The development of efficient and reliable chemical sensors for detecting toxic gases, such as ammonia (NH₃), is crucial for environmental monitoring, industrial safety, and health applications. This study focuses on the fabrication and characterization of a polyaniline (PANI)-based chemical sensor specifically designed for the detection of ammonia gas. Polyaniline, a conductive polymer, was chosen due to its unique electrical properties, environmental stability, and ease of synthesis, making it an ideal material for gas sensing applications.
Fabrication Process
The fabrication process involved the chemical polymerization of aniline monomers to form polyaniline, which was then deposited onto a suitable substrate to create the sensing layer. The polymerization was carried out using an oxidizing agent in an acidic medium, resulting in the formation of emeraldine salt, the conductive form of polyaniline. The PANI film was deposited using techniques such as spin coating or drop casting, ensuring uniform coverage and optimal thickness for gas detection. Post-deposition treatments, including doping with acids like hydrochloric acid (HCl), were employed to enhance the sensor’s sensitivity and response time.
Characterization and Sensitivity Analysis
The fabricated sensor was characterized using various analytical techniques to determine its morphological, electrical, and sensing properties. Scanning electron microscopy (SEM) was employed to analyze the surface morphology of the PANI film, confirming its uniformity and porosity, which are critical for effective gas adsorption. Fourier-transform infrared spectroscopy (FTIR) was used to verify the chemical structure of polyaniline and confirm the successful doping process.
The sensor’s electrical properties were assessed by measuring its resistance in the presence of ammonia gas at varying concentrations. The PANI-based sensor exhibited a significant change in resistance upon exposure to ammonia, attributed to the deprotonation of the polymer by the basic gas, which reduces the conductivity of the polyaniline. The sensor demonstrated high sensitivity to low concentrations of ammonia, with a rapid response time and excellent repeatability, making it a suitable candidate for real-time ammonia detection.
Performance Evaluation
The performance of the PANI-based ammonia sensor was further evaluated by testing its response under different environmental conditions, including variations in temperature and humidity. The sensor showed consistent performance across a range of temperatures, with minimal drift in baseline resistance, indicating its robustness and stability. However, humidity was found to influence the sensor’s response, necessitating further optimization or the integration of humidity compensation techniques to ensure accurate detection in humid environments.
