A silicon-based bulk micro-machined microelectrode biosensor with SU-8 micro reaction pool

Abstract

A new silicon-based amperometric microelectrode biosensor made with bulk micromachining technology is provided. We designed this new biosensor and fabricated it with anisotropic silicon wet etching technique. P-type silicon wafers, Au and SU-8 are used for making substrate, microelectrode and micro reaction pool respectively. To our knowledge, consecutive platinization and polymerization of pyrrole is firstly used consecutively for microelectrode surface modification. The sensor aims for low unit cost, small dimensions and compatibility with CMOS technology. SU-8 micro reaction pools are made to contain detection solution to reduce reagent volume and unit cost. Bulk micromachining, platinization and polymerization of pyrrole enhance sensitive coefficient, thus helping to miniaturize its dimensions and to reduce unit cost. Using p-type silicon wafers as substrates make compatibility with CMOS technology possible. Successful experimental results have been achieved for glucose detection. Compared to conventional amperometric biosensors and amperometric microelectrode biosensors made with surface micromachining technology, it has several advantages, such as smaller sensing surface area (1 mm /spl times/ 1 mm), lower detection limit (1/spl times/10/sup -4/ M), larger sensitive coefficient (39.640 nA mM/sup -1/ mm/sup -2/), broader linear range (1/spl times/10/sup -4/-1/spl times//sup -2/ M), better replicability (3.2% RSD for five respective detections) and stability (enzyme efficiency remains well above 95% after being stored for a month), easier to be made into arrays and to be integrated with processing circuitry, etc.