Liquid dispensing devices and methods of controlling the same

Abstract

The present disclosure provides a method of dispensing liquid, and a liquid dispensing device. The method and device include a controller having a multi-phase droplet ejection cycle stored thereon. The multiphase droplet ejection cycle dispenses the droplet in two stages. Advantageously, this provides highly accurate droplets of very small volumes without the formation of satellite droplets.

What is claimed is: 
     
         1 . A method of dispensing fluid from a pump, wherein said pump comprises:
 a cylinder having an inlet port and an outlet port; and   a piston within said cylinder, wherein said piston has a linear speed along a longitudinal axis of said cylinder and a rotational speed around said longitudinal axis,   the method comprising the steps of:   dispensing a first volume of the fluid through said outlet port to form a pendant droplet in said outlet port;   dispensing a second volume of the fluid through said outlet port; and   ejecting a full droplet from said outlet port, wherein the volume of said full droplet is the sum of said first volume and said second volume.   
     
     
         2 . The method of  claim 1 , wherein said first volume is less than said second volume. 
     
     
         3 . The method of  claim 1  or  2 , wherein said first volume is greater than said second volume. 
     
     
         4 . The method of  claims 1  to  3 , wherein said dispensing steps comprise:
 during a first ejection phase, controlling said linear speed and said rotational speed to increase to a first linear set point and a first rotational set point, respectively, thereby forming said pendant droplet having said first volume at said outlet port; 
 during a filling phase, controlling said rotational speed to increase from said first rotational set point to a second rotational set point greater than said first rotational set point, and reducing said linear speed to zero, so that additional fluid is drawn through said inlet port into said cylinder; 
 during a dwell phase, controlling each of said rotational speed and said linear speed to reduce to zero; and 
 during a second ejection phase, increasing said rotational speed to a third rotational set point and said linear speed to a second linear set point, so that said second volume is passed through said outlet port. 
 
     
     
         5 . The method of  claims 1  to  4 , wherein said first rotational set point and said third rotational set point are equal. 
     
     
         6 . The method of  claim 4 , wherein said first volume is less than said second volume. 
     
     
         7 . The method of  claim 4 , wherein said first volume is greater than said second volume. 
     
     
         8 . The method of any of the preceding claims, wherein said dispensing steps comprise:
 during a first ejection phase, controlling said linear speed and said rotational speed to increase to a first linear set point and a first rotational set point, and forming said pendant droplet having said first volume at said outlet port;   during a filling phase, controlling said rotational speed to increase from said first rotational set point to a second rotational set point greater than said first rotational set point, and reducing said linear speed to zero, so that additional fluid is drawn into said cylinder; and   during a second ejection phase, increasing said rotational speed to a third rotational set point and said linear speed to a second linear set point, so that said second volume is passed through said outlet port.   
     
     
         9 . The method of  claim 8 , wherein said first rotational set point and said third rotational set point are equal. 
     
     
         10 . The method of  claim 8 , wherein said first volume is less than said second volume. 
     
     
         11 . The method of  claim 8 , wherein said first volume is greater than said second volume. 
     
     
         12 . The method of any of the proceeding claims wherein the full droplet comprises one or more pharmaceutically or cosmetically acceptable agents. 
     
     
         13 . The method of  claim 12  wherein the full droplet is dispensed onto a receiving medium. 
     
     
         14 . The method of  claim 13  wherein the receiving medium is a pharmaceutically acceptable tablet, or a receiving vial. 
     
     
         15 . A liquid dispensing device, comprising:
 a cylinder having an inlet port and an outlet port;   a piston within said cylinder, wherein said piston has a linear speed along a longitudinal axis of said cylinder and a rotational speed around said longitudinal axis; and   a controller having a multi-phase droplet ejection cycle stored thereon, said controller being operatively connected to said piston,   wherein said controller controls said linear speed and said rotational speed of said piston to eject a droplet of the liquid from said outlet port in two distinct phases.   
     
     
         16 . The liquid dispensing device of  claim 15 , wherein said droplet has a droplet volume that is the sum a first volume and a second volume, and said controller controls said piston to eject said first volume during a first of said two distinct phases, and to eject a second volume during a second of said two distinct phases. 
     
     
         17 . The liquid dispensing device of  claim 15  or  16 , further comprising a linear encoder in electrical communication with said controller, wherein said controller controls a linear actuator to adjust a stroke length of said piston within said cylinder, thereby adjusting said droplet volume. 
     
     
         18 . The liquid dispensing device of  claims 15  to  17 , further comprising a circulation loop in fluid communication with said inlet port of said cylinder, wherein the fluid is circulated continuously within said circulation loop.