A miniature fiber optic pH sensor for physiological use

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Medical Devices

Background:

• Accurate and reliable pH monitoring is crucial for physiological assessment.
• Existing pH measurement technologies may have limitations in flexibility and invasiveness for certain applications.

Purpose of the Study:

• To develop and evaluate a novel flexible fiber optic pH probe for physiological use.
• To assess the probe's accuracy and performance compared to standard methods in various environments.

Main Methods:

• Development of a 0.4-mm diameter flexible fiber optic probe using two plastic strands.
• Utilizing a dye indicator within a sealed cellulosic hollow fiber permeable to hydrogen ions.
• Employing an electronic module for illumination, light sensing, signal processing, and optical density measurements at 560 nm and red wavelengths.

Main Results:

• The fiber optic probe demonstrated high agreement with standard glass pH electrodes (within 0.01 pH units in buffers).
• Excellent accuracy was maintained in heparinized dog blood in vitro (within 0.017 pH units).
• Successful in vivo performance was achieved during implantation in a sheep's jugular vein.

Conclusions:

• A flexible fiber optic pH probe has been successfully developed and validated.
• The probe shows significant potential for accurate and reliable physiological pH monitoring.
• This technology offers a promising alternative for applications requiring flexible and minimally invasive pH sensing.