Gaseous Ammonia Sensing from Liquids via a Portable Chemosensor with Signal Correction for Humidity

Area of Science:

• Materials Science
• Sensor Technology
• Analytical Chemistry

Background:

• Ammonia (NH3) detection is crucial for environmental, industrial, food safety, and health diagnostics.
• Current methods lack portability and suitability for point-of-care (POC) applications due to complexity and interference.
• Water vapor interference is a significant challenge in existing polyaniline (PANI)-based ammonia sensors.

Purpose of the Study:

• To develop a compact, portable device for POC detection of gaseous ammonia released from liquid samples.
• To create a selective sensor resistant to liquid interference and water vapor.
• To establish a robust signal processing strategy for accurate ammonia quantification.

Main Methods:

• Fabrication of a polyaniline (PANI)-based chemoresistive sensor with interdigitated electrodes.
• Encapsulation within a gas-permeable hydrophobic membrane for selective ammonia vapor detection.
• Optimization of PANI nanoparticle ink formulation and signal processing to extract resistance variation slope.
• Testing sensor performance across a concentration range of 1.7 to 170 ppm.

Main Results:

• The PANI nanoparticle suspension showed optimal characteristics for sensor fabrication.
• The device effectively prevented liquid interference and minimized water vapor impact.
• The sensor achieved high correlation coefficients (R2=0.99 logarithmic, R2=0.96-0.97 linear) for ammonia quantification.
• Reliable performance was demonstrated across a wide concentration range.

Conclusions:

• A feasible POC platform for sensitive and selective ammonia detection was developed.
• The device offers a practical solution for real-time ammonia monitoring in various applications.
• This technology advances portable sensing for clinical and environmental monitoring.