Electron Microscope Medical Presentation

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Electron microscope By Ghady Ismail – Loujen Hasan – Raghad Lahza – Riyana Bokhari – Nema Saleh
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Content: Inroduction Types Components Mechanism of action Uses History preparation
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Types Transmission electron microscope (TEM) Scanning electron microscope (SEM) Reflection electron microscope (REM) Scanning transmission electron microscope (STEM)
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Components Transmission electron microscope:
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Scanning electron microscope:
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scanning electron microscope The basic principle when electron release that cause heating the surface of the sample. we have upon heating the surface the electron have different phases. the different phases of electron in the (SEM): 1- Absorb >> primary electron release 2- Reflect electron 3- Secondary electron release from the specimen The detecting different variety of electron that will describe the surface structure of the molecule sample as well as describe also the composition of the molecule and the type of the sample depend on the percentage all this variety of electron .
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The major type of electron detector 1-Back scatter electron detector : detect only reflect electron whatever its coming in the same electron coming out its just reflect no other electron from the specimen 2- Secondary electron detector: that can only detect the secondary electron that came from the specimen detector registers these scattered electrons and turns them into a picture ,A hugely magnified image of the object is displayed on a TV screen from the detector
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Mechanism of action for (SEM) First of all release the electron from the electron gum to heated the surface of the specimen passing through areas and the main part of the machine (where the object is scanned) is contained within a sealed vacuum chamber because precise electron beams can't travel effectively through air. Magnetic lens: work as condenser lens, condense the electron beam to be focus on the particle Scanning coils: are used to raster the beam onto the sample and steers the electron beam from side to side
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“It can be used to research drug formulations or to study the crystal growth and morphology of chemicals in general,” “It can also be used to look at how drugs interact in the body or the effect of drugs on tissues and cells.” New Opportunities in Drug Discovery and Development
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Features for the Electron Microscopy The sample never experiences vacuum even with scanning electron microscopy (SEM) imaging: Because the sample is in an open environment the ClairScope is well suited for dynamic studies, like adding a drug to a sample, following the live cells with the optical scope, and then fixing and staining the preparation for SEM.” In the SEM mode, this scope provides a resolution of about 8 nm. To make it easier for researchers to gather EM data, JEOL offers the JEOL Automated Data Acquisition System (JADAS) software. “This artificial intelligence helps a scientist image a high-resolution structure of any macromolecule, like for instance a virus,” says Brink. This software can automatically collect hundreds of thousands of images without user intervention. “At that resolution, you can even see amino acid side chains,” Brink explains.
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History of development The beginning The first electromagnetic lens was developed in 1926 by the German Hans Busch. Then The physicist Ernst Ruska and the electrical engineer Max Knoll constructed the prototype electron microscope in 1931, capable of 400 power magnification. ; the apparatus was the first demonstration of the principles of electron microscopy. Two years later, in 1933, Ruska built an electron microscope that exceeded the resolution attainable with an optical (light) microscope.
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In 1932, Ernst Lubcke of Siemens & Halske built and obtained images from a prototype electron microscope. Five years later (1937), the firm financed the work of Ernst Ruska and Bodo von Borries, and employed Helmut Ruska (Ernst’s brother) to develop applications for the microscope, especially with biological specimens. The first commercial electron microscope was produced in 1938 by Siemens. Then the first commercial scanning electron microscopes (SEMs)which was introduced in 1965 opened up a new world of analysis for materials to many scientists.
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Recent history Ultrahigh voltage TEM instruments in France and Japan during the 1960s and 1970s gave electrons higher energy to penetrate more deeply into thick samples. The evolution and addition of other detectors made the SEM into a true analytical electron microscope (AEM). Tilting specimen stages permitting examination of the specimen from different angles aided significantly in the determination of crystal structure. Lastly, Computer technology for automated control of electron microscopes and for the analysis of the resulting micrographs.
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Scanning electron microscope (SEM) Transmission electron microscopy (TEM) Preparation of electron microscope
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Fixation and dehydration are important for preparing samples for both the TEM and the SEM. However, other aspects of sample preparation differ greatly because the two microscopes have different requirements.
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TEM samples are also treated with heavy metals to increase the level of contrast in the final image. The parts of the sample that interact strongly with the metals show up as darker areas. This is to allow electrons to pass right through the sample. TEM
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Samples aren’t cut into thin sections. because the SEM visualizes the surface of three-dimensional objects. Without the metal coating, many samples build up electrons, and this can cause ‘charging artefacts’. SEM
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Refrences: http://www.explainthatstuff.com/electronmicroscopes.html https://www.youtube.com/watch?v=VdNhREmkrmE https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/materials/public/ElectronMicroscope/EM_HistOverview.htm Mathys, Daniel, Zentrum für Mikroskopie, University of Basel: Die Entwicklung der Elektronenmikroskopie vom Bild über die Analyse zum Nanolabor, p. 8 Dannen, Gene (1998) Leo Szilard the Inventor: A Slideshow (1998, Budapest, conference talk). dannen.com Ruska, Ernst (1986). "Ernst Ruska Autobiography". Nobel Foundation. Retrieved 2010-01-31. Rudenberg, H Gunther; Rudenberg, Paul G (2010). "Chapter 6 – Origin and Background of the Invention of the Electron Microscope: Commentary and Expanded Notes on Memoir of Reinhold Rüdenberg". Advances in Imaging and Electron Physics. 160. Elsevier. doi:10.1016/S1076-5670(10)60006-7. ISBN 978-0-12-381017-5.
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Refrences: https://www.ntnu.edu/documents/139994/141053151/SEM+sample+preparation.pdf/867c2d56-6453-4d8f-9d26-19e2c5dc143b https://www.ntnu.edu/documents/139994/141053151/TEM+sample+preparation.pdf/eb6c557f-8243-4923-9135-cc8f8fa5c37f https://www.sciencelearn.org.nz/resources/500-preparing-samples-for-the-electron-microscope Mike May, Drug Discovery & Development magazine: Vol. 13, No. 4, May 2010, p. 5