910 Multispecimen Cryotransfer System

Examine multiple cryospecimens with one transfer

Cryospecimens are difficult to prepare, and often several grids must be examined before suitable areas for data collection are found. Since current holder designs usually accommodate one specimen, the procedure to reload a fresh grid involves loss of productive time during holder exchange. The 910 avoids this problem by allowing two to three grids to be loaded into an interchangeable specimen cartridge that then fits into the tip of a cryotransfer holder. A stationary cryoshield protects samples from frost during transfer to the TEM. The 910 has a single tilt capability of up to ±50°, depending upon pole-piece configuration.

Rapid, frost-free transfer

Gatan technology made frost-free transfer possible with the introduction of the Cryoshield in 1980, and we have continued to provide new concepts to preserve sample integrity. In the 910 Multispecimen Cryotransfer holder, a stationary cryoshield protects grids during holder insertion and specimen cartridge movement is controlled externally by the operator. The cartridge is retracted under the stationary cryoshield during sample loading, the samples are sequentially exposed during the imaging session. A positive click-stop ensures that each specimen is correctly positioned under the electron beam and the actual specimen under view is indicated by a number in a window at the rear of the holder. During specimen loading, the holder tip inserts into the Workstation's liquid-nitrogen well, surrounding the holder tip and frozen sample grid in a protective, cold and dry nitrogen gas atmosphere.

Hexring® System

The Hexring® was developed for easy sample loading without the difficulties associated with spring clips and slotted, threaded rings. This method of securing samples allows easy grid manipulation and ensures specimen clamping control. Hexring® are fabricated of beryllium for analytical applications or phosphor bronze for routine applications since both metals have good mechanical properties, are UHV-compatible and are easy to clean.

Precise temperature control

The specimen holder tip temperature is monitored by a calibrated silicon diode. This type of sensor has the following advantages over a thermocouple: (1) its output is not affected by cold-junction temperature gradients, (2) it is more sensitive, and (3) it has a more linear temperature response. The conduction rod connecting the specimen holder tip to the nitrogen dewar contains an electric heater to control the specimen temperature. Gatan cooling holders are designed so that the whole specimen holder tip is cooled and not just the specimen cradle. This ensures the minimum possible temperature gradient around the specimen.