阻抗负载SAW传感器中的二维能量控制问题

Wireless passive impedance-loaded SAW sensors have broad application prospects for their unique advantages in line with the technical requirements of Internet of Things. However, their application were limited by the detection range for their high loss. The energy dissipation needs to be minimized. This project is intended to introduce the 2D phononic crystal into the structure of the impedance-loaded SAW sensors. The research about the generation and modulation of SAW by the new type interdigital transducer loaded with 2D pillars will be performed, focusing on the influence of the local resonance of the pillars and intending to control the energy dissipation (diffraction effects, bulk wave radiation et al.) to increase the Q value of the sensors. The mass loading effect and the charge distribution, which were not included in the previous work, will be considered in the constructed quasi three-dimensional numeric SAW propagation model for the piezoelectric /two-dimensional phononic crystal structure using combined Green's function and finite element method. The local resonance modes will be extracted and analyzed based on the results of the calculated Green's function. New structures of the transducers that will generate SAW are intended to be proposed. The parameters used in the phenomenological model in the small frequency range will be extracted based on the constructed strict quasi three-dimensional model. Then the phenomenological model could be used for the impedance-loaded SAW sensor optimization process. A sample of the new type impedance-loaded gas sensors with high resolution and detection range of 1 m will be designed and prepared based on our previous research.

无线无源阻抗负载声表面波传感器有许多独特优点，符合物联网的技术要求，有广阔应用前景。但其无线传感距离受到损耗限制，需要对能量耗散进行控制。本项目拟将二维声子晶体结构应用于阻抗负载声表面波传感器的研究中，研究加载二维点阵的新型叉指换能器对声表面波的激发与调制问题，特别是其中局域共振模式的独特作用，来控制器件中的二维能量耗散（衍射效应、体波辐射等），以提高传感器Q值。拟采用格林函数法结合有限元法建立压电晶体/二维周期点阵的准三维分析模型和快速等效模型，充分考虑二维点阵的质量加载效应和电荷分布对模型的影响。通过格林函数提取二维点阵的局域共振模式进行分析，提出激发声波的新结构。对窄带范围内声子晶体禁带附近的频率特性进行精确计算，以提取快速二维唯象模型中的等效声学参数，对阻抗负载传感器进行优化设计。结合前期基础，最终制备出高分辨率、无线传输距离大于1m的新型阻抗负载气体传感器样品。

无线无源阻抗负载声表面波传感器具有精度高、适应范围广、适于批量制作的特点，在信息通讯、航空航天和极端环境等领域已显示出巨大的发展空间和应用需求。但其无线传感距离受到损耗限制，需要对能量耗散进行控制。. 本项目将二维声子晶体结构应用于阻抗负载声表面波传感器的研究中，研究加载二维点阵的新型叉指换能器对声表面波的激发与调制问题，来控制器件中的二维能量耗散（衍射效应、体波辐射等），以提高传感器Q值，增加传感器的无线读取距离。.根据研究内容，主要取得如下进展：.（1）声子晶体的分析建模与设计：研究了声子晶体本身的特性，并优化设计出系列声波在固体基体中无损传播的新模式。.（2）阻抗负载传感器的整体建模：在基于FEM/BEM方法的阻抗负载声表面波传感器模型基础上，提出了体波的优化算法，并针对阻抗负载传感器的特殊边界条件对模型进行了改进，在保持精确度的前提下提升了运算速度。.（3）传感器的优化设计：采用声子晶体结构设计出了几款无线无源声表面波传感器，实现了课题减小能量损耗、增大无线传输距离的目标。在50mW的功率下，温度传感器无线无源探测距离达到10.8米。.（4）相关敏感材料的制备与优化：提出了一种新型柔性气体传感器，并将在可见光波段具有优良催化性质的半导体材料与气敏材料结合，改善了半导体氧化物气敏材料的室温气敏性能。.研究成果方面，在Nano Research、APL等国内外权威期刊上发表学术论文12篇，会议论文6篇；申请中国发明专利8项，已授权3项；受邀报告2次，参加国际会议3次；培养博士后1人、博士1人、硕士7人；极端环境下无线无源声表面波传感器方面的工作获得中国电子学会技术发明一等奖。同时，研究成果在航天重大工程、汽车胎压监测等领域得到了应用。