Figure 1: P11 Sample changer overview. Sample gripper (1A & 1B), gripping principle (1C), sample Dewar (1D).
The automatic sample changer at P11 consists of a StäubliTX60L robotic arm which is equipped with an inhouse developed flexure-based sample gripper with integrated sample cooling (see Figure 1A). The gripper head is fitted with a calcium silicate tube acting as a liquid nitrogen (LN2) reservoir (see Figure 1B). Whenever the gripper is inserted into the LN2 in order to grip a sample the reservoir is filled with LN2. Once the gripper is moved out of the Dewar the temperature raises and cold nitrogen gas is slowly released from the calcium silicate. This keeps the sample at cryogenic temperatures during the mounting procedure and also prevents ice formation on the sample surface by forming a continuous cold gas stream surrounding the sample.
In contrast to other grippers our inhouse design allows sample gripping from beneath as illustrated in Fig. 1C. This requires very accurate positioning but reduces the holding force to a minimum which allows using relatively thin carbon fibre arms with a much lower heat conductivity than the steel arms commonly used. The sample gripper is commercially available via Suna Precision.
The large sample Dewar provides space for 23 pucks which results in a total load capacity of 368 samples (see Figure 1D). This allows to perform measurements for several hours without the need to load the Dewar with new samples.
Sample holders
For our sample changing robot we strongly recommend to use SPINE standard pins (see Figure 2). Other pins may cause problems upon sample exchange and could be a risk to your experiment.
Figure 2: SPINE pin. |
Figure 3: Unipuck. |
Unipucks
The P11 sample changer is based on Unipuck (Universal Puck) format (see Figure 3). Detailed instructions for working with Unipucks can be found here:
- Loading samples into the Unipuck
- Loading Unipucks into the robot Dewar
- Removing samples from Unipucks
During your experiment you are welcome to loan Unipucks from us. Tools for repacking your samples from SPINE pucks or canes to Unipucks are available on-site. Unipucks can also be purchased from the following suppliers:
