Design and fabrication of nickel microdisk-arrayed diamond electrodes for a non-enzymatic glucose sensor based on control of diffusion profiles.

A non-enzymatic glucose sensor, consisting of a regular array of nickel microdisks on a diamond electrode substrate designed to control the diffusion processes of glucose and interfering species such as ascorbic acid and uric acid, was fabricated. Each nickel microdisk acts as a microelectrode for glucose (hemispherical diffusion) due to the inactive diamond surface for glucose oxidation while interfering species are oxidized at the diamond surface (linear diffusion). The difference in diffusion profiles gives a difference in the time dependence of the amperometric response. That is, the glucose concentration gives rise to a constant amperometric response whereas the concentration of mixed interfering species gives rise to a time dependent response, because the hemispherical diffusion profile yields a constant response and the linear diffusion profile yields a transient current following Cottrell's equation. The results show that the fabricated electrodes exhibit a high selectivity for glucose in solutions containing ascorbic and uric acids.