Magnetic levitation stirring devices and machines for mixing in vessels

• US 6,357,907 B1
• Filed: 06/15/1999
• Issued: 03/19/2002
• Est. Priority Date: 06/15/1999
• Status: Expired due to Term

• Current Assignee: V&P Scientific, Inc.
• Original Assignee: V & P Scientific, Inc.
• Inventors: Markle, John R., Cleveland, Patrick H.
• Primary Examiner(s): Cooley, Charles E.
• Assistant Examiner(s): Sorkin, David L.
• Application Number:
  US09/333,589
• Time in Patent Office: 1,008 Days
• Field of Search: 366/273, 366/274, 422/64
• US Class Current: 366/273
• CPC Class Codes: B01F 33/452 using independent floating stirring elements
• CPC Class Codes: B01J 2219/00315 Microtiter plates
• CPC Class Codes: B01J 2219/00484 by shaking, vibrating or oscillating of the reaction vessels
• CPC Class Codes: C40B 60/14 for creating libraries

Abstract

The invention provides a simple method, devices and several machines for simultaneously stirring and aerating thousands of vessels or wells of microplates in a robust manner and with economy. This method uses the simple principle of magnetic stirrers being levitated vertically when passed laterally or vertically through a strong horizontal dipole magnetic field. The dipole magnetic fields may be produced by using permanent magnets, electromagnets or a modulating/reversing electro-magnetic field. Each vessel contains a magnetic ball, disc, bar, dowel or other shape (stirrers) which in their magnetic attraction to the dipole magnetic field will cause the stirrers to levitate up in the vessel as the stirrer'"'"'s magnetic poles attempt to align with the center of the dipole'"'"'s magnetic field. The stirrers will fall to the bottom of the vessel by gravity or by changing the relative position of the levitating magnetic field to pull them down, or by passing the vessel laterally over another magnetic field. The up and down movement of the stirrers provides a vigorous mixing of the contents of many vessels at same time. If the level of the vessel'"'"'s meniscus is situated so the stirrers pass through it on their way up and down, the air/liquid interface is significantly increased thereby significantly increasing aeration of the liquid.

Claims

1. A system for mixing liquid and/or solid contents of an array of vessels, comprising

means for receiving the array of vessels;

magnetic stirrers disposed within respective vessels of the array; and

means disposed in relation to the receiving means for subjecting the received array of vessels to a magnetic field that causes magnetic stirrers within respective vessels of the array to levitate at variable levels within the contents of said respective vessels, whereby the contents of said respective vessels are mixed by said variable-level levitations of the magnetic stirrers therein;

wherein the subjecting means comprise

a circular array of a plurality of pairs of separated magnetic poles, wherein each pair is disposed for focusing a magnetic field within a space between the respective pair of poles; and

a carousel for moving the received array of vessels through the respective spaces between the respective pairs of poles to thereby levitate the magnetic stirrers when the respective vessels are within said respective spaces; and

wherein the magnetic stirrers are stir balls.

2. A system according to claim 1, wherein the magnetic stirrers are elongated;

and

wherein adjacent pairs of the plurality of pairs of separated magnetic poles are disposed for focusing magnetic fields of opposite South-North and North-South polarities to thereby cause the magnetic stirrers to reverse their orientation and rotate polarly within the respective vessels by aligning in accordance with the magnetic polarities of alternating South-North and North-South magnetic fields as the array of vessels moves through the respective spaces between the adjacent pairs of separated magnetic poles to thereby effect horizontal stirring of the contents of said respective vessels.

3. A system according to claim 1, further comprising

a plurality of pull-down magnets respectively disposed beneath the carousel between different pairs of poles so that said movement of the respective vessels by the carousel moves the array of vessels over one of the pull-down magnets subsequent to movement of the array of vessels through the space between one of the pairs of poles to thereby pull the magnetic stirrer within each vessel of said respective vessels toward the bottom of each said vessel.

4. A system according to claim 1, further comprising the array of vessels, wherein the array of vessels are embodied as wells in a microplate and are received by the receiving means.

5. A system according to claim 1, wherein the vessels are cylindrical and the stir balls have diameters that are nearly the same as the diameters of the respective vessels in which the stir balls are disposed.

6. A system for mixing liquid and/or solid contents of a plurality of arrays of vessels, comprising

a plurality of array receiving means for receiving the plurality of arrays of vessels;

and

means disposed in relation to the plurality of receiving means for subjecting the received arrays of vessels to a magnetic field that causes magnetic stirrers within respective vessels of the arrays to levitate at variable levels within the contents of said respective vessels, whereby the contents of said respective vessels are mixed by said variable-level levitations of the magnetic stirrers therein;

wherein the subjecting means comprise

a circular array of a plurality of pairs of separated magnet poles, wherein magnets of each pair are disposed for focusing a magnetic field within a space between the respective pair of poles; and

a carousel for moving the received arrays of vessels seriatim through the respective spaces between the respective pairs of poles to thereby levitate the magnetic stirrers when the respective vessels are within said respective spaces; and

a plurality of pull-down magnets respectively disposed beneath the carousel between different pairs of poles so that said movement of the respective vessels by the carousel moves each array of vessels over one of the pull-down magnets subsequent to movement of the array of vessels through the space between one of the pairs of poles to thereby pull the magnetic stirrer within each vessel of said respective vessels toward the bottom of each said vessel.

7. A system according to claim 6, wherein the plurality of array receiving means are so disposed on the carousel that the carousel moves a first said array of vessels over one of the pull-down magnets while moving a second array of vessels through the space between one of the pairs of poles.

8. A system according to claim 6, wherein the plurality of array receiving means are so disposed on the carousel that the carousel moves a first said array of vessels over one of the pull-down magnets and moves a second array of vessels through the space between one of the pairs of poles while moving a third array of vessels from the space between said one of the pairs of poles to a space over said one of the pull-down magnets.

9. A system according to claim 6, further comprising

magnetic stirrers disposed within said respective vessels.

10. A system according to claim 6, further comprising the arrays of vessels, wherein the arrays of vessels are embodied as wells in microplates and are received by the receiving means.

11. A system for mixing liquid and/or solid contents of an array of vessels with magnetic stirrers, comprising

a pair of magnetic poles disposed for focusing a magnetic field within a space between the poles;

means for receiving the array of vessels;

wherein the receiving means are disposed for a relative vertical movement through the space between the pair of poles that results in the focused magnetic field causing magnetic stirrers within respective vessels of the received array to levitate at variable levels within the contents of said respective vessels as the received vessels are moved through said space and thereby mix said contents; and

means for coupling a motor to the receiving means or the pair of magnetic poles for effecting said relative vertical movement.

12. A system according to claim 11, consisting of said pair of magnetic poles, said receiving means;

and said coupling means.

13. A system according to claim 12, further comprising the array of vessels, wherein the array of vessels are embodied as wells in a microplate and are received by the receiving means.

14. A system according to claim 11, further comprising

magnetic stirrers for placement within said respective vessels.

15. A system for mixing liquid and/or solid contents of an array of vessels with magnetic stirrers, comprising:

a pair of magnetic poles disposed for focusing a magnetic field within a space between the poles;

a pull-down magnet disposed apart horizontally from and beneath the level of the pair of magnetic poles;

means for receiving the array of vessels;

wherein the receiving means are disposed for a relative horizontal movement through the space between the pair of poles that results in the focused magnetic field causing magnetic stirrers within respective vessels of the received array to levitate at variable levels within the contents of said respective vessels as the received vessels are moved horizontally through said space and thereby mix said contents, and for a movement over the pull-down magnet that results in the magnetic stirrer within each vessel of said respective vessels being pulled toward the bottom of each said vessel; and

means for coupling a drive means to the receiving means for effecting said movements.

16. A system according to claim 15, wherein the relative horizontal movement is back-and-forth.

17. A system according to claim 15, in combination with

magnetic stirrers for placement within said respective vessels.

18. A system according to claim 15, further comprising the array of vessels, wherein the array of vessels are embodied as wells in a microplate and are received by the receiving means.

19. A system for mixing liquid and/or solid contents of an array of vessels with magnetic stirrers, comprising:

a pair of magnetic poles disposed for focusing a magnetic field within a space between the poles;

means for receiving the array of vessels;

wherein the receiving means are disposed for a relative horizontal movement through the space between the pair of poles that results in the focused magnetic field causing magnetic stirrers within respective vessels of the received array to levitate at variable levels within the contents of said respective vessels as the received vessels are moved horizontally through said space and thereby mix said contents;

means for coupling a drive means to the receiving means or the pair of magnetic poles for effecting said relative horizontal movement; and

magnetic stirrers disposed within said respective vessels;

wherein the magnetic stirrers are stir balls.

20. A system according to claim 19, wherein the relative horizontal movement is back-and-forth.

21. A system according to claim 19, further comprising the array of vessels, wherein the array of vessels are embodied as wells in a microplate and are received by the receiving means.

22. A system according to claim 19, wherein the vessels are cylindrical and the stir balls have diameters that are nearly the same as the diameters of the respective vessels in which the stir balls are disposed.