Cryo scanning electron microscope

该提案的主题是一种带有热发射器的低温扫描电子显微镜（cryo SEM），它特别符合对导电性差的塑料和生物样品进行检查的要求。除了在低加速电压下的高成像性能之外，这还需要低真空下的操作模式和具有高灵敏度的能量色散X射线光谱（EDX）系统。对于敏感材料的样品制备，使用低温氩离子抛光有望制造高质量的横截面，通过该横截面，在许多样品中实现了SEM图像的显着增加的信息价值，或者使评估成为可能。使用冷冻制备装置，可以在制备和检查期间通过用液氮冷却来检查在室温下不稳定的样品。与此同时，可以使用SEM成像模拟、检查和监测冷冻和解冻过程。所要求的系统是对汉诺威莱布尼茨大学现有设备的补充。特别是，首次实现了低温扫描电镜检查和氩离子抛光样品制备。使用所需系统进行的经常性研究任务包括评估纤维表面、非织造布、界面质量和纤维增强塑料开发中的失效机制。为了评价纤维-基体的粘合性，除了断裂面分析外，还将使用氩离子抛光的截面分析。在开发新的塑料回收方法时，SEM研究有助于分析复杂材料（包括多层复合材料）的结构，以便在此基础上开发合适的加工策略。中间产品和最终产品的SEM分析提供了有关加工步骤对材料特性影响的信息。在塑料海洋降解性项目中，需要检查现场试验的试样，这些试样通常显示出明显的生物覆盖率。用氩离子抛光，可以在这里产生不破坏生物膜的横截面。在冷冻技术的研究领域中，研究生物样品（悬浮细胞、组织）以及组合产品（组织工程和再生医学的细胞/组织的聚合物载体结构）的冷冻和解冻过程的工艺参数的影响。低温制备单元能够模拟典型的工艺步骤。同时，结构影响可以量化，其分辨率上级IMP可用的低温显微镜。

The subject of the proposal is a cryo scanning electron microscope (cryo SEM) with a thermal emitter, which specifically meets the requirements for the examination of poorly conductive plastic-based and biological samples. In addition to a high imaging performance at low acceleration voltages, this requires an operating mode in low vacuum and a system for energy dispersive X-ray spectroscopy (EDX) with high sensitivity. For sample preparation of the sensitive materials, the use of cryo argon ion polishing promises the fabrication of high-quality cross sections, through which a significantly increased informative value of the SEM images is achieved in many samples or an evaluation is made possible at all. Using a cryopreparation unit, it will be possible to examine samples that are not stable at room temperature by cooling them with liquid nitrogen during preparation and examination. At the same time, freezing and thawing processes can be simulated, examined and monitored using SEM imaging.The requested system complements the equipment already available at Leibniz University Hannover. In particular, cryo SEM examinations and sample preparation using argon ion polishing are made possible for the first time.The recurring research tasks to be processed with the requested system include the evaluation of fiber surfaces, nonwovens, interface qualities and failure mechanisms in the development of fiber-reinforced plastics. For the evaluation of the fiber-matrix adhesion, in addition to fracture surface analysis, the cross section analysis using argon ion polishing will be used.When developing new recycling approaches for plastics, SEM investigations serve to analyze the structure of complex materials (including multi-layer composites) in order to develop suitable processing strategies based on them. SEM analyzes of the intermediate and end products provide information about the influence of processing steps on the material characteristics.In projects on the marine degradability of plastics, test specimens from field tests are to be examined, which often show significant biological coverage. With argon ion polishing, cross sections can be produced here that do not destroy the biofilms. This makes it possible to evaluate the degradation mechanisms inside the specimen.In the research field of cryotechnology, the influences of the process parameters of freezing and thawing processes of biosamples (suspended cells, tissue) as well as combination products (polymeric carrier structures with cells / tissue from tissue engineering and regenerative medicine) are to be investigated. The cryopreparation unit enables the typical process steps to be simulated. At the same time, structural influences can be quantified with a resolution that is superior to the cryo microscopy available at the IMP.