Research On Silicon-based Bulk Micro-machined Amperometric Microelectrode Biosensors

A new silicon-based bulk micro-machined amperometric microelectrode biosensor is designed and fabricated with anisotropic silicon wet etching. Silicon wafers, Au and SU-8 are used for making substrates, microelectrodes and micro reaction pools, respectively. Consecutive platinization and polymerization of pyrrole is, to our knowledge, used for surface modification for the first time.The sensor aims for low unit cost, small dimensions and compatibility with IC (integrated circuit) technology.SU-8 micro reaction pools are made to contain detection solution to reduce reagent volume and unit cost. Both bulk micromachining technology and consecutive platinization and polymerization of pyrrole are used to enhance sensor sensitivity, which helps to miniaturize its dimensions. Using silicon wafer as substrate makes compatibility with IC technology possible.Several surface modification methods and enzyme immobilization methods were designed and tried to search for the best surface modification method and the best enzyme immobilization method.A voltage scanning module was designed and fabricated to carry out the cyclic voltammetric detection. It well meets the experimental requirements.Successful experimental results have been achieved for glucose detection. Compared with conventional amperometric sensors and amperometric microelectrode sensors made with surface micromachining technology, the bulk micro-machined sensor has several advantages, such as smaller sensitive surface area, lower detection limit, broader linear range, larger sensitive coefficient, better replicability and stability, easier to be made into arrays and to be integrated with processing circuitry, etc.Feasibility, advantages, and crucial problems to be resolved, of amperometric microelectrode immunosensor are theoretically discussed.