Pioneering resin technology developed to improve hospital diagnostic ability

To date, transmission electron microscopy (TEM) has been the preferred technique for bio-imaging because of the high resolution it provides. Unfortunately, the system has a significant drawback - the pictures of your samples that it delivers are 2D. If you want to see a 3D TEM image, a highly time-consuming technique is necessary, with serial sections first of all fabricated and then imaged individually.

On the other hand, SEM (scanning electron microscopy) gives you much faster 3D images – in hours rather than the weeks needed with TEM – but until now these have not been of a particularly high resolution.

Next-generation SEM microscope technology

What could change everything is the next-generation SEM microscope technology that has come on to the market and which offers considerably improved resolution. These new techniques, with their automated processing, are a big step forward – but their potential is being limited by today’s last-generation resin technology.

The problem is that current resins – into which cellular systems are embedded – are prone to electron beam damage, which ultimately leads to images being lost.

Resins become damaged because of the chain scission process, which is commonly seen with materials such as PMMA. Here the atoms in the resin are removed by the diamond knife. Because of this, the inspection field cannot be imaged. Unfortunately, the process is accumulative as the electrons will always penetrate the resin.

So far, the new SEM microscopes have utilised low contrasting epoxy and acrylic resins such as Araldite and LR white but these have produced relatively low resolution images because of the scission process and inherent electron charging. In short, resin technology is lagging behind microscope technology and acting as a brake.


Figure 1: section of the block face. Electron beam damage has occurred due to higher magnification in that area and is indicated in the black box.