill device is proposed.