Wireless Flexible System for Highly Sensitive Ammonia Detection Based on Polyaniline/Carbon Nanotubes

Area of Science:

• Materials Science
• Environmental Science
• Sensor Technology

Background:

• Ammonia (NH3) is a significant atmospheric pollutant impacting environment, health, and food safety.
• Wearable flexible gas sensors are crucial for convenient, real-time NH3 monitoring.
• Existing sensors may lack sensitivity, selectivity, or long-term stability for practical applications.

Purpose of the Study:

• To propose a flexible ammonia gas sensing system integrated with Internet of Things (IoT) capabilities.
• To develop a wearable sensor with high sensitivity, selectivity, and stability for real-time NH3 detection.
• To demonstrate a portable and effective IoT solution for edge-based data collection and cloud processing.

Main Methods:

• Fabrication of a flexible gas sensor using polyaniline (PANI) decorated with multiwall carbon nanotubes (MWCNTs) on a silver interdigital electrode/polyethylene terephthalate (PET) substrate.
• Integration of the sensor with a Wi-Fi enabled microcontroller to create a flexible electronic system for IoT connectivity.
• Experimental evaluation of sensor performance including sensitivity, selectivity, humidity resistance, stability, and detection threshold.

Main Results:

• The flexible sensor achieved a low detection threshold of 0.3 ppm, suitable for exhaled breath analysis (0.425–1.8 ppm).
• Demonstrated high selectivity with negligible response to interfering gases like ethanol, acetone, and methanol.
• Exhibited excellent stability under varying humidity, repeated bending, and diverse orientations, along with a long lifespan.

Conclusions:

• A portable, stable, and effective flexible IoT system for real-time ammonia sensing has been successfully demonstrated.
• The developed sensor meets critical specifications for environmental and health monitoring applications.
• This technology enables edge data collection, cloud processing, and user-end display for comprehensive NH3 monitoring.