Single sided continuous optoelectrowetting (SCEOW) device for droplet manipulation with light patterns

Patent metadata

Field	Value
Publication number	US-9533306-B2
Application number	US-201113194966-A
Country	US
Kind code	B2
Filing date	Jul 31, 2011
Priority date	Aug 2, 2010
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

A single-sided continuous optoelectrowetting (SCOEW) device for manipulating droplets retained in a fluid over the SCOEW device with dynamic patterns of low intensity light, such as from a display screen, is described. A single pair of lateral electrodes are utilized for providing a lateral electric field bias, with transport motion controlled in response to projecting light through a photoconductive layer and dielectric layer adjacent to which droplets are retained. The device is configured for optically manipulating droplets having volumes spanning over five orders of magnitude, and can be configured to perform droplet dispensing, transport, splitting, merging, mixing and other droplet manipulation functions involving any of the above on a single sided surface.

First claim

What is claimed is:

1. An apparatus for optically manipulating one or more droplets, comprising:
a featureless photoconductive layer;
a first electrode and a second electrode disposed laterally along a plane of said featureless photoconductive layer, there being a gap between said first electrode and said second electrode, wherein said featureless photoconductive layer comprises a conductive path from said first electrode to said second electrode;
a voltage source connected to said first and second electrodes for producing a lateral electric field between said first and second electrodes in said featureless photoconductive layer; and
a hydrophobic dielectric layer disposed over said featureless photoconductive layer and configured for retaining a first fluid and the one or more droplets of a second fluid;
wherein each droplet of said second fluid is subject to transport along a surface of said hydrophobic dielectric layer in response to a difference between a contact angle of a first edge of said droplet with respect to said surface and a contact angle of a second edge of said droplet with respect to said surface;
wherein said difference is induced in response to a difference in optical illumination of a first region of said featureless photoconductive layer adjacent said first edge and optical illumination of a second region of said featureless photoconductive layer adjacent said second edge, said first region and said second region each forming part of said conductive path of said featureless photoconductive layer;
wherein said gap between said first electrode and said second electrode is larger than an area of said hydrophobic dielectric layer contacted by the one or more droplets of said second fluid having a volume of at least 250 picoliters; and
wherein said first region and said second region are adjacent to said gap.

2. The apparatus as recited in claim 1 , wherein said first and second electrodes are disposed on said featureless photoconductive layer.

3. The apparatus as recited in claim 1 , wherein a thickness of said hydrophobic dielectric layer is less than or equal to ten micrometers.

4. The apparatus as recited in claim 1 , wherein said voltage source comprises a direct current (DC) bias voltage.

5. The apparatus as recited in claim 1 , wherein said contact angle at said first edge of said droplet is determined by a local voltage drop across said hydrophobic dielectric layer between said first edge of said droplet and said first region of said featureless photoconductive layer as given by

cos
⁢

⁢
θ

=

cos
⁢

⁢

θ
0

+

1

2
⁢
γ

⁢

cV
2

,

in which c is specific capacitance, γ is surface tension between said droplet and surrounding medium, and V is voltage drop across said hydrophobic dielectric layer in a vertical direction at a three-phase contact line, with θ 0 and θ representing said contact angle at said first edge before and after said optical illumination of said first region of said featureless photoconductive layer.

6. The apparatus as recited in claim 1 , wherein said featureless photoconductive layer comprises a hydrogenated semiconductor layer.

7. The apparatus as recited in claim 6 , wherein said hydrogenated semiconductor layer comprises a hydrogenated amorphous silicon layer.

8. The apparatus as recited in claim 1 , wherein said hydrophobic dielectric layer comprises an amorphous fluorocarbon polymer layer.

9. The apparatus as recited in claim 1 , wherein said first fluid comprises an oil.

10. The apparatus as recited in claim 1 , further comprising:
at least one reservoir from which said second fluid is dispensed through at least one aperture or microtube into said first fluid on said hydrophobic dielectric layer;
wherein the one or more droplets of consistent sizing are dispensed and moved along said hydrophobic dielectric layer in response to movements of dynamic light patterns optically illuminating said featureless photoconductive layer.

11. The apparatus as recited in claim 1 further comprising an optical projector configured to focus dynamic light patterns onto said featureless photoconductive layer, wherein said dynamic light patterns comprise said optical illumination of said first region of said featureless photoconductive layer and said optical illumination of said second region of said featureless photoconductive layer.

12. The apparatus as recited in claim 1 , further comprising a substrate layer proximal said featureless photoconductive layer, and having sufficient transparency for said optical illumination to pass through said substrate layer onto said featureless photoconductive layer.

13. The apparatus as recited in claim 1 further comprising a fluidic chamber configured to retain said first fluid and said one or more droplets of said second fluid, wherein said featureless photoconductive layer and said first and second electrodes are part of a same wall of said fluidic chamber.

14. The apparatus as recited in claim 1 further comprising a fluidic chamber configured to retain said first fluid and said one or more droplets of said second fluid, wherein said featureless photoconductive layer and said first and second electrodes are on a same side of said fluidic chamber.

15. The apparatus as recited in claim 1 , wherein said first and second electrodes and said gap are parallel to said surface of said hydrophobic dielectric layer.

16. The apparatus as recited in claim 1 , wherein said first and second electrodes are disposed between said hydrophobic dielectric layer and said featureless photoconductive layer.

17. The apparatus as recited in claim 1 , wherein said first and second electrodes are disposed on a same surface of said featureless photoconductive layer, which is parallel to said surface of said hydrophobic dielectric layer.

18. The apparatus as recited in claim 1 , wherein said difference in optical illumination at said first region and said second region of said featureless photoconductive layer creates a corresponding difference between a first electrical conductivity of said conductive path at said first region and a second electrical conductivity of said conductive path at said second region.

19. The apparatus as recited in claim 18 , wherein said difference between said first electrical conductivity of said conductive path at said first region and said second electrical conductivity of said conductive path at said second region creates a difference between a first voltage drop from said surface of said hydrophobic dielectric layer at said first edge of said droplet to said first region of said

Assignees

• Chiou Pei-Yu
• Park Sung-Yong
• Univ California

Inventors

• Chiou Pei-Yu
• Park Sung-Yong

Classifications

• B01L3/502792 Primary

  for moving individual droplets on a plate, e.g. by locally altering surface tension · CPC title

• B01L2300/0816

  Cards, e.g. flat sample carriers usually with flow in two horizontal directions · CPC title

• B01L2400/0427

  Electrowetting · CPC title