High-performance, low-voltage electroosmotic pumps with molecularly thin nanomembranes

Abstract

Thin pnc-Si membranes operate as high-flow-rate EOPs at low applied voltages. In at least some instances, this may be due to the small electrical resistance presented by the membrane and high electric fields across the molecularly thin membrane. The normalized flow rates of some pnc-Si EOPs may be 20 times to several orders of magnitude higher than other low-voltage EOPs.

We claim: 
     
         1 . A micro-fluidics device comprising a micro-fluid input, a micro-fluid output and an electroosmotic pump in fluid communication with the micro-fluid input and output, the electroosmotic pump including a nano-porous membrane having a thickness of 2-100 nm, the electrosmotic pump configured to move a fluid through the nano-porous membrane from the micro-fluid input into the micro-fluid output. 
     
     
         2 . The micro-fluidics device of  claim 1 , wherein the nano-porous membrane includes pores having widths in the range of 2 nm-100 nm. 
     
     
         3 . The micro-fluidics device of  claim 1 , wherein the thickness of the nano-porous membrane is in the range of 5-40 nm. 
     
     
         4 . The micro-fluidics device of  claim 1 , wherein the nano-porous membrane is a nano-porous membrane comprising silicon. 
     
     
         5 . The micro-fluidics device of  claim 4 , wherein the nano-porous membrane is a nano-porous membrane comprising silicon nitride. 
     
     
         6 . The micro-fluidics device of  claim 1 , wherein the nano-porous membrane is a porous nanocrystaline silicon membrane. 
     
     
         7 . The micro-fluidics device of  claim 6 , wherein the electroosmotic pump comprises a substrate, a passage extending through the substrate, and the porous nanocrystaline silicon membrane being over the passage extending through the substrate. 
     
     
         8 . The micro-fluidics device of  claim 7 , further comprising a plurality of passages extending through the substrate and one or more porous nanocrystaline silicon membranes over the plurality of passages. 
     
     
         9 . The microfluidics device of  claim 7 , wherein the substrate comprises a silicon substrate. 
     
     
         10 . The micro-fluidics device of  claim 1 , wherein the electroosmotic pump is configured to move the fluid through the nano-porous membrane at an applied voltage between 10 mV and 50 V. 
     
     
         11 . The micro-fluidics device of  claim 1 , wherein the nano-porous membrane comprises a zeta potential of approximately -5 mV to -40 mV. 
     
     
         12 . The micro-fluidics device of  claim 1 , wherein the nano-porous membrane comprises a zeta potential of approximately 100 mV to -100 mV. 
     
     
         13 . The micro-fluidics device of  claim 1 , further comprising a fluid channel extending from the micro-fluid output, wherein the nano-porous membrane has an active area that is at least 25% of a cross-sectional area of the fluid channel. 
     
     
         14 . The micro-fluidics device of  claim 13 , wherein the active area is at least 75% of the cross-sectional area. 
     
     
         15 . A micro-fluidics device comprising a micro-fluid input, a micro-fluid output and an electroosmotic pump in fluid communication with the micro-fluid input and output, the electroosmotic pump including a nano-porous membrane having a thickness of 2-100 nm, the electrosmotic pump configured to move a fluid through the nano-porous membrane from the micro-fluid input into the micro-fluid output at a flow rate of 50-800 mL·min −1 ·cm −2 ·V −1 , wherein cm corresponds to an active area of the nano-porous membrane and V corresponds to a transmembrane voltage of the nano-porous membrane. 
     
     
         16 . The micro-fluidics device of  claim 15 , wherein the electrosmotic pump is configured to move the fluid through the nano-porous membrane from the micro-fluid input into the micro-fluid output at a flow rate of 100-500 mL·min-1·cm-2·V-1. 
     
     
         17 . A method of moving a fluid in a micro-fluidic device, the micro-fluidic device comprising a micro-fluid input, a micro-fluid output and an electroosmotic pump comprising a nano-porous membrane having a thickness of less than 100 nm in fluid communication with the micro-fluid input and output, the method comprising:
 applying a voltage of less than 50 V across the nano-porous membrane; and   in response to the applied voltage, moving a fluid through the nano-porous membrane at a normalized flow rate of 50-800 mL·min −1 ·cm −2 ·V −1 , wherein cm corresponds to an active area of the nano-porous membrane and V corresponds to a transmembrane voltage of the nano-porous membrane.   
     
     
         18 . The method of  claim 17 , wherein the nano-porous membrane includes pores having widths in the range of 2 nm-100 nm and the thickness of the nano-porous membrane is in the range of 5-40 nm. 
     
     
         19 . The method of  claim 17 , wherein applying the voltage comprises applying a voltage of less than 1 V across the nano-porous membrane. 
     
     
         20 . A micro-fluidics device comprising a fluid reservoir, a sample input, and an electroosmotic pump in fluid communication with the fluid reservoir and the sample input, the electroosmotic pump including a nano-porous membrane having a thickness of 2-100 nm, the electrosmotic pump configured to move a fluid from the fluid reservoir through the nano-porous membrane to move a sample from the sample input through a portion of the micro-fluidics device. 
     
     
         21 . A micro-fluidics device comprising an electroosmotic pump, a cooling fluid, a heat source, and a heat sink, the electroosmotic pump including a nano-porous membrane having a thickness of 2-100 nm, the electrosmotic pump configured to move the cooling fluid past the heat source and to the heat sink.