No abstract

A novel flexible, ultra-sensitive, selective, and room temperature operable polyaniline/iron-oxide (PAni/α-Fe 2 O 3 ) nanocomposite 5 ammonia (NH 3 ) gas sensor was developed onto a flexible polyethylene terephthalate (PET) substrate by in-situpolymerization process.The observations were recorded to 100ppm fixed level for various gases including NO 2, CH 3 OH, C 2 H 5 OH, NH 3 , and H 2 S through monitoring the change in resistance of the developed sensor. The flexible PAni/α-Fe 2 O 3 nanocomposite sensor demonstrated better selectivity towards NH 3 (response = 39% and stability = 74%). The synergistic response of the flexible PAni/α-Fe 2 O 3 sensor was remarkable than that of the PAni and α-Fe 2 O 3 alone; indicating the effective improvement in the performance of PAni flexible sensor on 10 nanocomposite process. Moreover, the flexible sensor detected NH 3 at low concentration (5ppm) with a fast response (27s) and very short recovery time (46s). Further, PAni/α-Fe 2 O 3 flexible sensor films were characterized by X-ray diffraction, field-emission scanning electron microscopy, UV-visible and Raman spectroscopy, Fourier transform infrared and X-ray photoelectron for structural analysis, morphological evolution, optical and surface related studies. 15

Flexible and highly sensitive polyaniline-based (PAni) ammonia (NH 3 ) gas sensors were developed through an in-situ chemical oxidative polymerization process of aniline on a polyethylene terephthalate substrate at three different temperatures viz. 35⁰C, 0⁰C and -5⁰C. In the beginning stage, they were characterized with respect to their structural, morphological, and compositional analysis studies and in second stage, selectivity was tested for oxidizing (nitrogen dioxide, NO 2 ) and reducing (NH 3 , ethanol, methanol and hydrogen sulphide, H 2 S) gases. The sensor fabricated at 0 o C showed optimum response of 26% to 100 ppm NH 3 gas which was superior to those obtained for 10 sensors developed at 35⁰C (19%) and -5⁰C (23%). As-developed low-temperature flexible gas sensor has demonstrated fast response (19 s) as well as recovery times (36 s), 99 % reproducibility and good stability, enabling potential of commercial application, for example in industry where high temperature operation is prohibited. The impedance spectroscopy was used to investigate the plausible interaction mechanism of NH 3 gas molecules with flexible PAni film. Operation of NH 3 gas sensor, fabricated on a laboratory scale was tested and explored as a demo-video clip; available online as EIS. 15 45

No abstract

A simple and inexpensive chemical bath deposition method was employed for the preparation of lead sulfide (PbS) thin films.