Systems and methods of forming particles

• US 20070054119A1
• Filed: 03/03/2006
• Published: 03/08/2007
• Est. Priority Date: 03/04/2005
• Status: Abandoned Application

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Stone, Howard, Gitlin, Irina, Takeuchi, Shoji, Kumacheva, Eugenia, Nie, Zhihong, Garstecki, Piotr, Whitesides, George, Xu, Shengqing, Lewis, Patrick, Weibel, Douglas, Seo, Min
• Application Number:
  US11/368,263
• Publication Number:
  US 20070054119A1
• Time in Patent Office: Days
• US Class Current: 428/402
• CPC Class Codes: B01F 23/41 Emulsifying
• CPC Class Codes: B01F 33/3011 using a sheathing stream of a fluid surrounding a central stream of a different fluid, e.g. for reducing the cross-section of the central stream or to produce droplets from the central stream
• CPC Class Codes: B01J 19/0093 Microreactors, e.g. miniaturised or microfabricated reactors laboratory containers with capillary fluid transport in microfabricated channels or chambers B01L3/5027
• CPC Class Codes: B01J 19/06 Solidifying liquids making microcapsules B01J13/02
• CPC Class Codes: B01J 2219/00873 Heat exchange
• CPC Class Codes: B22F 1/06 Metallic powder characterised by the shape of the particles nanosized particles B22F1/054
• CPC Class Codes: B22F 9/06 starting from liquid material
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

The present invention generally relates to systems and methods of forming particles and, in certain aspects, to systems and methods of forming particles that are substantially monodisperse. Microfluidic systems and techniques for forming such particles are provided, for instance, particles may be formed using gellation, solidification, and/or chemical reactions such as cross-linking, polymerization, and/or interfacial polymerization reactions. In one aspect, the present invention is directed to a plurality of particles having an average dimension of less than about 500 micrometers and a distribution of dimensions such that no more than about 5% of the particles have a dimension greater than about 10% of the average dimension, which can be made via microfluidic systems. In one set of embodiments, at least some of the particles may comprise a metal, and in certain embodiments, at least some of the particles may comprise a magnetizable material. In another set of embodiments, at least some of the particles may be porous. In some embodiments, the invention includes non-spherical particles. Non-spherical particles may be formed, for example, by urging a fluidic droplet into a channel having a smallest dimension that is smaller than the diameter of a perfect mathematical sphere having a volume of the droplet, and solidifying the droplet, and/or by exposing at least a portion of a plurality of particles to an agent able to remove at least a portion of the particles.

Claims

1. A collection of articles comprising a plurality of particles, at least some of which are non-spherical;

and/or comprise a metal and/or a magnetizable material and/or a nylon and/or a ferrofluid; and

/or at least some of which particles have a ratio of a largest dimension to a smallest dimension that is less than about 5; and

/or at least some of which particles have a porosity of at least about 0.1; and

/or at least some of which particles are microparticles having a core and a shell, the shell comprising a semi-permeable portion and/or a polymer made by a process comprising urging a fluid comprising a polymer precursor into a microfluidic channel, and hardening the polymer precursor in the channel to form the polymer;

wherein the particles have an average dimension of less than about 500 micrometers and a distribution of dimensions such that no more than about 5% of the particles have a dimension greater than about 10% of the average dimension.

2. The collection of articles of claim 1, wherein at least some of the particles each have a shape that is one of rod shaped, disk shaped or ellipsoid shaped.

3. The collection of articles of claim 1, made by a process comprising urging a fluidic droplet defining a precursor of one of the particles into a microfluidic channel and hardening the particle in the channel.

4. The collection of articles of claim 1, wherein at least some of the particles comprise one or more metals, at least one of which is selected from the group consisting of lead, cadmium, tin, indium, zinc, antimony, copper, silver, gold, gallium, bismuth, or iron.

5. The collection of articles of claim 1, wherein no more than about 5%, about 3%, about 1%, about 0.1%, or about 0.1% of the particles have a dimension greater than about 5%, about 3%, about 1%, about 0.1%, or about 0.01% of the average dimension.

6. The collection of articles of claim 1, wherein the droplets have an average dimension of less than about 100 micrometers, about 50 micrometers, about 40 micrometers, about 25 micrometers, about 10 micrometers, about 5 micrometers, about 1 micrometer, about 0.3 micrometers, about 0.1 micrometers, or about 0.01 micrometers.

7. The collection of articles of claim 1, wherein at least some of the particles have a porosity of at least about 0.2, about 0.3, or about 0.4.

8. The collection of articles of claim 1, wherein the ferrofluid comprises an iron oxide.

12. The method of claim 1, wherein at least some of the fluid droplets comprise one or more metals, at least one of which is selected from the group consisting of lead, cadmium, tin, indium, zinc, antimony, copper, silver, gold, gallium, bismuth, or iron.

9. A method, comprising an act of:

solidifying at least a portion of a plurality of fluidic droplets, at least some of which comprise a metal and/or a magnetizable material and/or a nylon and/or a ferrofluid, wherein the fluidic droplets have an average dimension of less than about 500 micrometers and a distribution of dimensions such that no more than about 5% of the droplets have a dimension greater than about 10% of the average dimension.

10. A collection of articles comprising a plurality of particles, at least some of which are made using the method of claim 9.

11. The method of claim 9, comprising cooling at least some of the fluidic droplets to a temperature sufficient to cause the fluidic droplets to at least partially solidify.

13. The method of claim 9, wherein no more than about 5%, about 3%, about 1%, about 0.1%, or about 0.1% of the fluidic droplets have a dimension greater than about 5%, about 3%, about 1%, about 0.1%, or about 0.01% of the average dimension.

14. The method of claim 9, wherein the fluidic droplets have an average dimension of about 100 micrometers, about 50 micrometers, about 40 micrometers, about 25 micrometers, about 10 micrometers, about 5 micrometers, about 1 micrometer, about 0.3 micrometers, about 0.1 micrometers, or about 0.01 micrometers.

15. The method of claim 9, comprising solidifying at least some of the fluidic droplets to form non-spherical particles.

16. The method of claim 9, wherein the ferrofluid comprises an iron oxide.

17. A method, comprising acts of:

urging a fluidic droplet into a microfluidic channel having a smallest cross-section dimension that is smaller than the diameter of a perfect mathematical sphere having a volume of the droplet; and

solidifying the fluidic droplet within the channel to form a non-spherical particle.

18. A collection of articles comprising a plurality of particles, at least some of which are made using the method of claim 17.

19. The method of claim 17, wherein the channel has a largest cross-sectional dimension that is less than about 500 micrometers, about 100 micrometers, about 50 micrometers, about 10 micrometers, about 5 micrometers, or about 1 micrometer.

20. The method of claim 17, wherein the fluidic droplet comprises a metal.

21. The method of claim 17, wherein the fluidic droplet comprises one or more metals, at least one of which is selected from the group consisting of lead, cadmium, tin, indium, zinc, antimony, copper, silver, gold, gallium, bismuth, or iron.

22. The method of claim 17, comprising cooling the fluidic droplet to a temperature sufficient to cause the fluidic droplet to at least partially solidify.

23. The method of claim 17, comprising solidifying the fluidic droplet into a non-spherical shape.

24. The method of claim 17, wherein the particle has a ratio of a largest dimension to a smallest dimension that is less than about 5.

25. The method of claim 17, wherein the fluidic droplet has a volume greater than about 1 nl, about 3 nl, about 10 nl, about 30 nl, about 100 nl, about 300 nl, or about 1000 nl.

26. The method of claim 17, comprising urging a plurality of fluidic droplets into the microfluidic channel, and solidifying the plurality of fluidic droplets to form a plurality of particles having an average dimension of less than about 500 micrometers, about 100 micrometers, about 50 micrometers, about 40 micrometers, about 25 micrometers, about 10 micrometers, about 5 micrometers, about 1 micrometer, about 0.3 micrometers, about 0.1 micrometers, or about 0.01 micrometers and a distribution of dimensions such that no more than about 5%, about 3%, about 1%, about 0.1%, or about 0.1% of the particles have a dimension greater than about 10%, about 5%, about 3%, about 1%, about 0.1%, or about 0.01% of the average dimension.

27. A method, comprising an act of:

exposing at least a portion of a plurality of particles to an agent able to remove at least a portion of the particles, wherein the particles have an average dimension of less than about 500 micrometers, about 100 micrometers, about 50 micrometers, about 40 micrometers, about 25 micrometers, about 10 micrometers, about 5 micrometers, about 1 micrometer, about 0.3 micrometers, about 0.1 micrometers, or about 0.01 micrometers and a distribution of dimensions such that no more than about 5%, about 3%, about 1%, about 0.1%, or about 0.1% of the particles have a dimension greater than about 10%, about 3%, about 1%, about 0.1%, or about 0.01% of the average dimension.

28. The method of claim 27, wherein the agent is able to dissolve at least some of the particles.

29. The method of claim 27, wherein the agent comprises an organic solvent.

30. The method of claim 27, wherein the agent comprises acetone.

31. The method of claim 27, wherein the agent comprises a porogen.

32. The method of claim 27, wherein the agent comprises dioctyl phthalate.

33. The method of claim 27, wherein at least some of the particles, after exposure to the agent, are porous.

34. The method of claim 27, comprising removing a portion of at least some of the particles such that the particles become non-spherical.

35. A method, comprising an act of:

hardening a polymeric material around a sectioned optical fiber.

36. The method of claim 35, wherein the optical fiber is concentrically sectioned.

37. The method of claim 35, wherein the optical fiber is incapable of transmitting light.

38. The method of claim 35, further comprising removing the sectioned optical fiber.

39. The method of claim 35, wherein the polymeric material is elastomeric.

40. The method of claim 35, wherein the polymeric material comprises poly(dimethylsiloxane).

41. An article made by the method of claim 35.

42. A collection of articles comprising a plurality of particles, at least some of which are microparticles having a core and a shell, the shell comprising a nylon.