NOISE-BASED HIGH RESOLUTION ULTRASOUND IMAGING USING MICROENGINEERED SURFACES AND TRANSDUCERS

本研究的目的是利用机电系统中普遍存在但很少被开发的宽带热机械噪声来开发超声成像方法。理论方法是基于漫射噪声源的格林函数检索和工程传播表面的深亚波长分辨率成像。微机械超声换能器用于记录热机械噪声，并为倏逝波提供可调的微尺度工程表面，形成了实现亚波长分辨率成像的实验平台。控制倏逝波速的最佳配置，从而实现有效的亚波长分辨率，将通过微尺度工程进行研究和实现。探讨噪声场特性对波激发、探测和成像性能的影响。在3-10MHz范围内，使用集成了低噪声电子器件的微机械阵列，在衍射极限（f值0.1-0.5）内进行高分辨率超声成像的可行性将得到验证。研究结果将影响生物成像和生物微流体微系统的设计和实现。该项目将通过成像和监测低至细胞水平的机械性能，影响集成低功耗生物医学系统，如医疗植入物。使用微尺度工程表面的基于噪声的高频超声可以为许多需要低频率高分辨率的成像应用提供变革性的工具。该项目涉及来自少数民族高中的科学教师，他们创建物理模块课程材料，并为学生提供实地参观大学实验室的机会。它还将为本科生提供模块化课程材料，并为pi教授的研究生课程提供跨学科内容。

The objective of this research is to develop ultrasonic imaging methods using the ubiquitously available but rarely exploited broad band thermal-mechanical noise in electromechanical systems. The theoretical approach is based on Green's function retrieval from diffuse noise sources and deep sub-wavelength resolution imaging with evanescent waves on engineered propagation surfaces. Micromachined ultrasonic transducers are used to record thermal-mechanical noise and provide a tunable microscale engineered surface for evanescent waves, forming the experimental platform to achieve sub-wavelength resolution imaging. Optimal configurations for controlling evanescent wave velocity, hence the effective sub-wavelength resolution, will be investigated and implemented through microscale engineering. Effects of noise field characteristics on the wave excitation and detection, and imaging performance will be explored. Feasibility of high resolution ultrasonic imaging within the diffraction limit (F-number 0.1-0.5) will be demonstrated in the 3-10MHz range using micromachined arrays integrated with low noise electronics. The results would impact design and implementation of microsystems for bio-imaging and bio-microfluidics. This project will impact integrated low-power biomedical systems such as medical implants through imaging and monitoring mechanical properties down to the cellular level. Noise-based high-frequency ultrasonics using microscale engineered surfaces can provide a transformative tool for many imaging applications requiring high resolution at lower frequencies. The project involves science teachers from predominantly minority enrolled high schools to create modular curriculum materials in physics and provides opportunities for student site visits to university laboratories. It will also lead to modular curriculum materials for undergraduate classes, and an interdisciplinary component for graduate classes taught by the PIs.