基于太赫兹超材料的微流体折射率传感器

太赫兹生物医学是目前光谱研究领域的热点，其主要难点在于如何有效避免水分的干扰，进行液相环境下样本的灵敏分析与检测。超材料太赫兹传感器由于具有高灵敏、快速检测、痕量分析等优势，而成为太赫兹生物医学传感领域的重要研究方法。设计加工了一种基于单开口谐振环超材料的太赫兹液相传感芯片，为了有效克服水对太赫兹波的强烈吸收，利用微纳加工技术刻蚀深度为50 μm的流体通道。传感芯片整合了超材料基底与PDMS流道，在THz频段有两个位于0.771和2.129 THz的谐振峰。以水、无水乙醇作为常见化学溶剂进行传感实验，相对于空白传感器本身的THz时域谱而言，液体的加入导致时域峰的相位延迟和幅度减小。同时，由于水的折射率大于乙醇，THz透射频谱结果显示为水的频移改变量大于乙醇，且峰2大于等于峰1。上述结果表明，构建的超材料液相传感芯片是一个灵敏的折射率传感器，也证明了该传感器在测量液态样品方面的可行性。此外，利用该芯片研究了不同浓度的PBS溶液，发现水溶液中加入离子会导致谐振频率红移（以水为参考），随着离子浓度增加，谐振频率改变量依次增加，10X PBS红移量最大，峰1为22.9 GHz，峰2为30.5 GHz。比较两个谐振峰的传感性能，峰2的传感能力更好，但是峰1对低浓度的离子溶液更加敏感。因此，构建的微流体传感器及检测体系作为一个灵敏的折射率传感器，可开发一个灵敏的无标记THz传感平台，为太赫兹生物医学研究提供新思路。

Microfludic Refractive Index Sensor Based on Terahertz Metamaterials

Terahertz biomedicine is a hot spot in the field of spectroscopy.The main difficulty lies in how to effectively avoid the interference of moisture and perform sensitive analysis and detection of samples in the liquid environment.Metamaterials terahertz sensors have become an important research method in the field of terahertz biomedical sensing due to their advantages such as high sensitivity,fast detection,and trace analysis.A terahertz liquid-phase sensor chip based on a single-open resonance ring metamaterial was designed and developed.In order to effectively solve the strong absorption of terahertz waves by water,a microfluidic channel with a depth of 50μm was etched by photolithography.The sensor chip integrates a metamaterial substrate and a PDMS flow channel.In the THz frequency band,there are two resonance peaks located at 0.771 and 2.129 THz.Compared with the THz time-domain spectrum of the blank sensor itself,the addition of liquid caused the phase delay and amplitude of the time-domain peak to decrease.At the same time,because the refractive index of water is greater than that of ethanol,the results of the THz transmission spectrum show that the frequency shift of water is greater than ethanol and peak 2 lagers than peak 1.The above results show that the constructed metamaterial liquid-phase sensing chip is a sensitive refractive index sensor,and it also proves the feasibility of the sensor in measuring liquid samples.In addition,using this chip to study PBS solutions of different concentrations,it was found that the addition of ions in the aqueous solution will cause the red shift of the resonance frequency(using water as a reference).As the ion concentration increases,the amount of change in the resonance frequency will increase in turn,with the largest red shift of 10×PBS,Peak 1 is 22.9 GHz,and peak 2 is 30.5 GHz.Comparing the sensing performance of the two resonance peaks,peak 2 has better sensing capabilities,but Peak 1 is more sensitive to low-concentration ion solutions.Therefore,as a sensitive refractive index sensor,the constructed microfluidic sensor and detection system can develop a sensitive label-free THz sensing platform to provide new ideas for terahertz biomedical research.