Device for electrostatic manipulation of droplets

• US 5,486,337 A
• Filed: 02/18/1994
• Issued: 01/23/1996
• Est. Priority Date: 02/18/1994
• Status: Expired due to Fees

• Current Assignee: General Atomics, Inc.
• Original Assignee: General Atomics, Inc.
• Inventors: Ohkawa, Tihiro
• Primary Examiner(s): Snay, Jeffrey R.
• Application Number:
  US08/198,947
• Time in Patent Office: 704 Days
• Field of Search: 422/100, 436/180, 239/690
• US Class Current: 422/502
• CPC Class Codes: B01F 33/30 Micromixers
• 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: B01J 2219/0065 by the use of liquid beads
• CPC Class Codes: B01J 2219/00653 the compounds being bound to electrodes embedded in or on the solid supports
• CPC Class Codes: B01J 2219/00659 Two-dimensional arrays
• CPC Class Codes: B01L 3/0262 using touch-off at substrate or container
• CPC Class Codes: B01L 3/5088 confining liquids at a location by surface tension, e.g. virtual wells on plates, wires B01L3/50857 takes precedence
• CPC Class Codes: B41J 2002/14395 Electrowetting
• CPC Class Codes: H02N 1/004 in which a body is moved along a path due to interaction with an electric field travelling along the path
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

Abstract

A method and apparatus are disclosed for manipulation of very small droplets of liquid, by placing the droplets on wettable positioning electrodes on a non-wettable substrate, applying voltages to the positioning electrodes to electrostatically charge the droplets, and applying voltages of opposite polarity to target electrodes, thereby attracting the droplets from the positioning electrodes toward the target electrodes. The electrodes can be on a manipulation surface or on a separate portable dispensing tool or pickup tool.

Claims

1. A device for manipulation of liquid droplets,comprising:

a positioning means for establishing an initial position of an individual liquid droplet, said positioning means being electrically conductive;

an attraction means adjacent to said positioning means for electrostatically attracting a droplet from said positioning means; and

a voltage application means for applying a first voltage to said positioning means, thereby electrostatically charging the droplet, then raising said first voltage to a higher magnitude and applying a second voltage of opposite polarity to said attraction means to generate a force urging the droplet from said positioning means toward said attraction means;

wherein;

said positioning means and said attraction means comprise first and second electrodes, respectively;

said first and second electrodes comprise wettable surfaces exposed to the droplet; and

said first and second electrodes are surrounded by a non-wettable surface.

2. A device as claimed in claim 1, wherein:

said first electrode is initially occupied by a droplet;

said second electrode is not initially occupied by a droplet; and

said voltage application means relocates the droplet from said first electrode to said second electrode.

3. A device as claimed in claim 1, wherein:

said first electrode is initially occupied by a droplet;

said second electrode is initially occupied by a droplet; and

said voltage application means mixes the two droplets.

4. A device for manipulation of liquid droplets, comprising:

a non-wettable substrate for supporting a plurality of liquid droplets;

a plurality of wettable electrodes mountable on said substrate;

a voltage source for applying voltage to said wettable electrodes; and

a controller for selectively controlling the polarity and magnitude of said voltage applied to each of said wettable electrodes to first electrically charge each of the droplets at one of said wettable electrodes and then electrostatically attract each of the droplets to another of said wettable electrodes.

5. A device as claimed in claim 4, further comprising a plurality of non-wettable electrodes for electrostatically controlling movement of the droplet between said wettable electrodes, said non-wettable electrodes being subjected to voltage of selected polarity and magnitude by said controller to generate forces on the droplet for control of speed and direction.

6. A device as claimed in claim 4, wherein:

a first set of said plurality of wettable electrodes are initially occupied by droplets;

a second set of said plurality of wettable electrodes are initially unoccupied by droplets; and

said controller relocates a droplet from one of said wettable electrodes in said first set to one of said wettable electrodes in said second set.

7. A device as claimed in claim 4, wherein:

a first set of said plurality of wettable electrodes are initially occupied by droplets;

a second set of said plurality of wettable electrodes are initially occupied by droplets; and

said controller mixes a droplet from one of said wettable electrodes in said first set with a droplet on one of said wettable electrodes in said second set.