This paper describes the detection and discrimination of volatile organic compounds (VOCs) using an e-nose system based on a multiparameter virtual sensor array (VSA), which consists of a single-chip temperaturecompensated film bulk acoustic wave resonator (TC-FBAR) coated with 20-bilayer self-assembled poly(sodium 4-styrenesulfonate)/poly(diallyldimethylammonium chloride) thin films. The high-frequency and microscale FBAR multiparameter VSA was realized by temperature modulation, which can greatly reduce the cost and complexity compared to those of a traditional e-nose system and can allow it to operate at different temperatures. The discrimination effect depends on the synergy of temperature modulation and the sensing material. For proof-of-concept validation purposes, the TC-FBAR was exposed to six different VOC vapors at six different gas partial pressures by real-time VOC static detection and dynamic detection. The resulting frequency shifts and impedance responses were measured at different temperatures and evaluated using principal component analysis and linear discriminant analysis, which revealed that all analytes can be distinguished and classified with more than 97% accuracy. To the best of our knowledge, this report is the first on an FBAR multiparameter VSA based on temperature modulation, and the proposed novel VSA shows great potential as a compact and promising e-nose system integrated in commercial electronic products.
Cointegration and coupling a perfect metamaterial absorber (PMA) together with a film bulk acoustic wave resonator (FBAR) in a monolithic fashion is introduced for the purpose of producing ultracompact uncooled infrared sensors of high sensitivity. An optimized ultrathin multilayer stack was implemented to realize the proposed device. It is experimentally demonstrated that the resonance frequency of the FBAR can be used efficiently as a sensor output as it downshifts linearly with the intensity of the incident infrared irradiation. The resulting sensor also achieves a high absorption of 88% for an infrared spectrum centered at a wavelength of 8.2 μm. The structure is compact and can be easily integrated on a CMOS-compatible chip since both the FBAR and PMA utilize and share the same stack of metal and dielectric layers.
By creatively using R.F Magnetic sputtering technique , we have successfully prepared ZnSe polycrystalline thin films on glass substrates..The effect of different sputtering powers on the structural, morphological and optical properties of the as-deposited films were studied. The films were characterized by using X-ray diffraction, UV-VIS spectrometer ,scanning electrical microscope ,etc. The results indicate that :Under the pressure of o.8pa,with the diverse sputtering power varying from 60w to 100w,the intensities of XRD peaks of ZnSe thin films varied apparently ,while the morphological properties were almost the same. It should be noted here that the crystallinity of the ZnSe film, which was deposited with the power of 90W, showed a face-centered cubic phase. Besides, it showed relatively better performance: with strong [111] orientation ,smooth surface without obvious defects, comparatively large band gap and high transmission rate.
The CdTe thin film solar cells with the structure of ITO/ZnO/CdS/CdTe/Au were irradiated by 1.6MeV high-energy electrons with the fluences from 5×1013/cm2 to 1×1016/cm2. The characteristics of devices before and after irradiation were studied using dark current-voltage (I-V), capacitance-voltage (C-V) and admittance spectroscopy (AS) measurements in the temperature range from 303K to 353K. The results are shown that the diode ideal factor and dark saturation current for irradiated devices first decrease and then increase significantly with fluences from 5×1013/cm2 to 1×1016/cm2, meantime the effective carrier concentration at room temperature of CdTe absorbing layer increases first and then decreases. The carrier transport mechanisms in CdTe solar cells are analyzed before and after irradiation. The non-irradiated devices and irradiated devices with fluences less than 5×1014/cm2 are dominated by the recombination current of electron-hole pairs in the depletion layer. However, it is dominated by the recombination current of tunneling at the interface after the irradiation of higher fluences. The changes of types and amount of defects caused by electron irradiation are the major reasons for the above mentioned variations.
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