Droplet dispensing system

Abstract

A droplet dispensing system for forming and dispensing droplets of a liquid sample is provided. The droplet dispensing system is fabricated on the tip of a dispensing pin. The tip of the dispensing pin includes a droplet ejection nozzle, a filling channel, a chamber and an actuator for ejecting droplets on demand. The system further includes a holder for mounting the dispensing pin. The holder also contains a control circuit for activating the actuator.

1 . A droplet dispensing system, comprising: 
 a first pin having a tip; and    a dispensing pin having a tip and spaced adjacent to the first pin so as to form a sample filling channel between the first and second pin, the dispensing pin tip having a sample chamber located in fluid communication with the sample filling channel, an ejection nozzle for ejecting a droplet from the sample chamber, and an actuator for triggering formation and ejection of a droplet from the ejection nozzle.    
     
     
         2 . The droplet dispensing system of  claim 1 , wherein the first pin and the second pin are movable relative to each other, so as to vary the size of the sample filling channel.  
     
     
         3 . The sample dispensing system of  claim 1 , wherein the first pin tip and the dispensing pin tip have a diameter between about 0.5 millimeters and about 5 millimeters.  
     
     
         4 . The sample dispensing system of  claim 3 , wherein the dispensing pin tip diameter is about 1.0 millimeters.  
     
     
         5 . The sample dispensing system of  claim 1 , further comprising a holder for mounting the first pin and the dispensing pin.  
     
     
         6 . The sample dispensing system of  claim 5 , wherein the holder contains a control circuit for activating the actuator.  
     
     
         7 . The sample dispensing system of  claim 6 , further comprising an electrical connector for providing an electrical connection between the control circuit and the actuator.  
     
     
         8 . The sample dispensing system of  claim 1 , wherein the first pin and the dispensing pin are formed from a silicon wafer.  
     
     
         9 . The sample dispensing system of  claim 1 , wherein the filling channel includes a filling nozzle for introducing a liquid sample to the filling channel.  
     
     
         10 . The sample dispensing system of  claim 9 , wherein the filling nozzle extends beyond the ejection nozzle, such that when the first pin tip and the dispensing pin tip are dipped into a reservoir, the filling nozzle is immersed in a liquid supply without immersing the ejection nozzle of the dispensing tip.  
     
     
         11 . The sample dispensing system of  claim 1 , wherein the droplet ejection nozzle has an ejection port, said ejection port having a diameter between about thirty and about fifty microns.  
     
     
         12 . The sample dispensing system of  claim 1 , wherein the actuator comprises a piezoelectric film affixed to a side wall of the sample chamber.  
     
     
         13 . The sample dispensing system of  claim 1 , wherein the actuator comprises an electromechanical assembly for effecting ejection of a droplet from the ejection nozzle.  
     
     
         14 . The sample dispensing system of  claim 1 , wherein the actuator comprises a magnetic assembly for effecting ejection of a droplet from the ejection nozzle.  
     
     
         15 . The sample dispensing system of  claim 1 , wherein the actuator comprises a thermoelectric assembly for effecting ejection of a droplet from the ejection nozzle.  
     
     
         16 . The sample dispensing system of  claim 1 , wherein the filling channel and the sample chamber have a combined volume of between about 1 nanoliter and about 10 nanoliters.  
     
     
         17 . A method of forming and dispensing droplets of a liquid sample, comprising: 
 providing a droplet dispensing system comprising a pin having a tip, said tip forming a filling channel for filling the tip with a predetermined volume of liquid sample, a sample chamber for holding a predetermined volume of liquid sample, an ejection nozzle and an actuator for effecting formation of a droplet from said volume of liquid sample; and    activating the actuator to produce a droplet of liquid sample at the sample ejection nozzle.    
     
     
         18 . The method of  claim 17 , further comprising the step of filling the tip with a liquid sample prior to the step of activating the actuator.  
     
     
         19 . The method of  claim 18 , wherein the step of filling the tip comprises the step of immersing the tip in a reservoir containing a supply of liquid sample.  
     
     
         20 . The method of  claim 19 , wherein the step of immersing comprises immersing an intake port of the filling channel without immersing the ejection nozzle.  
     
     
         21 . The method of  claim 19 , wherein the step of filling comprises activating the actuator to pump a liquid sample into the filling channel.  
     
     
         22 . The method of  claim 17 , wherein the step of activating the actuator comprises transmitting a droplet ejection signal to the actuator from a control circuit.  
     
     
         23 . The method of  claim 17 , further comprising the step of directing the droplet of liquid sample to a fluid interface port.  
     
     
         24 . A sample dispensing system, comprising: 
 a dispensing pin having a tip;    a substantially U-shaped fluid path formed in the tip of the dispensing pin for conveying a liquid sample; and    an actuator coupled to a portion of the fluid path for forming a droplet of the liquid sample upon activation of the actuator.    
     
     
         25 . The sample dispensing system of  claim 24 , wherein said fluid path comprises: 
 a sample chamber for holding a predetermined volume of sample,    a sample filling channel in fluid communication with the sample chamber for loading a liquid sample into the sample chamber; and    a droplet ejection port in fluid communication with the sample chamber for ejecting a droplet of the liquid sample from the sample chamber.    
     
     
         26 . The sample dispensing system of  claim 25 , wherein the droplet ejection port forms a nozzle.  
     
     
         27 . A sample dispensing system, comprising: 
 a holder; and    a dispensing pin having a first end coupled to the holder and a second end forming a tip, wherein the tip includes a sample chamber formed in the tip for holding a predetermined volume of sample, a sample filling channel in fluid communication with the sample chamber for loading a liquid sample into the sample chamber, and a droplet ejection nozzle in fluid communication with the sample chamber for ejecting a droplet of the liquid sample from the sample chamber.