Filter Arrangement Using Elution Fluid and Method for Using the Same

Abstract

A filter arrangement with a top element and a bottom element and a filter element therebetween captures oversized particles on the upper surface of the filter element and tangentially rinses these particles using an elution fluid to provide a concentration of particles in a relatively low volume of fluid for further analysis. In an intermediate step, the particles captured by the filter may be rinsed with a rinsing fluid such as water to pass additional undersized particles through the filter, thereby providing a purer sample. To improve efficiency, check valves may be used for passageways with one-way flow. Additionally, a configuration of three-way stopcocks may also be utilized. Finally, a sandwich arrangement is possible, wherein a single bottom element is sandwiched between two opposing top elements.

1 - 37 . (canceled) 
     
     
         38 . A method of using the filter arrangement for isolating particles from a fluid/particle mixture, wherein the filter arrangement has:
 1) a top element having at least one open channel extending thereacross connecting a top element inlet to a first collector, wherein the channel is open on the underside of the top element and wherein the top element is connected to a fluid/particle supply and an elution fluid supply;   2) a bottom element having at least one open channel extending thereacross connected to a bottom element outlet which is connected to a suction supply for providing suction, wherein the channel is open on the upper side of the bottom element;   3) wherein the top element is secured to the bottom element such that the underside of the top element is secured against the upper side of the bottom element and wherein the channels align with one another;   4) a filter element which is generally flat and is positioned between the top element and the bottom element and overlapping with the channels;   5) wherein the top element open channel and the bottom element open channel extend beyond the first collector from a top element outlet into a second collector to define a first stage channel on one side of the first collector and a second stage channel on the other side of the first collector, wherein the method comprises the steps of:
 a) with suction applied to the bottom element outlet, introducing the fluid/particle mixture into the first stage channel of the top channel and over the filter element thereby depositing particles upon one portion of the filter element and passing permeate particles through the filter; 
 b) thereafter, with suction discontinued to the bottom element outlet, introducing elution fluid into the top channel and over the filter element such that the retentate particles deposited upon the filter are tangentially rinsed and collected into the first collector; and 
 c) after step b), with suction applied to the bottom element outlet, introducing the retentate into the second stage channel of the top channel and over the filter element thereby depositing retentate particles upon another portion of the filter element and passing permeate particles through the filter; and 
 d) thereafter with suction discontinued to the bottom element outlet, introducing the elution fluid into the top channel and over the filter element such that the retentate particles deposited upon the filter are tangentially rinsed and collected into the second collector, thereby providing a two-stage filter arrangement with retentate initially deposited within the first collector and thereafter finally being deposited within the second collector. 
   
     
     
         39 . The method according to  claim 38 , further comprising the step, immediately after each step 1) and 3), of applying suction to the bottom element outlet and introducing rinsing solution into the top channel and through the filter element to rinse the retentate. 
     
     
         40 . A filter arrangement for isolating particles from a fluid/particle mixture with elements arranged in a sandwiched relationship comprised of:
 a) a middle sandwich element having a thickness and at least one open channel extending thereacross connecting a middle sandwich element inlet to a first collector and extending through the thickness;   b) a top sandwich element having at least one open channel extending thereacross connected to a top sandwich element outlet for providing suction, wherein the channel is open on the underside of the top sandwich element;   c) a bottom sandwich element having at least one open channel extending thereacross connected to a bottom sandwich element outlet for providing suction; wherein the channel is open on the upper side of the bottom sandwich element;   d) wherein the top sandwich element is secured to the middle sandwich element such that the underside of the top sandwich element is secured against the upper side of the bottom element and wherein the channels align with one another;   e) wherein the bottom sandwich element is secured to the middle sandwich element such that the upper side of the bottom sandwich element is secured against the underside of the bottom sandwich element and wherein the channels align with one another;   f) a top filter element which is generally flat and is positioned between the top sandwich element and the middle sandwich element and overlapping with the channels; and   g) a bottom filter element which is generally flat and is positioned between the top element and the middle sandwich element and overlapping with the channels, thereby using a common middle sandwich element to provide a configuration capable of preforming two separate filtering operations simultaneously.   
     
     
         41 . A filter arrangement for isolating particles from a fluid/particle mixture comprised of:
 a) a top element having at least one open channel extending thereacross in fluid communication with a top channel inlet/outlet, wherein the channel is open on the underside of the top element;   b) a bottom element having at least one open channel extending thereacross connected to a bottom element outlet for providing suction; wherein the channel is open on the upper side of the bottom element;   c) wherein the top element is secured to the bottom element such that the underside of the top element is secured against the upper side of the bottom element and wherein the channels align with one another;   d) a filter element which is generally flat and is positioned between the top element and the bottom element and overlapping with the channels; and   e) wherein the top element open channel inlet/outlet is in direct fluid communication with both a first collector and a second collector, but only one at a time, through a valve arrangement such that in one configuration particles trapped by the filter when displaced are directed to the first collector while in another configuration particles trapped by the filter when displaced are directed to the second collector.   
     
     
         42 . The filter arrangement according to  claim 41 , wherein the valve arrangement is comprised of a plurality of three-way stop cock valves. 
     
     
         43 . A method of using the filter arrangement according to  claim 42  comprising the steps of:
 a) with suction applied to the bottom element outlet, introducing the fluid/particle mixture into the top channel and over the filter element thereby depositing retentate particles upon the filter element and passing permeate particles through the filter; 
 b) thereafter, with suction discontinued to the bottom element outlet, introducing elution fluid into the top channel and over the filter element such that the retentate particles deposited upon the filter are tangentially rinsed and collected into the first collector; and 
 c) after step 2), with suction applied to the bottom element outlet, introducing the retentate into the top channel and over the same filter element thereby depositing retentate particles upon the filter element and passing permeate particles through the filter; and 
 d) thereafter with suction discontinued to the bottom element outlet, introducing the elution fluid into the top channel and over the same filter element such that the retentate particles deposited upon the filter are tangentially rinsed and collected into the second collector, thereby providing a two-stage filter arrangement with retentate initially deposited within the first collector and thereafter finally being deposited within the second collector. 
 
     
     
         44 . The method according to  claim 43 , further comprising the step, immediately after each step 1) and 3), of applying suction to the bottom element outlet and introducing rinsing solution into the top channel and through the filter element to rinse the retentate.