Electrokinetic pump designs and drug delivery systems

Abstract

One embodiment of the present invention provides a piston assembly having a piston housing filled with an electrolyte; a housing within the piston housing that divides the piston housing into a first portion and a second portion, the housing having apertures, a shaft connecting the housing to a piston head outside of the piston housing; and a porous material inside of the housing in contact with the electrolyte. Additionally, there are provided a method for filling the delivery chamber with a delivery fluid by withdrawing the piston head from within the delivery chamber. Yet another embodiment provides a method for filling a fluid delivery assembly by withdrawing a shaft from within the fluid delivery assembly to simultaneously displace a moving pump element within the delivery chamber and bypass fluid around a housing in the pump chamber.

1 .- 28 . (canceled) 
     
     
         29 . A method for operating a fluid delivery system comprising:
 providing a delivery chamber having a piston assembly therein, wherein the piston assembly includes a pump housing having a pair of electrodes therein, a piston head outside of the pump housing and attached to a shaft extending through a wall in the pump housing, and a material housing attached to the shaft and between the electrodes; and   filling the delivery chamber with a delivery fluid by drawing the piston assembly at least partially out of the delivery chamber.   
     
     
         30 . (canceled) 
     
     
         31 . A method for operating a fluid delivery system according to  claim 29  further comprising:
 advancing the piston head in the delivery chamber to expel the delivery fluid from the delivery chamber. 
 
     
     
         32 . A method according to  claim 31  wherein advancing the piston head comprises electrokinetically moving pump fluid in the pump housing through the material housing. 
     
     
         33 . A method according to  claim 32  wherein electrokinetically moving pump fluid within the pump chamber comprises providing an electric field between the pair of electrodes. 
     
     
         34 . (canceled) 
     
     
         35 . A method for operating a fluid delivery assembly having a pump housing including a pump chamber and a delivery chamber, the method comprising:
 withdrawing a shaft from the pump housing to simultaneously displace a moving pump element within the delivery chamber and bypass fluid around a material housing in the pump chamber.   
     
     
         36 . A method for operating a fluid delivery assembly according to  claim 35  wherein withdrawing the shaft introduces a delivery fluid into the delivery chamber and into contact with the moving pump element. 
     
     
         37 . A method of operating fluid delivery assembly according to  claim 35  further comprising:
 advancing the moving pump element in the delivery chamber to expel the delivery fluid from the delivery chamber. 
 
     
     
         38 . A method of operating a fluid delivery assembly according to  claim 37 , wherein advancing the moving pump element comprises electrokinetically moving fluid in the pump chamber. 
     
     
         39 . The method of  claim 35  further comprising:
 actuating a bypass in the shaft during the withdrawing step. 
 
     
     
         40 . A method for operating a fluid delivery system according to  claim 31 , further comprising:
 fixing the position of the pump housing relative to the delivery chamber after filling the delivery chamber and before advancing the piston head.   
     
     
         41 . A method for operating a fluid delivery system according to  claim 29 , further comprising:
 removably attaching a container including the delivery fluid to an outlet in the delivery chamber prior to filling the delivery chamber, wherein filling the delivery chamber comprises drawing delivery fluid from the container into the delivery chamber.   
     
     
         42 . A method for operating a fluid delivery system according to  31 , further comprising:
 attaching a delivery device to an outlet in the delivery chamber prior to advancing the piston head, wherein the delivery fluid is expelled into the delivery device during the advancing step.   
     
     
         43 . A method for operating a fluid delivery system according to  claim 35 , further comprising:
 removably attaching a container including the delivery fluid to an outlet in the delivery chamber prior to withdrawing the shaft, wherein withdrawing the shaft comprises drawing delivery fluid from the container into the delivery chamber.   
     
     
         44 . A method for operating a fluid delivery system according to  claim 37 , further comprising:
 attaching a delivery device to an outlet in the delivery chamber prior to advancing the moving pump element, wherein the delivery fluid is expelled into the delivery device during the advancing step.   
     
     
         45 . A method for operating a fluid delivery system comprising:
 filling a delivery chamber with a delivery fluid by drawing a piston assembly at least partially out of the delivery chamber, the piston assembly including a piston head and a pump housing having a pair of electrodes therein;   providing an electric field between the pair of electrodes; and   advancing the piston head within the delivery chamber using electrokinetic energy created by the pair of electrodes such that the delivery fluid is expelled from the delivery chamber.   
     
     
         46 . The method of  claim 45 , wherein providing an electric field causes a pump fluid to move in the pump housing to create electrokinetic energy. 
     
     
         47 . The method of  claim 46 , wherein the fluid moves through a porous material in the material housing. 
     
     
         48 . The method of  claim 45 , wherein the piston system further includes a shaft extending through a wall in the pump housing, and wherein drawing the piston assembly at least partially out of the delivery chamber comprises moving the shaft. 
     
     
         49 . A method for operating a fluid delivery system according to  claim 45 , further comprising:
 removably attaching a container including the delivery fluid to an outlet in the delivery chamber prior to filling the delivery chamber, wherein filling the delivery chamber comprises drawing delivery fluid from the container into the delivery chamber.   
     
     
         50 . A method for operating a fluid delivery system according to  claim 45 , further comprising:
 attaching a delivery device to an outlet in the delivery chamber prior to advancing the piston head, wherein the delivery fluid is expelled into the delivery device during the advancing step.