Droplet-based surface modification and washing

Abstract

The present invention relates to droplet-based surface modification and washing. According to one embodiment, a method of splitting a droplet is provided, the method including providing a droplet microactuator including a droplet including one or more beads and immobilizing at least one of the one or more beads. The method further includes conducting one or more droplet operations to divide the droplet to yield a set of droplets including a droplet including the one or more immobilized beads and a droplet substantially lacking the one or more immobilized beads.

1 - 23 . (canceled) 
     
     
         24 . A droplet microactuator, comprising:
 (a) a first substrate and a second substrate, the second substrate arranged relative to the first substrate and spaced from the surface of the first substrate by a distance sufficient to define a space between the first substrate, wherein the space comprises a filler fluid;   (b) electrodes arranged on one or both of the first substrate and second substrate and configured for manipulating a droplet on a surface thereof;   (c) one or more reservoirs disposed at one of the first substrate and second substrate; and   (d) one or more input ports disposed at one of the first substrate and second substrate.   
     
     
         25 . The droplet microactuator of  claim 24  wherein one or more of the reservoirs comprise one or more waste reservoirs. 
     
     
         26 . The droplet microactuator of  claim 25  wherein the one or more waste reservoirs comprise a waste product. 
     
     
         27 . The droplet microactuator of  claim 24  wherein one or more of the reservoirs comprise one or more collection reservoirs. 
     
     
         28 . The droplet microactuator of  claim 24  wherein one or more of the reservoirs comprise one or more input reservoirs. 
     
     
         29 . The droplet microactuator of  claim 28  wherein the one or more input reservoirs are in fluid communication with one or more input ports and an interior volume of the droplet microactuator. 
     
     
         30 . The droplet microactuator of  claim 28  wherein the one or more input reservoirs are in direct fluid communication with one or more input ports and an interior volume of the droplet microactuator. 
     
     
         31 . The droplet microactuator of  claim 28  wherein the one or more input reservoirs are adjacent to one or more input ports suitable for introduction of a fluid from an exterior of the droplet microactuator into the one or more input reservoirs. 
     
     
         32 . The droplet microactuator of  claim 28  wherein the one or more input reservoirs comprise one or more openings configured to enable fluid communication with the interior volume of the droplet microactuator for dispensing of droplets into the interior volume. 
     
     
         33 . The droplet microactuator of  claim 32  wherein the one or more openings are configured to permit fluid to flow or be transported into the interior volume of the droplet microactuator onto a path or network of the electrodes. 
     
     
         34 . The droplet microactuator of  claim 28  wherein the one or more input reservoirs comprise one or more vents. 
     
     
         35 . The droplet microactuator of  claim 34  wherein the one or more vents are configured for permitting displacement of filler fluid from the one or more input reservoirs as fluid is introduced into or removed from the one or more input reservoirs. 
     
     
         36 . The droplet microactuator of  claim 28  wherein the one or more input reservoirs comprise one or more well walls defining an interior space and an opening. 
     
     
         37 . The droplet microactuator of  claim 36  wherein the interior space is at least partially isolated by the well walls from the remainder of the interior of the droplet microactuator. 
     
     
         38 . The droplet microactuator of  claim 36  wherein the one or more input reservoirs comprise one or more planar control electrodes disposed in at least one of the first substrate and second substrate and adjacent to or within the interior space defined by the well walls. 
     
     
         39 . The droplet microactuator of  claim 38  wherein the one or more planar control electrodes are configured such that upon activation of the one or more planar control electrodes during droplet dispensing in the presence of a fluid a pull force is exerted on the fluid in a direction which is generally opposite to the direction of droplet dispensing. 
     
     
         40 . The droplet microactuator of  claim 36  wherein the well walls are formed by protrusions from the first substrate or second substrate. 
     
     
         41 . The droplet microactuator of  claim 36  wherein the well walls are formed by deposition of a wall-forming material on a surface of the first substrate or second substrate. 
     
     
         42 . The droplet microactuator of  claim 41  wherein the wall-forming material comprises one of a soldermask material or polymeric gasket material. 
     
     
         43 . The droplet microactuator of  claim 36  wherein the well walls comprise one or more openings configured for enabling dispensing of droplets into the interior volume of the droplet microactuator. 
     
     
         44 . The droplet microactuator of  claim 28  further comprising a source of continuous or semi-continuous sample or reagent flow, wherein the source is coupled in fluid communication with one or more of the input ports. 
     
     
         45 . The droplet microactuator of  claim 28  wherein the one or more input reservoirs are loaded with reagents for conducting biochemical reactions on a sample. 
     
     
         46 . The droplet microactuator of  claim 45  wherein the reagents for conducting biochemical reactions comprise one or more of reagents for use in nucleic acid amplification protocols, affinity-based assay protocols, sequencing protocols, and protocols for analyses of biological fluids. 
     
     
         47 . The droplet microactuator of  claim 45  wherein the regents and samples are stored in one of reservoirs located on the droplet microactuator and in reservoirs or containers located off the droplet microactuator. 
     
     
         48 . The droplet microactuator of  claim 47  wherein the reservoirs or containers located off the droplet microactuator comprises one or more cartridges. 
     
     
         49 . A method of dispensing a droplet into an interior volume of a droplet microactuator, the method comprising:
 (a) providing a droplet microactuator, comprising:
 (i) a first substrate and a second substrate, the second substrate arranged relative to the first substrate and spaced from the surface of the first substrate by a distance sufficient to define a space between the first substrate, wherein the space comprises a filler fluid; 
 (ii) electrodes arranged on one or both of the first substrate and second substrate and configured for manipulating a droplet on a surface thereof; 
 (iii) one or more reservoirs at one of the first substrate and second substrate; and 
 (iv) one or more input ports disposed at one of the first substrate and second substrate; 
   (b) providing a quantity of a fluid sample to one of the one or more reservoirs; and   (c) dispensing a droplet from the provided fluid sample into the interior volume of the droplet microactuator.   
     
     
         50 . The method of  claim 49  wherein the one or more reservoirs comprise one or more input reservoirs. 
     
     
         51 . The method of  claim 50  wherein the droplet is dispensed from the one or more input reservoirs onto a path or network of the electrodes in the interior volume of the droplet microactuator. 
     
     
         52 . The method of  claim 50  wherein the one or more reservoirs comprising the fluid sample, further comprises one or more well walls defining an interior space and an opening. 
     
     
         53 . The method of  claim 52  wherein the interior space defined by the well walls is at least partially isolated by the well walls from the remainder of the interior volume of the droplet microactuator. 
     
     
         54 . The method of  claim 50  wherein the one or more input reservoirs are adjacent to a port suitable for introduction of the fluid from an exterior of the droplet microactuator into the reservoir. 
     
     
         55 . The method of  claim 53  wherein the well walls further comprise one or more openings configured to enable fluid communication with the interior volume of the droplet microactuator for dispensing of the droplet into this interior volume. 
     
     
         56 . A method of delivering a droplet to a reservoir, the method comprising:
 (a) providing a droplet microactuator, comprising:
 (i) a first substrate and a second substrate, the second substrate arranged relative to the first substrate and spaced from the surface of the first substrate by a distance sufficient to define a space between the first substrate, wherein the space comprises a filler fluid; 
 (ii) electrodes arranged on one or both of the first substrate and second substrate and configured for manipulating a droplet on a surface thereof; 
 (iii) one or more reservoirs at one of the first substrate and second substrate; 
 (iv) one or more input ports disposed in at least one of the first substrate and second substrate; and 
 wherein, the droplet is situated in the space between the first substrate and second substrate; 
   (b) transporting the droplet along a path or network of the electrodes; and   (c) releasing the droplet at an appropriate point along the path or network of the electrodes and allowing the droplet to float or sink, as applicable, to a target destination.   
     
     
         57 . The method of  claim 56  wherein the target destination comprises a designated reservoir. 
     
     
         58 . The method of  claim 57  wherein the reservoir comprises at least one of a waste reservoir and collection reservoir. 
     
     
         59 . The method of  claim 57  further comprising removing the delivered droplet from the droplet microactuator. 
     
     
         60 . The method of  claim 57  wherein the droplet delivered to the reservoir comprises reactant. 
     
     
         61 . The method of  claim 59  wherein the droplet delivered to the reservoir comprises amplified nucleic acid. 
     
     
         62 . The method of  claim 56  wherein the filler fluid is selected to have a particular density relative to the droplet to control or exploit buoyancy forces acting upon the droplet. 
     
     
         63 . A method of conducting a biochemical reaction, the method comprising:
 (a) providing a droplet microactuator, comprising:
 (i) a first substrate and a second substrate, the second substrate arranged relative to the first substrate and spaced from the surface of the first substrate by a distance sufficient to define a space between the first substrate, wherein the space comprises a filler fluid; 
 (ii) electrodes arranged on one or both of the first substrate and second substrate and configured for manipulating a droplet on a surface thereof; 
 (iii) one or more reservoirs at one of the first substrate and second substrate, the one or more reservoirs comprising at least one waste reservoir; 
 (iv) one or more input ports disposed in at least one of the first substrate and second substrate; and 
 wherein, the droplet is situated in the space between the first substrate and second substrate; 
   (b) conducting a biochemical reaction, wherein the biochemical reaction produces a waste product; and   (c) transporting the waste product along a path or network of the electrodes to the waste reservoir.   
     
     
         64 . The method of  claim 62  wherein conducting the biochemical reaction comprises
 (a) loading a sample and one or more reagents associated with the desired biochemical reaction onto the droplet microactuator; 
 (b) dispensing one or more sample droplets of the sample onto the electrodes; 
 (c) dispensing one or more reagent droplets onto the electrodes; 
 (d) transporting the one or more reagent droplets and/or one or more sample droplets such that the one or more reagent droplets interact with the one or more sample droplets; and 
 (e) detecting an effect of the interaction of the reagent droplet with the sample droplet.