Electromagnetically-actuated microfluidic flow regulators and related applications

Abstract

A variable, closed-loop apparatus for regulating a microfluidic flow that employs a low-power deflection assembly, which is surface-mounted over a flexible membrane overlying a chamber integrated into a microfabricated platform. A flexible membrane, moveable between two positions, sealingly overlies the chamber. One of the positions of the membrane restricts the flow through the chamber to a greater degree than the other position. A deflection assembly disposed on the substrate over the membrane unidirectionally deflects the membrane, thereby regulating the flow through the chamber.

1 . An apparatus for regulating a microfluidic flow, the apparatus comprising: 
 a substrate defining a fluid-conducting chamber;    a flexible membrane sealingly overlying the chamber, the membrane moveable between a first position and a second position, one of the positions of the membrane restricting the flow through the chamber to a greater degree than the other position; and    an electromagnetically-driven assembly disposed on the substrate over the membrane for unidirectionally deflecting the membrane from the first position to the second position, thereby regulating the flow through the chamber.    
     
     
         2 . The apparatus of  claim 1 , further comprising a resilient means for urging the membrane towards the first position.  
     
     
         3 . The apparatus of  claim 2  wherein the second position of the membrane restricts the flow through the chamber to a greater degree than the first position.  
     
     
         4 . The apparatus of  claim 3  wherein, upon deactivation of the electromagneticatty-driven assembly, the membrane elastically reverts into the first position.  
     
     
         5 . The apparatus of  claim 3  wherein, upon deactivation of the electromagnetically-driven assembly, the membrane is moveable into the first position by the flow through the chamber.  
     
     
         6 . The apparatus of  claim 2  wherein the first position of the membrane restricts the flow through the chamber to a greater degree than the second position.  
     
     
         7 . The apparatus of  claim 6 , further comprising a valve seat disposed in the chamber generally opposite to the membrane, the membrane being elastically engageable against the valve seat by the resilient means and deflectable away from the valve seat towards the second position by the electromagnetically-driven assembly.  
     
     
         8 . The apparatus of  claim 7  wherein the valve seat is attached to the interior surface of the chamber by means of a dry adhesive, the valve seat comprising a polymer.  
     
     
         9 . The apparatus of  claim 1  wherein the electromagnetically-driven assembly comprises an actuator and a magnetizable member, the actuator being moveable towards the magnetizable member by magnetic force.  
     
     
         10 . The apparatus of  claim 9  wherein the actuator comprises a first material having high magnetic permeability.  
     
     
         11 . The apparatus of  claim 9  wherein the actuator is fixedly attached to the flexible membrane, the membrane being moveable towards the second position when the magnetic force is applied to the actuator by the magnetizable member.  
     
     
         12 . The apparatus of  claim 9  wherein, when the magnetic force is applied to the actuator, the membrane is moveable towards the second position by the flow through the chamber.  
     
     
         13 . The apparatus of  claim 9  wherein the magnetizable member comprises: 
 an inner core member; and    a wire coil surrounding the inner core member.    
     
     
         14 . The apparatus of  claim 13  wherein the magnetizable member further comprises an outer core member, the inner core member being axially disposed in the outer core member, at least one of the core members comprising a second material having high magnetic permeability.  
     
     
         15 . The apparatus of  claim 14  wherein the inner core member is integrally formed with the outer core member as a unitary structure.  
     
     
         16 . The apparatus of  claim 14  further comprising a spring disposed between the inner core member and the wire coil, the spring urging the membrane towards the first position, the first position restricting the flow through the chamber to a greater degree than the second position.  
     
     
         17 . The apparatus of  claim 9  wherein the membrane is moveable from the first position towards the second position in response to axial movement of the actuator when the magnetic force is applied to the actuator, the second position restricting the flow through the chamber to a greater degree than the first position.  
     
     
         18 . The apparatus of  claim 17  wherein the magnetizable member comprises: 
 an inner core member defining a axial lumen therethrough, the actuator being at least partially slidably disposed in the lumen; and    a wire coil surrounding the inner core member.    
     
     
         19 . The apparatus of  claim 18  wherein the magnetizable member further comprises an outer core member; the inner core being axially disposed in the outer core member, at least one of the core members comprising a third material having high magnetic permeability.  
     
     
         20 . The apparatus of  claim 19  wherein the inner core member is integrally formed with the outer core member as a unitary structure.  
     
     
         21 . The apparatus of  claim 18  wherein the electromagnetically-driven assembly further comprises a plunger connected to the actuator and at least partially disposed in the lumen for urging the membrane from the first position towards the second position in response to axial movement of the actuator when the magnetic force is applied to the actuator.  
     
     
         22 . The apparatus of  claim 21  wherein the plunger comprises a fourth material having low magnetic permeability.  
     
     
         23 . The apparatus of  claim 1  wherein the membrane comprises polyimide.  
     
     
         24 . The apparatus of  claim 23  wherein a thickness of the membrane ranges from about 20 μm to 30 μm.  
     
     
         25 . The apparatus of  claim 1  wherein a height of the electromagnetically-driven assembly ranges from about 3.5 mm to about 5 mm.  
     
     
         26 . The apparatus of  claim 1 , further comprising a power source in electric communication with the electromagnetically-driven assembly for supplying the electric current thereto.  
     
     
         27 . The apparatus of  claim 26 , further comprising a flow sensor disposed in the fluid-conducting chamber for generating a signal in response to the flow through the chamber.  
     
     
         28 . The apparatus of  claim 27 , further comprising a control system for varying a duty cycle of the electromagnetically-driven assembly in response to the signal from the flow sensor.  
     
     
         29 . The apparatus of  claim 1  wherein the substrate comprises a plurality of laminated polymer layers.  
     
     
         30 . The apparatus of  claim 29  wherein at Least one of the laminated Layers comprises polyimide.  
     
     
         31 . The apparatus of  claim 29  wherein the layers are laminated by means of a phenolic resin adhesive.  
     
     
         32 . The apparatus of  claim 31  in which the phenolic resin adhesive is etched to a thickness ranging from about 3 μm to about 10 μm.  
     
     
         33 . The apparatus of  claim 31  in which the phenolic resin adhesive is selectively removed from at least a portion of the surface of the chamber by etching.  
     
     
         34 . The apparatus of  claim 1  wherein the substrate is microfabricated.  
     
     
         35 . The apparatus of  claim 1  wherein the substrate comprising a substantially rigid top layer defining an aperture for exposing the membrane, the electromagneticatty-driven assembly being attached to the top layer over the aperture.  
     
     
         36 . The apparatus of  claim 35  wherein the top layer comprises ceramic.  
     
     
         37 . The apparatus of  claim 1  wherein the electromagneticatly-driven assembly is reattachable to the substrate.  
     
     
         38 . The apparatus of  claim 1  wherein the electromagneticatly-driven assembly is permanently attached to the substrate.  
     
     
         39 . A peristaltic micropump comprising: 
 a substrate defining a ftuid-conducting chamber;    at least three flexible membranes seatingly overlying the chamber, each of the membranes being moveable between a first position and a second position, one of the positions of each of the membranes restricting the flow through the chamber to a greater degree than the other position; and    at least three electromagnetically-driven assemblies sequentially disposed on the substrate, each assembly being associated with one of the membranes and disposed thereover for unidirectionally deflecting the membrane such that each of the membranes is moved from the first position to the second position in a predetermined order, thereby causing a directional flow through the chamber.    
     
     
         40 . A micropump comprising: 
 a substrate defining a fluid-conducting chamber, a first lumen, and a second lumen, the first lumen and the second lumen being in fluid communication with the chamber;    a first check valve disposed in the first lumen;    a second check valve disposed in the second lumen;    a flexible membrane sealingty overlying the chamber, the membrane moveable between a first position and a second position; one of the positions of the membrane restricting the flow through the chamber to a greater degree than the other position; and    an electromagnetically-driven assembly disposed on the substrate over the membrane for unidirectionally deflecting the membrane from the first position to the second position, thereby causing a directional flow through the chamber.    
     
     
         41 . The apparatus of  claim 40  where at least one of the check valves comprises a plurality of laminated polymer layers.  
     
     
         42 . A method for manufacturing of an apparatus for regulating a microfluidic flow, the method comprising: 
 (a) providing a plurality of platform layers, each platform layer having an adhesive layer disposed thereon, the plurality of platform layers including a first layer defining a flexible membrane;    (b) forming at least one aperture in each layer of a first portion of the plurality of platform layers;    (c) disposing a deflection assembly over the membrane; and    (d) laminating the plurality of platform layers to form a substrate defining a chamber therein such that the membrane overlies the chamber, the membrane being moveable between a first position and a second position, one of the positions of the membrane restricting the flow through the chamber to a greater degree than the other position, wherein the membrane is unidirectionally deflectable by the deflection assembly to regulate the flow through the chamber.    
     
     
         43 . The method of  claim 42  further comprising, after step (a), the step of thinning at least one of adhesive layers.  
     
     
         44 . The method of  claim 42  wherein at least one of the platform layers comprises polyimide.  
     
     
         45 . The method of  claim 42  wherein at least one of the adhesive layers comprises a phenolic resin.  
     
     
         46 . The method of  claim 42 , further comprising, prior to step (d), defining at least one additional feature of the substrate.  
     
     
         47 . The method of  claim 42 , further comprising disposing a second layer over the first Layer, the second layer defining an opening for exposing the membrane, wherein step (c) comprises attaching the electromagnetically-driven assembly to the second layer over the opening.  
     
     
         48 . The method of  claim 42 , wherein the deflection assembly is electromagnetically-driven.  
     
     
         49 . The method of  claim 48  wherein the electromagnetically-driven deflection assembly comprises an actuator and a magnetizable member, the actuator being moveable towards the magnetizable member by magnetic force.