Interdigitated electrode (IDE) sensor of polyaniline (PANI) nanoparticles thin film for detection of methanol vapour

• Main Author: Zulkhairi, Zakaria
• Format: Thesis
• Language: English
• Published: Universiti Malaysia Perlis (UniMAP) 2014
• Subjects: Methanol vapour; Interdigitated electrode (IDE) sensor; IDE detection system; Thin film; PANI nanoparticle
• Online Access: http://dspace.unimap.edu.my:80/dspace/handle/123456789/31917

Methanol is released to the environment during industrial uses or naturally from volcanic gases, vegetation, and microbes. Exposure may occur from ambient air and during the use of solvents. Methanol has a high toxicity to humans. If ingested, for example, as little as 10 ml of pure methanol can cause permanent blindness, and 30 ml is potentially fatal. This thesis reports a study on interdigitated electrode (IDE) sensor of PANI nanoparticles thin film for detection of methanol vapour. The research covers the sensor development, characterization method of PANI nanoparticles and setting up a IDE detection system. IDE was fabricated by evaporation technique on polyethylene terephthalathe (PET) substrate using aluminum as electrode material. The digit width and gap of the sensor were 0.25 mm and 0.51 mm. PANI nanoparticles was synthesized by emulsion polymerization method. Inkjet printing method was used to deposit the PANI nanoparticles onto IDE. The size of PANI nanoparticles was 152 nm. FTIR spectra analysis correspond to well-doped PANI-ES with the existence of peaks at 3321, 1637, 1204 and 1037 cm-1. UV-Vis spectra of the PANI nanoparticles shown the three band transitions appear at 340, 420 and 790-800 nm. Resistance of inkjet-printed PANI nanoparticles films was decreased over number of prints from 8.34 to 3.24 MΩ. The surface of the inkjet-printed PANI nanoparticles films became smoother and more uniform with increasing number of prints and good homogeneity could be observed at 21 and 28 prints. Porous film morphology with non-uniform pores distribution was observed by SEM. The size of pores distribution to be bigger after exposure to methanol vapour indicated that diffusion gas molecule had occurred. Increasing the number of prints shown that the response time increase and output voltage was decreased but recovery time not changing. Seven print shown the optimum sensor with response time 10s. Good repeatability and reproducibility was observed by constant response. Sensitivity analysis shown that decreasing the concentration of methanol vapour would decrease the output voltage. The limit detection of the sensor was 20 ppm. Selectivity analysis express that an increasing the carbon chain of alcohols will be decrease the output voltage. The shelf life of this sensor was 28 days.