# US 11,305,280 B2 · Magnetic separation filters for microfluidic devices

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- Number: US 11,305,280 B2
- Document ID: US11305280B2
- Status: Granted
- Kind: B2
- Application number: 16/411,284
- Filed: 2019-05-14
- Published: 2019-11-07
- Granted: 2022-04-19
- Earliest claimed: 2013-07-26
- Assignees: The Trustees of the University of Pennsylvania
- Applicants: The Trustees of the University of Pennsylvania
- Inventors: David Aaron Issadore; Melaku Muluneh Woldemariam
- Web page: https://patentgrep.com/patent/US11305280B2

## CPC

- B01L 3/502753: {characterised by bulk separation arrangements on lab-on-a-chip devices, e.g. for filtration or centrifugation}
- B03C 1/035: Open gradient magnetic separators, i.e. separators in which the gap is unobstructed, characterised by the configuration of the gap
- B03C 1/288: {disposed at the outer circumference of a recipient}
- G01N 33/56911: {Bacteria}
- G01N 33/5758: {involving compounds serving as markers for tumours, cancers or neoplasias, e.g. cellular determinants, receptors, heat shock/stress proteins, A-protein, oligosaccharides or metabolites}
- B01L 2200/0647: Handling flowable solids, e.g. microscopic beads, cells, particles
- B01L 2300/06: Auxiliary integrated devices, integrated components
- B01L 2300/0681: Filter
- B03C 2201/18: Magnetic separation whereby the particles are suspended in a liquid
- B03C 2201/26: for use in medical or biological applications
- B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- 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)
- 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

A magnetic separation device has a membrane having a plurality of pores, a magnetically soft material layer disposed on the membrane, and a passivation layer disposed on the magnetically soft material layer. The magnetic separation device may be part of a microfluidic device having a lateral flow channel and a vertical flow magnetic separation filter. The magnetic separation device may be used to separate magnetically tagged particles, such as cells.

## Claims

### Claim 1

A magnetic separation device, comprising:
a membrane including a plurality of pores;
a layer of magnetically soft material adjacent the membrane; and
a passivation layer adjacent the layer of magnetically soft material;
wherein the plurality of pores extend through the layer of magnetically soft material and through the passivation layer.

### Claim 2 (depends on 1)

The device of claim 1, wherein the membrane comprises a material chosen from cellulose, polymers and metal oxides.

### Claim 3 (depends on 1)

The device of claim 1, wherein the membrane comprises a material chosen from polycarbonate, polyester, nylon, and aluminum oxide.

### Claim 4 (depends on 1)

The device of claim 1, wherein the membrane comprises at least 1000 pores/mm2.

### Claim 5 (depends on 1)

The device of claim 1, wherein the plurality of pores have an average diameter ranging from about 100 nm to 100 μm.

### Claim 6 (depends on 1)

The device of claim 1, wherein the plurality of pores have an average diameter ranging from about 500 nm to about 25 μm.

### Claim 7 (depends on 1)

The device of claim 1, wherein the layer of magnetically soft material comprises nickel.

### Claim 8 (depends on 1)

The device of claim 1, wherein the layer of magnetically soft material comprises a nickel-iron alloy.

### Claim 9 (depends on 1)

The device of claim 1, wherein the passivation layer comprises nickel or gold.

### Claim 10

A microfluidic device comprising:
at least one lateral flow channel; and
at least one vertical flow magnetic separation filter in fluidic communication with the at least one lateral flow channel;
wherein the at least one vertical flow magnetic separation filter comprises: (i) a membrane including a plurality of pores; (ii) a layer of magnetically soft material adjacent the membrane; and (iii) a passivation layer adjacent the layer of magnetically soft material, wherein the plurality of pores extend through the layer of magnetically soft material and through the passivation layer.

### Claim 11 (depends on 10)

The microfluidic device of claim 10, further comprising a flow converter positioned between the at least one lateral flow channel and the at least one vertical flow magnetic separation filter.

### Claim 12 (depends on 11)

The microfluidic device of claim 11, wherein the flow converter comprises a plurality of branching passages capable of evenly distributing fluid to the at least one vertical flow magnetic separation filter.

### Claim 13 (depends on 10)

The microfluidic device of claim 10, comprising n vertical flow magnetic separation filters, wherein n=2 to 10.

### Claim 14 (depends on 10)

The microfluidic device of claim 10, wherein the at least one vertical flow magnetic separation filter has a surface area of at least 0.2 cm2.

### Claim 15 (depends on 10)

The microfluidic device of claim 10, wherein the membrane comprises a material chosen from polycarbonate, polyester, nylon, and aluminum oxide.

### Claim 16 (depends on 10)

The microfluidic device of claim 10, wherein the plurality of pores have an average diameter ranging from about 100 nm to 100 μm.

### Claim 17 (depends on 10)

The microfluidic device of claim 10, wherein the layer of magnetically soft material comprises a nickel-iron alloy.

### Claim 18 (depends on 10)

The microfluidic device of claim 10, wherein the passivation layer comprises nickel or gold.

### Claim 19

A method for separating magnetically tagged particles, comprising:
flowing a suspension comprising the magnetically tagged particles through a magnetic separation device comprising: (i) a membrane including a plurality of pores; (ii) a layer of magnetically soft material adjacent the membrane; and (iii) a passivation layer adjacent the layer of magnetically soft material, wherein the plurality of pores extend through the layer of magnetically soft material and through the passivation layer;
capturing the magnetically tagged particles by exposing the magnetic separation device to an external magnetic field; and
releasing the magnetically tagged particles by removing the external magnetic field.

### Claim 20 (depends on 19)

The method of claim 19, wherein the membrane comprises a material chosen from polycarbonate, polyester, nylon, and aluminum oxide.

### Claim 21 (depends on 19)

The method of claim 19, wherein the plurality of pores have an average diameter ranging from about 100 nm to 100 μm.

### Claim 22 (depends on 19)

The method of claim 19, wherein the layer of magnetically soft material comprises a nickel-iron alloy.

### Claim 23 (depends on 19)

The method of claim 19, wherein the passivation layer comprises nickel or gold.