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Abstract: A nitrogen dioxide (NO2) gas sensor using dual track surface acoustic wave (SAW) device was developed and fabricated in this paper. The dual track architecture and the MSCs were skillfully applied to the sensor. The external perturbations were eliminated by the dual track architecture, and the bulk acoustic wave (BAW) was suppressed by Multistrip coupler (MSC). The input IDT apodized by Morlet wavelet function can improve the side lobe rejection compared with uniform IDT. Utilizing Tungsten powders, hydrogen peroxide, absolute methanol and polyvinylpyrrolidone as raw materials, the micro-porous network Tungsten trioxide (WO3) film sensitive to NO2 gas was fabricated in measurement acoustic track of dual track SAW device. Experiments results confirm that the NO2 gas sensor using dual track SAW device has good response characteristics to different concentrations NO2 gas from 0.5ppm to 10ppm. Furthermore, the NO2 gas sensor using dual track SAW device has good reproducibility and stability. [Copyright &y& Elsevier]

Abstract: In this paper, we propose dual track architecture and time synchronous scheme for wavelet reconstruction processor using surface acoustic wave (SAW) device based on multistripe coupler (MSC). An arbitrary scale wavelet reconstruction processor with dual track architecture consists of a wavelet interdigital transducer (IDT) apodized by the envelope of wavelet function, two MSCs, and two reconstruction wavelet IDTs apodized by the envelope of identical reconstruction wavelet function. The SAW launched by wavelet IDT is bidirectional. Two reconstruction wavelet IDTs with identical design parameter are symmetrically deposited on the dual track of wavelet reconstruction processor. Therefore, the performances of wavelet reconstruction processor were improved due to bidirectional SAW received by two reconstruction wavelet IDTs. Furthermore, the delay time characteristic of SAW propagating on crystals substrate surface was skillfully applied to compensate the time asynchronous problem among wavelet reconstruction processor. This means ensures that all scale processors in wavelet reconstruction processor have identical response time. An experiment of wavelet reconstruction processor with dual track architecture and time synchronous scheme was presented. Experimental results confirm that the performances of wavelet reconstruction processor are improved, and time synchronous is realized in this wavelet reconstruction processor with three scales. [Copyright &y& Elsevier]