Ultrafast response sensor to formaldehyde gas based on metal oxide.

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Monitoring

Background:

• Formaldehyde (HCHO) is a volatile organic compound causing sick building syndrome.
• Effective semiconductor gas sensors are needed for real-time indoor air quality monitoring.
• Indium oxide (In2O3) is a promising material for gas sensing applications.

Purpose of the Study:

• To fabricate and characterize thick film indium oxide semiconductor gas sensors.
• To evaluate the sensor performance for formaldehyde detection.
• To assess the sensor's suitability for indoor environmental monitoring.

Main Methods:

• Fabrication of In2O3 thick films on Si substrate.
• Characterization using optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM).
• Gas sensing measurements under controlled formaldehyde concentrations and operating temperatures.

Main Results:

• Uniform In2O3 films with particle sizes of 20-30 nm were obtained.
• Sensors detected formaldehyde at sub-ppm levels, with a lowest detection limit of 25 ppb.
• High sensitivity (>25% at 800 ppb), fast response (8 s), and recovery (15 s) times were achieved at 350 °C.

Conclusions:

• The fabricated indium oxide gas sensors exhibit excellent performance for formaldehyde detection.
• The sensors show high sensitivity, selectivity, and reproducibility.
• These sensors are adaptable for monitoring indoor environments and mitigating sick building syndrome.