University of Cambridge > > Seminars at the Department of Biochemistry > "In situ liquid phase electron microscopy, 3D imaging and He ion microscopy"

"In situ liquid phase electron microscopy, 3D imaging and He ion microscopy"

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If you have a question about this talk, please contact Andrzej Szewczak-Harris.

The Cavendish electron microscope suite houses a range of electron microscopes and auxiliary equipment. It is an SRF providing services and support across the University. The aim of this overview talk is to highlight and discuss some of the techniques the Suite can provide support for, such as in situ nanoindentaion. Richard Langford, the Facility Manager will highlight the capabilities of the Suite using examples of his own research to stimulate ideas and possible use into other projects.

Richard’s current research focuses on the study of dentinal tubule occlusion using bioactive glasses. Bioactive glasses were originally developed for bone regeneration in war trauma injuries. The glass is a very open network structure which on contract with body fluids undergoes dissolution and drives the formation of hydroxyapatite like material. Part of Richard talk will focus on the techniques he has been using and developing to quantify the dentinal tubule occlusion when different toothpaste formulations are used. The techniques presented will include focused ion beam slice and view, X-ray tomography and in situ serial block microtoming. The relative advantages and disadvantages of the techniques in terms of volumes that can be analysed, time and spatial resolution will be discussed. Richard will also discuss the methodology he has been involved in developing for cryo-TEM site specific specimen preparation and the cryo FIB /SEM possibilities within the Suite which complement the cryo-TEM capabilities in the Biochemistry Department.

The main part of Richard’s talk will focus on in situ liquid phase electron microscopy (LPEM) and the newly installed He ion electron microscope. In situ LPEM enables a material system or process to be studied in real time in its native hydrated state at nm and atomic resolution while undertaking electrochemistry measurement using nanoelectrodes. It has been used to study battery processes, cellular activities and corrosion. Richard will highlight this technique using his students’ studies on the dissolution of bioactive glasses. In this work we have been able to visualise the dissolution of the bioglass and the repolymerised silica acting as a centre for calcium phosphate nucleation. The Helium ion microscope is very similar to a SEM except it scans a beam of He ions. These can be used for imaging and nanomachining for example machining sub 3 nm pores. Differences in the He beam solid angles (relative to an electron beam) and sample interactions results in this imaging technique having a relatively large depth of field and sub nm imaging. This tool is also equipped with a cryo stage and it is hoped that it can also be used for preparing site specific cryo-TEM samples with less damage to the side walls than would result when using a Ga beam.

This talk is part of the Seminars at the Department of Biochemistry series.

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