Select 100™ - Automated multi-specimen
imaging in the TEM

For the first time in the TEM it is now possible to screen a large number of specimens without the need for user intervention. The unique features of the Select100™ allow researchers in many fields to collect data automatically, either by collecting images from the whole grid or from user selected areas of interest. Serial sections, particle size distribution, catalyst process quality control, pathology and other fields where large numbers of specimens are produced may benefit from automation. For example, large numbers of different preparations may be screened to search for the formation of 2D crystals. The Select100 was developed, following an idea by Dr. S. Subramaniam, and in close collaboration with NCI-NIH, Bethesda, MD, USA

Select100’s independent pumping system conveniently allows specimens to be outgassed before transfer. Despite the automation, Select100 does not affect normal running of the TEM using other specimen holders.

The control software is kept as simple as possible but may be extended using the DigitalMicrographTM (DM) scripting language to add user specific functionality. This approach means the software remains versatile whilst also easy to learn.

The Hardware

The Gatan Select100 is a cartridge based, automated specimen loading system. Specimens are loaded into individual cartridges using an easy load cartridge support. These cartridges are then mounted on the exchange spiral which, when fully populated, is fitted to the main system block and automatically evacuated by a dry turbo pumped vacuum system.

Once the necessary vacuum has been reached the system is opened to the column vacuum and the turbo system is isolated. All the user then has to do is tell the software how many cartridges have been loaded and the screening can start automatically.

Advanced Specimen Centering

Designed to be as simple to use as possible whilst maintaining versatility and expandability the software runs under Gatan’s industry standard DigitalMicrograph software interface. Once a grid has been automatically loaded onto the specimen holder a low magnification mapping image is taken.

Submitted paper: Automated 100-Position Specimen Loader and Image Acquisition System for Transmission Electron Microscopy; Jonathan Lefman, Robert Morrison, Sriram Subramaniam

Because a common point of reference is needed to automate data collection, off-centre specimen grids (B) are realigned according to a reference image

Cross-correlation using 360º rotated images finds both the translation and rotation of the grid relative to the reference image.

The system will automatically set the eucentric height and focus of the specimen. The user may define the magnification, dose and exposure time for the images in advance.

Specification

Max no. of specimens 100
Specimen diameter 3mm
Pumping system Dry turbo cube
Isolation valves Pneumatically operated

Supplied software
Basic specimen exchange, specimen centering,
selected area screening, auto eucentric height
adjustment, auto focus

Supplied components:
The main exchange system
Motorised specimen holder
100 cartridges
100 clamp rings
Clamp ring tools
Cartridge loading station
Control PC with all interface cards
All necessary connection cables and pneumatic pipework (uses TEM pneumatics)
Networking cables
Support bracket for linear drive
Turbo pumping system with all valving, venting and gauging
Basic control and acquisition software