LGS声表面波传感器温度应变特性研究

发布时间：2018-07-05 15:24

本文选题：LGS + SAW传感器　；参考：《电子科技大学》2017年硕士论文

【摘要】：声表面波(Surface acoustic wave,SAW)器件因为其具有体积小、品质因数高、响应快、成本低、可以无线无源工作等优点,因此非常适合高温高压、高速移动或旋转、有毒有害等恶劣环境中进行传感。随着对航空航天、工业制造等领域的结构健康监控(Structure health monitor,SHM)的需求日益增多,能无源无线传感的SAW传感器有着广泛的应用前景。因此展开在恶劣环境下进行温度、应变等物理量进行传感的SAW传感器的研究有着十分重要的意义。本文采用了一种具有优秀的高温应变特性的新型压电基底材料硅酸镓镧(Langasite,LGS)来制备SAW温度应变传感器。设计出的SAW传感器为谐振器结构,叉指对数为100对,叉指宽度为2μm,金属化比率为0.5,孔径长度为100λ,其中叉指换能器(IDT)与反射栅(Reflector bank)之间的距离为6μm。并利用COMSOL Multiphsycs软件对所设计的器件进行了仿真计算。本文选用的LGS基底的欧拉角为(0°,138.5°,26.6°),采用微电子工艺在基底材料上制作SAW谐振器。并对工艺参数进行了优化,得到了性能优异的SAW传感器。本文对所制得的LGS声表面波传感器进行了温度性能测试,温度测试范围为20℃~400℃。在不同温度下LGS传感器均保持了良好的SAW特性,其谐振频率随着温度的升高而降低,经过线性拟合,我们计算出了基于欧拉角为(0°,138.5°,26.6°)的LGS传感器的其一阶和二阶温度频率系数的值分别为-4.229×10~(-4)和-2.034×10~(-5)。为了验证LGS声表面波传感器的温度重复性,我们对其进行了温度循环测试,测试结果表明循环测试下传感器的温度重复性良好,其最大误差为2.39%,满足测试需求。本文还对20℃~250℃下LGS传感器的应变特性进行了研究。通过悬臂梁结构测试了LGS的频率应变特性,测试表明LGS传感器的谐振频率随着应变的增加呈线性降低,应变灵敏度为-162.94Hz/με,应变频率系数为-0.488ppm/με。通过温度应变测试可知,随着温度的升高,传感器的应变灵敏度逐渐降低,到250℃时,灵敏度为-120.75Hz/με,应变频率系数为-0.363 ppm/με。本文还研究了SAW传播方向与应变方向夹角的关系。通过不同角度粘接传感器的方式,改变传感器的SAW传播方向与应变的夹角,研究了其应变特性。粘接器件的角度分别为0°,30°,60°,90°,测试结果表明,SAW的传播方向与应变方向的夹角发生改变时,传感器谐振频率对应变的响应也随之发生改变,夹角为30°,60°,90°时,其谐振频率会随着应变的增加而增加,其灵敏度分别为179.17 Hz/με,325.09 Hz/με,162.48 Hz/με。频率应变系数分别为0.536 ppm/με,0.973 ppm/με,0.486 ppm/με。另外还对这些传感器进行了不同温度下的应变测试,其灵敏度亦随着温度的上升而降低。最后,本论文对LGS传感器进行了应变误差分析.计算了传感器的相对线性误差,在全温测量范围内,相对误差范围为0.22%~1.68%,表明传感器具有良好的线性度。为了研究应变滞后误差,对传感器进行了应变循环测试,测试结果显示,在常温下所有器件的应变之后误差均在3%以内,随着温度的升高,应变滞后误差开始升高,在10%以内。
[Abstract]:Surface acoustic wave (SAW) devices have the advantages of small volume, high quality factor, fast response, low cost, and wireless passive work. Therefore, it is very suitable for sensing in high temperature and high pressure, high speed moving or rotating, toxic and harmful environment. The demand for Structure health monitor (SHM) is increasing, and the SAW sensor with passive wireless sensor has a wide application prospect. Therefore, it is of great significance to develop a SAW sensor for sensing the temperature, strain and other physical quantities in a bad environment. This paper uses an excellent high temperature strain characteristic. A new type of piezoelectric base material Langasite (LGS) is used to prepare the SAW temperature strain sensor. The designed SAW sensor is a resonator structure, the cross finger logarithm is 100 pairs, the cross finger width is 2 mu m, the metallization ratio is 0.5, the aperture length is 100 lambda, and the distance between the cross finger transducer (IDT) and the reflective gate (Reflector bank) is 6 micron. The COMSOL Multiphsycs software is used to simulate the designed devices. The Euler angle of the selected LGS substrate is (0, 138.5, 26.6). The microelectronic technology is used to make the SAW resonator on the base material. The process parameters are optimized and the SAW sensor with excellent performance is obtained. The LGS surface wave transmission is made in this paper. The temperature performance was tested at 20 ~400 C. The LGS sensor maintained good SAW characteristics at different temperatures, and its resonant frequency decreased with the increase of temperature. After linear fitting, we calculated the first and two order temperature frequencies of LGS sensors based on the Euler angle (0 degrees, 138.5 degrees, 26.6 degrees). The values of the coefficients are -4.229 * 10~ (-4) and -2.034 x 10~ (-5). In order to verify the temperature repeatability of the LGS surface acoustic wave sensor, we have tested the temperature cycle of the sensor. The test results show that the temperature repeatability of the sensor is good and the maximum error is 2.39% to meet the test requirements. The LGS sensor at 20 C ~250 is also tested in this paper. The strain characteristics of the LGS are tested by the cantilever beam structure. The test shows that the resonant frequency of the LGS sensor decreases linearly with the increase of strain, the strain sensitivity is -162.94Hz/ um, and the strain frequency coefficient is -0.488ppm/ um. The sensitivity is reduced gradually, at 250 C, the sensitivity is -120.75Hz/ um and the strain frequency coefficient is -0.363 ppm/ um. The relationship between the direction of the propagation of SAW and the angle of the strain direction is also studied. The strain characteristics of the sensor are studied by changing the angle between the direction of the propagation of SAW and the strain of the strain by means of different angle bonding sensors. The strain characteristics of the sensor are studied. The angles are 0 degrees, 30 degrees, 60 degrees, 90 degrees respectively. The results show that the response of the resonant frequency of the sensor to the strain is also changed when the angle of the propagation direction of SAW and the direction of strain changes. When the angle is 30, 60, 90 degrees, the resonant frequency will increase with the increase of strain, and the sensitivity is 179.17 Hz/, 325.09 Hz/, respectively. The frequency strain coefficient is 162.48 Hz/ um. The frequency strain coefficient is 0.536 ppm/ um, 0.973 ppm/ and 0.486 ppm/ respectively. In addition, the strain measurements at different temperatures are carried out on these sensors. The sensitivity is also reduced with the increase of temperature. Finally, the strain error analysis of the LGS sensor is carried out in this paper. The relative linear error of the sensor is calculated. In the range of total temperature measurement, the relative error range is 0.22%~1.68%, which indicates that the sensor has good linearity. In order to study strain lag error, the strain cycle test is carried out on the sensor. The test results show that the error of all the strain of all the devices is within 3% at normal temperature, and the strain lag error begins with the increase of temperature. Rise, within 10%.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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