Single-sided light-actuated microfluidic device with integrated mesh ground

Patent metadata

Field	Value
Publication number	US-2016158748-A1
Application number	US-201514960010-A
Country	US
Kind code	A1
Filing date	Dec 4, 2015
Priority date	Dec 5, 2014
Publication date	Jun 9, 2016
Grant date	—

Abstract

Single-sided optoelectrowetting (SSOEW)-configured substrates are provided, as well as microfluidic devices that include such substrates. The substrates can include a planar electrode, a photoconductive (or photosensitive) layer, a dielectric layer (single-layer or composite), a mesh electrode, and a hydrophobic coating. Fluid droplets can be moved across the hydrophobic coating of such substrates in a light-actuated manner, upon the application of a suitable AC voltage potential across the substrate and the focusing of light into the photoconductive layer of the substrate in a location proximal to the droplets. Walls can be disposed upon the substrates to form the microfluidic devices. Together the walls and substrate can form a microfluidic circuit, through which droplets can be moved.

First claim

1 . A substrate comprising:
a planar electrode; a photoconductive layer; a dielectric layer; a mesh ground electrode; and a hydrophobic coating; wherein the photoconductive layer is interposed between the planar electrode and the dielectric layer, with a bottom surface of the photoconductive layer adjoining a top surface of the planar electrode and a top surface of the photoconductive layer adjoining a bottom surface of the dielectric layer; wherein the mesh ground electrode adjoins a top surface of the dielectric layer, wherein the planar electrode and the mesh ground electrode are configured to be connected to an AC voltage source; and wherein, when the planar electrode and the mesh ground electrode are connected to opposing terminals of the AC voltage source, the substrate is capable of applying an opto-electrowetting (OEW) force to aqueous droplets in contact with the hydrophobic coating.

2 . The substrate of claim 1 , wherein the substrate forms all or part of the base of a microfluidic device.

3 . The substrate of claim 1 , wherein the photoconductive layer comprises hydrogenated amorphous silicon (a-Si:H).

4 . The substrate of claim 1 , wherein the dielectric layer comprises a metal oxide.

5 . The substrate of claim 4 , wherein the dielectric layer has a thickness of at least 125 nm and/or an impedance of about 10 kOhms to about 50 kOhms.

6 . The substrate of claim 4 , wherein the dielectric layer was formed by atomic layer deposition.

7 . The substrate of claim 1 , wherein the dielectric layer is a composite dielectric layer having at least a first dielectric layer and a second dielectric layer, with a bottom surface of the first dielectric layer adjoining the photoconductive layer.

8 . The substrate of claim 7 , wherein the mesh ground electrode is interposed between the first dielectric layer and the second dielectric layer.

9 . The substrate of claim 7 , wherein the first and second dielectric layers both comprise a metal oxide.

10 . The substrate of claim 9 , wherein the first and second dielectric layers are both formed by atomic layer deposition.

11 . The substrate of claim 7 , wherein the composite dielectric layer has a thickness of about 125 nm to about 175 nm and/or an impedance of about 10 kOhms to about 50 kOhms.

12 . The substrate of claim 1 , wherein the mesh ground electrode comprises wires that are arranged in a lattice shape.

13 . The substrate of claim 12 , wherein the mesh ground electrode comprises gold or aluminum.

14 . The substrate of claim 12 , wherein the mesh ground electrode comprises aluminum that has an oxidized outer surface.

15 . The substrate of claim 12 , wherein the mesh ground electrode has a linear fill factor β less than or equal to 10%.

16 . The substrate of claim 15 , wherein wires of the mesh ground electrode have a pitch of about 200 microns to about 500 microns.

17 . The substrate of claim 1 , wherein the hydrophobic coating has a bottom surface that adjoins at least a portion of a top surface of the dielectric layer, and optionally, wherein the bottom surface of the hydrophobic coating further adjoins a top surface of the mesh ground electrode.

18 . The substrate of claim 17 , wherein the hydrophobic coating comprises an organofluorine polymer having at least one perfluorinated segment.

19 . The substrate of claim 17 , wherein the hydrophobic layer comprises a densely packed monolayer of amphiphilic molecules covalently bonded to molecules of the dielectric layer.

20 . The substrate of claim 17 , wherein the amphiphilic molecules of the hydrophobic layer each comprise:
a siloxane group, and wherein the siloxane groups are covalently bonded to the molecules of the dielectric layer; a phosphonic acid group, and wherein the phosphonic acid groups are covalently bonded to the molecules of the dielectric layer; or a thiol group, and wherein the thiol groups are covalently bonded to the molecules of the dielectric layer and/or the mesh ground electrode.

21 . The substrate of claim 20 , wherein the amphiphilic molecules of the hydrophobic layer comprise long-chain hydrocarbons having a chain of at least 16 carbons.

22 . The substrate of claim 20 , wherein the amphiphilic molecules of the hydrophobic layer comprise fluorinated carbon chains.

23 . The substrate of claim 22 , wherein the fluorinated carbon chains have the chemical formula CF 3 —(CF 2 ) m —(CH 2 ) n —, wherein m is at least 2, n is at least 2, and m+n is at least 9.

24 . The substrate of claim 20 , wherein the hydrophobic layer is patterned such that select regions are relatively hydrophilic compared to the remainder of the hydrophobic layer.

25 . A microfluidic device comprising:
a base comprising the substrate of claim 1 ; and walls disposed on a top surface of said base; wherein the base and the walls together define a microfluidic circuit.

26 . The microfluidic device of claim 25 further comprising a cover, wherein the cover is disposed on the walls.

27 . The microfluidic device of claim 25 , wherein the microfluidic circuit comprises at least one microchannel and a plurality of chambers, wherein each chambers opens off of one of the microchannels.

28 . A method of moving a droplet in a microfluidic device of claim 25 , the method comprising:
disposing a droplet of an aqueous solution on a top surface of a base of the microfluidic device; applying a AC voltage potential between the planar electrode and the mesh ground electrode; directing structured light at a position on the top surface of the base, in a location proximal to the droplet; and moving the structured light relative to the microfluidic device at a rate that induces the droplet to move across the top surface of the base.

29 . The method of claim 28 , wherein the AC voltage potential is about 10 ppV to about 80 ppV, or about 30 ppV to about 50 ppV.

30 . The method of claim 29 , wherein the AC voltage potential has a frequency of about 1 kHz to about 1 MHz, about 5 kHz to about 100 kHz, or about 5 kHz to about 20 kHz.

Assignees

• Berkeley Lights Inc
• Univ California

Inventors

• Wu Ming-Chiang
• Loo Jodi Tsu-An
• Pei Shao Ning
• Mathieu Gaetan L
• Gong Jian
• Lowe Jr Randall D
• Valley Justin K

Classifications

• B01L2300/12

  Specific details about materials · CPC title

• B01L3/502792

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

• B01L3/502715

  characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces · CPC title

• B01L3/50273 Primary

  characterised by the means or forces applied to move the fluids · CPC title

• B01L2400/0427

  Electrowetting · CPC title