A Robust Miniaturized Gas Sensor for H₂ and CO₂ Detection Based on the 3ω Method

Area of Science:

• Physics
• Materials Science
• Chemical Engineering

Background:

• Gas concentration monitoring is crucial for industrial and life science applications.
• Thermal conductivity sensors are widely used for gas analysis.
• The 3ω-method is a precise technique for material thermal property determination, primarily used for thin films.

Purpose of the Study:

• To systematically investigate the 3ω-method for determining gas thermal properties.
• To apply the 3ω-method to gas measurement technology.
• To evaluate the performance of a tungsten wire sensor for H2 and CO2 detection.

Main Methods:

• Utilized the 3ω-method with a helix-shaped tungsten wire sensing element.
• Conducted experiments in a compact, integrated measurement environment.
• Employed a simplified analytical model and Finite Element Method (FEM) simulations for validation.

Main Results:

• Experimental results showed good agreement with analytical models and FEM simulations.
• Achieved a lower detection limit of 0.62% for CO2.
• Demonstrated a very low detection limit of 0.062% for H2 at 1 Hz excitation frequency.

Conclusions:

• The 3ω-method is a viable and accurate technique for gas thermal property analysis.
• The tungsten sensor exhibits excellent robustness and sensitivity for gas sensing applications.
• This study presents one of the lowest detection limits reported for thermal conductivity hydrogen sensors.