Evaluation of an albumin-based, spin-coated, enzyme-immobilized membrane for an isfet glucose sensor by computer simulation

Abstract

An ISFET biosensor response was analyzed and evaluated using computer simulation, based on a ping-pong mechanism model [1], one of the two commonly used substrate models. Diffusion coefficients and K m values for glucose and oxygen were determined by comparing calculated responses with glucose sensor responses measured with an albumin-based membrane formed by the lift-off method. Diffusion coefficients for glucose and oxygen were estimated to be 2.5 x 10 -9 cm 2 sec and 7.5 x 10 -9 cm 2/sec, respectively. These low diffusion coefficients values mean that the membrane has a relatively dense structure. K m values for glucose and oxygen were estimated to be 8 m M and 0.05 ra M, respectively. These values suggest that the enzyme activity in the membrane is influenced by the membrane electric charge or mechanical condition. Responses for a biosensor with a membrane less than 1 μm thick were well described by the model.