谐振式检测器谐振腔对声表面波气相色谱仪灵敏度的影响

研究了谐振式检测器谐振腔对声表面波气相色谱仪灵敏度的影响。构建无液膜负载和有液膜负载下压电基片和金属指条结构的三维有限元模型,利用有限元方法提取不同周期结构的耦合模参量,结合P矩阵级联技术,推导出传感器灵敏度随检测器腔体结构改变的变化关系。实验制备了两种三换能器结构的声表面波谐振器,其输入换能器与输出换能器间距离分别为22.25倍波长和1.25倍波长,通过测试甲基膦酸二甲酯气体,验证理论计算结果。结果表明:缩短谐振器的谐振腔长度使器件中心处能量更为集中,有效地提高了声表面波气相色谱仪灵敏度。

Influence of resonant cavity of a resonance detector on the sensitivity of a surface acoustic wave gas chromatograph gas sensor system

The influence of resonant cavity of a resonance detector on the sensitivity of a surface acoustic wave (SAW) gas chromatograph (GC) gas sensor system was investigated. The 3-dimentional finite element method (FEM) models of the absence and presence of a liquid layer covering the electrode structures were established. By using the FEM the coupling-of-modes parameters in different periodic structures were extracted. The variation of sensors' sensitivity with different cavity length was deduced by using P-matrix cascading technique. In the experiments, two three-transducer- structure SAW resonators were fabricated, where the distances between input transducer and output transducer were 22.25 times the wavelength and 1.25 times the wavelength, respectively By detecting the same amount of dimethyl methylphosphonate the theoretical results were verified. The results showed that shortening the resonant cavity of a SAW resonator concentrated more acoustic energy towards the center area, realizing higher sensitivity of the SAW/GC gas sensor system.