Micro/mesoscale elastography based on real-time 3D tomography and cantilever force sensing

微/中尺度组织(0.1毫米到1毫米大小)的操作在临床手术和生物医学研究中扮演着重要的角色。这项技术对体外受精的胞浆内精子注射、癌症研究中的药物反应分析以及再生医学中生物工程组织的制造至关重要。然而，即使使用现有的工具和协议，影响这些程序成功的主要因素之一仍然是操作员的技能。还有一种尚未满足的需求，即提供定量和可靠信息的传感技术，而不仅仅是经验或直觉，以帮助操作员做出正确的决定。本项目旨在通过提供一种基于3D成像和微尺度力传感的实时微/中尺度操纵方法来满足这一需求。这将通过建立一个由微型悬臂力传感器和阵列显微镜组成的机械手系统来实现，以向操作员提供适当的实时视觉反馈。由于该系统采集的所有数据都是数字化的，因此可以通过互联网远程查看和控制系统，这使得该系统成为STEM教育的一个很好的平台。该团队将与当地一所高中合作，为K-12学生开发和测试教育生物实验。这将通过提供学生无法获得的基于应用的研究方法来增强他们的学习。弹性成像是一种新兴的成像方式，用于量化组织的弹性。当机械力施加到组织上时，诱导的内部应变分布指示出弹性图。与硬区相比，软区显示出更大的变形，反之亦然。这张弹性图提供了医疗诊断或手术工具指导所需的重要信息。目前弹性成像的使用是基于超声成像来观察大小在几厘米范围内的大小器官。要研究的中心假设是，弹性成像的益处可以缩小到比传统超声弹性成像研究的组织小约100倍的组织。该项目的目标是建立以0.1毫米至1毫米大小的生物样本为目标的实时微/中尺度弹性成像方法。将开发一种实时微/中尺度组织处理系统，以提供定量的三维力-变形分析，使操作者能够可靠地处理组织并做出明智的诊断选择。两项关键的使能技术是基于微悬臂的操纵和3D实时层析成像。当力传感悬臂向样品施加力时，从16个阵列的显微镜同时采集多角度图像，以重建高分辨率的3D图像。将生成3D变形图，以找出在样品和悬臂中诱导的应变。知道悬臂梁的机械刚度，就可以得到试件中产生的应力。由于所提出的方法是基于光学变形分析的，它将在不使用电动力传感器的情况下提供力传感能力。不仅是微型制造的悬臂梁，而且包括玻璃管和针在内的传统工具将被使用，一旦它们的刚度被校准，就会增加力传感功能。该系统的有效性将通过操纵3D微组织和使用斑马鱼卵子的精子注射实验来验证。可视化和操纵微/中尺度对象的能力在许多新兴的生物医学应用中扮演着重要的角色。然而，专注于如此规模的样品的机械工具仍处于初级阶段。这项拟议的研究是朝着这个方向迈出的第一步。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Manipulation of micro/mesoscale tissues (0.1 millimeters to 1 millimeter in size) plays an important role in clinical procedures and biomedical research. This technology is vital for intra-cytoplasmic sperm injection for in vitro fertilization, drug response assays in cancer research, and fabrication of bioengineered tissues in regenerative medicine. However, even with the existing tools and protocols, one of the main factors that affects the success of these procedures is still the skill of the operator. There is an unmet need for a sensing technique that provides quantitative and reliable information, rather than experiences or intuition alone, to help operators make a correct decision. This project aims to meet this need by providing a method of real-time micro/mesoscale manipulation based on 3D imaging and micro-scale force sensing. This will be accomplished by building a manipulator system comprised of microfabricated cantilever force sensors and arrayed microscopes to provide suitable real-time visual feedback to the operator. As all the data gathered by this system is digital, the system can be remotely viewed and controlled via the internet, which makes the system an excellent platform for STEM education. The team will work with a local high school to develop and test educational biological experiments for K-12 students. This will enhance their learning by providing application-based research methods otherwise not available to students.Elastography is an emerging imaging modality to quantify the elasticity of tissues. When a mechanical force is applied to a tissue, the induced internal strain distribution indicates the map of elasticity. Soft regions show larger deformation compared to the hard regions, and vice versa. This elasticity map provides crucial information needed for medical diagnosis or guidance of surgical tools. The use of elastography is currently based on ultrasound imaging to observe macroscale organs in the size range of a few centimeters. The central hypothesis to be investigated is that the benefit of elastography can be scaled down to tissues that are about 100 times smaller than those studied in conventional ultrasound elastography. The goal of the project is to establish the method of real-time micro/mesoscale elastography that targets biosamples between 0.1 millimeters and 1 millimeter in size. A real-time micro/mesoscale tissue manipulation system will be developed to provide quantitative 3D force-deformation analysis to enable operators to reliably manipulate tissues and make informed diagnostic choices. The two key enabling technologies are microscale cantilever-based manipulation and 3D real-time tomography. As the force-sensing cantilever applies a force to the sample, multi-angle images are simultaneously acquired from the 16-arrayed microscopes to reconstruct high-resolution 3D images. Maps of 3D deformation will be generated to find the strains induced within the sample and the cantilever. Knowing the mechanical stiffness of the cantilever, the stress induced in the sample will be found. Since the proposed method is based on optical deformation analysis, it will provide force sensing capabilities without using electrical force sensors. Not only the microfabricated cantilevers but also conventional tools including glass tubes and needles will be used with the added function of force sensing, once their stiffness is calibrated. The efficacy of the system will be validated through manipulation of 3D microtissues and sperm injection experiments using zebrafish eggs. The ability to visualize and manipulate micro/mesoscale objects plays an important role in many emerging biomedical applications. However, mechanical tools that focus on samples in such size scales are still in their infancy. The proposed research is among the first steps in this direction.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.