2.2.3. AFM analysis
Atomic force microscopy (AFM) measurements of the polyaniline nano samples were done at room temperature and humidity. The topographic images were taken using tapping mode, with a resonance frequency of 287.67 kHz and scan rate of 1.2 Hz in VEECO Multimode Nanoscope IIIa. The cantilever used in the study is RTESP.
2.2.4. XRD analysis
The XRD pattern of the synthesized polyaniline nanoparticles were recorded in a XPERT-PRO Diffractometer with 2_ ranging between 20–80 ◦C and CuK_ radiation (_=1.5406A˚ ).
2.3. Sensor fabrication
2.3.1. Screen-printed electrode
Disposable screen-printed three-electrode systems, with carbon working electrode, carbon counter electrode and silver/silver chloride reference electrode, printed on a 250 mm thick polyester sheet (Cadillac Plastic Ltd., Swindon, UK) using a DEK 248 screenprinter (DEK Printing Machines Ltd., Waymouth, UK) were used for gas sensing study. The detailed fabrication method for these disposable screen-printed electrodes has been discussed elsewhere [37,38]. These electrodes were modified by immobilizing PANI powder (1 mg per electrode) dissolved in pyrrolidone using 20% gelatin and 12.5% glutaraldehyde solution. The sensor so formed was housed in an airtight bottle with an NH3 inlet. While the gelatin polymer ensured diffusion of NH3 into the sensor, the PANI nanofibres gave rise to the electrochemical response.