Solid-state electrolyte sensors for rebreather applications: a preliminary investigation

Area of Science:

• Materials Science
• Sensor Technology
• Biomedical Engineering

Background:

• Zirconium dioxide and NASICON-based micro solid-state electrolyte sensors were developed for rebreather applications.
• The oxygen (O2) sensor offers a long operational life, while the carbon dioxide (CO2) sensor has a lifespan of approximately 700 hours.

Purpose of the Study:

• To evaluate the suitability of novel O2 and CO2 solid-state sensors for use in rebreather systems.
• To assess sensor performance characteristics including response time, linearity, cross-sensitivity, and power consumption.

Main Methods:

• Testing sensors in a pressure chamber up to 405 kPa for O2 and 10 kPa for CO2.
• Measuring response times and cross-sensitivity to helium using trimix.
• Modifying a rebreather mouthpiece for breath-by-breath gas analysis and measuring sensor power consumption.

Main Results:

• The O2 sensor exhibited non-linearity above 101.3 kPa PO2; the CO2 sensor showed an inverse logarithmic relationship.
• Observed cross-sensitivity to helium.
• Mean t90 response times were 90 ms for O2 and 100 ms for CO2 sensors; power consumption was 1.5-2 W per sensor.

Conclusions:

• Fast response times enable accurate breath-by-breath measurements.
• Multi-point calibration can address O2 sensor non-linearity, but further design is needed for trimix compatibility.
• High power consumption for sensor heating presents a significant disadvantage.