Hypersensitive H₂ sensor based on polymer planar Bragg gratings coated with Pt-loaded WO₃-SiO₂

Area of Science:

• Materials Science
• Chemical Sensing
• Optoelectronics

Background:

• Hydrogen sensors are crucial for safety and industrial processes.
• Polymer planar Bragg gratings offer a platform for optical sensing.
• Developing sensors with high sensitivity and low detection limits is an ongoing challenge.

Purpose of the Study:

• To demonstrate a novel hydrogen sensor utilizing a functionalized polymer planar Bragg grating.
• To investigate the sensor's response to hydrogen at low concentrations.
• To establish the potential of this sensor for hydrogen leak detection.

Main Methods:

• Fabrication of a polymer planar Bragg grating sensor.
• Coating the grating with platinum-loaded tungsten oxide-silicon dioxide (Pt-loaded WO3-SiO2).
• Measuring the Bragg grating's spectral response to varying hydrogen concentrations via wavelength shifts.

Main Results:

• The sensor exhibited distinct Bragg signal peak splitting due to substrate anisotropies.
• An exothermic reaction between hydrogen and the coating generated heat, influencing the Bragg signal.
• A hydrogen concentration of 50 ppm resulted in a -37 pm Bragg wavelength shift.
• An outstandingly low hydrogen detection limit of 5 ppm in air was achieved.

Conclusions:

• Functionalized polymer planar Bragg gratings are highly suitable for hydrogen sensing.
• The developed sensor demonstrates excellent sensitivity and a low detection limit for hydrogen.
• This technology holds significant promise for hydrogen leak detection applications.