Zinc oxide nanoparticle based optical fiber humidity sensor having linear response throughout a large dynamic range

Area of Science:

• Photonics and Sensing Technologies
• Materials Science
• Nanotechnology

Background:

• Accurate and reliable relative humidity (RH) monitoring is crucial across various scientific and industrial applications.
• Existing RH sensors often face limitations in linearity, dynamic range, and response time.
• Optical fiber sensors offer advantages such as remote sensing, immunity to electromagnetic interference, and miniaturization.

Purpose of the Study:

• To develop a highly linear optical fiber relative humidity (RH) sensor with an extended dynamic range.
• To utilize evanescent wave absorption spectroscopy for RH sensing.
• To investigate the sensor's performance characteristics, including sensitivity, response time, and reliability.

Main Methods:

• Synthesis of a zinc oxide (ZnO) nanoparticle-doped sol-gel nanostructured film on a decladded optical fiber.
• Fabrication of the optical fiber sensor by depositing the sensing film.
• Experimental characterization of the sensor's response to varying RH levels using evanescent wave absorption spectroscopy.

Main Results:

• The developed optical fiber RH sensor exhibited a remarkably linear response from 4% to 96% RH.
• A high linear sensitivity of 0.0012 RH(-1) was achieved.
• The sensor demonstrated a rapid average response time of 0.06 seconds during humidification.

Conclusions:

• The zinc oxide-based optical fiber sensor effectively meets the objective of providing a linear RH measurement over a wide dynamic range.
• The sensor's fast response, high reliability, repeatability, and excellent reversibility make it a promising candidate for advanced RH monitoring applications.
• This work contributes to the development of robust and efficient optical sensing technologies for environmental and industrial monitoring.