Optically encoded particles

• US 20050042764A1
• Filed: 01/31/2003
• Published: 02/24/2005
• Est. Priority Date: 02/07/2002
• 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: Sailor, Michael J, Schmedake, Thomas
• Granted Patent: US 8,765,484 B2
• Time in Patent Office: Days
• US Class Current: 436/166
• CPC Class Codes: B05D 1/00 Processes for applying liquids or other fluent materials B05D5/00, B05D7/00 take precedence
• CPC Class Codes: B05D 2451/00 Type of carrier, type of coating (Multilayers)
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/45 using interferometric methods; using Schlieren methods
• CPC Class Codes: G06K 19/06084 the marking being based on nanoparticles or microbeads
• CPC Class Codes: G06K 19/0614 the marking being selective to wavelength, e.g. color barcode or barcodes only visible under UV or IR methods or arrangements for sensing record carriers using a selected wavelength, see G06K7/12
• CPC Class Codes: G09F 3/00 Labels, tag tickets, or similar identification or indication means medals or badges A44C3/00; making labels B31D1/02; sheets temporarily attached together B42F; labelling B65C; labels on record carriers G11B23/38, G11B23/40; Seals; Postage or like stamps
• CPC Class Codes: Y10T 436/13 Tracers or tags
• CPC Class Codes: Y10T 436/143333 Saccharide [e.g., DNA, etc.]
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

The invention concerns a particle having a code embedded in its physical structure by refractive index changes between different regions of the particle. In preferred embodiments, a thin film possesses porosity that varies in a manner to produce a code detectable in the reflectivity spectrum.

Claims

1. An optically encoded particle comprising:

a first porous layer having a first porosity; and

n additional porous layers at least one of which has a porosity differing from said first porosity;

wherein

said first porous layer and said n additional porous layers are configured to produce an interference pattern in the reflectivity spectrum that forms an optical signature.

2. The particle of claim 1, wherein the particle has a diameter of hundreds of microns or less.

3. The particle of claim 1, wherein said first porous layer and said n additional porous layers have a matched optical thickness, wherein optical thickness comprises the product of refractive index and layer thickness.

4. The particle of claim 1, wherein said interference pattern in the reflectivity spectrum extends beyond the visible spectrum.

5. The particle of claim 1, wherein said first porous layer and said n additional porous layers alternate periodically and form a Bragg stack.

6. The particle of claim 1, wherein said first porous layer and said n additional porous layers form a Rugate reflector.

7. The particle of claim 1, wherein said first porous layer and said n additional porous layers are formed from a semiconductor.

8. The particle of claim 7, wherein said semiconductor comprises silicon.

9. The particle of claim 1, wherein said first porous layer and said n additional porous layers are formed from an insulator.

10. The particle of claim 1, further comprising a receptor for binding a predetermined analyte.

11. An optically encoded particle comprising a thin film in which porosity varies in a manner to produce a code detectable in the reflectivity spectrum.

12. The particle of claim 11, wherein the porosity varies periodically.

13. The particle of claim 12, wherein the particle comprises sets of porosities each varying to produce a code detectable in the reflectivity spectrum.

14. The particle of claim 11, further comprising a receptor.

15. The particle of claim 14, wherein said receptor is a receptor for a biological analyte.

16. The particle of claim 14, wherein said receptor is a receptor for a chemical analyte.

17. The particle of claim 14, wherein said receptor is a receptor for a gaseous analyte.

18. The particle of claim 11, further comprising a fluorescence tag for assaying the particle.

19. The particle of claim 11, wherein the thin film comprises porous silicon.

20. The particle of claim 11, being micron-sized.

32. A method for identification of an analyte bound to an encoded particle or identification of a host including an encoded particle of claim 11, the method comprising steps of:

associating the encoded particle with the analyte or the host;

generating an interference pattern in the reflectivity spectrum by illumination of the particle;

determining the particle'"'"'s code from the interference pattern;

identifying the analyte or the host based upon said step of determining.

33. The method according to claim 32, further comprising a step of designating the particle to bind an analyte by modifying the particle with a specific receptor or targeting moiety.

34. The method according to claim 33, wherein the targeting moiety is a sugar or polypeptide.

35. The method according to claim 33, further comprising a step of signaling binding of an analyte by fluorescence labeling or analyte autofluorescence.

21. A method for encoding thin films, comprising steps of:

etching a semiconductor or insulator substrate to form a thin film including pores;

varying etching conditions to vary porosity in the thin film according to a pattern that will generate a code in the reflectivity spectrum in response to illumination.

22. The method according to claim 21, further comprising a step of separating the thin film from the semiconductor or insulator substrate.

23. The method according to claim 22, further comprising a step of separating the thin film into particles.

24. The method according to claim 23, further comprising a step of placing a particle within a host.

25. The method according to claim 23, further comprising steps of:

generateng an interference pattern in the reflectivity spectrum by illumination of one or more of the particles;

determining a particle'"'"'s code from the interference pattern.

26. The method according to claim 22, wherein said step of varying etching conditions varies the etching conditions periodically.

27. The method according to claim 21, further comprising a step of spatially defining the semiconductor or insulator substrate to conduct said step of etching in a spatially defined location or locations.

28. The method according to claim 27, wherein said step of varying further varies etching conditions in different spatially defined locations to encode multiple codes in the thin film.

29. The method according to claim 27, further comprising a step of separating the thin film from the semiconductor or insulator substrate.

30. The method according to claim 29, further comprising a step of separating the thin film into particles.

31. The method according to claim 21, wherein said step of varying etching conditions in a pattern that further encodes based upon layer thickness.

36. A method of encoding micron sized particles, the method comprising steps of:

etching a wafer to form a thin film having a varying porosity that will produce a detectable optical signature in response to illumination;

applying an electropolishing current to the wafer to remove the porous film from the wafer;

dicing the film into micron-sized particles, each micron-sized particle maintaining an optical signature produced by said step of etching.

37. The method according to claim 36, further comprising a step of modifying the particles with a specific receptor or targeting moiety.

38. An encoded micron-sized particle having a code embedded in its physical structure by refractive index changes between different regions of the particle.

39. The encoded micron-sized particle of claim 38, wherein the refractive index changes result from a varying porosity.

40. The encoded micron-sized particle of claim 39, wherein different regions of the particle have different thickness.

41. The particle of claim 38, further comprising a receptor.

42. The particle of claim 41, wherein said receptor is a receptor for a biological analyte.

43. The particle of claim 41, wherein said receptor is a receptor for a chemical analyte.

44. The particle of claim 41, wherein said receptor is a receptor for a gaseous analyte.

45. The particle of claim 38, further comprising a fluorescence tag for assaying the particle.

46. The particle of claim 38, wherein the thin film comprises porous silicon.

47. An optically encoded particle comprising a porosity varying in layers to form a structure whose optical reflectivity spectrum can be recognized as a distinct interference pattern for the purposes of distinct identification of said particle.