Systems and methods for active particle separation

Abstract

A device and method for extracting particles contained in a ferrofluid medium are provided. Such methods may comprise suspending particles of different sizes in a ferrofluid medium and containing the ferrofluid medium in a cylindrical reservoir, and applying a first magnetic field to at least a portion of the reservoir. The first magnetic field is configured to indirectly exert a force on at least a portion of the particles of a predetermined size, and direct the portion of particles in a desired direction.

1 . A method for extracting particles contained in a ferrofluid medium, the method comprising:
 suspending particles of different sizes in a ferrofluid medium and containing the ferrofluid medium in a cylindrical reservoir;   applying a first magnetic field to at least a portion of the reservoir,   wherein the first magnetic field is configured to:
 indirectly exert a force on at least a portion of the particles of a predetermined size, and 
 direct the portion of particles in a desired direction. 
   
     
     
         2 . The method of  claim 1 , wherein applying the first magnetic field includes surrounding at least the portion of the reservoir with the magnetic field. 
     
     
         3 . The method of  claim 1 , wherein the particles comprise at least one of biological cells and moieties. 
     
     
         4 . The method of  claim 1 , where the reservoir includes or is in communication with an extraction opening. 
     
     
         5 . The method of  claim 4 , wherein the desired direction is toward the extraction opening. 
     
     
         6 . The method of  claim 4 , wherein the desired direction is away from the extraction opening. 
     
     
         7 . The method of  claim 1 , wherein the desired direction is toward a central axis of the reservoir. 
     
     
         8 . The method of  claim 1 , wherein the desired direction is away from a central axis of the reservoir. 
     
     
         9 . The method of  claim 1 , wherein the predetermined size comprises smaller particles relative to the remainder of the particles in the ferrofluid medium. 
     
     
         10 . The method of  claim 1 , wherein the predetermined size comprises larger particles relative to the remainder of the particles in the ferrofluid medium. 
     
     
         11 . The method of  claim 1 , wherein a flow outlet is provided on and/or in communication with the reservoir. 
     
     
         12 . The method of  claim 11 , wherein the exerted force is configured such that the portion of particles is carried away in a flow out of the reservoir via the flow outlet. 
     
     
         13 . The method of  claim 12 , further comprising applying an external force on the reservoir to establish the flow out the flow outlet. 
     
     
         14 . The method of  claim 13 , wherein the external force is applied via a pressure source. 
     
     
         15 . The method of  claim 14 , wherein the pressure source is a pump. 
     
     
         16 . The method of  claim 5 , further comprising accelerating a flow of the portion of particles via a second magnetic field, the second magnetic field generated by a second magnetic field source arranged on a portion of the reservoir positioned opposite to the extraction opening. 
     
     
         17 . The method of  claim 1 , further comprising providing a membrane within the reservoir. 
     
     
         18 . The method of  claim 17 , wherein the membrane comprises a non-magnetic membrane configured with pore sizes larger than particles within the reservoir to direct particles in a second desired direction. 
     
     
         19 . The method of  claim 18 , wherein the second desired direction is toward spaces between pores of the membrane, wherein the spaces are configured to retain particles of at least a first size. 
     
     
         20 . The method of  claim 18 , wherein the second desired direction is toward pores of the membrane, such that the particles pass through the membrane. 
     
     
         21 . The method of  claim 18 , wherein the non-magnetic membrane comprises a plastic sheet. 
     
     
         22 . The method of  claim 18 , wherein the membrane is configured to reduce the amplitude of or substantially eliminate the first magnetic field or the effects thereof. 
     
     
         23 . The method of  claim 22 , wherein the amplitude is selected based on the size of the portion of the particles. 
     
     
         24 . The method of  claim 18 , further comprising a plurality of non-magnetic beads suspended in the ferrofluid, the non-magnetic beads being functionalized with at least one predetermined receptor configured to bind with a target particle contained in the particles within the ferrofluid medium. 
     
     
         25 . The method of  claim 24 , wherein the at least one predetermined receptor include at least one of a molecule, a cell, an antibody, DNA or fragment thereof, and a ligand. 
     
     
         26 . The method of  claim 24 , wherein the first magnetic field is configured to direct target particles toward space between pores of the membrane which are configured to retain the target particles. 
     
     
         27 . method of  claim 26 , further comprising detecting means to at least one of track or count the retained target particles. 
     
     
         28 . The method of  claim 17 , further comprising providing at least one other nonmagnetic membrane, wherein the at least one other non-magnetic membrane is parallel to other membranes. 
     
     
         29 . The method of  claim 28 , wherein each membrane has a smaller pore size than a previous membrane. 
     
     
         30 . The method of  claim 17 , wherein the membrane comprises a magnetic membrane. 
     
     
         31 . The method of  claim 30 , wherein the magnetic membrane comprises a thin foil of nickel. 
     
     
         32 . The method of  claim 30 , further comprising providing a plurality of magnetic beads suspended in the ferrofluid medium, the magnetic beads being functionalized with at least one predetermined receptor configured to bind with a target particle contained in the particles within the ferrofluid medium. 
     
     
         33 . The method of  claim 32 , wherein the magnetic beads are directed toward a surface of the magnetic membrane between the pores. 
     
     
         34 - 60 . (canceled)