Nanoparticle metal-oxide films for micro-hotplate-based gas sensor systems

We report on the use of either reactive magnetron sputtering or screen printing to deposit tin and tungsten-oxide gas-sensitive layers onto integrated micromachined arrays. The procedures allow the deposition of the sensing layers before membranes have been etched, which leads to gas microsensors with an excellent fabrication yield. The microstructure of the sensitive films is analyzed by means of SEM and EDX. The response of the different microarrays to ethanol, acetone, and ammonia vapors and their binary mixtures, and toxic gases such as NO/sub 2/ and CO, is studied at different operating temperatures. The response of the different sensors to ambient humidity is also investigated. Finally, it is shown that by using PCA and fuzzy ARTMAP neural networks, it is possible to simultaneously identify and quantify the toxic gases with a 100% success rate. A 95% success rate is obtained in the semi-quantitative analysis of vapors and vapor mixtures. These results prove the viability and usefulness of the techniques introduced to obtain integrated sensor microarrays that are suitable for battery-powered gas/vapor monitors.

[1]  Giorgio Sberveglieri,et al.  LETTER TO THE EDITOR: A new technique for growing large surface area SnO2 thin film (RGTO technique) , 1990 .

[2]  Anna Vilà,et al.  Thermo-mechanical analysis of micro-drop coated gas sensors , 2002 .

[3]  Carles Cané,et al.  Screen-printed nanoparticle tin oxide films for high-yield sensor microsystems , 2003 .

[4]  J. Suehle,et al.  In situ conductivity characterization of oxide thin film growth phenomena on microhotplates , 1998 .

[5]  J. D. Sternhagen,et al.  Development of a micromachined hazardous gas sensor array , 2003 .

[6]  J. Suehle,et al.  Microhotplate Platforms for Chemical Sensor Research , 2001 .

[7]  Julian W. Gardner,et al.  Thermal modelling and characterisation of micropower chemoresistive silicon sensors , 1997 .

[8]  Benno Margesin,et al.  Gas-sensing device implemented on a micromachined membrane: A combination of thick-film and very large scale integrated technologies , 2000 .

[9]  J. Gardner.  A non-linear diffusion-reaction model of electrical conduction in semiconductor gas sensors , 1990 .

[10]  Jürgen Wöllenstein,et al.  Micromachined thin film SnO2 gas sensors in temperature-pulsed operation mode , 1999 .

[11]  Johnny K. O. Sin,et al.  A low-power CMOS compatible integrated gas sensor using maskless tin oxide sputtering , 1998 .

[12]  Richard E. Cavicchi,et al.  KINETICALLY CONTROLLED CHEMICAL SENSING USING MICROMACHINED STRUCTURES , 1998 .

[13]  C. Cané,et al.  Structural and dimensional control in micromachined integrated solid state gas sensors , 2000 .

[14]  Sholom M. Weiss,et al.  Computer Systems That Learn , 1990 .

[15]  Theodor Doll,et al.  Field-effect-induced gas sensitivity changes in metal oxides , 1997 .

[16]  Duk-Dong Lee,et al.  Classifying combustible gases using micro-gas sensor array , 2003 .

[17]  G. Sberveglieri,et al.  Microstructure and morphology of tin dioxide multilayer thin film gas sensors , 1997 .

[18]  R. Mlcak,et al.  Advanced Sensor Technology Based on Oxide Thin Film—MEMS Integration , 2000 .

[19]  Matteo Ferroni,et al.  Gas sensing through thick film technology , 2002 .

[20]  Martin Eickhoff,et al.  A new SiC/HfB2 based low power gas sensor , 2001 .

[21]  Johnny K. O. Sin,et al.  An integrated gas sensor based on tin oxide thin-film and improved micro-hotplate 1 Paper presented , 1998 .

[22]  Aaas News,et al.  Book Reviews , 1893, Buffalo Medical and Surgical Journal.

[23]  Stephen Grossberg,et al.  Fuzzy ARTMAP: A neural network architecture for incremental supervised learning of analog multidimensional maps , 1992, IEEE Trans. Neural Networks.

[24]  Balaji Panchapakesan,et al.  Spin-on nanoparticle tin oxide for microhotplate gas sensors , 2001 .

[25]  Eduard Llobet,et al.  Fuzzy ARTMAP based electronic nose data analysis , 1999 .

[26]  Carles Cané,et al.  A micromachined solid state integrated gas sensor for the detection of aromatic hydrocarbons , 1997 .

[27]  Carles Cané,et al.  Detection of low NO2 concentrations with low power micromachined tin oxide gas sensors , 1999 .

[28]  Carles Cané,et al.  Results on the reliability of silicon micromachined structures for semiconductor gas sensors , 2001 .