( Below)The electron microscopic image of a mouse retina demonstrates that using the KonTEM phase contrast system (right) makes previously invisible structures visible.


KonTEM’s product is aimed primarily at applications in the field of structural biology. To develop newmedicines you need to understand biological structures at the molecular level. Transmission electron microscopy is currently the best method of achieving this. Modern TEMs can take direct images of single atoms.

But the problem with biological materials is that the samples are almost completely transparent to the electron beam, given they consist predominantly of light atoms. Because light atoms interact with the electrons from the TEM beam only minimally, the image is almost invisible; as the contrast is very weak.

It is usually not desirable or not feasible to improve contrast by staining, or adding heavy metal salts. Defocusing can improve the contrast, it does impair resolution, making examinations at the molecular level impossible.

One way of solving this dilemma is to make use of a physical effect called phase contrast, a practice employed in light microscopy for decades on the basis of phase rings. But it had not been possible to use it in routine TEM operations because many technical challenges could not be satisfactorily resolved.

The product that KonTEM has developed is the first easy-to-use version that can be employed in routine examinations and combines both attributes – high image contrast and maximum object resolution – in a user-friendly application.



The basis of the new technology originated in research conducted at the Max Planck Institute of Biophysics in Frankfurt, which was then developed into a marketable product at The Centre of Advanced European Studies & Research (caesar ) foundation which is associated with the Max Planck Society.

It operates a neuroscientific research centre in Bonn. The science it conducts meets the Max Planck Society’s criteria for excellence. Both Max Planck Innovation, the Society’s technology transfer organisation and caesar have licenced the rights to the technology exclusively to KonTEM.



KonTEM’s PCS consists of the phase plate and the positioning mechanisms. The phase plate is the centrepiece of the KonTEM PCS and is the element that makes the phase contrast visible in the image. The KonTEM phase plate avoids the downsides of previous phase plate concepts.

The lifetime of the material is much longer. The phase plate is an ultra-thin perforated film. Refraction index of the material and an electric potential combine to shift the phase of the scattered electrons by exactly 90°. This creates interference; the phase contrast becomes visible and the object is depicted in sharp focus and high contrast. 

The second of the main components of the KonTEM PCS, the positioning mechanism, was developed to enable the perforations in the TEM to be positioned with nanometric precision. Powered by a ‘precision drive’ of this kind, perforations in the phase plate are positioned correctly to within a few nanometres in the TEM’s electron beam.

This secure and accurate positioning makes the system considerably easier to use. And the modular construction means that the system can be retrofitted to suit all of the common TEM models.

“Our new phase contrast system is of interest to research institutions and universities that focus on structural biology primarily, but it is also useful to companies in the polymer and pharmaceuticals industries, which have to deal with similar contrast issues,” explains (right) Joerg Wamser, director of KonTEM GmbH.

“With the support of Max Planck Innovation we were able to obtain funding from the EXIST research-transfer initiative run by the Federal Ministry of Economics and Technology (BMWi). This and the numerous awards the project has won underline what an outstanding and future-oriented technology we have here.”

Dr. Florian Kirschenhofer,  manager at Max Planck Innovation, adds: “It is very gratifying for us to be able to realise a technology from one of the Max Planck institutes in cooperation with the caesar research centre in such a promising spin-off.”


Leica Microsystems to launch

Gated STED 

Above: g-STED nanoscopy provides fundamentally improved spatial resolution over confocal microscopy in living cells. Here, the protein keratin is marked with the fluorescent protein Citrine in a living PtK2 cell. The insets show a magnified view of the marked areas, demonstrating the separation of features as small as 60 nm in the living cell. Fluorescence excitation at 485 nm, STED at 592 nm wavelength using a CW beam. Scale bars 1μm.
© Max Planck Institute for Biophysical Chemistry

Professor Stefan Hell, (left) director at the Max Planck Institute for Biophysical Chemistry, has inevitablytaken his idea of STED microscopy another momentous step further with gated STED.

This new technology significantly improves the resolution and contrast previously attained with CW-STED (Continuous-Wave Stimulated Emission Depletion) microscopy, while distinctly reducing laser intensity.

This enhances photostability as well as live cell capability, substantially extending the range of possible applications. Also, gated STED technology will considerably increase the number of issues that can be addressed with STED fluorescence correlation spectroscopy (STED-FCS). The main application of gated STED technology will be the observation of molecule movements in the membrane of living cells.