Microfabricated two-pin liquid sample dispensing system

Abstract

A two-pin liquid sample dispensing system is provided. The two-pin dispensing system comprises a pair of separately movable pins for holding a droplet of liquid therebetween. Each pin includes a tip spaced predetermined distance from the other pin to define a sample acquisition region. The pins acquire and hold a droplet of the liquid sample in the sample acquisition region formed in the space between the tips and apply the droplet to a selected sample handing system. The distance between the tips is variable to accommodate different liquid samples having varying physical properties and to vary the volume of the acquired droplet.

1 . A method of fabricating a liquid sample dispensing system, comprising: 
 providing a substrate;    applying a pattern to the substrate to define a holder, a first pin having a first tip and a second pin having a second tip spaced from the first tip to define a sample acquisition region; and    etching the substrate to remove excess portions of the substrate, thereby fabricating the liquid sample dispensing system.    
   
   
       2 . The method of  claim 1 , wherein the substrate comprises a silicon wafer.  
   
   
       3 . The method of  claim 1 , wherein the substrate comprises a glass plate.  
   
   
       4 . The method of  claim 1 , further comprising the step of applying a chemical coating to at least one of the first pin and the second pin.  
   
   
       5 . The method of  claim 1 , wherein the first and second pins are movable relative to each other.  
   
   
       6 . The method of  claim 1 , further comprising the step of coupling an actuator to the etched substrate for varying a separation distance between the first tip and the second tip.  
   
   
       7 . The method of  claim 1 , further comprising the step of coupling a sensor to the etched substrate for sensing the separation distance between the first tip and the second tip.  
   
   
       8 . The method of  claim 1 , further comprising the step of coupling a sensor to the etched substrate for measuring the physical properties of a liquid sample held in the sample acquisition region.  
   
   
       9 . The method of  claim 8 , further comprising the step of coupling an actuator to the etched substrate, wherein the actuator varies the separation distance in response to the measurement of the physical properties.  
   
   
       10 . The method of  claim 1 , wherein the pattern includes a driver for moving the first pin relative to the second pin.  
   
   
       11 . The method of  claim 1 , wherein the first pin and the second pin have a length of about five millimeters.  
   
   
       12 . The method of  claim 1 , wherein the sample acquisition region has a volume between about 6.25 nanoliters and about 31.5 nanoliters.  
   
   
       13 . The method of  claim 1 , wherein an array of liquid sample dispensing systems is formed on a single substrate.  
   
   
       14 . A method of microfabricating a liquid sample dispensing system, comprising the steps of: 
 providing a silicon wafer;    applying a pattern to the silicon wafer to define a holder, a first pin having a first tip and a second pin having a second tip spaced from the first tip to define a sample acquisition region; and    etching the silicon wafer to remove excess portions of the substrate, thereby fabricating the liquid sample dispensing system.    
   
   
       15 . The method of  claim 1 , wherein the silicon wafer has dimensions of about one square centimeter.  
   
   
       16 . The method of  claim 1 , wherein an array of liquid sample dispensing systems is formed on a single silicon wafer.  
   
   
       17 . A method of fabricating a liquid sample dispensing system, comprising: 
 providing a substrate;    applying a pattern to the substrate to define a holder and a first pin having a first tip defining a sample acquisition region;    etching the substrate to remove excess portions of the substrate, thereby fabricating the liquid sample dispensing system; and    applying a chemical coating to the first pin.    
   
   
       18 . The method of  claim 17 , wherein the chemical coating comprises one of a hydrophobic material and a hydrophilic material.  
   
   
       19 . The method of  claim 17 , wherein the chemical coating is applied in a predetermined pattern determined by a mask used in applying the chemical coating to the tip.  
   
   
       20 . The method of  claim 17 , wherein pattern also defines a second tip that is etched in the substrate spaced from the first tip to define the sample acquisition region.