Microfluidic devices with flexible optically transparent electrodes

Abstract

Microfluidic devices in which electrokinetic mechanisms move droplets of a liquid or particles in a liquid are described. The devices include at least one electrode that is optically transparent and/or flexible.

1 - 28 . (canceled) 
     
     
         29 . An electrokinetic microfluidic device, comprising:
 (a) a bottom channel configured to hold a liquid, comprising:
 (i) a first wall comprising a transparent flexible mesh electrode, wherein the first wall is configured to repeatedly deform without said mesh electrode losing conductivity after deforming 30 or more times, wherein the deformation closes off the bottom channel beneath the mesh electrode; and 
 (ii) a second wall opposite said first wall comprising an electrode; 
 (iii) wherein said first wall defines an upper surface and said second wall defines a lower surface of at least a portion of said bottom channel; and 
   (b) a top channel overlying at least a region of said bottom channel, wherein said top channel is formed with a flexible material; and   (c) wherein a membrane valve is formed at said region where said top channel and said bottom channel overlap.   
     
     
         30 . The device of  claim 29 , wherein said device is a dielectrophoresis (DEP) device. 
     
     
         31 . The device of  claim 29 , wherein said second wall comprises an array of fixed electrodes. 
     
     
         32 . The device of  claim 29 , wherein said second wall of said bottom channel comprises a photoconductive layer. 
     
     
         33 . The device of  claim 32 , wherein said device is an optoelectronic tweezers (OET) device. 
     
     
         34 . The device of  claim 32 , wherein said photoconductive layer of said second wall of said bottom channel comprises a hydrophobic coating on said lower surface of said portion of said bottom channel. 
     
     
         35 . The device of  claim 34 , wherein said device is an optoelectronic wetting (OEW) device. 
     
     
         36 . The device of  claim 29 , wherein said flexible material forming said top channel is transparent. 
     
     
         37 . The device of  claim 36 , wherein said flexible material is a polymer or silicone. 
     
     
         38 . The device of  claim 37 , wherein said flexible material is polydimethylsiloxane (PDMS). 
     
     
         39 . The device of  claim 29 , wherein said transparent flexible mesh electrode is a thin film. 
     
     
         40 . The device of  claim 29 , wherein said transparent flexible mesh electrode comprises nanoparticles. 
     
     
         41 . The device of claim  292 , wherein said nanoparticles comprise nanotubes or nanowires. 
     
     
         42 . The device of  claim 29 , wherein said transparent flexible mesh electrode comprises clusters of nanoparticles. 
     
     
         43 . The device of  claim 29 , wherein said transparent flexible mesh electrode comprises a single-walled nanotube material embedded within polydimethylsiloxane. 
     
     
         44 . The device of  claim 29 , further comprising a biasing voltage source disposed between said transparent flexible mesh electrode and said second wall. 
     
     
         45 . The device of  claim 29 , wherein the bottom channel height is about 19 microns. 
     
     
         46 . A method of manipulating a droplet of a liquid or particles in a liquid in a microfluidic device comprising a bottom channel and a top channel, comprising:
 (a) introducing a liquid or particles in a liquid to said bottom channel of said microfluidic device, said bottom channel comprising an upper wall comprising a transparent flexible mesh electrode configured to repeatedly deform without said mesh electrode losing its conductivity;   (b) applying an electrokinetic force to said liquid or said particles in said liquid in said bottom channel; and   (c) closing a membrane valve formed at a region of overlap between said bottom channel and said top channel by applying pressure to the top channel.   
     
     
         47 . A method of moving particles in a liquid in a microfluidic device, comprising:
 (a) introducing particles in a liquid to a bottom channel of said microfluidic device, wherein said microfluidic device comprises:
 (i) a first wall comprising a transparent flexible mesh electrode, said first wall configured to repeatedly deform without said mesh electrode losing its conductivity, and a second wall opposite said first wall comprises an electrode, wherein said first wall defines an upper surface and said second wall defines a lower surface of at least a portion of said bottom channel; and 
 (ii) a first top channel, a second top channel, and a third top channel overlying a respective first region, a second region, and a third region of said bottom channel, wherein said first, second, and third top channels are formed with a flexible material, and further wherein a first membrane valve, a second membrane valve, and a third membrane valve are formed at said respective first, second and third regions; and 
   (b) applying pressure consecutively to said first, second, and third membrane valves, thereby moving said particles in said liquid in said bottom channel.   
     
     
         48 . The method of  claim 47 , further comprising applying an electrokinetic force to said particles in said liquid in said channel. 
     
     
         49 . The method of  claim 47 , wherein said electrokinetic force is a dielectrophoretic force or an electrowetting force.