Flow device

Abstract

Liquid flow devices, particularly microfluidic devices, containing solid porous materials. Flow in the devices can be pressure-driven flow and/or electroosmotic flow. The porous materials are preferably pre-shaped, for example divided from a sheet of porous material, so that they can be assembled with liquid-impermeable barrier materials around them. The devices can for example be prepared by lamination. A wide variety of devices, including mixing devices, is disclosed. A mixing device is illustrated in FIG. 23.

1 . A novel flow device comprising a conduit which comprises 
 (1) a barrier member, and    (2) a porous flow member (PFM) which 
 (i) comprises a solid porous material, and  
 (ii) is enclosed by the barrier member so that the PFM comprises a flowthrough section through which there can be electroosmotic and/or pressure-driven flow of a liquid;  
 the device having at least one of the following characteristics  
 (A) the barrier member comprises a plurality of laminar barrier layers which have been laminated together around the PFM;  
 (B) the PFM is a pre-shaped PFM, or, if the device comprises more than one said conduit, the PFM in at least one of said conduits, e.g. the PFM in each of said conduits, is a pre-shaped PFM;  
 (C) the PFM is laminar and lies in a first plane, and the device comprises a conduit which (i) is in fluidic communication with the PFM, and (ii) lies in the first plane or in a plane substantially parallel to the first plane;  
 (D) the PFM is laminar and lies in a first plane, and the device comprises an electrode which (i) when the device is filled with an ionic liquid, is in electrical communication with the PFM, and (ii) lies in the first plane or in a plane substantially parallel to the first plane;  
 (E) the device comprises at least four laminar layers, at least two of the laminar layers comprising a laminar PFM;  
 (F) the device comprises  
   (1) a first said conduit comprising a first barrier member and a first PFM which comprises a first flowthrough section and a first transfer section, the first flowthrough section being enclosed by the first barrier member so that fluid can flow the first flowthrough section and into the first transfer section,    (2) a second said conduit comprising a second barrier member and a second PFM which comprises a second flowthrough section and a second transfer section, the second flowthrough section being enclosed by the second barrier member so that fluid can flow through the first flowthrough section and into the second transfer section;    the first and second transfer sections 
 (a) having overlapping surfaces which 
 (i) contact each other directly, or  
 (ii) are adjacent to each other and are separated from each other by a gap which optionally is filled by a porous material, and  
 
 (b) being enclosed by a third barrier member so that liquids flowing into the first and second transfer sections are mixed together;  
 (G) the device comprises  
   (1) a first said conduit in which the flowthrough section of the PFM is a first laminar PFM which lies in a first plane,    (2) a second said conduit in which the flowthrough section of the PFM is a second laminar PFM which lies in a second plane parallel to first plane and which overlaps the flowthrough section of the first conduit;    (H1) the PFM comprises    (a) a first layer which is composed of a first porous material,    (b) a second layer which is in contact with the first layer along an interface and which is composed of second porous material,    the first porous material having a first pore size and second porous material having a second pore size which is larger than the first pore size, or the pore geometry of the first porous material at the interface being such that particles above a certain pore size will not pass through the interface, and the device further comprises    (3) a fluidic inlet which communicates with the second layer but not with the first layer,    (4) a first fluidic exit which communicates with the first layer but not with the second layer, and    (5) a second fluidic exit which communicates with second layer but not with the first layer;    (H2) the PFM is composed of a porous material having an asymmetric pore size distribution such that the pore size increases, regularly or irregularly, across the thickness of the PFM, whereby the PFM has a first surface composed of relatively small pores and a second surface composed of relatively large pores, and the device further comprises    (3) a fluidic inlet which communicates with the PFM,    (4) a first fluidic exit which communicates with the first surface but not with the second surface, and    (5) a second fluidic exit which communicates with second surface but not with the first surface;    (I) the device comprises    (1) a first said conduit in which the PFM comprises a first solid porous material having a first zeta potential, the first conduit having a first inner end and first outer end,    (2) a second said conduit in which the PFM comprises a second solid porous material having a second zeta potential which is substantially different from the first zeta potential, the second conduit having a second inner end and a second outer end,    (3) an inner fluidic junction which communicates with the first and second inner ends,    (4) a first outer fluidic junction which communicates with the first outer end, and    (5) a second outer fluidic junction which communicates with the second outer end;    (J) the device comprises    (1) a first said conduit in which the flowthrough section of the PFM terminates at a first cross-sectional end surface;    (2) a second said conduit in which the flowthrough section of the PFM terminates at a second cross-sectional end surface which contacts the first surface at a butt junction; and    (3) an auxiliary porous member which contacts the sides of the first and second PFMs and bridges the butt junction;    (K) the PFM has a cross-section having a thickness of less than 4000 microns;    (L) the PFM has a cross-section having an equivalent diameter of less than 4000 microns; and    (M) the conduit is rigid.    
     
     
         2 . A device according to  claim 1  which has characteristic (A) and wherein the barrier layers have been laminated together with the aid of heat and pressure.  
     
     
         3 . A device according to  claim 1  which has characteristic (B) and which has at least one of the following characteristics 
 (B1) the PFM was divided from a sheet of porous material and has a rectangular cross-section;    (B2) the PFM was treated, before being contacted by any of the barrier member, to change the electrical or chemical properties of at least some of its surfaces;    (B3) the PFM includes at least one transfer section which extends from the flowthrough section by a distance of up to 4 mm;    (B4) the PFM has a constant thickness and a varying width; and    (B5) the PFM is a strip in the form of a smooth or angular spiral or zigzag.    
     
     
         4 . A device according to  claim 1  wherein the PFM comprises a liquid-impermeable tube filled with the solid porous material.  
     
     
         5 . A device according to  claim 1 , which has characteristic (F) and which has at least one of the following characteristics 
 (F1) at least one of the first and second PFMs comprises a flowthrough section having a width w 1  and a transfer section which comprises 
 (i) a flared section in which the width increases to w 3 , w 3  being from 2 to 4 times w 1 , and which has a length from 0.3 to 0.7 times w 3 , and  
 (ii) a pre-mixing section which is adjacent to the flared section and which has the width w 3 ;  
   (F2) the device includes a mixing member which 
 (i) is composed of a porous material, and  
 (ii) comprises an intermediate section which lies between and contacts the first and second transfer sections, and a continuation section which extends from the first and second transfer sections;  
   (F3) at least one of the PFMs is divided into two parts, each part having a flowthrough section and a transfer section, and the transfer sections of the first and second PFMs are interleaved with each other;    (F4) the area A between the overlapping transfer sections has an equivalent diameter d transfer  such that each of the ratios d transfer /t 1  and d transfer /t 2  is at least 5;    (F5) liquid flows in the first transfer section along a first flow axis and liquid flows in the second transfer section along a second flow axis, and the liquid flow in the second transfer section has a component which is parallel to the first flow axis and is at least 50% of the flow.    
     
     
         6 . A device according to  claim 1  which has characteristic (G) and which has at least one of the following characteristics 
 (G1) the first and second laminar PFMs overlap each other in an overlap area, and one of the barrier members is an intermediate barrier member which lies between the first and second PFMs, and which, over at least 70% of the overlap area, prevents liquid from flowing between the first PFM and second PFM.    (G2) the device comprises a junction which is in fluidic communication with the first and second PFMs;    (G3) the device comprises at least 3 laminar PFMs which lie in parallel but different planes.    
     
     
         7 . A device according to  claim 1 , which has characteristic (I) and which has at least one of the following characteristics 
 (I1) the first and second zeta potentials have an opposite sign;    (I2) the first and second zeta potentials differ by at least 10 mV; and    (I3) the device includes 
 (i) a first chamber communicating with the inner fluidic junction and having a wall which comprises a flexible diaphragm, and  
 (ii) a second chamber having a wall which comprises the flexible diaphragm.  
   
     
     
         8 . A device according to  claim 1  which has characteristic (J) and in which the auxiliary member is composed of the porous material having a pore size greater than the pore size of either of the PFMs.  
     
     
         9 . A method of causing electroosmotic flow which comprises applying an electrical potential to an ionic liquid in a flow device as claimed in  claim 1 .  
     
     
         10 . A method of causing liquid flow which comprises applying pressure to a liquid in a flow device as claimed in  claim 1 .  
     
     
         11 . A method of preparing a conduit which comprises 
 (1) a barrier member, and    (2) a porous flow member (PFM) which 
 (i) comprises a solid porous material, and  
 (ii) is enclosed by the barrier member so that the PFM comprises a flowthrough section through which there can be electroosmotic and/or pressure-driven flow of a liquid;  
 the method comprising placing the flowthrough section of the PFM between a plurality of barrier layers, and laminating the barrier layers together to form the barrier member.  
   
     
     
         12 . A method according to  claim 11  wherein the lamination is carried out with the aid of heat and pressure.  
     
     
         13 . A method according to  claim 11  wherein at least one of a fluid conduit and an electrode is placed between the barrier layers before the barrier layers are laminated together.  
     
     
         14 . A method of preparing a conduit which comprises 
 (1) a barrier member, and    (2) a porous flow member (PFM) which 
 (i) comprises a solid porous material, and  
 (ii) is enclosed by the barrier member so that the PFM comprises a flowthrough section through which there can be electroosmotic and/or pressure-driven flow of a liquid;  
 the method comprising placing the flowthrough section of the PFM in a mold, placing a hardenable liquid composition in the mold around the PFM, and hardening the composition to encapsulate the flowthrough section.