Frequently Asked Questions (FAQs) - Cooclk FlexCT project

To apply for our services, please fill in our user form. One of our colleagues will then contact you further to discuss your request.

• Generally, we do not charge costs for a first test measurements (except when CT measurements are directly requested on a larger batch of samples, e.g. for industrial purposes).
• When a more extensive study is required, we do charge operator and instrument costs.
• Scans that are charged are always effected through an official contract with the university spin-off imec (www.imec.be).

An entire CT scan can be as fast as only one minute! A CT scan with medium resolution and medium signal-to-noise ratio does generally not take any longer than 10 minutes. However, when high resolution scans and/or scans with high signal-to-noise ratio, scan times can increase up to several hours. Also keep in mind that a necessary proper reconstruction of a CT  dataset generally takes 5-15 minutes. If you plan to come over for a measurement, then reserve typically 2-3 hours (e.g. one morning or afternoon). This comprises introduction to the system, sample preparation, scan time, data processing and closing.

For a first test scan, we generally provide a few radiographs and CT cross-sections on a USB stick or mobile hard disc (provided by the user). Entire CT datasets are typically several tens of gigabytes, which is provided after the measurements using a BELNET link (equivalent of WeTransfer, but for academic purposes). Note that the link is only valid for limited amount of time, so download your data asap! Radiographs/CT slices (tif format) can be imaged using the freeware Fiji/ImageJ (https://fiji.sc/). 3D volumes (.pvl.nc format) can be viewed using the freeware Drishti (https://github.com/nci/drishti/wiki).

When requested, measurements for industry are kept strictly confidential. Confidentiality is also assured via the official imec contract containing a non-disclosure agreement (NDA).

Typically, micro-CT allows to look inside samples in a non-destructive manner, therefore only minimal sample preparation is required.

• Small samples (few mm, cm) are typically mounted on a sturdy carbon fibre rod (2 or 5 mm diameter, see Fig. 7, left). Samples are typically fixed on the rod using glue from a glue pistol glue, second glue or with double sided tape. Note that the fibreglass rods are fairly long as they also serve to bring the sample sufficiently close to the height of the X-ray tube, located approx. 20-30 cm above the sample platform.
• Fibreglass rods with an additional stub (i.e. small platform) on top for medium-sized samples are available as well (see Fig 7, right).
• Large samples (tens of cm, m) can be put directly onto the sample platform or on top of a low absorbing support to increase the height (e.g. polystyrene, floral foam).

Note:

• keep in mind that your sample should not contaminate the instrument! Samples which can do so are preferably kept in a container (e.g. plastic, card board box), with negligible absorption compared with the sample.
• moist or wet samples should be sealed from the environment to prevent drying/deformation during the CT scan.
• if the samples require specialized equipment to handle (e.g. microscopic particles), we advise to perform sample preparation at your home institute. Discuss this best in advance with us to have optimally prepared samples.
• if your samples cannot be brought in contact with any form of glue, a different kind of (specialized) mounting needs to be devised. This is also preferentially discussed beforehand.

Fig: Central base plate of the rotation stage. The base plate has a diameter of 27.5 cm with equidistant threaded holes (diameter 5 mm, M5 and 25 mm interspacing) on which sample holders or samples can be attached. Additionally, there are also magnetic mounts (see red arrow) on the base plate onto which clamps for fibre glass rods (and other sample holders) can be attached.

Fig: Examples of sample holders mounted on top of the base plate. Sample holders have a cylindrical head which can clamp rods of variable diameter (up 5 mm) and material (e.g. fibre glass, wood, metal). The sample is directly attached on top of the rods using glue (e.g. using superglue, glue from a glue gun, nail polish, see left figure) or a stub is put on top of a hollow fibreglass rod which is then covered with double sided tape to attach the sample (right figure).

Yes, we very much support pilot experiments in test environments (e.g. pressure cell, furnace, humidity control). The rotation stage is equipped with a connector with IO ports, RJ45, AC/DC power which is fully compatible with rotation via an electrical slip ring. Note that such specialized measurements require more preparation in advance!

Yes, in between measurements, lunch/snacks can be found at restaurant Komida@3 Eiken restaurant (building G on campus map, every weekday from 11h45 to 13h45) or the university hospital canteen (UZA) within walking distance (see weblinks for more info).