Single-sided lateral-field and phototransistor-based optoelectronic tweezers

• US 7,956,339 B2
• Filed: 09/24/2009
• Issued: 06/07/2011
• Est. Priority Date: 03/28/2007
• 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: Jamshidi, Arash, Hsu, Hsan-Yin, Neale, Steven L., Wu, Ming-Chiang, Ohta, Aaron, Chiou, Pei-Yu
• Primary Examiner(s): Sohn; Seung C
• Application Number:
  US12/565,984
• Publication Number:
  US 20100101960A1
• Time in Patent Office: 621 Days
• Field of Search: 250/559.04, 250/551, 250/208.1, 204/547, 204/643
• US Class Current: 250/559.04
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals

Abstract

Described herein are single-sided lateral-field optoelectronic tweezers (LOET) devices which use photosensitive electrode arrays to create optically-induced dielectrophoretic forces in an electric field that is parallel to the plane of the device. In addition, phototransistor-based optoelectronic tweezers (PhOET) devices are described that allow for optoelectronic tweezers (OET) operation in high-conductivity physiological buffer and cell culture media.

Claims

1. A planar optoelectronic tweezers apparatus, comprising:

a first electrode; and

a second electrode;

said first and second electrodes spaced apart by a gap;

said first and second electrodes supported by a substrate layer;

each said electrode comprising a conductive layer adjacent to said substrate layer and a photosensitive layer adjacent to said conductive layer;

wherein said electrodes are configured to create optically-induced dielectrophoretic forces in an electric field that is parallel to the plane of the apparatus.

2. An apparatus as recited in claim 1, wherein said conductive layer undercuts said photosensitive layer.

3. An apparatus as recited in claim 1, wherein said photosensitive layer surrounds said conductive layer.

4. An apparatus as recited in claim 1, further comprising a thin insulating layer around said conductive layer.

5. An apparatus as recited in claim 1, further comprising an insulating layer around said conductive layer and filling said gap.

6. A planar optoelectronic tweezers apparatus, comprising:

a first planar array of photosensitive electrodes;

a second planar array of photosensitive electrodes;

wherein electrodes in said first electrode array are spaced apart from electrodes in said second electrode array by an electrode gap;

a substrate layer supporting said first and second electrode arrays;

each said electrode comprising a conductive layer adjacent to said substrate layer and a photosensitive layer adjacent to said conductive layer; and

a cover layer spaced apart from and positioned adjacent said photosensitive layer, whereby a chamber for containing a liquid/particle solution is formed;

wherein said electrode arrays are configured to create optically-induced dielectrophoretic forces in an electric field that is parallel to the plane of the apparatus.

7. An apparatus as recited in claim 6, wherein said conductive layer undercuts said photosensitive layer.

8. An apparatus as recited in claim 6, wherein said photosensitive layer surrounds said conductive layer.

9. An apparatus as recited in claim 6, further comprising a thin insulating layer around said conductive layer.

10. An apparatus as recited in claim 6, further comprising an insulating layer around said conductive layer and filling said electrode gap.

11. An apparatus as recited in claim 6, further comprising a second conductive layer between said chamber and said cover layer.

12. A planar optoelectronic tweezers apparatus, comprising:

a first planar array of photosensitive electrodes;

a second planar array of photosensitive electrodes;

wherein electrodes in said first electrode array are spaced apart from electrodes in said second electrode array by an electrode gap;

wherein electrodes in said first electrode array and electrodes in said second array are interdigitated;

a substrate layer supporting said first and second electrode arrays;

each said electrode comprising a conductive layer adjacent to said substrate layer and a photosensitive layer adjacent to said conductive layer; and

a cover layer spaced apart from and positioned adjacent said photosensitive layer, whereby a chamber for containing a liquid/particle solution is formed;

wherein said electrode arrays are configured to create optically-induced dielectrophoretic forces in an electric field that is parallel to the plane of the apparatus.

13. An apparatus as recited in claim 12, wherein said conductive layer undercuts said photosensitive layer.

14. An apparatus as recited in claim 12, wherein said photosensitive layer surrounds said conductive layer.

15. An apparatus as recited in claim 12, further comprising a thin insulating layer around said conductive layer.

16. An apparatus as recited in claim 12, further comprising an insulating layer around said conductive layer and filling said gap.

17. An apparatus as recited in claim 12, further comprising a second conductive layer between said chamber and said cover layer.

18. A planar optoelectronic tweezers apparatus, comprising:

a photosensitive layer on an insulating substrate;

a first electrode; and

a second electrode;

said first electrode and second electrode spaced apart by a gap;

said first and second electrodes supported by the photosensitive layer that is adjacent to said substrate;

wherein said electrodes are configured to create optically-induced dielectrophoretic forces in an electric field that is parallel to the plane of the apparatus.

19. An apparatus as recited in claim 18, further comprising an insulating layer encapsulating the electrodes.

20. A planar optoelectronic tweezers apparatus, comprising:

a photosensitive layer on an insulating substrate;

a first planar array of electrodes;

a second planar array of electrodes;

wherein electrodes in said first electrode array are spaced apart from electrodes in said second electrode array by an electrode gap;

said photosensitive layer supporting said first and second electrode arrays; and

a cover layer spaced apart from and positioned adjacent said photosensitive layer, whereby a chamber for containing a liquid/particle solution is formed;

wherein said electrode arrays are configured to create optically-induced dielectrophoretic forces in an electric field that is parallel to the plane of the apparatus.

21. An apparatus as recited in claim 20, further comprising an insulating layer encapsulating the electrodes.

22. A planar optoelectronic tweezers apparatus, comprising:

a photosensitive layer on an insulating substrate;

a first planar array of electrodes;

a second planar array of electrodes;

wherein electrodes in said first electrode array are spaced apart from electrodes in said second electrode array by an electrode gap;

wherein electrodes in said first electrode array and electrodes in said second array are interdigitated;

said photosensitive layer supporting said first and second electrode arrays; and

a cover layer spaced apart from and positioned adjacent said photosensitive layer, whereby a chamber for containing a liquid/particle solution is formed;

wherein said electrode arrays are configured to create optically-induced dielectrophoretic forces in an electric field that is parallel to the plane of the apparatus.

23. An apparatus as recited in claim 22, further comprising an insulating layer encapsulating the electrodes.

24. A phototransistor optoelectronic tweezers apparatus, comprising:

a cover layer;

a substrate layer;

a photoconductive layer between said cover layer and said substrate layer; and

a liquid layer between said cover layer and said photoconductive layer;

wherein said photoconductive layer comprises a phototransistor.

25. An apparatus as recited in claim 24, wherein said phototransistor has a vertical bipolar junction transistor structure.

26. An apparatus as recited in claim 24, wherein said phototransistor comprises:

a low to moderately doped n-type material as both a collector and a substrate;

a moderately doped p-type base layer over said n-type material; and

a highly doped n-type emitter layer over said base layer.

27. An apparatus as recited in claim 24, wherein said phototransistor comprises:

an n-type material as both a collector and a substrate;

a p-type base layer over said n-type material; and

a polysilicon n⁺ emitter layer over said base layer.

28. An apparatus as recited in claim 24, wherein said phototransistor comprises:

a substrate layer;

an n⁺ collector/emitter layer over said substrate layer;

a p-type base layer over said collector/emitter layer; and

an n⁺ emitter/collector layer over said base layer.

29. An apparatus as recited in claim 24, wherein said phototransistor comprises:

a low resistivity substrate layer;

an n-type collector layer over said substrate layer;

a p-type base layer over said collector layer; and

an n⁺ emitter/collector layer over said base layer.

30. An apparatus as recited in claim 24, wherein said phototransistor comprises:

an n-type material as both a collector and a substrate;

a p-type base layer over said collector layer; and

an n⁺ emitter/collector layer over said base layer.

31. A phototransistor optoelectronic tweezers apparatus, comprising:

a cover layer;

a substrate layer;

a photoconductive layer between said cover layer and said substrate layer; and

a liquid layer between said cover layer and said photoconductive layer;

wherein said photoconductive layer comprises a plurality of phototransistors separated by a dielectric gap.

32. An apparatus as recited in claim 31, wherein each said phototransistor has a vertical bipolar junction transistor structure.

33. An apparatus as recited in claim 31, wherein each said phototransistor comprises:

a low to moderately doped n-type material as both a collector and a substrate;

a moderately doped p-type base layer over said n-type material; and

a highly doped n-type emitter layer over said base layer.

34. An apparatus as recited in claim 31, wherein said phototransistor comprises:

an n-type material as both a collector and a substrate;

a p-type base layer over said n-type material; and

a polysilicon n⁺ emitter layer over said base layer.

35. An apparatus as recited in claim 31, wherein said phototransistor comprises:

a substrate layer;

an n⁺ collector/emitter layer over said substrate layer;

a p-type base layer over said collector/emitter layer; and

an n⁺ emitter/collector layer over said base layer.

36. An apparatus as recited in claim 31, wherein said phototransistor comprises:

a low resistivity substrate layer;

an n-type collector layer over said substrate layer;

a p-type base layer over said collector layer; and

an n⁺ emitter/collector layer over said base layer.

37. A method of fabricating a phototransistor as recited in claim 33, comprising:

providing a low to moderately doped n-type silicon wafer as a substrate;

forming a moderately-doped p-type base layer over said silicon wafer by Boron implantation followed by a drive-in step;

forming a highly doped n-type emitter layer over said base layer by arsenic implantation and annealing;

defining individual phototransistors by deep reactive ion etching and creating gaps in said emitter layer, base layer and substrate; and

defining opening areas on top of the emitter surface using photoresist or another dielectric in said gaps and on said emitter surface.