College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China.
Key Laboratory of on Site Processing Equipment for Agricultural Products, Ministry of Agriculture and Rural Affairs, Hangzhou 310058, China.
ACS Appl Mater Interfaces. 2020 Sep 30;12(39):44281-44287. doi: 10.1021/acsami.0c11461. Epub 2020 Sep 17.
There is an increasing recognition that terahertz (THz) spectroscopy can be used for high-sensitivity molecular sensing. Therefore, in recent years, much work has been devoted to developing flexible, compact, and high-sensitivity THz sensors. However, most designs employ metamaterials, which require complicated, and often expensive, fabrication procedures. Also, the metamaterial structures create a gap between the sensor surface and the target surface, which decreases the effective contact area between them, resulting in reduced sensing performance. Here, we fabricated a metamaterial-free graphene-based THz sensor with user-designed patterns for sensing at bio-interfaces. External molecules can strongly interact with π electrons in graphene, which moves the Fermi level and changes the amount of THz absorption. We used this sensor to successfully detect chlorpyrifos methyl with a limit of detection at 0.13 mg/L. We also detected pesticide molecules of a concentration of 0.60 mg/L on the surface of an apple, revealing the flexibility of this sensor. The flexible graphene THz sensor showed high sensing stability and robustness over 1000 cycles of bending. These results show that our graphene-based thin-film sensors are easy to fabricate, flexible, versatile, and suited for a wide range of sensing applications.
人们越来越认识到太赫兹（THz）光谱学可用于高灵敏度的分子传感。因此，近年来，许多工作都致力于开发灵活、紧凑和高灵敏度的太赫兹传感器。然而，大多数设计都采用了需要复杂且昂贵的制造工艺的超材料。此外，超材料结构在传感器表面和目标表面之间形成了一个间隙，这减少了它们之间的有效接触面积，导致传感性能下降。在这里，我们制造了一种无超材料的基于石墨烯的太赫兹传感器，具有用户设计的图案，用于生物界面传感。外部分子可以与石墨烯中的π电子强烈相互作用，移动费米能级并改变太赫兹吸收的数量。我们使用这个传感器成功地检测到了甲基毒死蜱，检测限为 0.13mg/L。我们还在苹果表面检测到了浓度为 0.60mg/L 的农药分子，显示出这种传感器的灵活性。这种灵活的石墨烯太赫兹传感器在 1000 次弯曲循环中表现出了高的传感稳定性和鲁棒性。这些结果表明，我们的基于石墨烯的薄膜传感器易于制造、灵活、多功能，适用于广泛的传感应用。
