InSb光栅耦合的太赫兹表面等离激元共振传感方法  

A sensing method based on InSb grating coupled terahertz surface plasmon polariton resonance

作　　者：陈钇成 张成龙 张丽超 祁志美 Chen Yi-Cheng;Zhang Cheng-Long;Zhang Li-Chao;Qi Zhi-Mei(State Key Laboratory of Transducer Technology,Aerospace Information Research Institute,Chinese Academy of Sciences,Beijing 100190,China;School of Electronic,Electrical and Communication Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;School of Materials Science and Optoelectronic Technology,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院空天信息创新研究院,传感技术国家重点实验室,北京100190 [2]中国科学院大学电子电气与通信工程学院,北京100049 [3]中国科学院大学材料科学与光电技术学院,北京100049

出　　处：《物理学报》2024年第9期287-296,共10页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2021YFB3200100);国家自然科学基金(批准号:62121003,61931018,61871365)资助的课题

摘　　要：仿真设计了一种光栅耦合型太赫兹(THz)表面等离激元(SPP)共振生化传感结构,该结构通过在锑化铟(InSb)基底表面刻蚀亚毫米光栅形成.基于波矢匹配方程的仿真结果表明,当TM偏振的THz平行波束以30°入射角照射到光栅区间时,光栅的–1和+1级THz衍射波束能够分别激励传播方向相反的低频SPP和高频SPP.由于采用商业THz时域谱装置可以准确测量低频SPP,本文系统地分析了低频SPP的共振和传感特性对光栅结构参数的依赖关系.仿真结果表明:InSb光栅耦合的THz-SPP共振传感芯片的折射率灵敏度随光栅周期的增大而减小;当光栅周期为120μm、入射角为30°时,折射率灵敏度为1.05 THz/RIU,在此条件下,传感芯片不能对生物分子单分子吸附层作出可探测的响应,究其原因是,低频SPP的消逝场穿透深度远大于生物分子尺寸,致使两者相互作用不足.为了探测生物分子,仿真分析了多孔薄膜覆盖InSb光栅的增敏方法.多孔薄膜具有分子富集作用,能够将THz表面波与生物靶标的相互作用从单分子尺度扩展至整个薄膜厚度,从而提高传感器的生物检测灵敏度.以酪氨酸吸附为例的仿真结果表明,当InSb光栅表面覆盖厚度为120μm、孔隙率为0.4的多孔聚甲基丙烯酸甲酯(PMMA)薄膜后,其吸附灵敏度为0.39 THz/单位体积分数.A grating-coupled terahertz(THz)surface plasmon polariton(SPP)resonant biochemical sensing structure is designed with simulation,which can be easily prepared by etching a submillimeter grating on the surface of indium antimonide(InSb)substrate.The simulation results based on the phase matching equation show that when the TM-polarized broadband terahertz collimated beam is incident on the InSb grating at a 30°angle,the low-frequency SPP and high-frequency SPP with opposite propagation directions can be simultaneously excited by the–1st and+1st order diffraction beams of the grating,respectively.Since the low-frequency SPP is easy to accurately measure with a commercial THz time-domain spectroscopy devices,the dependence of the resonance characteristics and sensing characteristics of low-frequency SPP on the grating structure parameters is systematically simulated in this paper.The simulation results show that the refractive-index sensitivity of the InSb grating-coupled THz-SPP resonant sensor chip decreases with the increase of the grating period,and is 1.05 THz/RIU at a grating period of 120μm and an incident angle of 30°.Under these conditions,the sensor chip cannot make a detectable response to the monolayer adsorption of biomolecules,because the evanescent field penetration depth of the low-frequency SPP is much greater than the biomolecular size,resulting in insufficient field-biomolecular interaction at the surface.In order to detect biomolecules,a sensitivity enhancement method based on porous thin films is proposed and analyzed with simulation.The porous films enable not only to enrich biomolecules,but also to extend the interaction between THz-SPP and biomolecules from the molecular size to the entire film thickness,thereby improving the sensitivity of the sensor to biomolecular adsorption.Taking tyrosine adsorption as an example,the simulation results show that when the InSb grating is covered with a porous polymethyl methacrylate(PMMA)film with a thickness of 120μm and a porosity of 0.4,the sensor

关 键 词：太赫兹表面等离激元共振 InSb光栅 生化传感 多孔材料 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置] O441.4[自动化与计算机技术—控制科学与工程]