Hybrid magnet devices for molecule manipulation and small scale high gradient-field applications

• US 7,474,184 B1
• Filed: 02/15/2006
• Issued: 01/06/2009
• Est. Priority Date: 02/15/2005
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Pollard, Martin J., Hong, Seok-Cheol, Humphries, David E.
• Primary Examiner(s): Barrera; Ramon M
• Application Number:
  US11/355,462
• Time in Patent Office: 1,056 Days
• Field of Search: 335/302-306,296 210/222,695 436/526
• US Class Current: 335/306
• CPC Class Codes: B03C 1/002 High gradient magnetic separation
• CPC Class Codes: B03C 1/0332 using permanent magnets
• CPC Class Codes: B03C 1/288 disposed at the outer circumference of a recipient
• CPC Class Codes: B03C 2201/18 Magnetic separation whereby the particles are suspended in a liquid
• CPC Class Codes: B03C 2201/22 characterised by the magnetical field, special shape or generation
• CPC Class Codes: B03C 2201/26 for use in medical applications
• CPC Class Codes: H01F 7/0278 for generating uniform fields, focusing, deflecting electrically charged particles for magnetic separation by Lorentz force B03C1/023; specially adapted for NMR applications G01R33/383

Abstract

The present disclosure provides a high performance hybrid magnetic structure made from a combination of permanent magnets and ferromagnetic pole materials which are assembled in a predetermined array. The hybrid magnetic structure provides means for separation and other biotechnology applications involving holding, manipulation, or separation of magnetizable molecular structures and targets. Also disclosed are hybrid magnetic tweezers able to exert approximately 1 nN of force to 4.5 μm magnetic bead. The maximum force was experimentally measured to be ˜900 pN which is in good agreement with theoretical estimations and other measurements. In addition, a new analysis scheme that permits fast real-time position measurement in typical geometry of magnetic tweezers has been developed and described in detail.

Claims

1. Hybrid magnetic tweezers comprising paired mirror image hybrid magnetic structures, wherein each of said hybrid magnetic structures comprising:

a. a non-magnetic base;

b. a ferromagnetic pole having a wedge-shaped tip, wherein said tip features a notch or concavity in cross-section to concentrate magnetic fields in a discrete region of interest inside the notch or concavity;

c. at least two blocks of permanent magnet material;

wherein the at least two blocks of permanent magnet material are assembled onto said base on opposite sides of and adjacent to said ferromagnetic pole, wherein the magnetization orientations of the blocks of permanent magnet material are oriented in opposing directions and orthogonal to the height of the ferromagnetic pole, and said blocks of permanent magnet material extend below the bottom edge of said ferromagnetic pole when assembled onto said base; and

,

wherein the ferromagnetic pole tip extends beyond each block of permanent magnet material, wherein the shaped tip is angled or bent from 0 to 90 degrees relative to the ferromagnetic pole, and wherein the magnetic field strength in the region of interest at least 1.0 Tesla.

2. The hybrid magnetic tweezers of claim 1, further comprising a clevis, wherein the clevis is a multi-walled housing and the hybrid magnetic tweezers are mounted therein, and wherein the hybrid magnetic tweezers can be moved to different Z positions or angles by rotation, translation and movement in the clevis using various means for fastening the hybrid magnetic tweezers to the clevis and/or means for orientation and position control, thereby resulting in various ranges of force in three-dimensions to be applied to a target.

3. The hybrid magnetic structure of claim 1, further comprising a flow vessel having a target.

4. The hybrid magnetic structure of claim 3, wherein the target is a magnetized molecule or particle.

5. The hybrid magnetic structure of claim 1, wherein said pole tip has a wedge shape in cross section and a notch of about 0.5 mm in depth in cross section at the tip.

6. The hybrid magnetic structure of claim 1, wherein said pole tip is angled about 45 degrees relative to the ferromagnetic pole.

7. The hybrid magnetic structure of claim 1, wherein the non-magnetic base is aluminum.

8. The hybrid magnetic structure of claim 1, wherein the ferromagnetic pole is made of steel.

9. The hybrid magnetic structure of claim 1, wherein the blocks of permanent magnet material comprise a rare earth element.

10. The hybrid magnetic structure of claim 9, wherein the blocks of permanent magnet material comprise neodymium iron boron.

11. A method of manipulating magnetized molecular particles from a sample, comprising the steps of:

placing said sample containing magnetized molecular particles in the region of interest of the hybrid magnetic tweezer of claim 1.

12. The method of claim 11, wherein the samples contain DNA coupled to a ferromagnetic material.