Highly Sensitive Chemo-Resistive Ammonia Sensor Based on Dodecyl Benzene Sulfonic Acid Doped Polyaniline Thin Film

ABSTRACTDodecyl benzene sulfonic acid (DBSA) doped polyaniline (PANI) has been synthesized by ex-situ doping inemeraldine base (EB). The optical and functional properties of as synthesized DBSA doped PANI (PANI-DBSA) have been studied by UV-Visible and FTIR spectroscopy, respectively. A chemo-resistive gas sensorwas prepared using spin coated PANI-DBSA thin film for quantitative detection of ammonia (NH 3 ) under ambi-ent conditions (27 C, 50% RH). The sensing characteristics of fabricated sensor were recorded using thedynamic resistance measurement, that revealed high sensitivity in relative response (∼4.5), response time(∼55 sec) and rapid recovery (∼100 sec). The PANI-DBSA thin film sensor shows good linearity ( R =0.996)and repeatability over a wide concentration range of NH 3 from 5 to 250 ppm.KEYWORDS: Conducting Polymers, Polyaniline, Dodecyl Benzene Sulfonic Acid (DBSA), Ammonia. 1. INTRODUCTION Ammonia (NH 3 ) is widely used in the production of fer-tilizer, chemicals, refrigeration systems, medical diagno-sis system, material processing and its global productionexceeds from 100 million tons per annum. Its long-termexposure of about 8 hours and inhalation to higher con-centrations≥5000ppmcancauseserioushealthhazards.