Methods and Apparatus for Processing Droplets

Abstract

An electrowetting-on-dielectric actuator may include an array of electrodes and a dielectric layer. The actuator may modulate voltage of the electrodes in such a way that time-varying electric fields created by the electrodes cause droplets of liquid to move relative to the actuator. The electric fields may cause the droplets to press up against a bottom surface of the actuator while the droplets are under and touching the bottom surface. The droplets may then be released from the bottom surface and thereby deposited on an object being fabricated. The release of droplets may be repeated, one layer of droplets at a time, to fabricate the object. Multiple actuators may simultaneously organize droplets in layers. A robot may move the actuators, one at a time, into position for releasing the droplets.

What is claimed: 
     
         1 . An apparatus comprising an electrowetting-on-dielectric (EWOD) actuator, wherein:
 (a) the EWOD actuator includes
 (i) an array of electrodes, and 
 (ii) a dielectric layer; and 
   (b) the EWOD actuator is configured to modulate voltage of each electrode in the array, respectively, in such a way that time-varying electric fields created by the electrodes cause drops of liquid to undergo movement relative to the array.   
     
     
         2 . The apparatus of  claim 1 , wherein the apparatus includes a robot that is configured to actuate rotation of the EWOD actuator in such a way that a given surface of the EWOD actuator comprises a top surface of the EWOD actuator before the rotation and comprises a bottom surface of the EWOD actuator after the rotation. 
     
     
         3 . The apparatus of  claim 2 , wherein the EWOD actuator is configured to modulate voltage of each electrode in the array, respectively, in such a way that electric fields created by the electrodes cause the drops to touch and press against the actuator throughout the entire rotation. 
     
     
         4 . The apparatus of  claim 1 , wherein the EWOD actuator is configured to cause at least a subset of the drops to move simultaneously. 
     
     
         5 . The apparatus of  claim 1 , wherein the EWOD actuator is configured to cause an entire row of the drops or an entire column of the drops to move simultaneously during, and as part of, the movement. 
     
     
         6 . The apparatus of  claim 1 , wherein the EWOD actuator is configured to repeatedly release layers of drops, one layer at a time, in such a way that the layers of drops fabricate an object. 
     
     
         7 . The apparatus of  claim 6 , wherein the object comprises an electromechanical device. 
     
     
         8 . The apparatus of  claim 1 , wherein the drops include cells or fragments of cells. 
     
     
         9 . The apparatus of  claim 1 , wherein:
 (a) the drops include a first drop and second drop; and   (b) the first drop has a first material composition and the second drop has a second material composition, the first and second material compositions being different from each other.   
     
     
         10 . The apparatus of  claim 9 , wherein the movement includes merging the first and second drops in such a way that the merging forms a larger drop. 
     
     
         11 . The apparatus of  claim 9 , wherein the movement includes merging the first and second drops in such a way that the merging triggers a chemical reaction. 
     
     
         12 . The apparatus of  claim 1 , wherein the array comprises electrodes arranged in rows and columns. 
     
     
         13 . The apparatus of  claim 1 , wherein, during the movement, at least one of the drops has a volume per drop that is greater than or equal to 10 picoliters and less than or equal to 100 picoliters. 
     
     
         14 . An apparatus comprising a set of electrowetting-on-dielectric (EWOD) actuators, wherein:
 (a) the set of actuators includes multiple EWOD actuators; and   (b) each specific EWOD actuator in the set
 (i) includes
 (A) an array of electrodes, and 
 (B a dielectric layer, and 
 
 (ii) is configured to modulate voltage of each electrode in the array, respectively, in such a way that time-varying electric fields created by the electrodes cause drops of liquid to undergo movement relative to the array. 
   
     
     
         15 . The apparatus of  claim 14 , wherein:
 (a) the multiple EWOD actuators include an EWOD actuator and a second EWOD actuator; and   (b) the first and second EWOD actuators move drops at the same time.   
     
     
         16 . The apparatus of  claim 14 , wherein the apparatus:
 (a) includes a robot that is configured to carry the set of EWOD actuators, one EWOD actuator at a time, to a specific position; and   (b) is configured to cause drops to be released from each particular EWOD actuator in the set, respectively, when the particular EWOD actuator is in the specific position.   
     
     
         17 . The apparatus of  claim 14 , wherein the apparatus is configured to cause layers of drops to be released from the set of EWOD actuators, in such a way that:
 (a) one layer of drops is released at a time; and   (b) each layer of drops, respectively, is released from only a single EWOD actuator in the set.   
     
     
         18 . The apparatus of  claim 14 , wherein the apparatus is configured to position the EWOD actuators in such a way that drops released from the EWOD actuators fabricate an object