基于SnO2气体传感器检测农药残留的表面动态响应特性

利用单个SnO2气体传感器在方波变化的温度条件下实现对敌百虫和乙酰甲胺磷及其混合气体的快速检测和识别.实验结果表面,SnO2气体传感器在温度范围为250～300℃、温度变化频率为20MHz的工作条件下对敌百虫和乙酰甲胺磷及其混合气体表现出高的灵敏度和清晰的动态响应特征.通过快速傅立叶变换(FFT)实现对敌百虫和乙酰甲胺磷及其混合气体的定量分析.

Characteristic Dynamic Responses for Pesticide Residue Detecting on the Surface of the SnO2 Gas Sensor

A new rapid detecting method (called dynamic measurements) to detect and distinguish the presence of two pesticide gases acephate and trichlorphen and their mixture in the ambient atmosphere is reported. The method only employed a single SnO2-based gas sensor in a sinusoidal temperature mode to perform the qualitative analysis of pure pesticide gas and mixture of binary gases (acephate and trichlorphon) in air. The dynamic responses under different concentrations are also discussed. Experimental results show that high selectivity of the sensor presents in the range of temperatures 250～300℃ and the modulating frequency 20 MHz. The quantitative analysis between the pure pesticide gases and their mixture was performed by Fast Fourier Transformation (FFT). The higher harmonic terms of the FFT characterized the nonlinear properties of the response at the sensor surface. The amplitudes of the high harmonic terms exhibited characteristic changes which depend on the concentration and the kinetic reaction of gas species on the sensor surface. Nonlinear responses are discussed in relation to the kinetics of the gas species at the sensor surface and the surface barrier potential.