PIPETTE TIP ADAPTER ASSEMBLY

Abstract

 An adapter for connecting an array of pipette tips having through bores with conical upper ends to a multichannel air displacement pipettor having a plurality of ports with compliant internal sealing surfaces. The adapter comprises a planar base with an array of openings extending between its top and bottom surfaces. Sealing tubes project upwardly from the top surface, and tip mounting tubes project downwardly from the bottom surface, with pairs of sealing tubes and tip mounting tubes being arranged coaxially and in communication with respective ones of the openings in the base. The tip mounting tubes are externally dimensioned and configured for insertion into the conical upper ends of the pipette tips, and the sealing tubes are externally configured and dimensioned for insertion into the ports of the pipettor and into sealing interengagement with their compliant internal sealing surfaces.

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims benefit, under 35 U.S.C. §119(e), of U.S. Provisional Application Serial No. 61509577, filed July 20, 2011, the entire contents and substance of which is herein incorporated by reference.

BACKGROUND

1. Field on the Invention

[0002] This invention relates generally to multichannel air displacement pipettors employing disposable pipette tips, and is concerned in the particular with the provision of an adapter for providing an interface between the pipette tips and the pipettor.

2. Description of the Related Art

[0003] Air displacement pipettors are typically used to transfer liquids between vessels as part of an assay. Common vessels are microtiter plates, test tubes and reservoirs.

[0004] Air displacement pipettors frequently make use of a piston and cylinder arrangement, which is used to create positive and negative pressure in an attached pipette tip. When the open end of the tip is placed into a liquid, the change in pressure causes the liquid to be aspirated into, or dispensed from, the interior of the pipette tip.

[0005] Cross contamination can occur when a first liquid sample aspirated into and then dispensed from a pipette tip leaves a residual amount of sample in the tip. A subsequently aspirated sample mixes with the residual first sample and is thus contaminated. This type of cross contamination can also occur through residual sample on the exterior of the pipette tip.

[0006] In order to avoid cross contamination errors, most air displacement pipettors are designed to make use of pipette tips that are relatively low cost and therefore, in critical applications, disposable after each aspirate-dispense cycle. The design of the pipette tip and its associated mounting shaft is well established. The pipette tips are commonly injection molded in a chemically resistant material such as polypropylene. They are conical in shape. The pipettor's mounting shaft is typically cylindrical with a slight taper that closely matches the conical angle and diameter of the tip. The tip is installed by applying an axial force to the mounting shaft that forces the tapered portion of the shaft into the tip. Flexibility of the tip material allows it to stretch radially and provide both an air-tight seal and mechanical stability of the tip to the pipetting device. The typical axial force required to securely mount a single tip onto a tip mounting shaft is between 1.5 and 4 lbs. To remove the pipette tip from the pipettor, a stripper mechanism is typically used to push the tip from the mounting shaft. Tip ejection forces are in the same range as the mounting forces.

[0007] In order to increase productivity, air displacement pipettors with 96, 384 and higher numbers of channels have been developed. These multichannel pipettors must generate relatively high force in the direction of the axis of the tips in order to simultaneously install the array of tips. For example, a 96 channel pipettor using tips with average insertion forces will require over 2001bs of axial force to successfully install all of the tips. These forces are typically generated through the use of mechanical force multipliers (levers) or powered electromechanical systems. The structure of the pipettor has to be robust in order to support the high tip loading force without distortion. This leads to heavier designs that require more power to operate effectively. In addition to these design issues, the safety of the user is also a significant concern when such high forces are present.

[0008] Pipette tips are frequently packaged in a rack that positions them with their top surfaces in a common plane with centerline spacing that matches that of the instrument. For example, a 96 channel pipette tip rack holds an 8 x 12 array of tips with 9mm between centers. The high forces required to attach all of the tips in the rack often causes the tip rack to bow in the center of the array, resulting in poor sealing and attachment of centrally located tips. To counter this, tip manufacturers reinforce the tip racks intended for use with multichannel pipettors. This, in turn, increases the cost of the racks and therefore the cost to operate the instrument.

[0009] Other multichannel pipettor manufacturers have developed proprietary pipette tips that are designed to lower the insertion and ejection forces. These tips are often more complex and expensive to produce and usually lock the customer into purchasing the manufacturer's specially designed tip for the life of the instrument.

SUMMARY

[0010] Broadly stated, embodiments of the present invention address the drawbacks of the prior art by providing a pipette tip adapter whose purpose is to adapt commonly available low cost pipette tips to a multichannel air displacement pipettor in a way that reduces the mounting and ejection forces described above. Any universal pipette tip available in the marketplace can be assembled to the pipette tip adapter. End users of the related multichannel air displacement pipettor designed to accept the pipette tip adapter would install the assembly onto the pipettor. The pipette tip adapter reduces the forces required to mount and seal the tips to less than 10 lbs. Ejection forces are equally reduced.

[0011] In exemplary embodiments, the pipette tip adapter of the present invention comprises a planar base with an array of openings extending between its top and bottom surfaces. Sealing tubes project upwardly from top surface of the base, and tip mounting tubes project downwardly from the bottom surface of the base. Pairs of sealing tubes and tip mounting tubes re arranged coaxially and in communication with respective ones of the openings in the base. The tip mounting tubes are externally dimensioned and configured for insertion into the conical upper ends of pipette tips, and the sealing tubes are externally configured and dimensioned for insertion into ports of a multichannel air displacement pipettor.

[0012] The base may preferably be strengthened by networks of reinforcing ribs on its top and/or bottom surfaces.

[0013] These and other objects, features and advantages of the present invention will become more apparent from a reading of the following detailed description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] 

Fig. 1 is a top perspective view of a pipette tip adapter in accordance with an exemplary embodiment of the present invention;

Fig. 2 is a top view of the pipette tip adapter;

Fig. 3 is a bottom perspective view of the pipette tip adapter;

Fig. 4 is a bottom view of the pipette tip adapter;

Fig. 5 is a bottom perspective view showing the pipette tip adapter attached to an array of pipette tips;

Fig. 6 is a partial sectional view through the pipette tip adapter and attached pipette tips;

Fig. 7 is a perspective view of a multichannel air displacement pipettor designed to employ the pipette tip adapter of the present invention;

Fig. 8 is a sectional view on an enlarged scale taken through the operating head of the pipettor shown in Fig. 7, and showing the pistons fully withdrawn;

Fig. 9 is an enlarged view of a portion of the illustration in Fig. 8; and

Fig. 10 is a view similar to Fig. 8, showing the pistons of the pipettor partially advanced.

DETAILED DESCRIPTION

[0015] With reference initially to Figs. 1- 6, a pipettor tip adapter in accordance with an exemplary embodiment of the present invention is generally indicated at 10. The pipette tip adapter comprises a planar base 12 with an array of openings 14 extending between bottom and top surface 16, 18 of the base.

[0016] Sealing tubes indicated typically at 20 project upwardly from the top surface 16, and tip mounting tubes indicated typically at 22 project downwardly from the bottom surface 18. Pairs of sealing tubes 20 and mounting tubes 22 are arranges coaxially and in communication with respective ones of the openings 14 in the base 12.

[0017] The sealing tubes 20 and tip mounting tubes 22 may be arranged in an array of rows and columns. The spacing of the rows and columns matches the commonly available tip spacing of both multichannel pipettors and associated racks found in the marketplace. These in turn match the well positions of commonly available microtiter plates. Nine and four and a half millimeters are two common spacing distances. By way of example, a 96 channel pipettor has twelve rows and eight columns of tips on nine millimeter spacing, while a 384 channel pipettor has a twenty four by sixteen matrix on a four and a half millimeter spacing. This invention can also be used in a one-dimensional array format. For example, a single row of twelve on a nine mm spacing.

[0018] As can be best seen in Fig. 6, the tip mounting tubes 22 comprise truncated conical cones configured and dimensioned for insertion and sealing interengagement with the conical upper ends 24 of pipette tips 26. Fig. 5 shows an array of pipette tips 26 secured to the tip mounting tubes of the adapter.

[0019] Base 12 may be advantageously strengthened by a network of upper reinforcing ribs 28 on its top surface 16, and/or a similar network of lower reinforcing ribs 30 on its bottom surface 18. The sealing tubes 20 may be located where the upper reinforcing ribs 28 converge, whereas the tip mounting tubes 22 may be located in areas of the bottom surface bracketed by the lower reinforcing ribs 30.

[0020] The sealing tubes 20 have cylindrical walls with chamfered upper ends 20a. The tip mounting tubes 22 project downwardly below the lower reinforcing ribs 30, and the sealing tubes 20 project upwardly above the upper reinforcing ribs 28.

[0021] With reference to Fig. 7, a multichannel air displacement pipettor is generally indicated at 32. The head 34 of the pipettor is designed to accept the pipette adapter 10 of the present invention. To this end, the pipette adapter may be provided with laterally extending rails 36 which are designed to slide into receiving slots in the pipettor head. Tabs 35 also may be provided to facilitate handling the adapter.

[0022] As shown in Figs. 8 and 10, the pipettor head has an array of cylinders indicated typically at 38 matching the array of sealing tubes 20 of the tip adapter 10. The cylinders 38 lead to ports lined with O-rings providing compliant internal sealing surfaces. Although O-rings 40 are shown, any equivalent compliant seal material and appropriate geometry could be employed. For example, a sheet of elastomeric material with a matrix of aligned bore holes could be employed.

[0023] The chamfered upper ends 20a of the sealing tubes serve to lower the insertion forces of the sealing tubes into the ports of the pipettor cylinders 38 while also reducing wear and tear of the O-rings 40 or other like compliant sealing surfaces.

[0024] Pistons indicated typically at 42 are arranged for reciprocal movement in the cylinders 38. In Fig. 8, the pistons 42 are withdrawn in the cylinders 38 away from the adapter 10, and in Fig. 10, the pistons are shown advanced in the cylinders.

[0025] The tip adapter 10 is preferably injection molded using standard tooling methods and common processing techniques. Materials can include any rigid injection moldable polymer, with polypropylene being preferred. Additionally, a polymer with an internal lubricant that blooms to the surface of the part is preferable because the presence of the lubricant on the surface will reduce insertion forces and wear and tear on the seals.

[0026] The exemplary embodiment herein described is preferably disposable. A non-disposable version is also possible, its design being essentially identical but produced from a material that is more robust and autoclavable. In such a design, the tips are installed to the adapter by the user with a dedicated fixture.

[0027] To reduce the capital cost required to build injection molds, multiple tip size geometries can be accommodated in a single adapter by arranging the tip mounting tubes in a tiered geometry, where the larger tips fit on one tier and the smaller tips on a second tier.

[0028] Often, disposable pipette tips incorporate filters. The purpose of the filter is to avoid aerosol contamination of the pipette mechanism by the liquid being pipetted. The pipette tip adapter of the present invention may be configured to accept such filters, thereby eliminating the need to use expensive tips with filters pre-installed in them.

[0029] In light of the above, it will now be appreciated by those skilled in the art that the adapter of the present invention offers significant and heretofore unavailable advantages. The chamfered upper ends 20a of the sealing tubes 20 interact with the O-rings or equivalent compliant sealing materials to beneficially reduce the forces required to connect the pipette tips to the pipettor. For example, in the case of a 96 channel pipettor, the adapter's sealing tubes 20 can be successfully inserted into the cylinder ports of the pipettor with a minimal coupling force on the order of 10lbs. This can be accomplished safely without exposing an operator to potential injury.

[0030] The adapter base 12, preferably when strengthened by the upper and/or lower reinforcing ribs 28, 30, provides a rigid platform supporting the tip mounting tubes 22 and sealing tubes 20. Thus, the adapter can be pressed onto an array of pipette tubes without undergoing deflection that might otherwise compromise uniform and reliable sealed insertion of the tip mounting tubes 22. This same rigidity, when coupled with the minimal coupling forces referenced above, results in a more uniform and reliable insertion of the sealing tubes into the pipettor cylinder ports.

[0031] Higher forces may be required to install the pipette tips on the adapter, but this can be accomplished in a factory setting prior to supplying the loaded adapter to a user, or by the user with a specially designed press incorporating appropriate safety features.

[0032] The invention also relates to the following aspects:

a) An adapter for connecting a multichannel air displacement pipettor to an array of pipette tips, said pipette tips having through bores with conical upper ends, and said pipettor having a plurality of ports with compliant internal sealing surfaces, said adapter comprising:
a planar base with an array of openings extending between top and bottom surfaces of said base; sealing tubes projecting upwardly from said top surface, and tip mounting tubes projecting downwardly from said bottom surface, pairs of sealing tubes and tip mounting tubes being arranged coaxially and in communication with respective ones of the openings in said base, said tip mounting tubes being externally dimensioned and configured for insertion into the conical upper ends of said pipette tips, and said sealing tubes being externally configured and dimensional for insertion into the ports of said pipettor and into sealing interengagement with said compliant internal sealing surfaces.

b) The adapter of aspect a wherein said base is strengthened by a network of upper reinforcing ribs on said top surface.

c) The adapter of aspect b wherein said sealing tubes project upwardly above said upper reinforcing ribs.

d) The adapter of aspects a or b wherein said base is strengthened by a network of lower reinforcing ribs on said bottom surface.

e) The adapter of aspect d wherein tip mounting tubes project downwardly below said lower reinforcing ribs.

f) The adapter of aspect a wherein said tip mounting tubes comprise hollow truncated conical cones.

g) The adapter of aspect a wherein said sealing tubes comprise cylindrical walls with tapered upper ends.

h) An adapter for connecting a multichannel air displacement pipettor to an array of pipette tips, said pipette tips having through bores with conical upper ends, and said pipettor having a plurality of ports with compliant internal sealing surfaces, said adapter comprising:
a planar base with an array of openings extending between top and bottom surfaces of said base, said base being strengthened by networks of upper and lower reinforcing ribs arranged respectively on said top and bottom surfaces; sealing tubes projecting upwardly from said top surface and above said upper reinforcing ribs, and tip mounting tubes projecting downwardly from said bottom surface and below said lower reinforcing ribs, pairs of sealing tubes and tip mounting tubes being arranged coaxially and in communication with respective ones of the openings in said base, said tip mounting tubes being externally dimensioned and configured for insertion into the conical upper ends of said pipette tips, and said sealing tubes being externally configured and dimensional for insertion into the ports of said pipettor and into sealing interengagement with said compliant internal sealing surfaces.

i) The adapter of aspect h wherein said tip mounting tubes comprise hollow truncated conical cones.

j) The adapter of aspect h wherein said sealing tubes comprise cylindrical walls with tapered upper ends.

k) A pipette tip adapter comprising:
a planar base with an array of openings extending between top and bottom surfaces of said base; sealing tubes projecting upwardly from said top surface, and tip mounting tubes projecting downwardly from said bottom surface, pairs of sealing tubes and tip mounting tubes being arranged coaxially and in communication with respective ones of the openings in said base, said tip mounting tubes being externally dimensioned and configured for insertion into conical upper ends of pipette tips, and said sealing tubes being externally configured and dimensional for insertion into ports of a multichannel air displacement pipettor.

aa) A method of connecting a multichannel air displacement pipettor to an array of pipette tips (26), said pipette tips (26) having through bores with conical upper ends, (24) characterized in that said pipettor has a plurality of ports with compliant internal sealing surfaces, (40), said method comprising the steps of:

providing an adaptor (10) that includes a planar base (12) with an array of openings (14) extending between top and bottom surfaces (16, 18) of said base (12), sealing tubes (20) that project upwardly from said top surface (16) and tip mounting tubes (22) that project downwardly from said bottom surface (18) such that pairs of sealing tubes (20) and tip mounting tubes (22) are in communication with respective ones of the openings (14) in said base (12);

inserting said tip mounting tubes (22) into the conical upper ends (24) of said pipette tips (26);

inserting said sealing tubes (20) into the ports of said pipettor; and

engaging the sealing tubes (20) in sealing interengagement with said compliant internal sealing surfaces (40) within the plurality of ports of the pipettor.

bb) The method of aspect aa wherein said base (12) is strengthened by a network of upper reinforcing ribs (28) on said top surface (16).

cc) The method of aspect bb wherein said sealing tubes (20) project upwardly above said upper reinforcing ribs (28).

dd) The method of aspect aa or bb wherein said base (12) is strengthened by a network of lower reinforcing ribs (30) on said bottom surface (18).

ee) The method of aspect dd wherein tip mounting tubes (22) project downwardly below said lower reinforcing ribs (30).

ff) The method of aspect aa wherein said tip mounting tubes (22) comprise hollow truncated conical cones.

gg) The method of aspect aa wherein said sealing tubes (20) comprise cylindrical walls with tapered upper ends (20a).

hh) The method of aspect aa wherein the adaptor is formed by injection moldable polymer.

ii) The method of aspect aa wherein the adaptor includes laterally extending rails (36) that are adapted to slide into receiving slots in a pipettor head.

jj) The method of aspect aa wherein the adaptor includes tabs (35) to facilitate handling the adaptor.

kk) The method of aspect aa wherein the multichannel air displacement pipettor (32) includes an array of pipettor cylinders (38).

ll) The method of aspect kk wherein the multichannel air displacement pipettor (32) further includes an array of pistons (42) arranged for reciprocal movement in the array of pipettor cylinders (38).

mm) The method of aspect 11 wherein each pipettor cylinder (38) of the multichannel air displacement pipettor (32) further includes compliant sealing material (40).

nn) The method of aspect mm wherein the compliant seal material is provided as an array of O-rings (40) that interact with an outer surface of each sealing tube (20).

oo) The method of aspect aa, wherein the method further includes the step reciprocally moving pistons (42) in the cylinders (38).

[0033] While exemplary embodiments of the invention have been disclosed, modification, additions and deletions can be made without departing from the spirit and scope of the inventions as set forth in the following claims.

Claims

1. An assembly comprising an adapter (10) and an array of pipette tips (26), wherein:

the adapter (10) comprises a planar base (12) with an array of openings (14) extending between top and bottom surfaces (16, 18) of the base (12), sealing tubes (20) projecting upwardly from the top surface (16), and tip mounting tubes (22) projecting downwardly from the bottom surface (18);

pairs of sealing tubes (20) and tip mounting tubes (22) of the adapter (10) are arranged coaxially and in communication with respective openings (14) in the base (12);

the tip mounting tubes (22) are externally dimensioned and configured for insertion into the conical upper ends (24) of the pipette tips (26);

the sealing tubes (20) are externally configured and dimensioned for insertion into ports of a multichannel air displacement pipettor;

the pipette tips (26) comprise through bores with conical upper ends (24); and

each of the tip mounting tubes (22) of the adapter (10) is engaged with one of the pipette tips (26).

2. The assembly of claim 1, wherein the base (12) is strengthened by a network of upper reinforcing ribs (28) on the top surface (16).

3. The assembly of claim 2, wherein the sealing tubes (20) project upwardly above the upper reinforcing ribs (28).

4. The assembly of any one of claims 1-3, wherein the base (12) is strengthened by a network of lower reinforcing ribs (30) on the bottom surface (18).

5. The assembly of claim 4, wherein tip mounting tubes (22) project downwardly below the lower reinforcing ribs (30).

6. The assembly of any one of claims 1-5, wherein the tip mounting tubes (22) comprise hollow truncated cones.

7. The assembly of any one of claims 1-6, wherein the sealing tubes (20) comprise cylindrical walls with tapered upper ends (20a).

8. The assembly of any one of claims 1-7, wherein the adapter comprises an injection moldable polymer.

9. The assembly of any one of claims 1-8, wherein the adapter includes laterally extending rails (36).

10. The assembly of any one of claims 1-9, wherein the adapter includes tabs (35) to facilitate handling of the adapter.

11. A pipetting system, comprising the assembly of any one of claims 1-10, and a multichannel air displacement pipettor (32), wherein the sealing tubes (20) of the adapter (10) are inserted into ports of the pipettor (32).

12. The pipetting system of claim 11, wherein the multichannel air displacement pipettor (32) includes an array of pipettor cylinders (38).

13. The pipetting system of claim 12, wherein the multichannel air displacement pipettor (32) comprises an array of pistons (42) arranged for reciprocal movement in the array of pipettor cylinders (38).

14. The pipetting system of claim 12 or claim 13, wherein each pipettor cylinder (38) of the multichannel air displacement pipettor (32) comprises a compliant sealing material (40).

15. The pipetting system of claim 14, wherein the compliant seal material is an array of O-rings (40) that interact with an outer surface of each sealing tube (20).

Drawing