Thawing and Mixing Workcells

ARUP’s automation includes three Yaskawa America (Motoman, Irvine CA) automated thawing and mixing workcells (TMWs), which were implemented in 2015 along with the rest of ARUP’s Automated Transport and Sorting System. They were substantially redesigned from two previous Motoman TMWs that had been installed in 2007. In December of that year, we had published the invention, validation, and implementation of ARUP’s first TMW in Clinical Chemistry.1 A narrated video of a current TMW in operation can be viewed by clicking here.

Approximately 35% of ARUP’s testing volume arrives frozen. A significant portion of the frozen specimens are so-called critical frozens, usually meaning that the specimens can only be thawed immediately prior to testing or that the specimens must be shipped frozen since the analyte is not stable refrigerated long enough to reach the laboratory and be tested. Once at the laboratory, however, many of these frozen tests will be tested promptly, so having the specimens already thawed when they arrive at the testing bench shortens turn-around time.

The basic concept of the TMW is to use directional nozzles with 2 mm orifices to blow room temperature air at high velocity at specimen tubes which are positioned inside cylindrical aluminum holders (see close up photo to the right). Each holder has a vertical slit through which the air is directed. The air then swirls around the tube on all sides, thawing more rapidly than if the tube were not in a holder, in which case the blowing air would simply deflect off the front of the tube, resulting in a longer thawing time for the specimen. Only room temperature air is used, since many analytes are not stable at higher temperatures. After the specimen has been thawed it is mixed by a six-axis robot which alternately rotates the specimen 126° four times in each direction, which was proven to adequately mix each specimen. The throughput of each system is approximately 1000 specimens thawed and mixed per hour.

The main design difference between the 2014 TMW and the older version is due to the conveyor system. In the older system specimens were transported in standardized transport carriers (STCs). The STCs were lifted from the conveyor and placed on the deck of the TMW in front of the nozzles. The STCs were spaced from each other on the deck by the same pitch as on the track, so that 10 STCs occupied approximately 11 lateral inches of space. However, the magnetic pucks on the new MagneMover® track repel each other and 10 pucks requires 1 meter of conveyor. Therefore, a separate robotic system lifts the specimen tubes out of the pucks and laterally compresses the distance between tubes to the same pitch as in the old system. This robot then transfers the tubes to the six-axis robot, which places the tubes in the aluminum holders that have the same desired pitch of approximately 11 inches for ten tubes. In nearly every other aspect, however, the design is the same as the older system.

Whereas the old TMWs only served specimens directed to ARUP’s Automated Core Laboratory, ARUP’s new automation enables the TMWs to be used for any specimen, based on the specimen’s ordered test code(s). Each laboratory section determines which tests should go through the TMW. ARUP is very proud of these state-of-the-art robotic systems, the only automated TMWs in the world.

1Hawker CD, Roberts WL, Dasilva A, Stam GD, Owen WE, Curtis D, Choi B-S, Ring TA, 2007. Development and validation of an automated thawing and mixing workcell, Clin Chem 53(12):2209-2211.