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Updated: Jul 10, 2026
09:48
Fiber Optic Distributed Sensors for High-resolution Temperature Field Mapping
Published on: November 7, 2016
Relative humidity sensor with optical fiber Bragg gratings
Optics Letters
|November 21, 2007
Summary
A new intrinsic relative humidity (RH) sensor uses polyimide-coated fiber Bragg gratings. This sensor shows accurate, reversible performance across a wide RH range and temperature spectrum.
Area of Science:
- Materials Science
- Optical Sensors
- Environmental Monitoring
Background:
- Accurate relative humidity (RH) monitoring is crucial for various applications.
- Existing RH sensors often face challenges with long-term stability and calibration.
- Fiber optic sensing offers potential for robust and intrinsic humidity measurements.
Purpose of the Study:
- To present a novel intrinsic relative humidity (RH) sensor concept.
- To investigate the performance of polyimide-recoated fiber Bragg gratings for RH sensing.
- To determine the sensor's response characteristics and material properties.
Main Methods:
- Fabrication of fiber Bragg gratings coated with polyimide layers of varying thicknesses.
- Testing the sensor's response in a controlled environmental chamber with controlled RH and temperature.
- Characterization of sensor performance, including linearity, reversibility, accuracy, and sensitivity.
- Determination of the polyimide coating's thermal and hygroscopic expansion coefficients.
Main Results:
- The developed sensor demonstrated a linear and reversible response to relative humidity (RH) from 10% to 90%.
- Accurate sensing performance was confirmed within the tested temperature range of 13-60 degrees C.
- RH and temperature sensitivities were successfully correlated with polyimide coating thickness.
- Key material properties, including thermal and hygroscopic expansion coefficients, were quantified.
Conclusions:
- Polyimide-recoated fiber Bragg gratings offer a promising approach for intrinsic RH sensing.
- The sensor exhibits excellent performance characteristics suitable for demanding environmental monitoring applications.
- Understanding the relationship between coating thickness and sensitivity allows for sensor optimization.
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