Selective Detection of NO and NO₂ with CNTs-Based Ionization Sensor Array.

Area of Science:

• Environmental Science
• Materials Science
• Sensor Technology

Background:

• Nitrogen oxides (NOx) are significant environmental pollutants and pose risks to human health.
• Accurate detection of NO and NO₂ is crucial for environmental monitoring and health protection.

Purpose of the Study:

• To develop a selective and simultaneous detection method for NO and NO₂ using an array of carbon nanotubes (CNTs)-based ionization sensors.
• To investigate the response characteristics of CNTs-based sensors with varying electrode separations to NO and NO₂.

Main Methods:

• Fabrication of a sensor array using two CNTs-based ionization sensors with different electrode separations (80 µm and 100 µm).
• Characterization of the sensors' intrinsic response to varying concentrations of NO and NO₂.
• Evaluation of the array's capability for simultaneous detection of NO and NO₂ in a gas mixture.

Main Results:

• CNTs-based ionization sensors demonstrated a monotonically decreasing response to both NO and NO₂.
• The sensor with 80 µm separation showed a sensitivity of -0.11 nA/ppm to NO, while the 100 µm sensor exhibited -0.49 nA/ppm sensitivity to NO₂.
• The sensor array successfully achieved simultaneous detection of NO and NO₂ concentrations without prior gas component separation.

Conclusions:

• The proposed CNTs-based sensor array offers a promising solution for selective and simultaneous detection of NO and NO₂.
• The sensor array's ability to differentiate between NO and NO₂ concentrations in mixtures is vital for environmental and health applications.
• Further optimization of sensor design and operating conditions could enhance sensitivity and selectivity for NOx monitoring.