Work Function Gas Sensors at Room Temperature by means of Conductive Polypyrrole Thin-films C. R. Zamarreño 1 , P. Davydovskaya 2 , R. Pohle 2 , M. Fleischer 2 , I. R. Matias 1 , F. J. Arregui 1 1 Public University of Navarra, Campus Arrosadia, 31006 Pamplona SPAIN, carlos.ruiz@unavarra.es 2 SIEMENS AG, Otto-Hahn-Ring 6, 81739 Munich GERMANY Abstract: This work presents a first approach to the fabrication of room temperature floating gate GasFETs based on the readout of the work function of conductive polypyrrole (PPy) coatings. PPy coatings have been fabricated onto Au and Pt coated alumina substrates by means of the in-situ polymerization technique. The response of the coatings to different gases and volatile organic compounds (VOCs), such as ethanol, acetone, methylamine or isopropanol and gases has been tested using the Kelvin probe (KP) setup. Results have revealed good sensitivities to isopropanol and methylamine at room temperature. Relative humidity (RH) was found to be a decisive factor, which conditioned the sensitivity of the coatings to VOCs and gases as well as the overall coating response. Additionally, good sensitivity to low weight hydrocarbons was found when the substrate was heated to 180ºC. Key words: work function, polypyrrole, in-situ polymerization, Kelvin probe, relative humidity, volatile organic compounds. Introduction Nowadays, gas sensing applications cover a vast and heterogeneous field from air or combustion monitoring in industrial and domestic environments to the detection of diseases in breath analysis, which requires the accomplishment of specific premises for each case. For instance, high-temperature operated sensors that can provide high stability and fast response in some cases should be discarded for portable wireless long-term operation with batteries or when the operation temperature can derive in degradation and bad operation of the sensor itself [1-2]. Conductive polymers have largely concentrated the attention of the scientific community for the fabrication of gas sensors at room temperature by means of monitoring the change of resistance [3]. Apart from resistance readout there are other properties of conducting polymers that change upon exposure to volatile compounds, such as work function, which is basically based on surface interactions, and can be measured at room temperature [4-5]. This work presents a first approach for the fabrication of ambient temperature floating gate FET devices based on the readout of the work function of conductive polypyrrole (PPy) coatings. PPy coating Fabrication All chemicals were used without further purification. The samples have been fabricated from Pt and Au films sputtered onto alumina squares (0.5x0.5cm). The samples were washed before testing with ethanol and distilled water and then dried with nitrogen. PPy coatings have been fabricated by means of the in-situ polymerization technique using FeCl 3 as dopant as it is described elsewhere [6]. Pyrrole monomer (Py) solution (5mmol) and FeCl 3 solution (10mmol) were prepared separately in 10 ml and 15 ml distilled water respectively. Then, the Py solution was added to the FeCl 3 solution and stirred vigorously. The samples were placed afterwards into the solution in vertical position for 5 hours. After the polymerization process, the samples were rinsed thoroughly with distilled water in order to remove the bad adhered material, dried under nitrogen flow and then kept in a desiccator overnight before testing. Work Function Measurements All the measurements were performed at room temperature (23-25ºC), 40% relative humidity (RH) and at a constant gas flow (synthetic air as the carrier) of 1 l/min unless otherwise stated. DOI 10.5162/IMCS2012/P1.8.10 IMCS 2012 – The 14th International Meeting on Chemical Sensors 1137