High fidelity fibre-based physiological sensing deep in tissue.

Area of Science:

• Biomedical Engineering
• Optical Sensing
• In Vivo Diagnostics

Background:

• Physiological sensing deep within biological tissues presents significant clinical challenges.
• Minimally invasive techniques are crucial for accurate in vivo measurements.

Purpose of the Study:

• To develop a flexible, miniaturized sensing optrode for minimally invasive in vivo, in situ physiological measurements.
• To enable high-precision photonic measurements of pH and oxygen concentration in challenging anatomical locations.

Main Methods:

• Fabrication of a sensing optrode by depositing silica microspheres functionalized with ratiometric fluorophores onto etched pits of a 150 µm optical fiber.
• Utilizing carboxyfluorescein-coupled silica microspheres to detect pH via inverse fluorescence shift.
• Implementing photonic measurements for oxygen concentration determination.

Main Results:

• Demonstrated high-density deposition of functionalized silica microspheres on an optical fiber.
• Achieved precise measurements of pH (±0.02 units) and oxygen concentration (±0.6 mg/L) in the distal alveolar space.
• Observed near-instantaneous response times for both pH and oxygen sensing.

Conclusions:

• The developed flexible sensing optrode offers a viable platform for minimally invasive physiological monitoring.
• The technology provides fast, accurate, and real-time data for pH and oxygen levels.
• The flexible architecture allows for the integration of multiple sensors for comprehensive physiological assessment.