Bead Manipulation Techniques

Abstract

The invention provides a method of redistributing magnetically responsive beads in a droplet. The method may include conducting on a droplet operations surface one or more droplet operations using the droplet without removing the magnetically responsive beads from the region of the magnetic field. The droplet operations may in some cases be electrode-mediated. The droplet operations may redistribute and/or circulate the magnetically responsive beads within the droplet. In some cases, the droplet may include a sample droplet may include a target analyte. The redistributing of the magnetically responsive beads may cause target analyte to bind to the magnetically responsive beads. In some cases, the droplet may include unbound substances in a wash buffer. The redistributing of the magnetically responsive beads causes unbound substances to be freed from interstices of an aggregated set or subset of the magnetically responsive beads.

1 - 46 . (canceled) 
     
     
         47 . An apparatus comprising:
 a first substrate comprising:
 an electrowetting (EW) configuration comprising a droplet operations surface; and 
 a dielectrophoresis (DEP) configuration comprising a surface, 
 wherein the DEP configuration is disposed adjacent to the EW configuration such that the surface of the DEP configuration is adjacent to the droplet operations surface. 
   
     
     
         48 . The apparatus of  claim 47  wherein the droplet operations surface comprises one or more electrodes arranged for conducting one or more droplet operations on the surface. 
     
     
         49 . The apparatus of  claim 48  wherein the one or more electrodes comprise electrowetting electrodes. 
     
     
         50 . The apparatus of  claim 48  wherein the one or more electrodes comprise a path of electrowetting electrodes. 
     
     
         51 . The apparatus of  claim 48  further comprising a dielectric layer atop the one or more electrodes. 
     
     
         52 . The apparatus of  claim 47  wherein the DEP configuration comprises a DEP electrode configuration comprising one or more electrodes. 
     
     
         53 . The apparatus of  claim 52  wherein the DEP electrode configuration is arranged for attracting and/or trapping one or more particles in a droplet situated on the droplet operations surface. 
     
     
         54 . The apparatus of  claim 52  further comprising a dielectric layer atop the one or more electrodes. 
     
     
         55 . The apparatus of  claim 47  wherein the apparatus further comprises a second substrate separated from the droplet operations surface to form a droplet operations gap. 
     
     
         56 . The apparatus of  claim 55  wherein the second substrate comprises a DEP electrode configuration. 
     
     
         57 . The apparatus of  claim 56  further comprising a plurality of EW configurations and/or a plurality of DEP configurations. 
     
     
         58 . A method comprising:
 providing an apparatus of  claim 47 ; and   dispensing a droplet onto the droplet operations surface or the surface of the DEP configuration, wherein the droplet optionally comprises one or more particles.   
     
     
         59 . The method of  claim 58  wherein the one or more particles, if provided, is selected from the group consisting of beads, cells, and combinations thereof. 
     
     
         60 . The method of  claim 58  further comprising conducting one or more droplet operations to transport the droplet along the droplet operations surface or the surface of the DEP configuration. 
     
     
         61 . The method of  claim 58  further comprising conducting one or more droplet operations to transport the droplet along the droplet operations surface from the EW configuration to the DEP configuration, or along the surface of the DEP configuration from the DEP configuration to the EW configuration. 
     
     
         62 . The method of  claim 61  further comprising trapping at least one of the one or more particles, if provided, at the DEP configuration. 
     
     
         63 . A method of  claim 62  further comprising conducting one or more droplet operations to transport the droplet without the trapped at least one of the one or more particles along the droplet operations surface away from the DEP configuration. 
     
     
         64 . A method of  claim 58  further comprising conducting one or more droplet operations to split the droplet into two daughter droplets. 
     
     
         65 . The method of  claim 64  wherein at least one of the daughter droplets comprises at least a subset of the one or more particles, if provided. 
     
     
         66 . The method of  claim 64  wherein at least one of the daughter droplets comprises all of the one or more particles, if provided.