Surface Tension Controlled Valves

Abstract

The present teachings relate to surface tension controlled valves used for handling biological fluids. The valves controlled by optically actuating an electrowetting circuit.

What is claimed is: 
     
         1 . A surface tension controlled valving system for biological fluid, the system comprising:
 a channel connected to an internal volume for the valving system, wherein the internal volume is bound by an insulating layer resistant to the flow of the biological liquid, and wherein the channel is not resistant to the flow of the biological liquid;   a photoconductive material coupled to the insulating layer;   an electrode coupled to the photoconductive material and configured to electrically couple with the insulating layer through the photoconductive material; and   a power source electrically coupled to the electrode, wherein the power source is configured to provide an electrical potential difference across the insulating layer,   wherein the photoconductive material is activatable by directed light to provide the electrical potential difference across the insulating layer, and wherein the electrical potential difference is configured to reduce the resistance of the insulating layer to the flow of the biological liquid.   
     
     
         2 . The system according to  claim 1 , further comprising a conductive layer between the insulating layer and the photoconductive material. 
     
     
         3 . The system according to  claim 1 , wherein the biological liquid is an electrolyte. 
     
     
         4 . The system according to  claim 1 , wherein the channel is connected to a reservoir. 
     
     
         5 . The system according to  claim 4 , wherein the valve controls the flow of the biological liquid from the first reservoir to a second reservoir. 
     
     
         6 . The system according to  claim 4 , wherein said reservoir is chosen from wells and channels. 
     
     
         7 . The system according to  claim 1 , wherein the insulating material is resistant to the flow of the biological liquid because it is hydrophobic. 
     
     
         8 . The system according to  claim 1 , wherein the resistance of insulating material to the flow of the biological liquid is lowered because the insulating material is hydrophilic when activated. 
     
     
         9 . A device for biological fluid handling, the device comprising:
 a valve configured for light activation;   a channel connected to an internal volume of the valve, wherein the internal volume is bound by an insulating layer resistant to the flow of the biological liquid, and wherein the channel is not resistant to the flow of the biological liquid;   a photoconductive material coupled to the insulating layer;   an electrode coupled to the photoconductive material and configured to electrically couple with the insulating layer through the photoconductive material;   a power source electrically coupled to the electrode, wherein the power source is configured to provide an electrical potential difference across the insulating material; and   a light source configured to activate the photoconductive material thereby providing the electrical potential difference across the insulating layer,   wherein the electrical potential difference is configured to reduce the resistance of the insulating layer to the flow of the biological liquid.   
     
     
         10 . The device according to  claim 9 , wherein the light source is chosen from collimated light sources. 
     
     
         11 . The device according to  claim 10 , wherein the collimated light source is chosen from lasers, lamps, and light emitting diodes. 
     
     
         12 . The device according to  claim 9 , wherein the light source is directed over a portion of the photoconductive material by an array of microfabricated mirrors. 
     
     
         13 . The device according to  claim 9 , wherein the light source is a laser beam, and the laser beam is directed over a portion of the photoconductive material by a galvo-mirror. 
     
     
         14 . The device according to  claim 9 , wherein the light source is configured to direct a beam of light through the insulating layer and through the biological liquid to reach the photoconductive material. 
     
     
         15 . The device according to  claim 9 , wherein the light source is configured to direct a beam of light to the photoconductive material substantially axially. 
     
     
         16 . The device according to  claim 9 , wherein the channel is configured to provide a waveguide for the light. 
     
     
         17 . The device according to  claim 16 , wherein walls of the channel are the waveguide. 
     
     
         18 . The device according to  claim 16 , wherein the channel is the waveguide. 
     
     
         19 . A device for biological fluid handling, the device comprising:
 means for providing the biological fluid to a valving means, wherein the means for providing the biological fluid is not resistant to the flow of the biological liquid, and wherein the valving means is resistant to the flow of the biological liquid;   means for electrowetting the valving means to reduce the resistance of the valving means to the flow of the biological liquid; and   means for optically activating the means for electrowetting.   
     
     
         20 . The device according to  claim 19 , wherein the means for optically activating comprises means for selectively positioning light onto a portion of the valving means.