Droplet Dispensing Device and Methods

• US 20100032293A1
• Filed: 04/10/2008
• Published: 02/11/2010
• Est. Priority Date: 04/10/2007
• Status: Abandoned Application

• Current Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Original Assignee: Advanced Liquid Logic, Inc. (Illumina Incorporated)
• Inventors: Pamula, Vamsee K., Srinivasan, Vijay, Pollack, Michael G.
• Application Number:
  US12/531,809
• Publication Number:
  US 20100032293A1
• Time in Patent Office: Days
• US Class Current: 204/450
• CPC Class Codes: B01F 33/3021 the components to be mixed being combined in a single independent droplet, e.g. these droplets being divided by a non-miscible fluid or consisting of independent droplets
• CPC Class Codes: B01F 33/3031 using electro-hydrodynamic [EHD] or electro-kinetic [EKI] phenomena to mix or move the fluids
• CPC Class Codes: B01L 2200/0605 Metering of fluids
• CPC Class Codes: B01L 2200/0647 Handling flowable solids, e.g. microscopic beads, cells, particles
• CPC Class Codes: B01L 2200/0668 Trapping microscopic beads
• CPC Class Codes: B01L 2200/16 Reagents, handling or storing thereof
• CPC Class Codes: B01L 2300/0819 Microarrays; Biochips
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2300/0867 Multiple inlets and one sample wells, e.g. mixing, dilution
• CPC Class Codes: B01L 2300/088 Channel loops
• CPC Class Codes: B01L 2300/089 Virtual walls for guiding liquids
• CPC Class Codes: B01L 2400/0427 Electrowetting
• CPC Class Codes: B01L 2400/043 magnetic forces
• CPC Class Codes: B01L 3/502761 specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads, for physically stretching molecules investigating characteristics of particles G01N15/00
• CPC Class Codes: B01L 3/502792 for moving individual droplets on a plate, e.g. by locally altering surface tension
• CPC Class Codes: G01N 27/447 using electrophoresis

Abstract

The invention provides nonlimiting examples of structures for and methods of dispensing droplets in a droplet actuator. The droplet actuator structures and methods of the invention exhibit numerous advantages over droplet actuators of the prior art. In various embodiments, the structures and methods of the invention provide, among other things, improved efficiency, throughput, scalability, and/or droplet uniformity, as compared with existing droplet actuators. Further, in some embodiments, the droplet actuators provide configurations for improved methods of loading and/or unloading fluid and/or droplets. In yet other embodiments, the droplet actuators provide fluid loading configurations for loading numerous fluid reservoirs in a substantially simultaneous and/or substantially sequential manner.

Claims

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4. A method of forming multiple droplets on a droplet actuator, the method comprising:

(a) providing a droplet actuator comprising a base substrate comprising droplet operation electrodes configured for conducting one or more droplet operations;

(b) conducting the following steps in any order to provide fluid on one or more activated electrodes;

(i) flowing fluid onto at least a portion of the droplet operation electrodes; and

(ii) activating one or more of the droplet operation electrodes; and

(c) draining fluid from around the activated electrodes, leaving droplets on the activated droplet operation electrodes.

5. The method of claim 4, further comprising:

(a) providing the droplet operation electrodes in a channel on the base substrate; and

(b) using an external pressure source for flowing fluid into and retracting fluid from the channel.

6. The method of claim 4, further comprising:

(a) providing larger droplet transport electrodes alongside the droplet operation electrodes; and

(b) using the droplet transport electrodes for flowing fluid into and retracting fluid from the channel.

7. The method of claim 4 wherein the fluid comprises beads.

8. The method of claim 4 wherein the fluid comprises biological cells.

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17. A method of dispensing one or more sub-droplets from a droplet on a droplet actuator, the method comprising:

(a) providing a droplet actuator comprising;

(i) a base substrate comprising electrodes configured for conducting droplet operations; and

(ii) a top substrate separated from the base substrate to form a gap, the top plate comprising;

(1) a reservoir; and

(2) an opening forming a fluid path from the reservoir into the gap;

wherein the reservoir opening is arranged such that when a fluid is provided in the reservoir, the fluid is brought into proximity to a first electrode, which first electrode is adjacent to a second electrode;

(b) causing the first and second electrodes to be activated, thereby causing fluid to flow from the reservoir onto the first and second electrodes; and

(c) deactivating the first electrode, causing a droplet to form on the second electrode and causing the remaining fluid to return substantially to the reservoir.

18. The method of claim 17 wherein the fluid comprises beads.

19. The method of claim 17 wherein the fluid comprises biological cells.

20. A method of dispensing one or more sub-droplets from a droplet on a droplet actuator, the method comprising:

(a) providing a droplet actuator comprising;

(i) a base substrate comprising;

(1) droplet operation electrodes configured for conducting droplet operations; and

(2) a recessed reservoir region configured for holding a droplet in proximity to one or more of the electrodes; and

(ii) a top substrate separated from the base substrate to form a gap;

(b) causing a first electrode adjacent to the recessed reservoir region and a second electrode adjacent to the first electrode to be activated, thereby causing fluid to flow from the reservoir onto the first and second electrodes; and

(c) deactivating the first electrode, causing a droplet to form on the second electrode and causing the remaining fluid to return substantially to the recessed reservoir region.

21. The method of claim 20 wherein the fluid comprises beads.

22. The method of claim 20 wherein the fluid comprises biological cells.

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28. A droplet actuator comprising:

(a) a base substrate comprising;

(i) droplet operation electrodes configured for conducting droplet operations; and

(ii) a recessed reservoir region configured for holding a droplet in proximity to one or more of the droplet operation electrodes; and

(b) a top substrate separated from the base substrate to form a gap.

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83. A method of manipulating droplets on a droplet actuator, the method comprising:

(a) providing a droplet actuator comprising;

(i) a structure comprising an opening in fluid connection with a plurality of other openings;

(ii) a plurality of fluid reservoirs respectively in fluid communication with each of the other openings;

(iii) a plurality of electrodes in respective fluid communication with the fluid reservoirs; and

(iv) a plurality of flow paths through the opening, the other openings, the reservoirs and the electrodes; and

(b) flowing fluid through the plurality of flow paths.

84. The method of claim 83 further comprising serially flowing fluid through the plurality of the flow paths.

85. The method of claim 83 further comprising flowing fluid through the plurality of the flow paths in parallel.

86. A method of manipulating a droplet on a droplet actuator, the method comprising:

(a) supplying a droplet to a reservoir electrode comprising an electrode embedded in the reservoir electrode;

(b) selectively activating the embedded electrode so as to retain a portion of the droplet proximate the embedded electrode; and

(c) evacuating another portion of the droplet from the reservoir electrode.

87. The method of claim 86 further comprising another electrode embedded in the reservoir electrode, wherein the other embedded electrode is configured to retain another portion of the droplet while the other portion is evacuated.

88. The method of claim 86 wherein the droplet comprises beads.

89. The method of claim 86 wherein the droplet comprises biological cells.

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108. A method of manipulating a droplet comprising magnetic beads within a droplet actuator, the method comprising:

(a) providing a droplet actuator comprising;

(i) a plurality of transport electrodes configured to transport the droplet; and

(ii) a magnetic field present at a portion of the plurality of transport electrodes; and

(b) positioning a magnetic shielding material in the droplet actuator to selectively minimize the magnetic field.

109. The method of claim 108 wherein positioning the magnetic shielding material further comprises using Mu metal.

110. The method of claim 108 wherein positioning the magnetic shielding material further comprises using nickel and iron.

111. The method of claim 108 further comprising arranging a magnet producing the magnetic field and the plurality of transport electrodes into a lane.

112. The method of claim 111 further comprising positioning a plurality of lanes in the droplet actuator.

113. The method of claim 112 further comprising positioning the magnetic shielding material to minimize the affects of the magnetic fields emanating from the respective lanes.

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119. A method of re-suspending particulate within a droplet in a droplet actuator, the method comprising:

(a) providing a droplet actuator comprising;

(i) a reservoir electrode configured to manipulate a droplet; and

(ii) a plurality of transport electrodes in fluid communication with the reservoir electrode;

(b) separating a slug of the droplet from the droplet on the reservoir electrode; and

(c) recombining the slug with the droplet at the reservoir electrode.

120. The method of claim 119 further comprising transporting the slug along the plurality of transport electrodes.

121. The method of claim 119 further comprising repeating steps (b) and (c).

122. The method of claim 119 wherein the particulate comprises a bead.

123. The method of claim 119 wherein the particulate comprises a biological cell.

124. A method of re-suspending particulate within a droplet in a droplet actuator, the method comprising:

(a) providing a droplet actuator comprising;

(i) a reservoir electrode configured to manipulate a droplet; and

(ii) a plurality of transport electrodes in fluid communication with the reservoir electrode; and

(b) selectively applying across the reservoir electrode a voltage from an alternating current source to agitate the droplet.

125. The method of claim 124 wherein the particulate comprises a bead.

126. The method of claim 124 wherein the particulate comprises a biological cell.

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