# US 7,744,737 B1 · Microfluidic device for the assembly and transport of microparticles

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- Number: US 7,744,737 B1
- Document ID: US7744737B1
- Status: Granted
- Kind: B1
- Application number: 12/028,907
- Filed: 2008-02-11
- Granted: 2010-06-29
- Earliest claimed: 2007-07-26
- Assignees: Sandia Corporation
- Inventors: Conrad D. James; Anil Kumar; Boris Khusid; Andreas Acrivos
- Web page: https://patentgrep.com/patent/US7744737B1

## CPC

- B01D 57/02: by electrophoresis (treatment of water, waste water, sewage or sludge by electrophoresis C02F1/469; electrophoretic production of compounds or non-metals C25B7/00; investigating or analysing materials by using electrophoresis G01N27/26)
- B01L 3/502792: {for moving individual droplets on a plate, e.g. by locally altering surface tension}
- B03C 5/005: {Dielectrophoresis, i.e. dielectric particles migrating towards the region of highest field strength}
- B03C 5/026: {using open-gradient differential dielectric separation, i.e. using electrodes of special shapes for non-uniform field creation, e.g. Fluid Integrated Circuit [FIC]}
- B03C 5/028: {using travelling electric fields, i.e. travelling wave dielectrophoresis [TWD]}
- B01L 2200/10: Integrating sample preparation and analysis in single entity, e.g. lab-on-a-chip concept
- B01L 2300/0645: Electrodes
- B01L 2400/0427: Electrowetting
- G01N 27/44713: {Particularly adapted electric power supply}
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- 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 microfluidic device comprising independently addressable arrays of interdigitated electrodes can be used to assembly and transport large-scale microparticle structures. The device and method uses collective phenomena in a negatively polarized suspension exposed to a high-gradient strong ac electric field to assemble the particles into predetermined locations and then transport them collectively to a work area for final assembly by sequentially energizing the electrode arrays.

## Claims

### Claim 1

A microfluidic device for assembling and transporting microparticles, comprising:
a channel formed on a substrate for flow of a fluid therein, the fluid comprising a negatively polarizable suspension of microparticles in a liquid;
at least two arrays of independently addressable electrodes disposed successively in the channel;
means for applying ac voltages of different magnitudes to the at least two arrays of independently addressable electrodes to generate a high-gradient electric field within the channel, thereby causing the microparticles to concentrate in regions of low field strength in the channel; and
means for moving the high-gradient electric field within the channel by sequencing the application of the ac voltages of different magnitudes to the at least two arrays of independently addressable electrodes.

### Claim 2 (depends on 1)

The microfluidic device of claim 1, wherein the electrodes comprise at least three arrays of independently addressable electrodes.

### Claim 3 (depends on 1)

The microfluidic device of claim 1, wherein the at least two arrays of independently addressable electrodes comprise interdigitated electrodes.

### Claim 4 (depends on 1)

The microfluidic device of claim 1, wherein the at least two arrays of independently addressable electrodes comprise four arrays of interdigitated electrodes that are independently addressable.

### Claim 5 (depends on 1)

The microfluidic device of claim 1, wherein the electrodes of the at least two arrays are substantially planar and substantially parallel.

### Claim 6 (depends on 1)

The microfluidic device of claim 1, wherein the height of the channel is less than 100 microns.

### Claim 7 (depends on 1)

The microfluidic device of claim 1, wherein the ac voltage comprises a frequency of 0.5 to 30 MHz.

### Claim 8 (depends on 1)

The microfluidic device of claim 1, wherein the ac voltage difference between successive electrodes is greater than 3 rms volts.

### Claim 9 (depends on 1)

The microfluidic device of claim 1, wherein the at least two arrays of independently addressable electrodes are disposed on a top or a bottom wall of the channel.

### Claim 10 (depends on 9)

The microfluidic device of claim 9, wherein the wall opposite the top or bottom wall on which the independently addressable electrodes are disposed is non-conducting.

### Claim 11 (depends on 9)

The microfluidic device of claim 9, wherein the wall opposite the top or bottom wall on which the independently addressable electrodes are disposed is conducting.

### Claim 12 (depends on 11)

The microfluidic device of claim 11, wherein the conducting wall is grounded.

### Claim 13 (depends on 11)

The microfluidic device of claim 11, wherein the conducting wall is energized with an applied voltage.

### Claim 14 (depends on 9)

The microfluidic device of claim 9, wherein the wall opposite the top or bottom wall on which the independently addressable electrodes are disposed comprises additional energized electrodes.

### Claim 15

A method for assembling and transporting microparticles, comprising:
providing a microfluidic device for assembling and transporting microparticles, wherein the microfluidic device comprises:
a channel formed on a substrate for flow of a fluid therein, the fluid comprising a negatively polarizable suspension of microparticles in a liquid;
at least two arrays of independently addressable electrodes disposed in the channel wherein the electrodes of the at least two arrays are configured successively in the channel; and
means for applying ac voltages of different magnitudes to the at least two arrays of independently addressable electrodes to generate a high-gradient electric field within the channel;
applying different voltages to the at least two arrays thereby causing the microparticles to assemble in regions of low field strength in the channel; and
sequencing the application of the ac voltages of different magnitudes to the at least two arrays, thereby causing the microparticles to be transported to sequenced regions of low field strength in the channel.