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基于负电晕放电原理的气体传感器利用局部高压电场将目标气体电离,根据电离特性对气体进行识别。采用MEMS技术制备硅尖阵列电极,利用电喷ZnO纳米颗粒对电极表面进行修饰,结合金平板正电极构建了多针-板结构电晕放电气体传感器。研究了电极间距对传感器负电晕放电特性的影响,综合考虑起晕电压、信号输出范围及稳定放电范围,优化电极间距为100μm。测试了在-0.70 kV放电电压下传感器对乙酸气体的敏感特性。该传感器对乙酸气体的响应灵敏度约为1.05 mV/10-6,理论检测限(三倍噪声)约为8.6×10-6,测试范围内传感器响应同乙酸气体体积分数近似呈线性关系。实验结果表明,ZnO纳米颗粒修饰减小了放电尖端曲率半径,增加了放电尖端个数,消除了硅尖阵列之间高度和顶端曲率半径的差异,从而有效降低了起晕电压,提高了传感器对乙酸气体响应灵敏度及电晕放电的稳定性。
The gas sensor based on the principle of negative corona discharge utilizes the local high-voltage electric field to ionize the target gas, and identifies the gas according to the ionization characteristics. The silicon tip array electrode was prepared by MEMS technology. The surface of the electrode was modified by electrospray ZnO nanoparticles. A multi-pin-plate structure corona discharge gas sensor was constructed by combining with the gold plate positive electrode. The influence of the electrode spacing on the negative corona discharge characteristics of the sensor was studied. Taking into account the corona onset voltage, the signal output range and the stable discharge range, the optimized electrode spacing was 100μm. The sensitivity of the sensor to acetic acid gas at -0.70 kV discharge voltage was tested. The sensitivity of the sensor to acetic acid gas is about 1.05 mV / 10-6. The theoretical detection limit (triple noise) is about 8.6 × 10-6. The sensor response in the test range is approximately linear with the volume fraction of acetic acid gas. The experimental results show that the modification of ZnO nanoparticles reduces the curvature radius of the discharge tip, increases the number of discharge tips, eliminates the difference between the height of the silicon tip array and the tip radius of curvature, thereby effectively reducing the corona onset voltage and improving the sensor pair Acetic acid gas response sensitivity and corona discharge stability.