Development of Lossy Mode Resonance Optical Fiber Humidity Sensor Using M13 Bacteriophage

In this study, we propose a lossy mode resonance (LMR)-based optical fiber humidity sensor developed by depositing M13 bacteriophage onto a D-shaped optical fiber (DSF) coated with an 80 nm-thick indium tin oxide (ITO) layer. A broadband wavelength-swept laser (WSL) was used as the light source to analyze the LMR dip shift under varying humidity conditions. As the humidity applied to the fabricated device increased, the LMR dip shifted to shorter wavelengths, with a measured humidity sensitivity of −1.01 nm/% R.H. In addition, the response time of the device was approximately 30 s for a 4% R.H. change, verifying its real-time detection capability. The response of the device to acetone gas exposure was also examined, revealing a minor shift in the LMR dip, indicating potential gas sensing applications. The proposed LMR-based fiber optic sensor, using M13 bacteriophage, has potential for use in environmental monitoring and biosensing applications.