# US 10,245,570 B2 · Multi-channel magnetic control system

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- Number: US 10,245,570 B2
- Document ID: US10245570B2
- Status: Granted
- Kind: B2
- Application number: 15/009,143
- Filed: 2016-01-28
- Published: 2017-03-23
- Granted: 2019-04-02
- Earliest claimed: 2015-09-21
- Assignees: National Tsing Hua University
- Applicants: National Tsing Hua University
- Inventors: Zung-Hang Wei; Jen-Hwa Hsu; Ching-Ray Chang; Hao-Ting Huang
- Web page: https://patentgrep.com/patent/US10245570B2

## CPC

- B01F 33/451: wherein the mixture is directly exposed to an electromagnetic field without use of a stirrer, e.g. for material comprising ferromagnetic particles or for molten metal
- B01L 3/5027: {by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip}
- B01L 3/502761: {specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads or physically stretching molecules}
- B03C 1/24: with material carried by travelling fields
- B03C 1/288: {disposed at the outer circumference of a recipient}
- B01L 2200/0668: Trapping microscopic beads
- B01L 2400/043: magnetic forces
- B01F: MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING (mixing paints B44D3/06)
- 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)

## Abstract

A multi-channel magnetic control system is provided, which is used for mixing fluids containing magnetic particles or separating magnetic species. In the multi-channel magnetic control system, a plurality of magnetic field switches are allocated to surround a plurality of channels, and the magnetization directions of the magnetic field switches are controlled to generate an uneven local magnetic field gradient, so as to achieve the purpose of fluid mixing or separating the magnetic species. This system can be also used as controllable flow resistance devices for magnetic fluids. Based on the demand of magnetic field distribution, overall or local control of the magnetic field switches can be executed to perform parallel processing over the multi-channel system of multi-dimensional allocation, so as to effectively save the processing time. The mixing or separation rate can be obtained via detecting residual magnetic species by magnetoresistive sensors arranged in inlets and outlets of channels.

## Claims

### Claim 1

A multi-channel magnetic control system, comprising:
a plurality of channels;
a plurality of magnetic field switches disposed around each of the plurality of channels, and each magnetic field switch comprises a plurality of magnetic elements having different magnetic anisotropies; and
a control module providing an external magnetic field to change a magnetization direction of the magnetic elements of the at least one magnetic field switch, so as to generate a local magnetic field gradient in the plurality of channels.

### Claim 2 (depends on 1)

The multi-channel magnetic control system of claim 1, wherein when the plurality of magnetic field switches allocated at two sides of each of the plurality of channels, the magnetic field switches allocated at one side of the channel and the magnetic field switches allocated at the other side of the channel are symmetrical to each other, or the magnetic field switches allocated at one side of the channel are between the magnetic field switches allocated at the other side of the channel.

### Claim 3 (depends on 2)

The multi-channel magnetic control system of claim 2, wherein the magnetic field switches allocated at the same side of the channel are arranged in a fixed distance from each other.

### Claim 4 (depends on 3)

The multi-channel magnetic control system of claim 3, wherein the fixed distance is between 0.1 μm and 2000 μm.

### Claim 5 (depends on 1)

The multi-channel magnetic control system of claim 1, wherein the control module controls a magnetization direction of the magnetic field switches intermittently.

### Claim 6 (depends on 1)

The multi-channel magnetic control system of claim 1, wherein the control module controls the plurality of magnetic field switches entirely or locally.

### Claim 7 (depends on 1)

The multi-channel magnetic control system of claim 1, wherein each magnetic anisotropy of the magnetic elements is generated from a shape anisotropy or a magnetocrystalline anisotropy.