The polyaniline/PdO composite was synthesized by chemical oxidative polymerization of aniline with PdO nanoparticles. A methane gas sensor was made by deposition polyaniline/PdO thin films on a mass-type quartz crystal microbalance (QCM) device through layer-by-layer (LbL) self-assembly method. Scanning electron microscopy inspection shows that the polyaniline/PdO multilayers are formed with a dense network of nanofibers. The frequency responses of the polyaniline/PdO based QCM sensor to methane gas were measured at room temperature and 50℃. It exhibited that the polyaniline/PdO based QCM gas sensor has a better response at room temperature than that at 50℃. Meanwhile, the humidity effect is also discussed.

Tungsten trioxide (WO3) thin films were prepared by vacuum thermal deposition and subsequently annealed in the temperature range of 300–600 ◦C. X-ray diffractometry (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to analyze the structure and the morphology of the fabricated thin films. The results showed that the average grain size changed considerably with the variation of annealing temperature. Using a pair of interdigitated Au electrodes and glass ceramics as a substrate, the humidity and NO2 sensing properties of the WO3 thin films, manifested in relative conductivity changes, were measured. The results showed that the humidity sensitivity of the WO3 thin films was strongly dependent on the annealing temperature, and annealing and working temperature played an important role in the NO2 sensing characteristics. 2006 Elsevier B. V. All rights reserved.

Environmental sensors are developed and used for environmental assessment such as thermal and air environments. The items specified for the thermal environmental assessment are temperature, humidity and air flow rate and so on. And the items for air environmental assessment include all kinds of gas sensor. In this paper, Platinum temperature sensor, polyimide capacitive humidity sensor and zirconia oxygen sensors are made by magnetic sputtering technology, spin-coating method and sinter technology respectively. And the structure of combined environmentat sensors that include temperature sensor, humidity sensor and oxygen sensors item has also been designed. All the sensors used in the combined environmental sensors have been characterized and discussed.

An artificial olfactory system is constructed to determine the individual gas concentrations of gas mixture (CO and H2) with high accuracy. And a Back-Propagation (BP) neural network algorism has been designed using MATLAB neural network toolbox. And an effective study to enhance the parameters of the neural network, including pre-processing techniques and early stopping method is presented in this paper. It is showed that the method of BP artificial neural improves the selectivity and sensitivity of semiconductor gas sensor, and is valuable to engineering application

Zinc oxide (Zn0) thin films were identified as very suitable piezoelectric material for SAW on the basis of its relatively high electromechanical coupling coefficient, as well as high resistivity for low insertion loss and Iittle distortion in the frequency. In this paper Zno thin films were deposited on Si (100) substrate covered with Si02 using a reactive DC magnetic sputtering system from a zinc target. The effects of various deposition parameters on structural and performances have been investigated through experiments. Theoretical and experim ental results are also discussed in this paper. XRD showed that the prepared Zno films had strongly c-axis preferred-orientation. The composition of the film was also determined through high-resolution photoelectron spectroscopy (XPS). AFM showed that the films had smooth surface and that the crystallite sizes of deposited films were in the range 30 nm-50 nm. The above results showed that the films deposited by magnetic sputtering met the demands for sur: face acoustic wave (SAW) devices.