Controlling electrolytically generated gas bubbles in in-plane electroosmotic pumps

Abstract

An “in-plane” electroosmotic pump may reduce deterioration of performance due to electrolytic gas generation. By controlling the flow of gas generated at the electrodes, while allowing ionic current, the gas may be prevented from fouling the narrow slots which act as pumping channels.

1 . A method comprising: 
 controlling gases formed by an electrode of an electroosmotic pump while allowing the passage of liquid.    
   
   
       2 . The method of  claim 1  including surrounding the electrode with a membrane which passes ions but controls gases.  
   
   
       3 . The method of  claim 2  including surrounding said electrode with a proton exchange membrane.  
   
   
       4 . The method of  claim 3  including providing spacers between a tubular membrane and said electrode.  
   
   
       5 . The method of  claim 2  including providing a port to eject gases from within said membrane.  
   
   
       6 . The method of  claim 5  including providing a membrane over said port, which membrane passes gas but prevents liquid from passing.  
   
   
       7 . The method of  claim 6  including providing a membrane including Gortex® fabric.  
   
   
       8 . The method of  claim 1  including passing a liquid through a series of slots in said pump.  
   
   
       9 . The method of  claim 8  including forming a pair of reservoirs on either side of the series of slots in a semiconductor die.  
   
   
       10 . The method of  claim 9  including forming a sidewall around said reservoirs and forming a slot at the top of said sidewall to receive an electrode.  
   
   
       11 . An electroosmotic pump comprising: 
 a pair of electrodes;    a plurality of liquid passages between said electrodes; and    a sheath around at least one of said electrodes which sheath passes ions and reduces the passage of gas.    
   
   
       12 . The pump of  claim 11  wherein said sheath is a proton exchange membrane.  
   
   
       13 . The pump of  claim 11  including a semiconductor die with reservoirs formed therein, and passages formed between said reservoirs, said electrode positioned in one of said reservoir.  
   
   
       14 . The pump of  claim 13  including slots in said die to receive said electrode.  
   
   
       15 . The pump of  claim 12 , said sheath including a doubled tube of proton exchange membrane material surrounding said electrode.  
   
   
       16 . The pump of  claim 11  including spacers to space said sheath from said electrode.  
   
   
       17 . The pump of  claim 11  wherein said sheath is tubular and has a material which allows gas from within the sheath to pass outwardly of said pump while preventing liquid from within said sheath from passing through said material.  
   
   
       18 . The pump of  claim 17  wherein said material includes Gortex® brand fabric.  
   
   
       19 . The pump of  claim 17  wherein said material is positioned over said sheath on the outside of said pump.  
   
   
       20 . The pump of  claim 19  wherein said electrode passes through said material.  
   
   
       21 . The pump of  claim 19  wherein the passage of said electrode through said material is sealed with adhesive.  
   
   
       22 . A system comprising: 
 an integrated circuit;    a cooler associated with said circuit; and    an electroosmotic pump coupled to said cooler, said pump including an electrode covered by a sheath to pass ions and to control gas.    
   
   
       23 . The system of  claim 22  including a heat exchanger coupled to said pump.  
   
   
       24 . The system of  claim 22  wherein said cooler, said integrated circuit, and said pump are formed in one integrated circuit package.  
   
   
       25 . The system of  claim 24  wherein said sheath includes a proton exchange membrane.  
   
   
       26 . The system of  claim 25  wherein said sheath is a Nafion® tube.  
   
   
       27 . The system of  claim 22  including a semiconductor die with reservoirs formed therein, and slots formed between said reservoirs, and electrodes in said reservoirs.  
   
   
       28 . The system of  claim 22  including spacers to space said sheath from said electrode.  
   
   
       29 . The system of  claim 22  wherein said sheath is tubular and has a material which allows gas from within the sheath to pass outwardly of said pump while preventing liquid from within said sheath from passing through said material.  
   
   
       30 . The system of  claim 29  wherein said material includes Gortex® fabric.