New sensitive layer based on pulsed plasma-polymerized aniline for integrated optical ammonia sensor

Area of Science:

• Materials Science
• Chemical Sensors
• Optical Engineering

Background:

• Ammonia gas detection is crucial for environmental monitoring and industrial safety.
• Existing ammonia sensors often face limitations in sensitivity, response time, or operating conditions.
• Integrated optical sensors offer potential for high sensitivity and miniaturization.

Purpose of the Study:

• To design and develop a new integrated optical sensor for ammonia detection.
• To investigate the sensing properties of a plasma-elaborated polyaniline layer on an optical waveguide.
• To evaluate the sensor's performance at room temperature.

Main Methods:

• Fabrication of a sensor using plasma-enhanced chemical vapor deposition (PECVD) to create a polyaniline sensitive layer.
• Deposition of the polyaniline layer onto a single-mode planar SU-8 waveguide.
• Characterization of the sensor's response to ammonia gas at room temperature, analyzing output power changes.
• Evaluation of metrological parameters including sensitivity, response time, recovery time, reversibility, and repeatability.
• Investigation of the influence of interaction length, dopant type, and light polarization on sensor performance.

Main Results:

• A significant change in guided light output power was observed upon exposure to ammonia gas.
• The sensor demonstrated fast response and recovery times, along with good reversibility and repeatability.
• Metrological parameters were found to be significantly influenced by interaction length, dopant type, and light polarization.
• A logarithmic linear optical response was achieved within the ammonia concentration range of 92 to 4618 ppm.

Conclusions:

• The developed integrated optical sensor based on plasma-polyaniline is effective for ammonia detection at room temperature.
• The sensor exhibits promising performance characteristics, including speed, stability, and a defined response range.
• Further optimization of sensor design parameters can enhance its metrological properties for practical applications.