Microfluidic magnetophoretic device and methods for usig the same

• US 20080124779A1
• Filed: 10/18/2006
• Published: 05/29/2008
• Est. Priority Date: 10/18/2006
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Kim, Unyoung, Oh, Sang-Hyun, Soh, Hyongsok, Daugherty, Patrick Sean, Nawarathna, Dharmakirthi, Zhang, Yanting, Singh, Amarendra Kumar, Ferguson, Brian Scott
• Granted Patent: US 7,807,454 B2
• Time in Patent Office: Days
• US Class Current: 435/173.9
• CPC Class Codes: B01L 2200/0636 Focussing flows, e.g. to laminate flows
• CPC Class Codes: B01L 2200/0647 Handling flowable solids, e.g. microscopic beads, cells, particles
• CPC Class Codes: B01L 2200/0668 Trapping microscopic beads
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2400/043 magnetic forces
• CPC Class Codes: B01L 3/502761 specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads, for physically stretching molecules investigating characteristics of particles G01N15/00
• CPC Class Codes: B01L 3/502776 specially adapted for focusing or laminating flows
• CPC Class Codes: B03C 1/32 acting on the medium containing the substance being separated, e.g. magneto-gravimetric-, magnetohydrostatic-, or magnetohydrodynamic separation
• CPC Class Codes: B03C 2201/18 Magnetic separation whereby the particles are suspended in a liquid

Abstract

A microfluidic device may employ one or more sorting stations for separating target species from other species in a sample. The separation is driven by magnetophoresis. A sorting station generally includes separate buffer and sample streams. A magnetic field gradient applied to the sorting station deflects the flow path of magnetic particles (which selectively label the target species) from a sample stream into a buffer stream. The buffer stream leaving the sorting station is used to detect or further process purified target species labeled with the magnetic particles.

Claims

1. A microfluidic sorting device comprising:

(a) at least one inlet channel configured to provide separate streams of

(i) a sample comprising a target species, non target species, and magnetic particles having an affinity for the target species in the sample, and

(ii) a buffer that is substantially free of the sample;

(b) a sorting station fluidly coupled to said at least one inlet and located in a path of the sample stream;

(c) a magnetic field gradient generator for interacting with an external magnetic field to produce a change in magnetic field gradient in the sorting station and thereby deflecting the magnetic particles toward the buffer stream; and

(d) at least one outlet channel configured to separately receive the buffer stream with deflected magnetic particles and a waste stream containing said sample at least partially depleted of the target species.

2. The microfluidic sorting device of claim 1, wherein the at least one inlet channel comprises a first inlet channel for providing at least a portion of the buffer stream and a second inlet channel for providing at least a portion of the sample stream.

3. The microfluidic sorting device of claim 1, wherein the at least one inlet channel comprises

(i) a first inlet channel for providing the buffer stream, and

(ii) a second inlet channel and a third inlet channel for providing separate streams of the sample.

4. The microfluidic sorting device of claim 3, wherein the second and third inlet channels are located on opposite sides of the first inlet channel, such that, during operation, the buffer stream enters a sorting station straddled by 2 sample streams.

5. The microfluidic sorting device of claim 1, wherein the magnetic field gradient generator comprises a plurality of ferromagnetic elements patterned on the sorting device proximate the sorting station.

6. The microfluidic sorting device of claim 5, wherein the magnetic field gradient generator comprises a permanent magnet proximate the plurality of ferromagnetic elements.

7. The microfluidic sorting device of claim 6, wherein the magnetic field gradient generator comprises two permanent magnets located on opposite sides of the plurality of ferromagnetic elements.

8. The microfluidic sorting device of claim 5, wherein the magnetic field gradient generator comprises an electromagnet proximate the plurality of ferromagnetic elements.

9. The microfluidic sorting device of claim 5, wherein the plurality of ferromagnetic elements are disposed within a fluid pathway of the sorting station to allow fluid contact between the ferromagnetic elements and the sample stream.

10. The microfluidic sorting device of claim 5, wherein the ferromagnetic elements are micropatterned nickel elements.

11. The microfluidic sorting device of claim 5, wherein the plurality of ferromagnetic elements comprises one or more ferromagnetic strips

12. The microfluidic sorting device of claim 5, wherein the plurality of ferromagnetic elements comprises one or more pins or pegs.

13. The microfluidic sorting device of claim 1, wherein the sorting device comprises at least two magnetic field gradient generators.

14. The microfluidic sorting device of claim 13, wherein the at least two magnetic field gradient generators are located in fluid paths for two separate sample streams on opposite sides of a fluid path for the buffer stream.

15. The microfluidic sorting device of claim 13, wherein the at least two magnetic field gradient generators comprise two permanent magnets shared by the at least two magnetic field gradient generators.

16. The microfluidic sorting device of claim 1, wherein the at least one outlet channel comprises:

(i) a first outlet channel for collecting at least a portion of the buffer stream comprising purified target species; and

(ii) a second outlet channel for collecting at least a portion of the sample stream.

17. The microfluidic sorting device of claim 16, wherein the second outlet channel is sized and positioned to collect a separate portion of the buffer stream.

18. The microfluidic sorting device of claim 1, wherein the at least one outlet channel comprises:

(i) a first outlet channel for collecting at least a portion of the buffer stream comprising purified target species; and

(ii) a second outlet channel and a third outlet channel for collecting separate streams of the sample.

19. The microfluidic sorting device of claim 18, wherein the second and third outlet channels are located on opposite sides of the first outlet channel.

20. The microfluidic sorting device of claim 1, wherein the magnetic field gradient generator is configured to temporarily capture the magnetic particles and then release said magnetic particles to the at least one outlet channel.

21. A microfluidic sorting device comprising:

(a) at least one inlet channel configured to provide separate streams of

(i) a sample comprising magnetic particles and non-magnetic particles, and

(ii) a buffer that is substantially free of the sample;

(b) a sorting station fluidly coupled to said at least one inlet and located in a path of the sample stream;

(c) a magnetic field gradient generator for interacting with an external magnetic field to produce a change in magnetic field gradient in the sorting station and thereby deflecting the magnetic particles toward the buffer stream; and

(d) at least one outlet channel configured to separately receive the buffer stream with deflected magnetic particles and a waste stream containing said sample at least partially depleted of the magnetic particles.

22. A method of purifying a target species in a sample, the method comprising:

(a) providing the sample to at least a first inlet channel of a microfluidic sorting device, wherein the sample includes magnetic particles having an affinity for the target species;

(b) providing a buffer stream to the microfluidic sorting device;

(c) magnetizing a magnetic field gradient generator to divert at least some of the magnetic particles from the sample to the buffer stream; and

(d) collecting at least a portion of the buffer stream comprising purified target species with at least some of the magnetic particles at a collection outlet channel.

23. The method of claim 22, wherein providing the sample comprises providing two sample streams on opposite sides of the buffer stream in the microfluidic sorting device.

24. The method of claim 22, wherein the magnetic field gradient generator comprises a plurality of ferromagnetic elements.

25. The method of claim 24, wherein the ferromagnetic elements comprise micropatterned ferromagnetic material on the microfluidic device.

26. The method of claim 22, wherein magnetizing the magnetic field gradient generator comprises applying an external magnetic field from a permanent magnet or an electromagnet to the magnetic field gradient generator.

27. The method of claim 22, further comprising detecting the purified target species in the buffer stream collected in (d).

28. The method of claim 22, further comprising amplifying a nucleic acid of the target species in the microfluidic sorting device.

29. The method of claim 22, further comprising lysing cells in the microfluidic sorting device, wherein at least some of the cells comprise the target species.

30. The method of claim 22, further comprising separating genetic material from viruses in the microfluidic sorting device, wherein at least some of the viruses comprise the target species.

31. The method of claim 22, wherein collecting at least a portion of the buffer stream comprising purified target species comprises recovering at least 50% of the target species in the sample.

32. A method of sorting magnetic species in a sample, the method comprising:

(a) providing the sample to at least a first inlet channel of a microfluidic sorting device;

(b) providing a buffer stream to the microfluidic sorting device;

(c) magnetizing a magnetic field gradient generator to divert at least some of the magnetic species from the sample to the buffer stream; and

(d) collecting at least a portion of the buffer stream comprising at least some of the magnetic species at a collection outlet channel.

33. A method of purifying a target species in a sample including magnetic particles having an affinity for the target species, the method comprising:

(a) flowing the sample to into a microfluidic sorting device having a magnetic field gradient generator to thereby capture at least some of the magnetic particles;

(b) removing or reducing a magnetic field applied to the magnetic field generator to thereby release captured magnetic particles; and

(c) collecting purified target species with at least some of the magnetic particles at a collection outlet channel.

34. A microfluidic sorting device comprising:

(a) a magnetic field gradient generator for exerting a magnetic force on a sample to divert magnetic particles in the sample to a collection channel;

(b) an amplification station for amplifying nucleic acid of a target species associated with the magnetic particles in the collection channel; and

(c) a detection station for detecting amplified nucleic acid.

35. The microfluidic sorting device of claim 34, further comprising a cell lysis station.

36. The microfluidic sorting device of claim 34, further comprising a labeling station for labeling target species with magnetic particles, wherein labeling station is located upstream from the magnetic field gradient generator.

37. A microfluidic sorting device comprising:

(a) a labeling station for labeling target species in a sample with magnetic particles having an affinity for the target species;

(b) a magnetic field gradient generator for exerting a magnetic force on the sample to divert magnetic particles in the sample to a collection channel; and

(c) a detection station for detecting the target species.

38. The microfluidic sorting device of claim 37, further comprising a second labeling station for labeling diverted target species with a fluorophore having an affinity for the target species or for the magnetic particles.

39. The microfluidic sorting device of claim 37, further comprising a sample reservoir disposed upstream from the magnetic field gradient generator.

40. A microfluidic sorting device comprising:

(a) a magnetic field gradient generator for exerting a magnetic force on a sample to divert magnetic cells or viruses in the sample to a collection channel;

(b) a first detection station for detecting magnetic cells or viruses diverted to the collection channel;

(c) a component release station for releasing components from the magnetic cells or viruses; and

(d) a second detection station for detecting components of the magnetic cells or viruses.

41. The microfluidic sorting device of claim 40, further comprising:

a component manipulation station for modifying released components to facilitate their detection in the second detection station.

42. The microfluidic sorting device of claim 41, wherein the component manipulation station comprises

an amplification station for amplifying nucleic acid of the magnetic cells or viruses.

43. The microfluidic sorting device of claim 41, further comprising:

a labeling station for labeling cells or viruses in the sample with magnetic particles having an affinity for a target species on surfaces of target cells or viruses.

44. The microfluidic sorting device of claim 41, wherein the magnetic cells or viruses comprise cells or viruses associated with magnetic particles.

45. The microfluidic sorting device of claim 41, further comprising a sample reservoir disposed upstream from the magnetic field gradient generator.