【作者】 李淑红；

【导师】 赵启大；

【作者基本信息】 南开大学 ， 光学， 2010， 博士

【摘要】 声表面波(Surface Acoustic Wave, SAW)是沿物体表面传播的弹性波,外界的扰动对声表面波传感器来说或多或少会影响传播媒质的粘滞特性、质量密度、刚度系数、电导率和介电常数的变化；还有外界温度和压强的变化也会影响传播特性的改变,这些变化都会影响声表面波速度的变化,进而引起振荡器振荡频率的变化,因此通过对频率信号的检测就能获得外界微小扰动的信息。目前声表面波传感器已多方面的应用于不同的场合。声表面波气体传感器是涉及声表面波理论、器件工艺、薄膜理论、电磁、检测技术等科学领域的新型传感器,由于它具有高精度、高可靠性和动态响应快的特点,并且能广泛用于环保、安全检测领域,因而具有重要的经济和社会效益。声表面波气体传感器,是在延迟线上涂上能与被测气体有相互作用的薄膜,由此来改变声表面波的传播速度。这种相互作用直接决定了传感器的灵敏度、选择性和工作的可逆性。本文以声表面波传感技术为基础,研制了五通道声表面波气体传感器,其中包括叉指换能器的设计,基底材料的选择,敏感薄膜的选择和处理电路的设计。其主要内容包括：1.介绍了声表面波的基本原理和声表面波器件的常用分析模型。2.介绍了声表面波用压电材料的选择原则。并比较了基底为不同晶体及相同晶体不同切向时输出叉指上的电压。3.分别采用1/4和1/8波长分裂叉指,研制了多对并行的阵列叉指换能器,构成多通道传感器,分别为延迟型和谐振型声表面波传感器。声表面波传感器的中心频率分别选取为100MHz、148.5MHz和315MHz。4.重点分析了不同的气敏薄膜吸附气体后对频率移动的影响机理；理论推导了薄膜厚度对SAW传感器灵敏度的影响,给出了响应的最佳膜厚,并分析了传感器频率响应的线性区域；介绍了几种常用的敏感膜如酞菁化合物薄膜、氧化铟、氧化锌和氧化锡薄膜,以此作为多通道气体传感器薄膜选择的基础；用酞菁铜作为检测二氧化氮气体的敏感薄膜,采用双通道气体传感器进行了初步实验,验证了SAW传感器的灵敏度、可重复性以及电路模块的实用性。利用石英延迟线型和谐振型器件测试了一氧化碳和水蒸气响应的幅度特性。5.在原有文献和数据的基础上,克服传统声表面波气体传感器检测方法单一的缺点,制作频率和幅度检测电路,将频率检测和幅度检测统一在一起,对同一种气体,检测方法更加合理,精确。更多还原

【Abstract】 Surface Acoustic wave (SAW) is elasticitive wave propagating along the object surface,external perturbation affect more or less viscosity,mass density,stiffness,electrical conductivity and permittivity, The extrinsic temperature and pressure affect also the change of propagating characteristic.At present,The sensor based SAW has been widely applied in many different fields.Surface Acoustic Wave gas sensor is a new kind of sensor which involved Surface Acoustic Wave theory, device technology, film theory, electromagnetic, detection technology and other new scientific fields. As it has the characteristics of high precision, high reliability and rapid dynamic response and is widely applied in the fields of environment protection and safety detection, the SAW gas sensor has the significant economic and social benefit.For SAW gas sensors, the propagation velocity of SAW can be changed by painting film to the delay line.The interaction between the film and the measured gas directly determines the sensitivity, selectivity and reversibility of the sensor.In this paper, we develop the five channel gas sensors of SAW including the design of IDT,the choice of substrate material and sensitive film and design of circuit. The main contents are listed as follows:1.Introduce the basis theory of SAW and the analytical model of SAW device.2.Introduce the selection of piezo-materical and compare the voltage of output IDT which the substrate are the diffent crystals or the diffent cut of the same crystal3.Developed a number of parallel IDT arrays which constructed multi-channel SAW sensors for delay and resonance types by adopting 1/4 and 1/8 wavelength interdigital splits, respectively.The center frequencies of the SAW sensors were selected as 100MHz,148.5MHz and 315MHz, respectively4.Analyze particularly the main physical properties of various films which adsorbed gases. The influence of the thickness of the films on the sensitivities of the sensors is derived theoretically, and the best thickness is obtained. The linear response region of the measured frequency is analyzed. Several kinds of commonly used sensitive films, such as copper phthalocyanine, indium oxide, zinc oxide and tin oxide thin films, are introduced. With the copper phthalocyanine film detected nitrogen dioxide gas, the sensitivity, repeatability, and the practicality of the circuit module are validated by using a dual-channel gas sensor. In addition, the responses of the sensor on the carbon monoxide and water vapor are experimentally investigated by using Quartz delay-line type and resonator type devices.5.Based on former literatures and dates,we desigen the frequency and amplitude detection ways and unify the tow seperated mathods so as to make it more scientific, reasonable, accurate.更多还原