Sensitivity Improvement of Ammonia Gas Sensor Based on Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) by Employing Doping of Bromocresol Green
The aim of this research is to improve the sensitivity of ammonia gas sensor (hereafter referred to as sensor) based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) by employing the doping dye of bromocresol green (BCG). The doping process was carried out by mixing the BCG and the PEDOT:PSS in a solution with an optimum ratio of 1？:？1 in volume. The sensor was fabricated by using spin-coating technique followed by annealing process. For comparison, the BCG thin film and the PEDOT:PSS thin film were also deposited with the same method on glass substrates. For optical characterization, a red-light laser diode with a 650？nm wavelength was used as light source. Under illumination with the laser diode, the bare glass substrate and BCG film showed no absorption. The sensor exhibited linear response to ammonia gas for the range of 200？ppm to 800？ppm. It increased the sensitivity of sensor based on PEDOT:PSS with BCG doping being about twofold higher compared to that of without BCG doping. Furthermore, the response time and the recovery time of the sensor were found very fast. It suggests that the optical sensor based on BCG-doped PEDOT:PSS is promising for application as ammonia gas sensor. 1. Introduction Ammonia gas has pungent odour and is colourless and lighter than air. It is known as a toxic compound that can be harmful to the human health if presents at high concentration [1]. In this regards, the device to detect ammonia gas is extremely necessary. Recently, there are many reports related to the development of gas sensors based on polymers because of advantages such as easy fabrication, low power consumption, room temperature operation, and being independent from environmental interference [2]. A hybrid material for ammonia gas sensor has been developed by electrochemical incorporation of phthalocyanine in conducting polypyrrole [3–5]. The polypyrrole films have been electrochemically deposited on microelectrodes arrays by using silicon microtechnologies. Its sensing properties to ammonia gas were investigated by considering electrodeposition parameters [6, 7]. Beside polypyrrole, another polymer for ammonia gas sensor is polyaniline [8, 9]. The electrical impedance spectroscopy and amperometry of polyaniline have also been modified for ammonia gas sensor [10]. As gas sensor material, the conducting polymer interacts with gas molecules resulting in a change bipolaron density inside the band gap [2]. It is well known that the bipolaron excitations generally fall in the visible range, so that both electrical and optical properties
References
[1]
T. Hibbard, K. Crowley, and A. J. Killard, “Direct measurement of ammonia in simulated human breath using an inkjet-printed polyaniline nanoparticle sensor,” Analytica Chimica Acta, vol. 779, pp. 6–63, 2013.
[2]
Y.-S. Lee, B.-S. Joo, N.-J. Choi, J.-O. Lim, J.-S. Huh, and D.-D. Lee, “Visible optical sensing of ammonia based on polyaniline film,” Sensors and Actuators B, vol. 93, no. 1–3, pp. 148–152, 2003.
[3]
J. Janata and M. Josowicz, “Conducting polymers in electronic chemical sensors,” Nature Materials, vol. 2, no. 1, pp. 19–24, 2003.
[4]
H. Bai and G. Shi, “Gas sensors based on conducting polymers,” Sensors, vol. 7, no. 3, pp. 267–307, 2007.
[5]
T. Patois, J.-B. Sanchez, F. Berger et al., “Elaboration of ammonia gas sensors based on electrodeposited polypyrrole-Cobalt phthalocyanine hybrid films,” Talanta, vol. 17, pp. 45–54, 2013.
[6]
S. Carquigny, J.-B. Sanchez, F. Berger, B. Lakard, and F. Lallemand, “Ammonia gas sensor based on electrosynthesized polypyrrole films,” Talanta, vol. 78, no. 1, pp. 199–206, 2009.
[7]
T. Patois, J.-B. Sanchez, F. Berger, J.-Y. Rauch, P. Fievet, and B. Lakard, “Ammonia gas sensors based on polypyrrole films: influence of electrodeposition parameters,” Sensors and Actuators B, vol. 171-172, pp. 431–439, 2012.
[8]
H. Kebiche, D. Debarnot, A. Merzouki, F. Poncin-Epaillard, and N. Haddaoui, “Relationship between ammonia sensing properties of polyaniline nanostructures and their deposition and synthesis methods,” Analytica Chimica Acta, vol. 737, pp. 64–71, 2012.
[9]
D.-M. Xu, M.-Y. Guan, Q. -Hong Xu, and Y. Guo, “Multilayer films of layered double hydroxide/polyaniline and their ammonia sensing behavior,” Journal of Hazardous Materials, vol. 262, pp. 64–70, 2013.
[10]
S. P. Basak, B. Kanjilal, P. Sarkar, and A. P. F. Turner, “Application of electrical impedance spectroscopy and amperometry in polyaniline modified ammonia gas sensor,” Synthetic Metals, vol. 175, pp. 127–133, 2013.
[11]
K. Triyana, T. Yasuda, K. Fujita, and T. Tsutsui, “Improvement of heterojunction donor/acceptor organic photovoltaic devices by employing additional active layer,” Japanese Journal of Applied Physics, vol. 44, no. 4 A, pp. 1974–1977, 2005.
[12]
L. Aba, Y. Yusuf, Mitrayana, and K. Triyana, “Selectivity improvement of gas sensor based on poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) thin film by using imprinting method,” Journal of Modern Physics, vol. 3, no. 7, pp. 529–533, 2012.
[13]
F. Tavoli and N. Alizadeh, “Optical ammonia gas sensor based on nanostructure dye-doped polypyrrole,” Sensors and Actuators B, vol. 176, pp. 761–767, 2013.
[14]
Q. Zhong, H. Xu, H. Ding et al., “Preparation of conducting polymer inverse opals and its application as ammonia sensor,” Colloids and Surfaces A, vol. 433, pp. 59–63, 2013.
[15]
P. Pacher, A. Lex, S. Eder et al., “A novel concept for humidity compensated sub-ppm ammonia detection,” Sensors and Actuators B, vol. 145, no. 1, pp. 181–184, 2010.
[16]
D. Diamond, K. T. Lau, S. Brady, and J. Cleary, “Integration of analytical measurements and wireless communications—current issues and future strategies,” Talanta, vol. 75, no. 3, pp. 606–612, 2008.
[17]
A. El-Didamony and S. Hafeez, “Spectrophotometric determination of thioridazine hydrochloride in tablets and biological fluids by ion-pair and oxidation reactions,” Spectroscopy: An International Journal, vol. 27, no. 3, pp. 129–141, 2012.
