Department of Physics and Department of Energy Systems Research, Ajou University, Suwon 16499, Republic of Korea.
Sensors (Basel). 2023 Jun 21;23(13):5797. doi: 10.3390/s23135797.
We present a novel terahertz (THz) Fabry-Perot (FP) microcavity biosensor that uses a porous polytetrafluoroethylene (PTFE) supporting film to improve microorganism detection. The THz FP microcavity confines and enhances fields in the middle of the cavity, where the target microbial film is placed with the aid of a PTFE film having a dielectric constant close to unity in the THz range. The resonant frequency shift increased linearly with increasing amount of yeasts, without showing saturation behavior under our experimental conditions. These results agree well with finite-difference time-domain (FDTD) simulations. The sensor's sensitivity was 11.7 GHz/μm, close to the optimal condition of 12.5 GHz/μm, when yeast was placed at the cavity's center, but no frequency shift was observed when the yeast was coated on the mirror side. We derived an explicit relation for the frequency shift as a function of the index, amount, and location of the substances that is consistent with the electric field distribution across the cavity. We also produced THz transmission images of yeast-coated PTFE, mapping the frequency shift of the FP resonance and revealing the spatial distribution of yeast.
我们提出了一种新颖的太赫兹（THz）法布里-珀罗（FP）微腔生物传感器，该传感器使用多孔聚四氟乙烯（PTFE）支撑膜来提高微生物检测的能力。THz FP 微腔将电磁场限制并增强在腔体中部，在腔体中部放置目标微生物膜，同时借助在 THz 范围内介电常数接近 1 的 PTFE 薄膜。在我们的实验条件下，随着酵母数量的增加，共振频率的偏移呈线性增加，没有出现饱和行为。这些结果与有限差分时域（FDTD）模拟结果吻合较好。当酵母放置在腔的中心时，传感器的灵敏度为 11.7 GHz/μm，接近 12.5 GHz/μm 的最佳条件，但当酵母涂覆在反射镜侧时，没有观察到频率偏移。我们得出了一个明确的频率偏移与物质的折射率、数量和位置之间的关系，该关系与腔体内的电场分布一致。我们还制作了涂覆有酵母的 PTFE 的太赫兹传输图像，映射了 FP 共振的频率偏移，并揭示了酵母的空间分布。
