硅基局域共振声子晶体高频弹性波控制及其应用基础研究

High frequency elastic wave is widely used for sensing and detecting, the control of high frequency elastic wave by phononic crystals (PNCs) shows great value. Currently, all the high frequency elastic wave control are based on Bragg Scattering Phononic Crystal (PNC), and both the device size and elastic waves regulatory capacity are limited by the number of cells. Aiming at the high frequency control based on PNCs, this project first studies the silicon locally resonant PNC, which focuses on design and simulation of the locally resonant PNC cylinder stubs. With the introduction of different defect types, basic high frequency control element, such as waveguide, resonantor, splitter, point wave source, will be designed and fabricated. By using the laser-Doppler, high frequency elastic wave control based on local resonance theory will be characterized precisely and fast. Finally, the developed high frequency elastic wave control will be verified by its application in SAW microfludics chip. The guiding, reflection and localization of elastic wave will be implement by using locally resonant PNC, and the mechanisms of how the high frequency elastic wave control affecting the interaction between elastic wave and matter will be studied.The experimental result will give effect feedback supplement to the developed theory, fabrication method and characterization of high frequency elastic wave control based on locally resonant PNC. In this objective, the solid scientific foundation will be established for future elastic wave control based on locally resonant PNC and its application. New principles and new methods will also be provided for the interdisciplinary applications of high frequency control.

高频弹性波在传感、检测等领域广泛使用，因此声子晶体对高频弹性波的控制具有十分重要的应用价值。目前研究的高频声子晶体弹性波控制基本都采用布拉格散射类型声子晶体，其结构尺寸和弹性波调控能力都受到晶胞周期数的限制。本项目以声子晶体高频弹性波控制提高器件性能为目标，对硅基高频局域共振声子晶体开展研究，重点研究局域共振单元的结构设计仿真；通过不同类型缺陷的引入，设计波导、谐振器、功分器、点波源等一系列的高频弹性波控制基本元件；结合激光多普勒声场表征，实现局域共振声子晶体高频弹性波调控特性快速、精确表征；最终通过高频声子晶体弹性波控制在声表波微流控芯片中应用，实现局域共振声子晶体对弹性波的引导、反射和局域化，揭示弹性波控制对弹性波与物质相互作用影响的机制，并对声子晶体弹性波控制的理论、方法及测试表征形成有效地反馈补充。从而为局域共振声子晶体弹性波控制奠定坚实的基础，并为其在跨学科应用提供可借鉴的新思路

本项目对单晶硅微结构声学特性的研究围绕微米级单晶硅微结构声子晶体对高频弹性波的控制作用展开。声子晶体最独特的特性其所具备的，声学禁带，即某一频率范围内的声波或弹性波不能通过声子晶体。因为声学禁带的存在，声子晶体在声波控制领域有着非常广阔的应用潜力。本项目从基于局域共振原理的Y型波导和谐振器出发，研究声子晶体对弹性波的控制作用。首先，通过在硅完美声子晶体结构中引入缺陷的方法，设计了用于弹性波定向传输的Y型波导和用于弹性波能量局域的谐振器；基于布洛赫定理，建立了用于计算单晶硅声子晶体能带结构（色散曲线图）计算的有限元模型，并利用有限元的方法分别仿真Y型波导和谐振器对高频弹性波的控制作用；通过微机械加工工艺制备所设计的弹性波控制单元，并基于激光多普勒测试系统实验表征所设计的Y型波导和谐振器，实验验证了其对禁带内弹性波的控制作用。.将二维布拉格散射声子晶体应用到声表波驱动微流体中，利用声子晶体弹性波控制作用，实现了可以在短时间内离 心液滴内微纳颗粒、以及液滴移动的微流体芯片，降低了声表波驱动微流体系统的使用成本。 .从声子晶体的理论出发，尝试引入弹簧振子的概念来增强局域共振声子晶体共振体的谐振能力。尝试在传统硅基声子晶体晶胞基体中构建环形结构，使晶胞结构形成一个弹簧-质量体系。该体系的引入成功增强传统晶胞共振体的谐振能力，首次使微米尺度的局域共振声子晶体的禁带频率下探至千赫兹量级。定性研究各参数对禁带特性的影响，并探讨工艺实现条件，成功制备基于弹簧振子的声子晶体结构。