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Real-time frequency domain temperature and oxygen sensor with a single optical fiber
1Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA. sx134@po.cwru.edu
IEEE Transactions on Bio-Medical Engineering
|November 14, 1997
Summary
This study developed a single-fiber sensor using alexandrite and platinum tetraphenylporphyrin (Pt(TPP)) to monitor temperature and oxygen. The sensor achieves high precision for physiological ranges, enabling real-time physiological monitoring.
Area of Science:
- Optoelectronics
- Biomedical Sensing
- Materials Science
Background:
- Accurate physiological monitoring requires precise temperature and oxygen measurements.
- Existing sensors may have limitations in sensitivity, response time, or multiplexing capabilities.
- Phosphorescence-based sensing offers potential for non-invasive, real-time monitoring.
Purpose of the Study:
- To develop and validate a novel single-fiber optical sensor for simultaneous temperature and oxygen monitoring.
- To utilize the distinct phosphorescence lifetimes of alexandrite and platinum tetraphenylporphyrin (Pt(TPP)) for dual-parameter sensing.
- To achieve high precision and accuracy within the physiological ranges relevant to biological applications.
Main Methods:
- A single-fiber sensor was constructed integrating an alexandrite crystal and Pt(TPP) coating.
- Pulsed blue LED excitation and frequency domain analysis (Fast Fourier Transform) were employed.
- Phosphorescence lifetimes were measured and correlated to temperature and oxygen concentrations using empirical polynomial models.
- Signal processing involved amplification, band-limiting, sampling, averaging, and computation of phase delay and modulation ratios.
Main Results:
- The sensor accurately monitored temperature (15-45°C) with 0.24°C precision and 0.28°C accuracy.
- Oxygen concentration (0-50% O2) was monitored with 0.15% precision and 0.2% accuracy.
- System drift was minimal (0.24°C for temperature, 0.59% for oxygen) over 30 hours.
- Rapid update times (6s) and full response times (90s) were achieved.
Conclusions:
- The developed single-fiber sensor effectively enables simultaneous, precise, and accurate monitoring of temperature and oxygen in physiological ranges.
- The combined use of alexandrite and Pt(TPP) phosphorescence provides a robust platform for dual-analyte sensing.
- This technology holds promise for advanced biomedical monitoring and diagnostic applications.