Sensors and Actuators B 153 (2011) 382–391 Contents lists available at ScienceDirect Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb Nano particulate SnO 2 based resistive films as a hydrogen and acetone vapour sensor Salim F. Bamsaoud a,b,∗ , S.B. Rane c,∗∗ , R.N. Karekar d , R.C. Aiyer a,b,∗ a Microwave and Thin Film Lab, Department of Physics, University of Pune, India b Center for Sensor Studies, Department of Physics, University of Pune, India c Centre for Materials for Electronics Technology, Off Pashan Road, Pune, India d RCMF Transducer Lab, Department of Electronics, University of Pune, India article info Article history: Received 30 April 2010 Received in revised form 1 November 2010 Accepted 2 November 2010 Available online 23 November 2010 Keywords: Tin oxide Nano-particle Sensor Hydrogen Acetone abstract SnCl 2 (solution) was spin coated on soda lime glass and Al 2 O 3 substrate to obtain nano-particulate tin oxide film, directly by sintering at 550 ◦ C for 40 minutes (min). The surface morphology and crystal struc- ture of the tin oxide films were analyzed using atomic force microscopy (AFM) and X-ray diffraction (XRD). The size of SnO 2 nanostructure was determined from UV–vis and found to be .3 nm. These films were tested for sensing H 2 concentration of 0.1–1000 ppm at optimized operating temperature of 265 ◦ C. The results showed that sensitivity (R air /R gas per ppm) goes on increasing with decreasing concentration of test gas, giving concentration dependent changes. Special studies carried out at low concentration levels (0.1–1 and 1–10 ppm) of H 2 , give high sensitivity (200 × 10 -3 /ppm) for lowest concentration (0.1–1 ppm) of H 2 . The selectivity for H 2 against relative humidity (RH), CO 2 , CO and LPG gases is also good. The sen- sor, at operating temperature of 200 ◦ C, is showing nearly zero response to 300 ppm of H 2 , and offering response to acetone vapour of 11 ppm. Selectivity for acetone against RH% and CO 2 was also studied. These sensors can be used as H 2 sensor at an operating temperature of 265 ◦ C, and as an acetone sensor at the operating temperature of 200 ◦ C. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Gas sensors are highly in demand for detecting, monitoring and controlling the presence of hazardous and poisonous gases in the atmosphere. The fundamental requirements of highly sensitive, selective, stable and fast response gas sensors with economical considerations (multi gas sensor, small size, low production time and low cost) have lead to extensive research and development in gas sensing area. Generally, these sensors are made of metal oxide semiconductors as sensing materials. Tin oxide (SnO 2 ), compared to the other semiconductor materials based sensor, exhibited better response. Therefore further improvement in methods of material synthesis, surface modifications and sensor fabrication technolo- gies, are required to achieve better performance in tin oxide based gas sensor. The interest in developing solid-state hydrogen gas sensor is due to the fact that presently hydrogen is considered as ‘near- ∗ Corresponding authors at: Microwave and Thin Film Lab, Department of Physics, University of Pune, India. Tel.: +91 20 2569 2678; fax: +91 2569 1684. ∗∗ Corresponding author. Tel.: +91 20 2589 9273; fax: +91 20 2589 8180. E-mail addresses: saalem88@yahoo.com (S.F. Bamsaoud), sunitrane@yahoo.com (S.B. Rane), rca@physics.unipune.ernet.in (R.C. Aiyer). future’ fuel [1–12]. However, as hydrogen is highly explosive, safety remains a top priority. As a result, sensing hydrogen leak- age at low ppm even to ppb level during storage and transport becomes essential. The leak detection as well as concentration monitoring are important for applications of hydrogen sensors [11]. Room temperature operating hydrogen sensor based on SnO 2 is successfully developed for space-based applications to detect gas concentration in the range of 1–4 vol.% (10 4 to 4 × 10 4 ppm) [12]. Hydrogen sensor operating at relatively low temperature (120 ◦ C) for 50 ppm as a minimum detectable concentration is reported by Adamyan [5]. However, to develop hydrogen sensor having response to ppb concentration is still a challenge. Acetone is one of the highly volatile organic compounds, is often used as an organic solvent (plastic, fibre and spray-paint) or chemical intermediate (dyestuff, rubber, and lubricating oil). Although it is popularly regarded as having relatively low toxic effects, some investigations have indicated that chronical expo- sure to acetone vapour may damage the liver and kidney or nerve and cause inflammation [13,14]. SnO 2 based acetone vapour sensor detecting 10 ppm concentration, is reported by Gong et al. [15]. Jie et al. [16] developed SnO 2 sensor that responds to 2 ppm acetone concentration at room temperature having response time ≤20 s. The response to lowest acetone concentration (1 ppb) is reported 0925-4005/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2010.11.003