Droplet generation for droplet-based assays

Patent metadata

Field	Value
Publication number	US-9500664-B2
Application number	US-201113341669-A
Country	US
Kind code	B2
Filing date	Dec 30, 2011
Priority date	Mar 25, 2010
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

A system, including method and apparatus, for generating droplets suitable for droplet-based assays. The disclosed systems may include either one-piece or multi-piece droplet generation components configured to form sample-containing droplets by merging aqueous, sample-containing fluid with a background emulsion fluid such as oil, to form an emulsion of sample-containing droplets suspended in the background fluid. In some cases, the disclosed systems may include channels or other suitable mechanisms configured to transport the sample-containing droplets to an outlet region, so that subsequent assay steps may be performed.

First claim

We claim:

1. A system for forming a plurality of sample-containing droplets suspended in a background fluid, comprising:
a substrate having a bottom surface and a top surface;
a sample well, a background fluid well, and a droplet well each having an upper region protruding from the top surface of the substrate;
a network of channels formed in the bottom surface of the substrate and fluidically interconnecting the sample well, the background fluid well, and the droplet well; and
a droplet generation region defined by the network of channels and configured to generate sample-containing droplets suspended in the background fluid;
wherein the droplet generation region is defined by the intersection of a first channel, a second channel, and a third channel;
wherein the first channel is configured to transport sample-containing fluid from the sample well to the droplet generation region, the second channel is configured to transport background fluid from the background fluid well to the droplet generation region, and the third channel is configured to transport sample-containing droplets from the droplet generation region to the droplet well; and
wherein the substrate and the upper region of each well are injection molded as a single piece.

2. The system of claim 1 , wherein the first channel includes an air trap configured to prevent sample-containing fluid from being inadvertently drawn through the first channel by capillary action.

3. The system of claim 1 , wherein the second channel includes two background fluid sub-channels that intersect the first channel from two different directions to form a cross-shaped intersection region with the first channel and the third channel.

4. The system of claim 3 , wherein the two background fluid sub-channels have substantially equal hydraulic resistances.

5. The system of claim 1 , further comprising a sealing member forming a fluid tight seal with the bottom surface of the substrate and providing a bottom wall for each channel of the network of channels.

6. The system of claim 5 , wherein the sealing member provides a bottom wall for the sample well, the background fluid well, and the droplet well.

7. The system of claim 1 , further comprising a plurality of networks of channels, each network of channels being formed in the bottom surface of the substrate and forming a droplet generation region and fluidically interconnecting a sample well, a background fluid well, and a droplet well.

8. A method of generating sample-containing droplets suspended in a background fluid, comprising:
transporting sample-containing fluid into a sample well;
transporting background fluid into a background fluid well;
transporting sample-containing fluid through a first channel, from the sample well to a droplet generation region;
transporting background fluid through a second channel, from the background fluid well to the droplet generation region;
generating sample-containing droplets suspended in the background fluid at the droplet generation region; and
transporting the sample-containing droplets through a third channel, from the droplet generation region to a droplet well;
wherein an upper region of each of the sample well, the background fluid well, and the droplet well protrudes from the top surface;
wherein the first channel, the second channel, the third channel, and the droplet generation region are formed in a bottom surface of the substrate; and
wherein the substrate and the upper region of each well are injection molded as a single piece.

9. The method of claim 8 , wherein transporting sample-containing fluid through the first channel includes transporting the sample-containing fluid through an air trap region configured to prevent inadvertent transport of the sample-containing fluid to the droplet generation region.

10. The method of claim 8 , wherein transporting background fluid through the second channel includes transporting the background fluid through two background fluid sub-channels that intersect the first channel from two different directions to form a cross-shaped intersection region with the first channel and the third channel.

11. The method of claim 10 , wherein the two background fluid sub-channels are configured to have substantially the same hydraulic resistance.

12. The method of claim 8 , wherein a sealing member forms a fluid tight seal with the bottom surface of the substrate and provides a bottom wall for the first channel, the second channel, and the third channel.

13. The method of claim 12 , wherein the sealing member provides a bottom wall for the sample well, the background fluid well, and the droplet well.

14. A method of manufacturing a droplet generation system, comprising:
(i) forming a substrate having a bottom surface and a top surface;
(ii) forming a sample well;
(iii) forming a background fluid well;
(iv) forming a droplet well; and
(v) forming a droplet generation region defined by the intersection of a first channel fluidically connected with the sample well, a second channel fluidically connected with the background fluid well, and a third channel fluidically connected with the droplet outlet region;
wherein the substrate, an upper region of the sample well, an upper region of the background fluid well, and an upper region of the droplet well are injection molded as a single piece;
wherein the upper region of each well protrudes from the top surface of the substrate; and
wherein the first channel, the second channel, and the third channel are formed in the bottom surface of the substrate.

15. The method of claim 14 , further comprising attaching a sealing member to the bottom surface of the substrate to form a substantially fluid tight seal and a bottom wall for each of the channels and each of the wells.

16. The method of claim 14 , wherein a sealing member forms a fluid tight seal with the bottom surface of the substrate and provides a bottom wall for the first channel, the second channel, the third channel, the sample well, the background fluid well, and the droplet well.

Assignees

• Ness Kevin D
• Kelly Christopher F
• Masquelier Donald A
• Bio Rad Laboratories Inc

Inventors

• Ness Kevin D
• Kelly Christopher F
• Masquelier Donald A

Classifications

• G01N2035/00148

  Test cards, e.g. Biomerieux or McDonnel multiwell test cards · CPC title

• B01L2300/0829

  Multi-well plates; Microtitration plates · CPC title

• B01L3/502723

  characterised by venting arrangements · CPC title

• B01L3/502784 Primary

  specially adapted for droplet or plug flow, e.g. digital microfluidics · CPC title

• B01L2200/027

  for microfluidic devices · CPC title