# US 9,517,474 B2 · Devices and methods for separating particles

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- Number: US 9,517,474 B2
- Document ID: US9517474B2
- Status: Granted
- Kind: B2
- Application number: 13/873,424
- Filed: 2013-04-30
- Published: 2013-11-21
- Granted: 2016-12-13
- Earliest claimed: 2012-05-18
- Assignees: University of Georgia Research Foundation, Inc.
- Applicants: University of Georgia Research Foundation, Inc.
- Inventors: Leidong Mao; Taotao Zhu; Mark A. Eiteman
- Web page: https://patentgrep.com/patent/US9517474B2

## CPC

- B03C 1/288: {disposed at the outer circumference of a recipient}
- B03C 1/32: acting on the medium containing the substance being separated, e.g. magneto-gravimetric-, magnetohydrostatic-, or magnetohydrodynamic separation
- C12N 13/00: Treatment of microorganisms or enzymes with electrical or wave energy, e.g. magnetism, sonic waves
- G01N 27/74: of fluids (G01N24/00 takes precedence)
- B03C 2201/18: Magnetic separation whereby the particles are suspended in a liquid
- B03C 2201/26: for use in medical or biological applications
- B03C: MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS (separating isotopes B01D59/00; combinations of magnetic or electrostatic separation with separation of solids by other means B03B, B07B)
- C12N: MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA (microbiological testing media C12Q1/00)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Embodiments of the present disclosure provide for devices, methods for separating particles, and the like. In general, embodiments of the present disclosure include non-uniform magnetic field-assisted processes and devices for the separation of particles (e.g., cells) within a magnetic fluid. Under non-uniform magnetic fields, particles such as cells can experience the generated magnetic field direction to produce a magnetic buoyancy force, analogous to buoyancy force, as magnitude of the force is proportional to the volume of cell. This force can be used to spatially separate cells of different sizes. In some embodiments, devices for separating particles are provided having a magnetic device configured to direct a non-uniform magnetic force onto the magnetic fluid and the particles; and a plurality of outlets, wherein the non-uniform magnetic force causes the types of particles to be separated and flow into different outlets.

## Claims

### Claim 1

A kit, comprising a device and a first liquid including a magnetic fluid and two or more types of particles having different volumes;
wherein the device comprises a first fluid inlet and a second fluid inlet, each being in fluidic communication with a flow channel, wherein the first fluid inlet includes at least two turns prior to the flow channel, wherein the first fluid inlet, the second fluid inlet, or both flow the first liquid into the flow channel, wherein the flow channel has a tapered diameter along a portion of the length of the flow channel;
wherein the device comprises a permanent magnet configured to direct a non-uniform magnetic force onto the magnetic fluid to control the non-uniform magnetic force exerted on the particles and magnetic buoyancy force experienced by the particles; and
wherein the device comprises a plurality of outlets, wherein the permanent magnet is configured so that the non-uniform magnetic force causes the two or more types of particles to be separated and flow into different outlets based on the magnetic buoyancy force and the volume of the particles, wherein the plurality of outlets includes three or more outlets for separating particles based upon the different volumes.

### Claim 2 (depends on 1)

The kit of claim 1, wherein the particles are cells.

### Claim 3 (depends on 2)

The kit of claim 2, wherein the cells are selected from the group consisting of bacterial cells, yeast cells, blood cells, cancer cells, neural cells, and sperm cells.

### Claim 4 (depends on 2)

The kit of claim 2, wherein the particles are cells that have a size difference.

### Claim 5 (depends on 2)

The kit of claim 2, wherein each of the cells has a volume of 5 μm3 to 3000 μm3.

### Claim 6 (depends on 1)

The kit of claim 1, wherein the permanent magnet is disposed on one side of the device to generate the non-uniform magnetic force.

### Claim 7 (depends on 1)

The kit of claim 1, wherein the magnetic fluid is a colloidal mixture of nano-size magnetic particles covered by a surfactant.

### Claim 8 (depends on 7)

The kit of claim 7, wherein the nano-size magnetic particles have a diameter of 5 nm to 10 nm.

### Claim 9 (depends on 1)

The kit of claim 1, wherein the magnetic fluid is a ferrofluid, a paramagnetic solution, or a combination thereof.

### Claim 10 (depends on 1)

The kit of claim 1, wherein the particles are separated based upon the different buoyancy force experienced due to the different volumes of the particles.