Delivery of metered amounts of liquid materials

Abstract

Techniques for the delivery of metered amounts of liquid material include the use of a pin, such as an optical fiber. A sample of the liquid material may be placed on the tip of the pin for delivery to a target area, such as a specific location on a microarray, in a contactless manner. Light transmitted through the pin may be detected to facilitate accurate measuring of the pin's position.

1 . A method of depositing a metered drop of liquid onto a target area of a surface comprising: 
 moving a pin having a tip downwardly toward a target area;    causing the metered drop of liquid to adhere to the tip of the pin as the pin moves toward the target area;    sensing when the tip containing the drop is approximately a predetermined depositing distance above the target area; and    vibrating the pin to separate the drop of liquid material from the tip, whereupon the drop is deposited onto the target area, and the pin remains out of contact with said surface, wherein said depositing method is controlled by a programmed processor.    
   
   
       2 . The method of  claim 1  wherein the pin is optically transmissive and wherein the step of sensing includes detecting an optical signal transmitted upwardly through the pin from said surface.  
   
   
       3 . The method of  claim 2  further comprising comparing a detected light signal transmitted through the pin with an expected light intensity to determine whether the drop of liquid is adhered to the tip of the pin.  
   
   
       4 . The method of  claim 1  further comprising horizontally positioning the pin over the target area prior to depositing the metered drop of liquid.  
   
   
       5 . The method of  claim 1  further comprising vertically positioning the pin over the target area prior to depositing the metered drop of liquid.  
   
   
       6 . The method of  claim 1  wherein vibrating comprises high frequency vibrations.  
   
   
       7 . The method of  claim 1  wherein the pin is moved downwardly through a bore containing a delivery port through which the metered drop of liquid is delivered into the bore in the path of the tip of the downwardly moving pin.  
   
   
       8 . An article comprising a computer-readable medium containing computer-executable instructions for causing a processor-controlled system to carry out the depositing process of  claim 1 .  
   
   
       9 . The article of  claim 8  further comprising instructions for causing the processor-controlled system to detect an optical signal transmitted upwardly through the pin from said surface.  
   
   
       10 . The article of  claim 9  further comprising instructions for causing the processor to determine the size of the metered drop of liquid utilizing said detected optical signal.  
   
   
       11 . The article of  claim 9  further comprising instructions for causing the processor to compare the detected optical signal with an expected light intensity to determine whether the drop of liquid is adhered to the tip of the pin.  
   
   
       12 . The article of  claim 8  further comprising instructions for causing the processor-controlled system to horizontally position the pin over the target area prior to depositing the metered drop of liquid.  
   
   
       13 . The article of  claim 8  further comprising instructions for causing the computer system to vertically position the pin over the target area prior to depositing the metered drop of liquid.