The Desihn And Realization Of 3D Nanowire Cluster SAW Gas Sensor

Surface acoustic wave(SAW) sensors are a new type of sensors, which, comparing to other sensors with traditional techniques, are featured with faster response, more accurate sensitivity, and smaller volume. Sensors with three dimensional(3D) nanowire cluster structure have huge specific surface area and high gas sensitivity. Materials with this structure are very promising gas sensitive materials. In this paper, by joining the SAW technique and the 3D nanowire cluster structure materials, a microminiaturized, integrated, and intellectualized new type of gas sensor with high sensitivity, high integration, low weight and low cost is studied to quickly and reliably detect the target gas. This type of sensors is cost effective and able to work at room temperature.Based on the features of SAW sensors and 3D nanowire clusters, SAW devices are optimized. ZnO 3D nanowire clusters are designed and prepared on the sensitive area of SAW devices. A brand new 3D nanowire cluster structure SAW gas sensor is designed by modification of the nanowire clusters. And correlated programs for designing and testing is developed.For SAW sensors with a resonator structure, the sensitivity weight factors of the resonant cells at different areas varies dramatically, so the relationship among the Q factor, insertion loss, sensitive area, and weight factor should be considered. In this paper, a dedicated simulation tool is established on ADS platform. With the optimized results and MATLAB, an interdigital electrode board of a gas sensor is designed, and SAW resonator chips are prepared. The frequency temperature characteristics of the devices in three process states are studied by substrate selection. The loaded Q factor and the temperature characteristics are highly improved by the means of grooving and temperature compensation. As a result, the targeted operation frequency 198.99 MHz, insertion loss-13 dB and loaded Q factor 7400 are achieved.Nanowire clusters can grow on SAW device substrates containing lithography resist without impacting the interdigital figures on SAW piezoelectric substrates. Branched polymer is used to modify the nanowire cluster. Polymer film layers are created on the surface of 3D nanowire clusters by spray method. Hence the gas sensitivity to dimethyl methylphosphonate(DMMP), the stimulant of GB nerve agent, is achieved.The SAW resonance loop is designed using differential double channel configuration, and the signal extraction is achieved. The pattern recognition algorithm is studied on Back Propagation. Data collection and processing system development are achieved. The implement of them in the detection test of the 3D nanowire cluster SAW gas sensor makes a strong ability on recognition.