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Development of a medical fiber-optic pH sensor based on optical absorption
R Wolthuis1, D McCrae, E Saaski
1MetriCor Inc., Woodinville, WA 98072.
IEEE Transactions on Bio-Medical Engineering
|May 1, 1992
Summary
A novel fiber-optic pH sensor system offers high accuracy and rapid response for blood analysis. This cost-effective, solid-state device demonstrates excellent performance, making it suitable for clinical applications.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Sensor Technology
Background:
- Accurate pH monitoring is critical in clinical diagnostics, particularly for blood analysis.
- Existing pH sensing technologies may have limitations in terms of cost, response time, or invasiveness.
Purpose of the Study:
- To develop and evaluate a new fiber-optic pH sensor system for accurate and reliable pH measurements.
- To assess the sensor's performance in laboratory settings and with biological samples.
Main Methods:
- Utilized an absorptive indicator compound with a peak absorption near 625 nm for pH sensing.
- Employed a pulsed red LED for sensor interrogation and a dichroic mirror to split return light signals.
- Generated a ratiometric output signal from detected photocurrents for enhanced stability.
Main Results:
- Achieved high resolution (0.01 pH) and accuracy (+/- 0.01 pH) in laboratory tests.
- Demonstrated a rapid response time of 30-40 seconds.
- Showed excellent agreement (r = 0.992) with a clinical blood gas analyzer after gamma sterilization, even with heparinized human blood.
Conclusions:
- The developed fiber-optic pH sensor system exhibits excellent performance characteristics, including high accuracy, resolution, and rapid response.
- The sensor is suitable for use with biological samples, as validated by tests with human blood.
- The low-cost, solid-state design offers a promising alternative for clinical pH monitoring.