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Getting up close and personal with the Scanning Electron Microscope.

Bioquell is proud of the quality of its Biological Indicators (HPV-BI) which is why we publish not only our certificates of analysis but also those of the independent testing. Additionally images of individual BI discs taken using a scanning electron microscope (SEM) are available. These are used to indicate the mono layer formation of spores across the disc. A high quality BI will show an even distribution with minimal clumping of spores and free of foreign debris.

At a local research centre a selection of SEMs are used for analysis of organic matter. An SEM works by firing a beam of electrons at your ‘sample’. Any electrons that bounce off are caught by the detector and through magically programming produce an image. However, you are not able to simply push any kind of sample into the chamber and press fire, the sample must be electrically conductive prior to exposure. In our case of BIs the spores are not, so must be coated in a thin layer of conductive material, commonly carbon or gold. Gold is applied through a process known as sputter coating, which is the deposition of a physical vapour to form a thin film by utilizing strong electric and magnetic fields. Carbon in comparison is the thermal evaporation of carbon by passing high voltage across carbon robs and rising the temperature to its evaporation point.

SEMs allow extremely high magnification some 260 times that of a decent light microscope, giving details less than 1nm in size. This proves very useful for us when examining the quality of our BIs, it allows us to examine the individual condition of the indicator spores. You could even count how many spores are present, all >1x10^6, if you have the patience.

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