Parameters in the design of oxygen detecting oxidase enzyme electrodes

The response of an amperometric oxidase enzyme electrode, monitored by the consumption of oxygen, was numerically modeled using a two substrate model. The reduction current was found to be sensitive to the thiele modulus, Φ , which is dependent on the square of the biorecognition matrix thickness and the concentration of active enzyme within this matrix. The detectable concentration range to which the sensor can be used can be extended by reducing the membrane thickness or the enzyme loading, both of which reduce the signal change with substrate additions. The dependence of Φ on the square of the membrane thickness makes the sensor design exceedingly sensitive to minor changes in thickness and hence manufacturing of reproducible sensors with common deposition methods exceedingly difficult.