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.

Based on conventional metal-oxide-semiconductor field-effect transistor (MOSFET), a novel kind of chemical field-effect transistor (ChemFET) gas sensor array has been designed and fabricated. The obtained sensor consists of self-assembly polyaniline (PAhD composite film containing poly (acrylic acid) (PAA) which was used as gate material of MOSFET instead of conventional metallic gate. The UV-Vis absorption spectra of PAN/PAA films were characterized. The N02 gas sensitive property of the ChemFET sensor array was also Based on conventional metal-oxide semiconductor field-effect transistor (MOSFET), a novel kind of chemical field-effect transistor (ChemFET) gas sensor array has been designed and fabricated. The obtained sensor consists of self-assembly polyaniline (PAhD composite film containing poly (acrylic acid) (PAA) which was used as gate material of MOSFET instead of conventional metallic gate. The UV-Vis absorption spectra of PAN/PAA films were characterized. The N02 gas sensitive property of the ChemFET sensor array was also investigated. Results show that the drain current of devices increases with increasing of back-side voltage, and decreases with the increase of N02 concentration when the N02 concentration is below 20mg/g. The temperature dependence of ChemFET sensor array shows that the drain current of ChemFET sensor decreases with increasing of temperature.

A readout circuit for uncooled infrared focal plane arrays is successfully designed. The principle of the signal processing is studied and proper circuit is successfully designed and made to realize the signal processing. The feature of the signal processing circuit for the uncooled infrared focal plane array depends on the readout circuit Readout circuit discussed here is a RC oscillatory circuit. The resistor of the oscillatory circuit is VOx thin film, which is very sensitive to temperature. The relationship of the temperature and the period of the oscillatory circuit is discussed. The signal processing circuit employs the relationship to extract the temperature from the period of the output signal. The imaging processing part uses the extracted temperature information to get the infrared image.

Multilayer PVDF-BaTiO3/PDDA ultrathin composite film was prepared in the presence of BaTiO3 nanoparticles by electrostatic self-assembly method, and quartz crystal microbalance was in situ used to monitor the whole film fabrication process. The results showed that the film with 1: 1 weight ratio of PVDF to BaTiO3 is more uniform than that of 2: 1 ratio. The monolayer film thickness ranges from 19 to 25nm calculated by Sauerbery equation. Coupling agent enhanced the dispersion capability of BaTiO3 nanoparticles, and the ferroelectric property of PVDF/PDDA composite ultrathin film was improved with the assistance of inorganic nanoparticles.

BP algorithm in ANN is chosen to process gas sensor array signals. In this paper, an artificial olfactory system, which is composed of a gas sensor array with the pattern recognition technique of a feed forward neutral network, is designed to determine the individual gas concentrations of the gas mixture. And a BP artificial neural network has been designed by using MATLAB neural network toolbox to process the signals of the gas sensor arrays simulated by use of computer. The results in this paper show that the method of artificial neural (ANN) has good non-linear, approximation ability and high discrimination ratio.

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.

Organic light-emitting diodes (OLEDs) with a structure of indium-tin-oxide (ITO)/N, N'-bis (3-methylphenyl)-N, N'-diphenylbenzidine (TPD): polystyrene (PS)/tris (8-hydroxyquinoline)-aluminum (Alq3)/Mg: Ag were fabricated. Among them PS: TPD thin film acts as a hole transporting layer (HTL)and was prepared via dimethylbenzene solution dissolved with a mixture ofPS: TPD by spin-coating method. The influence of TPD dopde ratio in the mixture on the performance of device was investigated. Experimental results show that luminescent brightness of devices increase with the enhancement of TPD doped ratio, while electroluminescent spectra are not affected. In addition, lifetime of the device when the ratio of TPD to PS is 7: 3 was 4 times higher than that of pure-TPD device. This phenomenon was postulated that PS enhanced the uniformity of TPD film, which was characterized by the result of atomic force microscope (AFM)analysis, and thus overcame the shortcoming oflow stability of small-molecular film.

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

In order to identify hydrogen and carbon monoxide gases in the concentration range of 40 to 1000 ppm (10-6), the gas recognition system composed of a SnO2-based thick-film gas sensor array and the pattern recognition techniques of Self Organizing Competitive Network is developed. An on-line data acquisition system is built for measurement of dynamic and steady state in information across the sensor array, and three kinds of data normalization methods are used to pre-process the sensors responses for the discrimination of gas species and concentrations to get good separation among gases. The results are presented in this paper that the accurate identification of hydrogen and carbon monoxide in the finite range could be accomplished by the third normalization method.