The results of the theoretical simulation of an electrolyte-insulator-semiconductor (EIS) biosensor made on a silicon nanowire for the detection of low concentration DNA molecules are presented. The equivalent electrical scheme for the EIS structure is constructed. The phenomenon of charge distribution in a depletion layer of semiconductor is taken into account in computations. The behavior and dependence of the total capacitance for the EIS sensor and its capacitive sensitivity on the DNA concentration in aqueous solution are investigated and analyzed. It is shown that the capacitance of the EIS sensor is very sensitive to the presence of the DNA molecules and the sensitivity has comparatively high value at the low concentration of the DNA molecules. The increase of the DNA concentration results in the decrease of the EIS total capacity. It is shown that one can register and determine the number of charged DNA molecules in aqueous solution by measuring the changes in the EIS capacity. The sensitivity increases with the growth of the gate voltage. It is shown that the threshold of sensitivity can be very low and the signal-to-noise ratio can reach high values for the EIS biosensor.

提出了一种在硅纳米线上制备用于检测低浓度DNA分子的电解质-绝缘体-半导体（EIS）生物传感器的理论模拟结果。构造了EIS结构的等效电气方案。计算中考虑了半导体耗尽层中的电荷分布现象。研究和分析了EIS传感器的总电容的行为，依赖性及其电容灵敏度对水溶液中DNA浓度的影响。结果表明，EIS传感器的电容对DNA分子的存在非常敏感，并且在DNA分子浓度低时，其灵敏度相对较高。DNA浓度的增加导致EIS总容量的降低。结果表明，可以通过测量EIS容量的变化来注册并确定水溶液中带电DNA分子的数量。灵敏度随着栅极电压的增加而增加。结果表明，EIS生物传感器的灵敏度阈值非常低，信噪比可以达到很高的值。