NER: Acoustic Wave Nanoparticle Analyzer

该项目的目的是证明利用声波剪切波运动来表征纳米颗粒和纳米颗粒的组装及其与底物的相互作用的可行性。纳米粒子的大小、质量或密度以及粒子与衬底的结合能等属性是测量的目标参数。声波剪切波是由固态传感器产生的，它提供了一种向颗粒传递机械力的非接触式手段。这种力从传感器衬底延伸到环境空气中，大约在几十到几百纳米之间，它会刺激粒子进入共振运动。通过对这种共振运动的分析，可以推断出上述粒子的特征参数。具体地说，提出了几项精心设计的实验和理论工作，以研究声波纳米颗粒分析仪(Awna)的运行物理机制。采用方法：所建议的工作分为三个广泛的活动：设备开发、理论建模和概念验证。这三个领域不是相互排斥的，将同时进行。设备开发包括甚高频横波换能器的设计、制造和测试，以及有效产生机械界面力的电子学和软件。描述粒子与换能器表面相互作用的理论模型将结合系统的纳米级复杂性和待研究系统的多个长度尺度。这些进展将使用不同的模型进行验证，在这些模型中，将在仔细控制或模拟的实验条件下检查颗粒大小和界面作用力所产生的各种方面。最后，测量的声学响应将与标准光学(微米级颗粒)和原子力显微镜(AFM)技术相关联。拟议活动的智能优点：由于纳米级颗粒的许多性质和特征无法从更大规模的观察中预测，已发表的关于声波与宏观对象相互作用的工作和我们自己关于微米级颗粒的初步数据不能可靠地表明，纳米颗粒将观察到同样的现象。此外，由于纳米结构的尺寸减小(有限)，介于凝聚相和分子状态之间，使得连续介质模型和原子模型都不能直接适用于纳米颗粒，因此在理论上存在很大的困难。这些挑战突显了该项目的探索性。声横波纳米颗粒分析技术一旦开发出来，将是对目前用于纳米颗粒分离的微米和纳米颗粒技术的补充，如AFM或SEM。特别是，这项技术将提供一种根据纳米颗粒的大小、形状或相互作用性质来表征纳米颗粒的有效方法。无论纳米粒子的光学、电学和磁学性质如何，声波横波分析技术都是有效的，因此可以在不同的环境和不同的介质中使用。声学纳米粒子分析仪的这些独特功能将对纳米粒子的表征和应用领域产生重大影响。这项研究的长期目标是开发一种能够对气体和液体中的纳米颗粒进行自主和可编程分析的Awna芯片。AWNA芯片将提供一个实验平台，用于分析、设计和监测涉及无机纳米颗粒以及蛋白质或细胞等生物对象的各种生化和生物物理过程。拟议活动产生的更广泛影响：纳米颗粒的分析除了其技术重要性外，还为教学和宣传纳米技术带来了有效的工具。拟议的研究和教育工作将影响多个领域，具体地说，它将：(I)扩大关于纳米尺度界面现象的知识；(Ii)提供分析纳米颗粒的新研究工具，以及纳米制造过程的新工具；(Iii)提高公众对纳米技术的认识；(Iv)通过为实验室实验提供符合成本效益的仪器，加强以纳米技术为导向的课程；(V)吸引更多学生学习纳米技术领域；(Vi)由于其潜在的视觉吸引力(看到移动的颗粒)，它将激发高中生的想象力，(Vii)加强科学家在物理、生物、化学和工程方面的合作。NER计划的建议类别为“奈米尺度装置与系统架构”。

The goal of this project is to demonstrate the feasibility of using of acoustic shear wave motion for characterization of a nanoparticle and assembly of nanoparticles, and its/their interaction with a substrate. Such nanoparticle properties as size, mass or density, and the binding energy of a particle to the substrate are targetedparameters for measurements. An acoustic shear wave is generated by solid-state transducers, which provide a non-contact mean of delivering a mechanical force to the particle. This force, which extends from the transducer substrate into ambient air on the order on tens to hundreds of nanometers, excites a particle into a resonant motion. From the analysis of that resonant motion one can infer the above listed characteristic parameters of the particle. Specifically, several carefully designed experimental and theoretical efforts are proposed to study physical mechanisms of operation of an Acoustic Wave Nanoparticle Analyzer (AWNA).Employed methods: The work proposed falls into three broad activities: device development, theoretical modeling and the concept validation. These three areas are not mutually exclusive and will proceed simultaneously. Device development includes design, fabrication and testing of the very high frequency shear wave transducers, electronics and software for efficient generation of mechanical interfacial forces. Theoretical models describing an interaction of a particle with the surface of a transducer will incorporate the Nanoscale complexity of the system and the multiple length scales of the systems to be studied. These developments will be validated using different models in which various aspects created by particle size and interfacial forces will be examined in carefully controlled or simulated experimental conditions. Finally, the measured acoustical responses will be correlated with standard optical (micron-size particles) and Atomic Force Microscope (AFM) techniques.The intellectual merit of the proposed activity: Since many of the properties of nanometer-sized particles and features are not predictable from observation at a larger scale, the published work on the interaction of acoustic waves with macroscopic objects and our own preliminary data on micrometer sized particles cannot reliably suggest that same phenomena will be observed for nanoparticles. In addition, there are substantial theoretical difficulties because the reduced (finite) size of the nanostructural components, which is intermediate between the condensed-phase and molecular regimes, makes both continuum models and atomic model inapplicable directly to the nanoparticles. These challenges highlight the exploratory nature of this project. The acoustic shear wave nanoparticle analysis technique, once developed, will be complementary to current micro-and nano-particle techniques for nanoparticle separation, such as AFM or SEM. In particular, this technique will provide an efficient method for characterization of nanoparticles according to their size, shape or interaction properties. The acoustic shear wave analysis technique will be effective on nanoparticles regardless of their optical, electrical and magnetic properties, and thus can be used in various environments and in different media. These unique features of the acoustic nanoparticle analyzer will significantly impact the fields of characterization and application of nanoparticles. The long-term objective of this research is to develop an AWNA chip capable of autonomous and programmable analysis of nanoparticles in gases and liquids. AWNA chip will provide an experimental platform for analysis, design and monitoring of various biochemical and biophysical processes involving inorganic nanoparticles as well biological objects such as proteins or cells.The broader impacts resulting from the proposed activity: Analysis of nanoparticles, in addition to its technological importance, brings an effective tool for teaching and publicizing nanotechnology. The proposed research and educational efforts will impact many areas and specifically, it will: (i) expand the knowledge on interfacial phenomena at the nanoscale level, (ii) provide a new research tool for analysis of nanoparticles, as well a new tool for nanofabrication processes, (iii) enhance awareness of nanotechnology by the public, (iv) enhance nanotechnology-oriented curricula by providing cost-effective instrumentation for laboratory experimentation, (v) attract more students to the area of nanotechnology (vi) due to its potential visual appeal (seeing moving particles), it will capture the imaginations of high school students, including those with limited interest in science (females and underrepresented ethnic groups), and as a result will attract more students to science and engineering, (vii) enhance collaborations among scientists in physics, biology, chemistry and engineering.The category of the proposal in the NER program is "Nanoscale devices and system architecture".