| dc.description.abstract | The goal of this research is to develop an interdigitated capacitive biosensor with maximum capacitive response and highest sensitivity. This research concentrated on two-dimensional electric-filed simulation using ADS (Advanced Design System) to analyze and understand the capacitive response of interdigitated biosensors. Furthermore, Taguchi method was employed to find the optimal electrode geometric parameters. The optimal geometric parameters of interdigitated capacitive biosensor thus determined were: electrode width = 1200 μm, electrode spacing = 0.01 μm, electrode thickness = 500 μm, and overlapping length = 10000 μm. The capacitance of this optimal design was 795.17 times as big as that of an interdigitated capacitive biosensor with ordinary geometric parameters. The capacitance of an interdigitated biosensor is determined collectively by its geometric parameters. According to the results by Taguchi method, the relevant parameters and their weights of influences were: electrode width (31.65%), electrode spacing (26.154%), electrode thickness (23.154%), and overlapping length (19.039%). A suboptimal design was proposed to meet the current process limitation. The electrode width and spacing were both changed to 10um, whereas the electrode thickness and overlapping length followed the optimal geometric design. The resultant capacitance was reduced to 1/5.53 times as big as that of the optimal design. Nevertheless, it was still 142.96 times as big as that with the ordinary geometric parameters. For detection of DNA, protein, cell, et. al., by biosensors of suboptimal geometry design, the sensitivity doubled that of the ordinary design and was commensurate to that of the optimal design. Hence, the suboptimal design represents a good choice for capacitive biosensors to attain high sensitivity
under current process limitation.
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