Fluid dispenser and dispensing methods

Abstract

A fluid dispenser comprises a fluid chamber having two actuators coupled thereto. One of the actuators damps a fluid response of the other. The fluid chamber may comprises a cylindrical capillary, and the actuators may comprise spaced cylindrical piezoelectric elements.

What is claimed is:  
     
         1 . An apparatus for dispensing droplets of fluid comprising: 
 a fluid chamber having an opening therein for droplet dispensing;    a first actuator mechanically coupled to said fluid chamber and configured to alter the volume thereof;    a second actuator mechanically coupled to said fluid chamber and configured to alter the volume thereof, wherein said second actuator is further away from said opening than said first actuator; and    a driver connected to substantially simultaneously actuate said first and said second actuators so as to dispense fluid droplets from said fluid chamber.    
     
     
         2 . The apparatus of    claim 1   , wherein said driver is connected to actuate said second actuator prior to actuating said first actuator.  
     
     
         3 . The apparatus of    claim 1   , wherein said first and said second actuators are more than approximately 10 mm away from said opening.  
     
     
         4 . An apparatus for dispensing droplets of fluid comprising: 
 a fluid chamber having an opening therein for droplet dispensing;    a first actuator mechanically coupled to said fluid chamber and configured to alter the volume thereof;    a second actuator mechanically coupled to said fluid chamber and configured to alter the volume thereof; and    a driver connected to actuate said first and said second actuators so as to alter the volume of said fluid chamber, whereby a fluid response produced by said first actuator is damped by said second actuator.    
     
     
         5 . The apparatus of    claim 4   , wherein said driver is connected to actuate said first and said second actuators substantially simultaneously.  
     
     
         6 . The apparatus of    claim 4   , wherein said driver is connected to actuate said second actuator prior to actuating said first actuator.  
     
     
         7 . The apparatus of    claim 4   , wherein said first and said second actuators comprise piezoelectric material.  
     
     
         8 . A piezoelectric fluid aspiration and dispensing device comprising a capillary having an opening in one end for aspirating and dispensing fluid, wherein said capillary is at least partially surrounded by a plurality of cylindrical piezoelectric actuators positioned behind said opening, wherein said plurality of cylindrical piezoelectric actuators are coupled to drive circuitry for actuation; and wherein said glass capillary is unrestricted behind said piezoelectric actuators so as to allow aspirated particulate material to flow away from said opening during a reverse flush cycle.  
     
     
         9 . The dispensing device of    claim 8   , wherein a first cylindrical piezoelectric actuator extends from approximately 16 mm behind said opening to approximately 29 mm behind said opening.  
     
     
         10 . The dispensing device of    claim 9   , wherein a second cylindrical piezoelectric actuator extends from approximately 32 mm behind said opening to approximately 45 mm behind said opening.  
     
     
         11 . A method of depositing a volume of fluid comprising compressing a cylindrical capillary with a plurality of cylindrical actuators.  
     
     
         12 . The method of    claim 11   , wherein said compressing is performed substantially simultaneously.  
     
     
         13 . The method of    claim 11   , wherein a first one of said plurality of cylindrical actuators is actuated before a second one of said plurality of cylindrical actuators.  
     
     
         14 . A method of droplet deposition comprising: 
 altering the volume of a fluid chamber with a first actuator;    damping a fluid response to said volume alteration with a second actuator.    
     
     
         15 . The method of    claim 14   , wherein said altering comprises compressing said fluid chamber.  
     
     
         16 . The method of    claim 15   , wherein said damping comprises compressing said fluid chamber.  
     
     
         17 . The method of    claim 15   , wherein said compressing is performed substantially simultaneously.  
     
     
         18 . The method of    claim 17   , wherein said compressing is performed sequentially.  
     
     
         19 . The method of    claim 14   , wherein said altering comprises electrically actuating a first piece of piezoelectric material, and wherein said damping comprises electrically actuating a second piece of piezoelectric material.  
     
     
         20 . The method of    claim 19   , wherein said actuating a first piece of piezoelectric material and actuating a second piece of piezoelectric material are performed substantially simultaneously.  
     
     
         21 . A droplet dispensing apparatus comprising: 
 a fluid chamber;    a first means for altering the volume of said fluid chamber; and    a second means for altering the volume of said fluid chamber, wherein said second means additionally comprises means for damping a fluid response to said first means.    
     
     
         22 . The droplet dispenser of    claim 21   , wherein said first and said second volume altering means comprise piezoelectric material.  
     
     
         23 . The droplet dispensing apparatus of    claim 22   , additionally comprising a driver circuit connected in parallel to said first and said second piezoelectric means.  
     
     
         24 . A method of making a droplet deposition device comprising: 
 positioning a first actuator proximate to an ejection nozzle of a fluid chamber;    positioning a second actuator farther from said ejection nozzle than said first actuator; and    connecting both of said actuators to a driver.    
     
     
         25 . The method of    claim 24   , wherein said positioning comprises substantially surrounding a glass capillary with cylindrical piezoelectric actuators.  
     
     
         26 . The method of    claim 25   , wherein said connecting comprises connecting said piezoelectric actuators in parallel to a voltage source.  
     
     
         27 . A droplet dispensing apparatus comprising: 
 a fluid chamber;    a first piezoelectric means for altering the volume of said fluid chamber; and    a second piezoelectric means for damping a fluid response to said altering.