SiO_2微悬臂梁制备及其高阶谐振的传感器研究

Fabrication of SiO_2 micro-cantilever and its sensor application based on higher resonance modes

为了提高SiO2微悬臂梁动态检测灵敏度,对T型SiO2微悬臂梁的制备和高阶谐振模态传感器进行了研究。以绝缘体上Si(SOI)为起始材料制备了不同长度T型SiO2微悬臂梁,利用原子力显微镜(AFM)中精密的光学位置敏感检测器及数据处理系统对其频率进行表征,获得了与仿真结果相一致的数据。基于高阶谐振模态的免疫反应结果表明,对于相同的质量变化量,微悬臂梁的弯曲振动模式阶数越高,其频率偏移越大,从而达到较高的灵敏度;实验制备的SiO2微悬臂梁前三阶弯曲振动模式的检测灵敏度分别为1.36、9.78和26.92Hz/pg,利用二阶弯曲振动模式可检测出21.5pg的分子吸附。

SiO2micro-cantilever has been widely used in the field of chemical and biolo gical sensors due to its high sensitivity.In order to further improve the dynamic sensitivity of SiO2micro -cantilevers,the fabrication and its sensor application based on higher resonance modes are studied in this work.First,Silicon-on-insulator （SOI） is used as starting material for the fabrication of T-shaped SiO2micro-ca ntilevers with different lengths.Then,commercial atom force microscopy （AFM） wit h accurate photoelectron ic system is employed for the characterization of the frequency and the frequency shift before and after mass adsorption.It is found that the first three bending frequencies of the T-shaped SiO2micro-cantilevers with total length of 250μm are 18.86kHz,164.27kHz and 467.25kHz,respectively,which are well consistent with the simulated values.More over,for the same amount of mass change,the higher the flexural resonance mode is,the larger the frequency shift of the micro-cantilever will be,showing an increasing sensitivity.The frequency measur ement of gold deposition reveals that the sensitivities of the first three modes are 1.36Hz/pg,9.78Hz/pg and 26.92Hz/pg,respectively.Immunological reactions are also conducted.It is found that at the second harmonic,a 21.5pg m ass absorption can be detected.