Droplet Actuator Loading and Target Concentration

Abstract

A droplet actuator and method of providing a droplet comprising an target substance on the droplet actuator, and including discrete flow and continuous flow functionality. Discrete flow function is controlled by electrodes arranged for conducting droplet operations on a substrate surface. The continuous flow function includes a fluid path arranged for flowing a fluid therethrough. The discrete flow and continuous flow functions may be by a barrier, including a second fluid path through the barrier. The continuous flow function may include a capture surface comprising a component having an affinity for the target substance. Methods of the invention may include flowing a fluid comprising the target substance through the fluid path; capturing the target substance on the capture surface; and forming a droplet in the discrete flow region via the second fluid path and the electrodes comprising the captured target substance.

1 - 51 . (canceled) 
     
     
         52 . A method of providing a droplet on a droplet actuator, the method comprising:
 (a) providing a droplet actuator comprising a substrate comprising:
 (i) a discrete flow section comprising electrodes arranged for conducting droplet operations on a substrate surface; 
 (ii) a continuous flow section comprising a fluid path arranged for flowing a fluid therethrough, and separated from the discrete flow section by a barrier; 
 (iii) an opening in the barrier arranged relative to the electrodes such that a droplet from the fluid path passing through the opening comes into proximity to one or more of the electrodes; 
   (b) flowing a filler fluid comprising the droplet through the fluid path;   (c) causing the droplet to pass through the opening into proximity with one or more of the electrodes to permit one or more electrode mediated droplet operations to be performed on the droplet.   
     
     
         53 . The method of  claim 52  further comprising recirculating the filler fluid through the fluid path via a recirculation path. 
     
     
         54 . The method of  claim 53  wherein the fluid path and/or the recirculation path comprises a filler fluid reservoir. 
     
     
         55 . The method of  claim 53  wherein the recirculation is facilitated using a pump to cause filler fluid to flow through the recirculation path. 
     
     
         56 . The method of  claim 52  wherein the droplet comprises a sample droplet. 
     
     
         57 . The method of  claim 52  wherein the droplet comprises a reagent droplet. 
     
     
         58 . The method of  claim 52  wherein step 52(c) is mediated by one or more of the electrodes. 
     
     
         59 . The method of  claim 52  wherein step 52(c) is mediated by a pressure forcing the droplet through the opening. 
     
     
         60 . The method of  claim 52  wherein the filler fluid is a low viscosity oil. 
     
     
         61 . The method of  claim 52  wherein the filler fluid is silicone oil.