Porous-Cladding Polydimethylsiloxane Optical Waveguide for Biomedical Pressure Sensing Applications.

Area of Science:

• Materials Science
• Optical Engineering
• Biomedical Engineering

Background:

• Developing sensitive and reliable pressure sensors is crucial for biomedical applications, particularly for monitoring and preventing conditions like pressure injuries.
• Existing pressure sensors often face limitations in sensitivity, biocompatibility, or fabrication complexity.

Purpose of the Study:

• To introduce a novel pressure sensor concept based on polydimethylsiloxane (PDMS) with a solid core and porous cladding.
• To investigate the operational principles of frustrated total internal reflection for pressure sensing.
• To assess the sensor's performance in a biomedical dynamic pressure range for applications such as pressure injury prevention.

Main Methods:

• Fabrication of a flexible, rectangular cross-section waveguide using casting and molding.
• Incorporation and control of microbubbles within the PDMS waveguide to manage optical losses via temperature control during fabrication.
• Characterization of optical losses, microbubble concentration and diameter, and pressure sensitivity.

Main Results:

• Successful fabrication of a solid-core/clad waveguide with porous cladding exhibiting controlled optical losses (approx. 1.85 dB/cm).
• Demonstrated control over microbubble concentration (average diameter 239 ± 16 µm) influencing optical properties.
• Measured a high pressure sensitivity of 0.1035 dB/kPa optical power loss.

Conclusions:

• The developed PDMS-based pressure sensor operates effectively via frustrated total internal reflection.
• The sensor exhibits significant sensitivity within the biomedical dynamic pressure range (0 to 13.3 kPa).
• This technology holds promise for critical applications such as pressure injury prevention by indicating critical pressure threshold levels.