Temperature self-calibrated pH sensor based on GO/PVA-coated MZI cascading FBG
Optics Express
|May 14, 2021
Summary
A novel fiber optic sensor accurately measures pH and temperature simultaneously. This self-calibrated sensor utilizes a photonic crystal fiber structure coated with GO/PVA hydrogel for pH detection and a fiber Bragg grating for temperature compensation.
Area of Science:
- Optoelectronics
- Chemical Sensing
- Materials Science
Background:
- Accurate and real-time monitoring of pH is crucial for environmental and biological applications.
- Traditional pH sensors often suffer from temperature cross-sensitivity, requiring separate calibration.
- Developing integrated sensors for simultaneous pH and temperature measurement is highly desirable.
Purpose of the Study:
- To propose and demonstrate a temperature self-calibrated pH sensor.
- To integrate a Mach-Zehnder interferometer (MZI) with a fiber Bragg grating (FBG) for dual-parameter sensing.
- To utilize a graphene oxide/polyvinyl alcohol (GO/PVA) hybrid hydrogel for enhanced pH sensitivity.
Main Methods:
- Fabrication of a single mode fiber-tapered dual core photonic crystal fiber-single mode fiber (SMF-TDCPCF-SMF) structure.
- Coating the TDCPCF structure with GO/PVA hydrogel for pH sensing.
- Cascading the TDCPCF-MZI with an uncoated FBG for temperature calibration.
- Experimental characterization of sensor performance across various pH levels and temperatures.
Main Results:
- Achieved a pH sensitivity of 0.69 nm/pH with R²=0.99 and hysteresis loss < 0.007 within pH 4.00-9.85.
- Demonstrated response times ≤ 10s for pH changes.
- Obtained linear temperature responses with coefficients of 0.15 nm/°C (MZI) and 0.09 nm/°C (FBG) (R² > 0.97).
- Confirmed good repeatability, linearity, and reversibility of the sensor.
Conclusions:
- The proposed SMF-TDCPCF-SMF-FBG sensor effectively performs temperature self-calibrated pH monitoring.
- The sensor exhibits excellent performance metrics, including sensitivity, response time, and stability.
- This technology holds significant potential for environmental monitoring, biological sensing, and chemical analysis.
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