Electro-osmotic pump

Abstract

A pump for inducing liquid movement by means of polarisation electro-osmosis, comprising a passageway forming a flow path for fluid transport, at least one polarisable means located within said passageway so as to form at least one pore through said passageway, the at least one polarisable means being shaped such that at least a section of the pore walls are curved or inclined with respect to the longitudinal axis of the passageway, the pump further comprising a non-conductive porous membrane positioned across the flow path and in close proximity to the at least one polarisable means, the membrane comprising pores extending in a direction at least partially parallel to the longitudinal axis of the passageway and having a pore size smaller than the at least one pore formed by the polarisable means.

1 .- 41 . (canceled) 
     
     
         42 . A pump for inducing liquid movement by means of polarisation electro-osmosis, comprising
 a passageway forming a flow path for fluid transport,   at least one polarisable means located within said passageway so as to form at least one pore through said passageway,   the pump further comprising a non-conductive porous membrane positioned across the flow path and in close proximity to the at least one polarisable means, the membrane comprising pores extending in a direction at least partially parallel to the longitudinal axis of the passageway and having a pore size smaller than the at least one pore formed by the polarisable means, whereby, in use, an electric field generated across the polarisable means in the longitudinal direction of the passageway will cause fluid in the passageway to flow under the action of polarisation electro-osmosis.   
     
     
         43 . A pump as claimed in claim  1 , wherein the at least one polarisable means is shaped such that at least a section of the pore walls is curved or inclined with respect to the longitudinal axis of the passageway. 
     
     
         44 . A pump as claimed in claim  1 , wherein the at least one polarisable means has only surfaces which are substantially perpendicular to the longitudinal direction of the passageway and surfaces which are substantially parallel to the longitudinal direction of the passageway. 
     
     
         45 . A pump as claimed in claim  1 , wherein the membrane comprises uniform pores which are unidirectional. 
     
     
         46 . A pump as claimed in claim  1 , wherein the porous membrane is in direct contact with the at least one polarisable means. 
     
     
         47 . A pump as claimed in claim  1 , wherein the membrane has a pore size of between 30 nm and 10 μm. 
     
     
         48 . A pump as claimed in claim  1 , wherein the pores of the porous membrane are at least ten times smaller than the length of the polarisable means when measured in a direction parallel to the longitudinal axis of the passageway. 
     
     
         49 . A pump as claimed in claim  1 , wherein the membrane has a thickness of between 10 and 1000 μm 
     
     
         50 . A pump as claimed in claim  1 , wherein the membrane has a surface charge of the same sign as the polarisable means. 
     
     
         51 . A pump as claimed in claim  1 , wherein the polarisable means comprises at least one polarisable particle. 
     
     
         52 . A pump as claimed in claim  10 , wherein the polarisable means comprises a plurality of adjoining polarisable particles. 
     
     
         53 . A pump as claimed in claim  10 , wherein the porous membrane has a pore size at least  10  times smaller than the size of one polarisable particle measured in the longitudinal direction of the passageway. 
     
     
         54 . A pump as claimed in claim  1 , wherein the polarisable means comprises a porous membrane. 
     
     
         55 . A pump as claimed in claim  1 , wherein the polarisable means is fixedly located within the passageway between the porous membrane and a porous sealing element having pores which extend in a direction at least partially parallel to the longitudinal axis of the passageway. 
     
     
         56 . A pump as claimed in claim  1 , comprising a pair of non-conductive porous membranes, one on each side of the at least one polarisable means and each in close proximity to the at least one polarisable means. 
     
     
         57 . A pump as claimed in claim  1 , wherein the pump further comprises electrodes positioned on either side of the polarisable means in the longitudinal direction of the passageway which, in use, are arranged to generate an electric field across the polarisable means so as to cause fluid to flow under the action of polarisation electro-osmosis. 
     
     
         58 . A pump as claimed in claim  16 , wherein at least one of the electrodes is in direct contact with the porous membrane. 
     
     
         59 . A pump as claimed in claim  1 , wherein the passageway comprises a through hole within a housing, and the polarisable means comprises a plurality of adjoining polarisable particles packed within the through hole between said porous membrane and a porous sealing element. 
     
     
         60 . A microfluidic system comprising:
 a microchannel;   electrodes positioned within said microchannel, defining between them a pumping segment;   at least one polarisable means located within said pumping segment as so to form at least one pore through said pumping segment;   a non-conductive porous membrane positioned across the pumping segment and in close proximity to the at least one polarisable means, the membrane comprising pores extending in a direction at least partially parallel to the longitudinal axis of the pumping segment and having a pore size smaller than the at least one pore formed by the polarisable means; and   the pumping segment being arranged such that, in use, the electrodes generate an electric field across the polarisable means so as to cause fluid in the microchannel to flow under the action of polarisation electro-osmosis.   
     
     
         61 . A pump for inducing liquid movement by means of polarisation electro-osmosis, comprising:
 a housing containing a through hole therein, said through hole forming a passageway;   porous sealing elements sealing at least a section of the through hole;   a plurality of adjoining polarisable particles packed between said sealing elements, the polarisable particles creating pores through said passageway;   wherein one of said sealing elements comprises a non-conductive porous membrane comprising pores extending in a direction at least partially parallel to the longitudinal axis of the passageway and having a pore size smaller than the pores created by the polarisable particles.