Developing a Novel Terahertz Fabry-Perot Microcavity Biosensor by Incorporating Porous Film for Yeast Sensing

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/& mu;m, close to the optimal condition of 12.5 GHz/& mu;m, 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.

Automated summary

We propose a new terahertz Fabry-Perot microcavity biosensor using a porous polytetrafluoroethylene supporting film for improved microorganism detection. The microcavity confines and enhances fields in the middle, where the target microbial film is placed using a PTFE film with a dielectric constant close to unity in the THz range. The resonant frequency shift linearly increases with increasing amount of yeasts, and the sensor's sensitivity is 11.7 GHz/& mu;m when yeast is placed at the cavity's center.