Cassette Puller

Abstract

A cassette puller for an automated storage and retrieval system that stores biological or chemical samples in freezers maintained at ultra-low temperature (e.g., −80° C.) or cryogenic temperatures includes a vertical sleeve into which the selected cassette is lifted. The cassette puller is mounted to a traveling gantry and transports cassettes from one freezer location to another and to the system input / output module, and also includes an ejection mechanism that inserts and retrieves tube storage racks or plates from a selected shelf on the cassette. Other components such as a rack robot, a tube picking mechanism, a sample identification station, etc. are mounted on the traveling gantry as well.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Patent Application No. 61 / 381,832, filed on Sep. 10, 2010 entitled “Large Automated Storage and Retrieval System for Storing Biological or Chemical Samples at Ultra-Low or Cryogenic Temperatures”.FIELD OF THE INVENTION[0002]The invention relates to automated storage and retrieval systems for ultra-low temperature or cryogenic freezer systems used primarily to store biological or chemical samples. In particular, the present invention pertains to a robotic cassette puller that transports cassettes carrying multiple sample tube storage racks or sample storage plates normally stored in a horizontal, ultra-low temperature or cryogenic freezer. The cassette puller also places individual sample tube storage racks or plates on to a selected shelf on the cassette, and retrieves individual tube storage racks or plates from the cassette.BACKGROUND OF THE INVENTION[0003]Storage of biological and ch...

AI Technical Summary

Benefits of technology

[0007]The invention is directed to a cassette puller for an automated storage and retrieval system that stores biological or chemical samples in sample tube storage racks or plates within one or more horizontal ultra-low temperature (e.g., −80° C.) or cryogenic freezers contained within a refrigerated enclosure maintained at a temperature of approximately −15° C. to −30° C. In accordance with one aspect of the invention, the cassette puller is repositionable within the refrigerated enclosure above the one or more freezers, is configured to lift storage cassettes from the one or more freezers, and is further configured to eject selected tube storage racks or plates from a lifted cassette or place a tube storage rack or plate into an empty shelf on a lifted cassette. The cassette puller includes a vertical sleeve into which a selected cassette is lifted from the underlying freezer. One significant purpose of the sleeve is to minimize temperature rise of the samples when the cassette is lifted fully or partially from the freezer. In this regard, the sleeve is desirably capped at its top end to provide a substantially enclosed volume above the freezer into which the cassette is lifted. The sleeve necessarily contains at least one access opening to allow removal of a selected tube storage rack or plate on a shelf in a lifted cassette or to allow placement of a tube storage rack or plate on an empty shelf in the lifted cassette. Motor-operated doors cover the access openings and are opened in order to allow removal of a rack or plate from the cassette or placement of a rack or plate onto an empty shelf on the cassette. It has been found that capping the sleeve significantly reduces convective heat transfer and temperature rise of samples in the lifted cassette when the doors are opened to remove a rack or plate from a shelf in a lifted cassette or place a rack or plate on an empty shelf in the lifted cassette. Without the cap on the sleeve, opening the door creates a strong convective path of warmer (e.g. −20° C.) air through the sleeve. Some or all of the walls of the sleeve may be insulated in order to reduce conductive heat transfer to samples within the sleeve.

[0011]In accordance with another aspect of the invention, the cassette puller is mounted on a travelling gantry that provides a range of motion for the cassette puller over each of the horizontal freezer chests in the system as well as the input / output module. Preferably, the cassette puller is able to move in three dimensions with respect to the travelling gantry, thus facilitating efficient operation of the cassette puller once the travelling gantry is parked over an appropriate freezer bay or over the input / output module. In order to reduce sample temperature rise when picking samples from the system, it is desirable that the rack robot travel with the cassette puller and also that a tube picker travel with the cassette puller, which can be accomplished by mounting these components to the travelling gantry as well. The tube picker preferably includes a tube picking chamber maintained at the same ultra-low temperature or cryogenic temperature at which the freezers are maintained. Such a tube picking mechanism is described in detail in co-pending U.S. patent application Ser. No. 13 / 193,838, filed Jul. 29, 2011, entitled “Tube Picking Mechanisms with an Ultra-Low Temperature or Cryogenic Picking Compartment”, by Julian Warhurst, Bruce Zandi, Alexander Carbone, Frank Hunt, Robert Cloutier, James O'Toole, and Elizabeth Alexander which is incorporated herein by reference. Also, a lid lifter for lifting the lids from the freezer compartments can be mounted to the gantry frame. Preferably, the repositionable gantry moves horizontally along rails in the refrigerated enclosure over the freezer chests and the input / output module. Once the gantry is parked over a selected freezer bay or over the input / output module indexing drives move the cassette puller the parked gantry both in the horizontal Y-axis and X-axis directions and the vertical Z-axis direction. This three dimensional movement of the cassette puller with respect to the parked gantry allows the cassette puller to operate effectively without having to move the entire gantry frame, which as mentioned may contain several heavy components.

Problems solved by technology

The mating relationship between the position reference pins and the geometry of the position referencing stops on the outside surface of the lifted cassette mechanically center the shelf in the proper location for the ejector mechanism and access openings in case control of the belt drives results in slight vertical misalignment.

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