MRI: Acquisition of a Field Emission Cryo-Scanning Electron Microscope for Nanocharacterization and Patterning of Soft Materials

MRI：获取场发射冷冻扫描电子显微镜，用于软材料的纳米表征和图案化

• 批准号: 0922522
• 负责人: Matthew Libera
• 金额: $ 69.98万
• 依托单位: Stevens Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0922522&HistoricalAwards=false
• 关键词: MRI; Acquisition; Field; Emission; Cryo

0922522LiberaStevens Institute of TechnologyTechnical Summary: This project applies a new, state-of-the-art, cryo-scanning electron microscope (SEM) to measure soft-materials morphology at high spatial resolution. This new microscope will advance over ten research projects at Stevens Institute of Technology and enable them to follow important directions that amplify their ongoing and anticipated aims. All involve soft materials ? either synthetic polymers, biological structures, or combinations of the two. Among the materials being studied are: self-assembled, weak-polyelectrolyte, responsive micelles; nanoparticle composites; degradable scaffolds that mimic natural bone; infection-resistant orthopedic implants; natural extracellular matrix; and synthetic nanofiber extracellular matrices. Synthetic and natural polymers are challenging materials to study by electron microscopy because of their radiation sensitivity, weak intrinsic contrast, and susceptibility to electrical charging. This new microscope provides controllable electron accelerating voltages enabled at low voltages by a field-emission (FEG) electron source; gas compensation to mitigate specimen charging; high-efficiency electron detectors that minimize the required incident dose; robust methods for digital image acquisition/processing; cryo-imaging capabilities for studying frozen-hydrated materials; and hardware/software for robust electron-beam lithography. All of these features are either inadequate or unavailable on the SEM the new microscope replaces. Importantly, the new SEM is housed in a central user facility with a history of successful multidisciplinary training that spans high school through post-graduate school. Users receive substantial training both by concentrated hands-on self-user practice and by graduate lecture/lab course work. In addition to serving the immediate Stevens research community, the instrument plays an important role in community outreach and education by way of collaborative activities with the Stevens Center for Innovative Engineering and Science Education, an established K-16 outreach organization, and the Project SEED program of the American Chemical Society.Layman Summary: Scanning electron microscopes (SEMs) are used to study the surfaces of materials at magnifications between about 20 and 500,000 times. They can provide important information about the structure and composition of materials. So-called soft materials, such as plastics and biological tissue, are typically more challenging to study by electron microscopy than metals or semiconductors, because soft materials can become both electrically charged and chemically changed by the electrons used in the microscope. At Stevens Institute of Technology there are more than ten research projects, all of which involve soft materials, whose progress is limited by the need to do more and better SEM imaging and analysis. The newest scanning electron microscopes incorporate innovative features that can help Stevens researchers overcome the problems of specimen charging and chemical damage. To take advantage of these, this project is using a new, state-of-the-art, SEM to measure soft-materials morphology and help Stevens researchers make new discoveries. These scientists are, for example, using the microscope to develop new ways to delivery drugs, to make hip and knee implants more infection resistant, and to help heal major bone fractures. Because this new microscope is a complex instrument, it is housed in a laboratory with a dedicated staff and facilities to both maintain the microscope and provide the advanced training needed for university students to make the best use of this new tool. Importantly, however, many aspects of the microscope are relatively easy to use and understand, so this microscope is also helping Stevens develop connections to the surrounding community through a variety of high-school outreach programs designed to get more young people aware of and interested in science and engineering.

[09:22522]本项目采用最新的、最先进的低温扫描电子显微镜（SEM）在高空间分辨率下测量软材料的形态。这种新型显微镜将推进史蒂文斯理工学院的十多个研究项目，并使他们能够遵循重要的方向，扩大他们正在进行的和预期的目标。都涉及到软材料吗？无论是合成聚合物，生物结构，或两者的组合。研究的材料有：自组装、弱聚电解质、反应胶束；纳米复合材料;模拟天然骨骼的可降解支架；抗感染骨科植入物；天然细胞外基质；合成纳米纤维细胞外基质。合成聚合物和天然聚合物是具有挑战性的材料，通过电子显微镜研究，因为他们的辐射敏感性，弱的内在对比，和易受电荷。这种新型显微镜提供可控的电子加速电压，通过场发射（FEG）电子源在低电压下实现；气体补偿，以减轻试样的充电；高效电子探测器，最大限度地减少所需的入射剂量；稳健的数字图像采集/处理方法；研究冷冻水合材料的低温成像能力；以及稳健电子束光刻的硬件/软件。所有这些特征在新显微镜取代的扫描电镜上要么不足，要么不可用。重要的是，新的SEM被安置在一个中心用户设施中，该设施具有从高中到研究生院的成功多学科培训的历史。用户通过集中的动手实践和研究生讲座/实验室课程工作获得大量培训。除了直接服务于史蒂文斯研究社区外，该仪器还通过与史蒂文斯创新工程和科学教育中心（一个已建立的K-16外展组织）和美国化学会SEED项目的合作活动，在社区外展和教育方面发挥着重要作用。外行总结：扫描电子显微镜（sem）用于研究材料表面，放大倍数在20到50万倍之间。它们可以提供关于材料结构和组成的重要信息。所谓的软材料，如塑料和生物组织，通常比金属或半导体更具有挑战性，因为软材料在显微镜下使用的电子既可以带电，也可以发生化学变化。在史蒂文斯理工学院，有十多个研究项目，都涉及软材料，其进展受到需要做更多更好的扫描电镜成像和分析的限制。最新的扫描电子显微镜包含创新的功能，可以帮助史蒂文斯的研究人员克服样品充电和化学损伤的问题。为了利用这些优势，这个项目正在使用一种新的、最先进的扫描电镜来测量软材料的形态，并帮助史蒂文斯的研究人员做出新的发现。例如，这些科学家正在利用显微镜开发新的药物输送方式，使髋关节和膝关节植入物更具抗感染能力，并帮助治愈主要骨折。由于这种新型显微镜是一种复杂的仪器，它被安置在实验室里，有专门的工作人员和设施来维护显微镜，并为大学生提供充分利用这种新工具所需的高级培训。然而，重要的是，显微镜的许多方面都相对容易使用和理解，所以这台显微镜也帮助史蒂文斯通过各种高中外展项目与周围社区建立联系，旨在让更多的年轻人意识到并对科学和工程感兴趣。