PVA/Tween 20 thin-film-based fiber optic humidity sensor with enhanced sensing performance

Area of Science:

• Materials Science
• Optical Sensors
• Chemical Engineering

Background:

• Humidity sensors are crucial for environmental monitoring and industrial processes.
• Traditional sensors face challenges like slow response times and limited sensitivity.
• Developing novel materials for enhanced optical humidity sensing is an active research area.

Purpose of the Study:

• To fabricate and characterize a novel fiber optic humidity sensor.
• To investigate the effect of polyvinyl alcohol (PVA)/Tween 20 composite film on sensor performance.
• To understand the sensing mechanism of the developed optical fiber sensor.

Main Methods:

• Fabrication of a fiber optic sensor using PVA/Tween 20 as cladding and humidity-sensitive material.
• Modulation of transmitted light intensity through the optical fiber.
• Testing sensor response across a humidity range of 22%-82% RH.
• Analysis of sensor sensitivity, response/recovery times, and repeatability.

Main Results:

• A linear relationship was observed between the logarithm of output light intensity and relative humidity.
• The addition of Tween 20 resulted in a 13-fold increase in average sensitivity.
• The sensor demonstrated fast response (11 s) and recovery (9 s) times.
• Good repeatability was confirmed for the developed humidity sensor.

Conclusions:

• The PVA/Tween 20 composite film is effective for fiber optic humidity sensing.
• The sensor offers high sensitivity, fast response, and good repeatability.
• The sensing mechanism involves PVA swelling and its effect on evanescent wave scattering.