Variable Pressure cyro scanning electron microscope for biomedical characterization in micro nanoscale

变压电子扫描电子显微镜是观察完全水合材料或其他电子束和真空敏感样品的经济有效的手段，可用于研究真空敏感材料，如脆弱的生物结构，如真菌、植物、细胞、有机-无机杂化材料、金属、金属氧化物、脂类、合成聚合物和天然聚合物如DNA、RNA和蛋白质等，以及软的或易挥发的样品甚至液体。该技术的优点是简单、经济有效，样品将在扫描电子显微镜下原位冷冻干燥。通过俯视和横截面成像结合低温阶段冷却，我们将获得关于杂化材料的三维结构的新的和准确的知识，包括脂类、DNA和蛋白质修饰的纳米颗粒和凝胶材料。可以避免长时间的脱水和化学固定步骤。此外，它还能够在不涂覆样品的情况下成像，许多情况下，当涂上Au或其他金属时，表面细节会被遮盖。据我们所知，在瑞尔森或附近的大学，如多伦多大学，没有一种冷冻变压扫描电子显微镜能够将样品冷冻到零度以下，并在变压下运行。建议的设备是Ryerson在生物医学工程和微/纳米制造领域研究重点的重要补充。该设备的申请者来自多个系(生物医学工程、电气工程、机械工程和航空航天工程)，并将与来自几个实验室的研究人员和工作人员一起用于微米和纳米尺度的生物医学分析。

The proposed variable pressure Cyro SEM instrument is a cost effective means of looking at fully hydrated materials or other electron beam and vacuum sensitive samples .It can be used to studying vacuum sensitive materials such as such as fragile biological structures such as fungi, plants, cells, hybrid organic-inorganic materials, metals, metallic oxides, lipids, synthetic polymers and natural polymers such as DNA, RNA and proteins etc. as well as soft or volatile samples and even liquids. The advantage of this technique is that it is simple, cost effective and the sample will in situ freeze dry in the SEM. Through top-view and cross-sectional imaging combined with cryo-stage cooling we will obtain new and accurate knowledge regarding the three-dimensional structure of hybrid materials including lipid, DNA and protein modified nanoparticles and so-gel materials.. Long dehydration and chemical fixation steps can be avoided. Also it has the ability to image without coating the sample, many times surface details are masked when coated with AU or other metals. To the best of our knowledge there is no Cryo variable pressure scanning electron microscope which has the capability to freeze the sample to sub zero temperature and operating at variable pressure in Ryerson or nearby university such as university of Toronto. The proposed equipment is an important addition to Ryerson research focus in the direction of biomedical engineering and in micro/ nanofabrication. The applicants of the proposed equipments are from several departments (Biomedical engineering, electrical engineering, mechanical engineering and aerospace engineering) and will be joined used by research students and staff's from several laboratories for biomedical analysis in micro and nanoscale.