Optimisation of porous silicon used as a glucose biosensor enzyme carrier matrix

Presents results of a study on the optimisation of porous silicon when used as a surface enlarging carrier matrix for immobilized enzymes in a glucose monitoring system. The porous silicon samples were prepared by anodisation in an HF/ethanol electrolyte. Glucose oxidase was coupled onto the porous matrix and the influence of the obtained porous morphologies generated in n- or p-type silicon with varying dopant concentrations was investigated with respect to the corresponding catalytic turn-over. It was found that the recorded catalytic turn-over in general was higher for samples anodised at higher current densities. The highest increase in catalytic turn-over was 350 times for an n-type epi layer on n⁺-bulk silicon sample when comparing with the corresponding non-porous sample. The influence of the porous depth with respect to the catalytic turn-over was also investigated. Both planar samples and parallel vertical channel type reactors were investigated. It was found that the efficient porous depth for planar samples was approximately 15-20 μm, whereas the reactor structures displayed an efficient catalytic porous depth of 5-10 μm