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Methods of Distinguishing and/or Retrieving Droplets from Filler Fluid in a Droplet Actuator

IP.com Disclosure Number: IPCOM000238582D
Publication Date: 2014-Sep-04

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention provides methods of distinguishing and/or retrieving droplets from filler fluid in a droplet actuator. Methods and features are provided that use contrasting fluid color to visually distinguish droplets from filler fluid in a droplet actuator. Methods and features are provided that use a selective membrane to separate aqueous phase (e.g., aqueous droplets) from oil phase (e.g., filler fluid). Methods and features are provided that use vertical features for removing or “lifting” droplets out of the filler fluid of a droplet actuator. Methods and features are provided that use a pipette that includes droplet operations electrodes for assisting the removal of a droplet from the filler fluid of a droplet actuator. Methods and features are provided that use a recessed or sunken electrode for physically registering a droplet for easy locating and retrieval from a droplet actuator. Methods and features are provided that use a hydrophobic probe for retrieving aqueous droplets from a droplet actuator. Methods and features are provided that use a hydrophobic coating on the walls of a collection reservoir for retrieving aqueous droplets from a droplet actuator. The present invention also provides methods of using a magnetic probe for retrieving magnetically responsive beads from a droplet actuator.

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Page 01 of 41

Illumina, Inc.

Docket No. IP-0972-PRV:L251PRV Page 1 of 26

Methods of Distinguishing and/or Retrieving Droplets from Filler Fluid in a Droplet Actuator

1 Background

A droplet actuator typically includes one or more substrates configured to form a surface or gap for conducting droplet operations. The one or more substrates establish a droplet operations surface or gap for conducting droplet operations and may also include electrodes arranged to conduct the droplet operations. The droplet operations substrate or the gap between the substrates may be coated or filled with a filler fluid that is immiscible with the liquid that forms the droplets. In droplet actuators, it can be difficult to locate droplets in the filler fluid. Therefore, there is a need for new approaches for distinguishing and/or retrieving droplets from the filler fluid in a droplet actuator.


2 Definitions

As used herein, the following terms have the meanings indicated.

"Activate," with reference to one or more electrodes, means affecting a change in the electrical state of the one or more electrodes which, in the presence of a droplet, results in a droplet operation. Activation of an electrode can be accomplished using alternating current (AC) or direct current (DC). Any suitable voltage may be used. For example, an electrode may be activated using a voltage which is greater than about 150 V, or greater than about 200 V, or greater than about 250 V, or from about 275 V to about 1000 V, or about 300 V. Where an AC signal is used, any suitable frequency may be employed. For example, an electrode may be activated using an AC signal having a frequency from about 1 Hz to about 10 MHz, or from about 10 Hz to about 60 Hz, or from about 20 Hz to about 40 Hz, or about 30 Hz.

"Bead," with respect to beads on a droplet actuator, means any bead or particle that is capable of interacting with a droplet on or in proximity with a droplet actuator. Beads may be any of a wide variety of shapes, such as spherical, generally spherical, egg shaped, disc shaped, cubical, amorphous and other three dimensional shapes. The bead may, for example, be capable of being

CONFIDENTIAL

Inventors: Sohela de Rozieres (San Diego, CA), Jian Gong (San Diego, CA), and Eric Vermaas (San Diego, CA)


Page 02 of 41

Illumina, Inc.

Docket No. IP-0972-PRV:L251PRV Page 2 of 26

subjected to a droplet operation in a droplet on a droplet actuator or otherwise configured with respect to a droplet actuator in a manner which permits a droplet on the droplet actuator to be brought into contact with the bead on the droplet actuator and/or off the droplet actuator. Beads may be provided in a droplet, in a droplet operations gap, or on a droplet operations surface. Beads may be provided in a reservoir that is external to a droplet operations gap or situated apart from a droplet operations surface, and the reservoir may be associated with a flow path that permits a droplet including the beads to be brought into a drople...