基于微流控技术的磁流体载基液的太赫兹透射特性研究

太赫兹(THz)是指频率在0.1～10 THz的电磁波，其波长在30～3 000 μm范围内。由于自然界许多小分子的振动、转动等的频率均在太赫兹波段，并且太赫兹的低电子能特性使其在实验过程中不会对待测样品造成破坏，所以太赫兹技术被广泛地应用于无损检测、生物医学等领域。但是太赫兹在铁磁领域的相关报道还是较少的，因此本研究利用太赫兹时域光谱系统研究了一种新型磁性材料：磁流体的组成部分-载基液的太赫兹透射特性。磁流体是一种兼具液体流动性和固体磁性的新型功能材料，其打破了传统磁性材料的固体形态。磁流体由Fe₃O₄纳米级颗粒以及载基液构成。在前人的研究成果中发现磁性液体不仅具有良好的磁光效应，而且对于一定频率的太赫兹波具有高透射率；另外，在极低频电磁场作用下其可用于医学上的肿瘤治疗，可作为靶向治疗的载药系统。由于磁流体的组成部分-载基液成本较高，因此在实验中运用了微流控技术。微流控技术对检测样品的消耗少、检测速度快，并且可以根据实验需求自行设计沟道，因此是一种便捷的、灵活性好的检测方式。采用对太赫兹波具有高透过率的石英材料制成了夹心式的太赫兹微流控芯片。首先将两块3 cm×3 cm×2 mm的石英玻璃作为基片和盖片，再把强粘黏性双面胶剪刻成镂空样式，形成2 cm×2 cm的方形区域，然后把盖片和基片通过雕刻好的强粘黏性双面胶键合，其沟道厚度为50 μm，可以用于对少量液体的探测，并且可以使载基液呈薄膜状。之后将太赫兹技术和微流控技术相结合，利用太赫兹时域光谱(THz-TDS)系统研究了载基液的太赫兹透射特性，通过对太赫兹时域光谱以及频域光谱的研究发现，装有载基液的微流控芯片的信号强度高于空的微流控芯片，这一发现为载基液的应用和深入研究提供了技术支持。

Terahertz Transmission Characteristics of Magneto-Fluidic Carrier Liquid Based on Microfluidic Technology

Terahertz (THz) refers to an electromagnetic wave with a frequency of 0.1~10 THz and a wavelength of 30~3 000 μm. Because the frequencies of vibration and rotation of many small molecules in nature are in the terahertz band, and the low electron energy characteristics of terahertz will not cause damage to the samples to be tested in the experimental process, terahertz technology is widely used in the fields of nondestructive testing, biomedicine and so on. However, there are few reports on terahertz in the field of ferromagnetism. Therefore, in this study, terahertz transmission characteristics of new magnetic material, carrier liquid, a magnetic fluid component, are studied by terahertz time domain spectroscopy. Magnetic fluid is a new functional material with both liquid fluidity and solid magnetism, breaking traditional magnetic materials’ solid form. The magnetic fluid is composed of Fe₃O₄ nanoparticles and a carrier liquid. In the previous research results, it is found that magnetic fluid not only has a good magneto-optical effect but also has high transmittance to terahertz at a certain frequency. In addition, under the action of an extremely low-frequency electromagnetic field, it can be used in medical tumor therapy and as a drug delivery system for targeted therapy. Due to the high cost of carrier liquid, a magnetic fluid component, microfluidic technology is used in this experiment. Microfluidic technology has the advantages of less consumption of detection samples, fast detection speed, and can design channels according to experimental needs. Therefore, it is a convenient and flexible detection method. In this study, a sandwich terahertz microfluidic chip was made of quartz material with high transmittance to terahertz waves. First, put two pieces 3 cm×3 cm×2 mm quartz glass is used as the substrate and cover, and then the strong adhesive double-sided adhesive tape is cut and engraved into a hollow pattern to form 2 cm×2 cm square area, and then bond the cover sheet and the substrate through the engraved strong adhesive double-sided tape, with a channel thickness of 50 μm. It can be used to detect a small amount of liquid, and the carrier liquid can be made into a thin film. Then, combining terahertz technology and microfluidic technology, the terahertz transmission characteristics of carrier liquid are studied by terahertz time-domain spectroscopy (THz-TDS). The study of terahertz time domain spectroscopy and frequency domain spectroscopy shows that the signal intensity of microfluidic chip with carrier liquid is higher than that of empty microfluidic chip. This discovery provides technical support for the in-depth application and research of carrier liquid.