声表面波生物传感器质量灵敏度的理论与实验验证

Theoretical and experimental verification on mass sensitivity of surface acoustic wave biosensor

针对声表面波传感器在生物检测中的性能评价与优化,提出一种快捷验证适用于生物传感器的声表面波器件质量负载灵敏度的实时检测方法。首先基于二维近似假设和周期性边界条件,建立了以石英为压电基底材料、SiO_(2)为波导层的Love波传感器的三维有限元分析模型,从理论上验证了波导层对Love波传感器灵敏度的影响。在实验上,通过MEMS工艺制备以ST-90°X石英为基底的声表面波传感器,通过磁控溅射镀膜技术在其表面生长不同厚度的SiO_(2)波导层。利用热蒸镀技术在器件延迟线区域生长铝薄膜作为质量负载效应,利用Tetramethylammonium Hydroxide(TMAH)溶液对铝的缓慢腐蚀效果,模拟质量负载从有到无的逆过程,从而实现对声表面波传感器的灵敏度验证与评价,并从实验上探究不同厚度波导层对Love波传感器灵敏度的影响及其最佳波导层厚度。

The evaluation and improvement on the performance of the Surface Acoustic Wave Biosensor(SAWB)has attracted great attention.In this paper,a SAWB is designed and fabricated for detecting the specific binding of antibody to antigen.A real-time characterization method is proposed for test of the load sensitivity of this SAWB.In the first stage of the study,a three-dimensional finite element analysis model of the Love wave sensor on the SiO_(2) waveguide layer with quartz piezoelectric substrate was established based on the two-dimensional approximation hypothesis and periodic boundary conditions.Influence of the waveguide layer on the sensitivity of the Love wave sensor was theoretically verified as well.Further,the surface acoustic wave sensor on ST-90°X quartz substrate was prepared by MEMS process and SiO_(2) waveguide layers of different thickness allowed to grown on the substrate surface by magnetron sputtering coating technology.Using thermal evaporation technology,thin layer of aluminum film was coated on the delay line area and further the thin film was corroded off using TMAH from the substrate under the real-time monitoring of SAWB.Influence of thickness of SiO_(2) thin film on the sensitivity of SAWB was studied in detail and the optimum thickness for better sensitivity was find out.