GB2533571B - Method and apparatus for de-capping tubes and multiwell plates - Google Patents

Description

METHOD AND APPARATUS FOR DE-CAPPING TUBES AND MULTIWELLPLATES

Field of the Invention

The present invention relates methods and apparatus for the removal of caps fromcapped tubes, vials or wells in multiwell plates. It is particularly applicable to de-capping tubes, vials or wells in microplates or cluster tube racks of the types widelyused for the storage of samples and reagents and for the preparation, treatment andanalysis of samples in chemical, medical and biological sciences.

Background to the Invention

Multiwell plates and/or cluster tube racks comprising a plurality of tubes or wellsarranged in an array are used in a wide variety of test procedures and for storage ofsamples. These plates, also known as microplates, and racks of tubes are alsoused in the storage of chemical compounds. In addition, other fields of researchhave the need for storage of small amounts of materials these are also well-suitedfor this type of tube array. For example, biology and medical researchers often havethe need for long term storage of small volumes of biological materials such asbacterial, fungal, viral, chemical compounds or DNA samples, to name just a few.Many research institutions amass large libraries of samples and controls and maymake such materials available to other researchers. Forensic laboratories andparticularly law enforcement agencies have the need to retain evidence for longperiods of times, which evidence often includes biological specimens, such astissue, blood or other specimens for DNA testing. Industrial applications for suchcapabilities include the retention of standards for quality control and samples forbatch tracking. There are therefore a wide range of applications across virtuallyevery scientific discipline that benefit from the ability to store a large number of smallsamples in arrays of tubes or vials.

The process of analyzing chemical and biological samples may involve thousands ofdifferent samples and the demand for this type of analysis has led to thedevelopment of robotic laboratory automation systems. Modern robotic handlingmethods and other modern technologies mean that only very small aliquots ofmaterial are now required in many experiments and therefore small storagecontainers, such as compound storage vials, can be used to collect and store chemical and biological compounds. These are often stored in vast compound orsample libraries containing many thousands, if not millions, of samples. The scaleof such operations inevitably means that these storage containers have to behandled robotically.

The vials are normally kept in a rack or support specially designed for the storageand transportation of such vials. These racks come in varying sizes and hold avarying quantity of vials. A typical rack may hold an 8 x 12 array of 96 vials, or384vials in a 16 x 24 array. The vial size will depend on the required aliquot. Once allof the vials in the rack are filled with chemicals, the racks may be stacked one uponanother, or stored in special storage trays, and placed in a storage area often at lowtemperature. Dozens of these 96 vial racks may be used for collecting the chemicalcompounds from a single experiment and may need to be kept for futureevaluations. Racks that contain hundred of vials which hold only microlitres ofsolution are also available, as well as racks that hold only a few vials that containseveral millilitres.

For storage and transportation of the racks, and to protect the chemical compoundsfrom contamination or spillage, the vials are typically capped or sealed. Caps forthis purpose may be of the screw cap type or may be a push fit. Push fit caps aregenerally made from a non reactive, compliant plastic material. These push fit capsare pressed into the top of the vial or in some cases, onto and over the top of thevial. Both types of caps preferably form an air tight seal that protects the contents ofthe vials from the external environment and eliminate loss of the chemicalcompound. The caps also allow the racks to be stacked without compromising thechemical compounds within the vials.

The application and removal of screw caps from vials is both time consuming andexpensive (see below) and the present invention is not directed at the removal ofscrew caps, but rather at the removal of caps of the push fit variety.

An alternative method of sealing contents within an array of wells or vials is to heatseal them with a peelable sealing sheet, typically made from plastic or plastic coatedaluminium foil. Heat sealing systems for this purpose are commercially available,such as the Eppendorf Heat Sealer from Eppendorf AG, Barkhausenweg 1 22339Hamburg, Germany. Simple adhesive backed sealing sheets are also available.

When access to the contents of the vials is required this is can be achieved bypeeing back the sheet from the entire plate, or by piercing the seal, which cansubsequently be re-sealed by applying a new sheet of sealing material over thepierced seal. This process of piercing and re-sealing may be repeated multipletimes. A device and method for removing these sheet or film seals is described in EP2118669B (Nexus Biosystems, Inc). However, this device and method is limited toremoving a peelable film seal from an array of vials or wells.

When access to the contents of a capped vial or vials is required there is a need fora quick, reliable and convenient system and method for removing caps from anarray of vials. Manual removal can be time consuming and may even be impracticalwhere the number of vials involved is large. Although automated de-cappingsystems and methods for removing screw caps do exist, such as those described inUS 7,421,831 (Nexus Biosystems, Inc.), in order to operate effectively thesemethods require the use of very specific gripping machines and specially designedcaps, all designed and manufactured to very close tolerances. Since vast storesand libraries of capped tubes already exist, where the caps are not of this type andin fact are not necessarily of any one particular consistent design within a library,such methods are not practical or economic.

It is an object of the present invention to overcome or mitigate the problems outlinedabove and to provide a simple, inexpensive system and method for de-cappingtubes capped with a wide variety of caps.

Summary of the Invention

According to a first aspect of the present invention there is provided a method of de-capping capped tubes in a microplate array according to Claim 1. For examplethere is provided a method of de-capping capped tubes in a microplate/tube rackarray said method comprising the steps of:- (i) placing a microplate array of capped tubes into an adhesive filmapplication device; (ii) applying an adhesive film onto the top of the array of tube caps; (iii) applying an upward force on the film, away from the plane of themicroplate array, to peel the tube caps away from the tubes, complete withthe film to which the tube caps are attached, thus separating the tube capsfrom the tubes.

By using an adhesive film such as a heat sealable adhesive film of the type that isused as an alternative method to caps for sealing tubes/vials, the adhesive filmforms a strong bond to the exposed tops of the tube caps, and the caps can bepulled away from the tubes, the film and caps ultimately being discarded. Theadhesive film application device may therefore take the form of a conventional heatsealer. Heat sealable films are commercially available in rolls and in individualsheets. It will be understood that the adhesive film used in this method has anadhesive surface having a width substantially the same or greater than the width ofthe tube array, and a length substantially the same or greater than the length of thetube array.

Accordingly, preferably the adhesive film comprises a heat sealable film. By using aheat sealable film that is compatible with the material from which the caps are made,and the appropriate time and temperature for the heat sealing operation, the film canbe made to form a substantially permanent weld seal to the exposed tops of thetube caps in the tube array. It is then possible to peel the film away from the tubearray bringing with it the tube caps. An example of this material compatibility iswhere the caps are made from a material containing polypropylene and the heatsealable film includes a polypropylene containing layer on the side of the film that isplaced against the top of the caps. Many thermoplastics or thermosoftening plasticscan be used to form a substantially permanent weld seal in this application,depending on the composition of the caps. A wide variety of heat sealable films andfoils are already commercially available and well known to those skilled in the heatsealing process.

Accordingly in a preferred embodiment the adhesive film forms a substantiallypermanent weld seal to the top of the tube caps in the array. Suitable film or foil tomake a substantially permanent weld to a particular type of tube cap may bedetermined by a materials expert, or by experimentation.

Preferably the adhesive film includes a backing layer for additional strength.Suitable backing layers include films such as Polyester film, or foils such asaluminium foil.

Preferably the sheet of adhesive film used in step (ii) of the method comprises apre-cut sheet. In an alternative preferred embodiment the adhesive film used in step(ii) is derived from a roll or web of adhesive film. The choice will depend largely onthe type of sealing machine being used in the de-capping process. Where a roll orweb of adhesive film is being used this is preferably pre-perforated for easy divisioninto sheets before or during the sealing process or cut into suitable lengths withinthe sealing machine.

In a particularly preferred embodiment the adhesive film incorporates robotichandling means enabling a robot machine to engage with the adhesive film once ithas been attached to the caps in order to peel away the tube caps from the tubes.The robotic handling means can take a wide variety of forms and will depend in parton the design and capability of the robotic system being used.

Preferably the robotic handling means comprises one or more apertures in theadhesive film and the aperture(s) are preferably located substantially at or towardsan end of the film strip. Alternatively the aperture(s) may be located substantially ator towards a side of the film strip.

In an alternative preferred embodiment the robotic handling means comprises oneor more tabs.

The invention also extends to a device or apparatus for de-capping capped tubesin a microplate/tube rack array using the method as claimed and described herein.For example there is provided an apparatus for decapping capped tubes in amicroplate/tube rack array, said apparatus comprising:- (a) a transport system for transporting a microplate/tube rack array ofcapped tubes; (b) an adhesive film application station at which an adhesive film isapplied over the top of the array of caps; (c) a holding means adapted to hold down a microplate/tube rack in orderto resist an upward force applied to the film; (d) a de-capping station at which an upward force is applied to thefilm/cap combination in order to separate the film/cap combination from thede-capped tubes, which remain in their array; (e) a disposal means for disposing of the unwanted film/cap combination.

The apparatus may be microprocessor controlled or be controlled manually by anoperator.

Brief Description of the Drawings

Preferred embodiments of the present invention will now be described by way ofexample only with reference to the accompanying figures wherein:-

Figure 1 illustrates an array of 96 tubes in a microplate;

Figure 2 illustrates caps inserted into the tubes of Figure 1 to give an array of 96capped tubes;

Figure 3 illustrates an adhesive film strip applied onto the exposed tops of the capsof the capped tubes of Figure 2;

Figure 4 illustrates the adhesive film shown in Figure 3 in the process of beingpeeled away from the tube array complete with the caps adhered to the film;

Figure 5 illustrate a detail at the bottom of a tube showing how a tube locks into aplate to prevent rotation.

Description of the preferred embodiments

In a first embodiment of the invention shown in Figure 1, there is illustrated amultiwell plate 10 containing an 8 x 12 array of 96 individual tubes, wells or vials 11retained in microplate rack or tube rack 12. In this context the terms “tube”, “vial”and “well” all have a similar meaning and refer to sample holding containersdesigned to be stored or contained in a multiwell rack. In various possiblearrangements these wells may be individual, connected together in strips or integralwith microplate rack itself. A wide variety of storage tubes designs are already available on the market. Wherea tube is designed to take a screw cap the tube may include one or more finsaround the bottom of the tube which engage in corresponding feature(s) in the rackto prevent rotation of the tube as the cap is screwed on and off, as shown in Figure5. In other designs tubes may have a collar or recessed ring around them thatengages in a corresponding (opposite) feature on the rack which gives a positivepositional stop which holds the tube in place. It is important to note that none ofthese features are essential for the operation of the present invention and arementioned only by way of background information.

The microplate rack 12 has a skirt 13 and the lower edge 15 of the skirt 13 has anoutwardly directed rim 16 enabling the plate racks to be stacked one on top of eachother. The individual tubes 11 are mounted in openings in the rack 12 with the rims17 of the tubes extending above the surface of the body of the rack 12.

It will be appreciated that the design of multiwell plates is subject to a number ofstandards, such as the SBS Standard, in order to ensure compatibility betweenmicroplates from different manufacturers. But a number of variations are commonlyencountered. For example, a microplate typically contains 6, 24, 96, 384 or even1536 sample wells in a fixed array. The wells are usually substantially circular incross-section but for compound storage applications square wells with close fittinglids or caps may be preferred.

The wells may be integral with the plate or individual, separate, or stand aloneitems, as those shown in Figure 1. There is an advantage to using separate wells,rather than wells integral with the plate, because separate wells can be picked up,usually robotically, and re-organised into a new order in a different microplate. Thisis particularly important in sample or compound library applications.

In these applications the individual tubes or wells are inevitably capped and a 96well array of capped tubes is shown in Figure 2 where the same numbering systemas that used in Figure 1 has been employed.

Figure 2 shows individual caps 18, typically made from silicone rubber,thermoplastic elastomers such as Santoprene or Evoprene, or other soft deformableplastics material, inserted into each well. Such caps are either inserted into thewells manually or by robotic handling machines. A wide variety of these caps arecommercially available as both individual caps and strips of caps. The presentinvention works well with both cap formats

Having arranged the required capped wells into a microplate rack, in a first step ofthe method the microplate array is placed into a plate sealer, which is in effect atype of film application device. A wide variety of both manual and automatic platesealers are already commercially available such as those supplied by Thermo-Fisher, Agilent Technologies and 4titude Limited. These plate sealers are presentlyused to seal a film, usually a heat sealable film or an adhesive backed film, onto theexposed rims of the wells 17 and this provides an alternative method of sealingwells to the use of caps 18 as shown in Figure 2. We have unexpectedly found thatthe same types of film will also bond or weld effectively to the upper outsideexposed surface of the caps 18 in a second step of the method. A variety of sealing films are already commercially available, such as those suppliedby 4titude Limited, The North Barn, Surrey Hill Business Park, Damphurst Lane,Wotton, Surrey RH5 6QT, United Kingdom. These are supplied in both adhesiveseal and heat seal formats and in both sheet and roll form. Where a roll or web offilm is used this is preferably pre-perforated for easy division into strips or sheetsduring the heat sealing process or cut by the machine. A strong film such as aPolyester film is preferred and one which incorporates a foil layer gives suitable strength. A metal or metallic foil layer such as aluminium foil laminated to thesealing layer is particularly suitable.

In order to perform a third step of the method a strong bond between the film andthe top of each cap is important. A type of film which gives a substantiallypermanent weld between the film and the top of the cap is preferred. By using aheat sealable film that is compatible with the material from which the caps are made,and the appropriate time and temperature for the heat sealing operation, the heatsealable film can be made to form a substantially permanent weld seal to theexposed tops of the tube caps in the tube array. An example of this type of materialcompatibility is where the caps are made from a material containing polypropyleneand the heat sealable film includes a polypropylene containing layer on the side ofthe film that is placed against the top of the caps. Many thermoplastics orthermosoftening plastics can be used to form a substantially permanent weld seal ofthis type in this application, depending on the composition of the caps. A widevariety of heat sealable films and foils are already commercially available and wellknown to those skilled in the heat sealing process.

An example of a suitable film that gives a substantially permanent weld in this typeof method is Thermal Bond (4ti-0590) which is a laminate material where the sealinglayer comprises a 20 micron polypropylene layer laminated to a 60 micronaluminium layer.

As described above it is also possible to use a heat or pressure activated adhesivewhere an adhesive layer on the film is activated by heat or by pressure to make itbond strongly to the top of the caps.

An example of the result of performing this step of the method is shown in Figure 3,where a sheet of film 20 has been bonded to the top of the caps 18 across thewhole of the tube array.

In the third step in the method an upward force is applied to the film sheet whilstholding down the microplate. As a result the film is peeled or pulled back away fromthe microplate and the wells. The film, complete with the tube caps securely bondedor welded to it, is thus separated from the de-capped wells and can ultimately bediscarded. This operation is shown in progress in Figure 4. Friction between the side of the wells and the sides of the holes in which they sit in the mounting platehelps retain the wells in their original array format.

The caps and film strip combination are generally not re-used and can be disposedof. However, it would be possible to manually replace the same 96 caps onto thesame 96 wells if that was considered desirable.

The peeling away or pulling operation in step (iii) described above and shown inFigure 4 was carried out manually, but robotic handling is preferred in manyapplications. To assist with robotic handling some form of robotic handling meanscan be incorporated into the film strip. This handling means can take a wide varietyof forms such as holes or apertures in one or more edges of the strip (not shown). Arobotic hook or finger can be inserted into one or more of these holes in order toapply the necessary upwards force to carry out the peeling process. These hole(s)can be located along the short edge of the film or along the long edge, or even alongopposing edges.

An alternative handling means may be provided by one or more graspable tabs (notshown) again located along the short edge of the film, or along the long edge of thefilm, or along opposing edges.

Bearing in mind the peeling action required to remove the film strip/capscombination, it is particularly advantageous if at least one robotic handling means islocated on a corner of the film strip. This facilitates peeling the cap/stripcombination from one corner, as shown in Figure 4, and in a direction or axissubstantially diagonally across the microplate array.

This method lends itself to automation and one embodiment or aspect of theinvention provides an apparatus or device for carrying out such a process. Amicroplate or tray containing capped tubes is placed on a platform or conveyor beltand transported on this transport system to an adhesive film application station atwhich an adhesive film is applied over the top of the array of caps. The adhesivefilm has an adhesive surface which has a width substantially the same or greaterthan the width of the tube array, and a length substantially the same or greater thanthe length of the tube array.

Where the adhesive film is heat activated it may be necessary to allow the film tocool before carrying out the de-capping operation.

The microplate or tray is then held down to resist an upward force applied to thefilm. This holding down operation can be carried out in a number of ways dependingon the design of the microplates or trays being used. For example, if themicroplate/tray has a skirt, and the lower edge of the skirt has an outwardly directedrim, as shown as 16 in the Figures, then the microplate/tray can be held down bymeans of this rim. Alternatively, such microplates/trays often have indentations ordepressions around or near their edges such as indentations 21, 22, and 23 shownin Figure 1. These indentations, as well as the top upper edge surface of themicroplate/tray provide features through which a downward force or pressure can beapplied to resist the upward force being applied to peel or pull back the film/capcombination away from the microplate and the wells.

In the present description the terms "downward" and "upward" relate to thosedirections as applied to a microplate/tray in the configuration as shown in Figures 1to 4. So a downward force would press the microplate/tray into the plane that it isresting on and an upward force would tend to move the caps up and away from thetube openings.

The cap removal process may take place at a decapping station, away from theadhesive film application station. Where a continuous roll or web of adhesive film isused it is not essential to provide robotic handling means in the adhesive film, as theaction of pulling or lifting the roll of film away from the microplate/tube array as itpasses through the decapping station will cause the cap/film combination toseparate from the tube array. The film and caps can be collected on a collectionroller or take-up reel and discarded at an appropriate time. It will be appreciatedthat the web of film with the caps adhered to it will be very much thicker than the filmprior to use, and therefore take up a much greater volume on a reel. As analternative the film and cap combination may not be reeled up but simply collected ina waste receptacle.

Where individual sheets of adhesive film are used to bond to the tube caps thesesheets can be provided as an input feed to the de-capping apparatus or can beformed during the process from a continuous roll or web of adhesive film.

The motion of a microplate/tube rack through the various stages and operations inthe apparatus may be controlled by one or more microprocessor controllers, or maybe controlled manually by an operator.

Claims (15)

1. A method of de-capping capped tubes in a microplate/tube rack array saidmethod comprising the steps of;- (i) placing a microplate array of capped tubes into an adhesive filmapplication device; (ii) applying an adhesive film onto the top of the array of tube caps; (iii) applying an upward force on the film, away from the plane of themicroplate array, to peel the tube caps away from the tubes, complete with thefilm to which the tube caps are attached, thus separating the tube caps fromthe tubes.

2. A method according to Claim 1 wherein the adhesive film comprises a heatsealable film.

3. A method according to Claim 2 wherein the heat sealable film forms asubstantially permanent weld seal to the tops of the tube caps in the array.

4. A method according to any preceding claim wherein the adhesive film includesa foil layer for additional strength.

5. A method according to Claim 1 or Claim 2 wherein the adhesive film includes aheat stable polymer layer for additional strength.

6. A method according to claim 4, wherein the polymer layer is a Polyester layer.

7. A method according to any preceding claim wherein the adhesive film used instep (ii) comprises a pre-cut strip of adhesive film.

8. A method according to any of Claims 1 to 6 inclusive wherein the adhesive filmused in step (ii) is derived from a roll or web of adhesive film.

9. A method according to Claim 8 wherein the roll or web of adhesive film is pre-perforated for easy division into sheets before or during the sealing process.

10. A method according to any preceding claim wherein the adhesive filmincorporates robotic handling means enabling a robot machine to engage withthe film in order to peel away the tube caps from the tubes.

11. A method according to Claim 10 wherein the robotic handling means comprisesone or more apertures in the adhesive film.

12. A method according to Claim 11 wherein the aperture(s) are locatedsubstantially at or towards an end of the adhesive film.

13. A method according to Claim 11 wherein the aperture(s) are locatedsubstantially at or towards a side of the adhesive film.

14. A method according to Claim 10 wherein the robotic handling means comprisesone or more tabs.

15. An apparatus for de-capping capped tubes in a microplate/tube rack array, saidapparatus comprising:- (a) a transport system for transporting a microplate/tube rack array ofcapped tubes; (b) an adhesive film application station at which an adhesive film is appliedover the top of the array of caps; (c) a holding means adapted to hold down a microplate/tube rack in orderto resist an upward force applied to the film; (d) a de-capping station at which an upward force is applied to the film/capcombination in order to separate the film/cap combination from the de-cappedtubes, which remain in their array; (e) a disposal means for disposing of the unwanted film/cap combination.