Scanning opposed migration aerosol classifier

Patent metadata

Field	Value
Publication number	US-11697125-B2
Application number	US-201916555049-A
Country	US
Kind code	B2
Filing date	Aug 29, 2019
Priority date	Aug 31, 2018
Publication date	Jul 11, 2023
Grant date	Jul 11, 2023

Abstract

An opposed migration classifier classifies particles suspended in a sample fluid that are passed through a classification channel defined by two permeable walls. Sample flow distribution input and output channels are located asymmetrically with respect to a center of the classification channel such that trajectories of the one or more particles in the sample fluid deviate from constant voltage operation trajectories. A cross-flow fluid enters the classification channel through a permeable wall and exits through the other permeable wall. An imposed field, created by a time varying filed imposed in a direction normal to the permeable walls, causes the particles to migrate in a direction opposite to that of the cross-flow fluid, such that the particles travel between the permeable walls. The particles in the sample are classified based on their mobility. The sample fluid enters and exists through or within a threshold distance of the permeable walls.

First claim

What is claimed is:

1. An opposed migration classifier comprising:
(a) a classification channel through which passes a sample comprising one or more particles suspended within a sample fluid, the classification channel comprising a first wall and a second wall that are both permeable to a flow of fluid;
(b) a sample flow distribution input channel and sample flow distribution output channel that are located asymmetrically with respect to a center of the classification channel wherein a voltage applied to a channel wall varies during a transit of the one or more particles in the sample fluid such that trajectories of the one or more particles deviate from constant voltage operation trajectories;
(c) a cross-flow fluid that enters the classification channel through one of the permeable walls, wherein the cross-flow fluid flows at a first velocity and exits in a first direction through the other permeable wall;
(d) an imposed field that is applied causes one or more particles to migrate in a direction opposite to that of the cross-flow fluid, at a second velocity that at times during the scan is not equal to the first velocity of the cross-flow fluid, such that the one or more particles are carried along the classification channel between the permeable walls, wherein:
(i) the particles in the sample are classified in the classification channel based on their mobility;
(ii) the mobility comprises a migration velocity per unit of applied force;
(iii) the imposed field is created by a time varying field imposed in a second direction normal to the permeable walls; and
(iv) the sample fluid enters through or within a first threshold distance of one of the permeable walls, travels through the classification channel, and the classified particles exit through or within a second threshold distance of the same permeable wall.

2. The opposed migration classifier of claim 1 , wherein the cross-flow fluid rate is uniform.

3. The opposed migration classifier of claim 1 , wherein the time varying field is an electric field created by a scanning voltage on one of the permeable walls.

4. The opposed migration classifier of claim 1 , wherein a shape of the opposed migration classifier is radial.

5. The opposed migration classifier of claim 1 , wherein a shape of the opposed migration classifier is defined using parallel plates.

6. The opposed migration classifier of claim 1 , wherein a shape of the opposed migration classifier is defined by a coaxial cylinder.

7. An opposed migration classifier comprising:
(a) a classification channel through which passes a sample comprising one or more particles suspended within a sample fluid, the classification channel comprising a first wall and a second wall that are both permeable to a flow of fluid;
(b) a sample flow distribution input channel and sample flow distribution output channel that are located asymmetrically with respect to a center of the classification channel wherein a voltage applied to a channel wall varies during a transit of the one or more particles in the sample fluid such that trajectories of the one or more particles deviate from constant voltage operation trajectories;
(c) a cross-flow fluid that enters the classification channel through one of the permeable walls, wherein the cross-flow fluid flows at a first velocity and exits in a first direction through the other permeable wall, wherein the first velocity varies with time;
(d) an imposed field that is applied causes one or more particles to migrate in a direction opposite to that of the cross-flow fluid, at a second velocity that at times during the scan is not equal to the first velocity of the cross-flow fluid, such that the one or more particles are carried along the classification channel between the permeable walls, wherein:
(i) the particles in the sample are classified in the classification channel based on their mobility;
(ii) the mobility comprises a migration velocity per unit of applied force; and
(iii) the sample fluid enters through or within a threshold distance of one of the permeable walls, travels through the classification channel, and the classified particles exit through or within the threshold distance of the same permeable wall.

8. The opposed migration classifier of claim 7 , wherein the imposed field is gravity.

9. The opposed migration classifier of claim 7 , wherein a shape of the opposed migration classifier is radial.

10. The opposed migration classifier of claim 7 , wherein a shape of the opposed migration classifier is defined using parallel plates.

11. The opposed migration classifier of claim 7 , wherein a shape of the opposed migration classifier is defined by a coaxial cylinder.

12. A method for separating particles comprising:
(a) introducing a sample, comprising one or more particles suspended within a sample fluid, from a sample flow distribution input channel into a classification channel, wherein the sample flows through the classification channel and exits via the sample flow distribution output channel, and wherein the sample flow distribution input channel and sample flow distribution output channel are located asymmetrically with respect to a center of the classification channel wherein a voltage applied to a channel wall varies during a transit of the one or more particles in the sample fluid such that trajectories of the one or more particles deviate from constant voltage operation trajectories;
(b) passing the sample through the classification channel, wherein the classification channel comprises a first wall and a second wall that are both permeable to a flow of fluid;
(c) introducing a cross-flow fluid to the classification channel through one of the permeable walls, wherein the cross-flow fluid flows at a first velocity and exits in a first direction through the other permeable wall;
(d) applying an imposed field on the one or more particles, wherein the imposed field causes the one or more particles to migrate in a direction opposite to that of the cross-flow fluid, at a second velocity that at times during a scan is not equal to the first velocity of the cross-flow fluid, such that the one or more particles are carried along the classification channel between the permeable walls, wherein:
(i) the particles in the sample are classified in the classification channel based on their mobility;
(ii) the mobility comprises a migration velocity per unit of applied force;
(iii) the imposed field is created by a time varying field imposed in a second direction normal to the permeable walls; and
(iv) the sample fluid enters through or within a first threshold distance of one of the permeable walls, travels through the classification channel, and the classified particles exit through or within a second threshold distance of the same permeable wall; and

(e) discharging the particles that travel through the classification channel.

13. The method of claim 12 , wherein the cross-flow fluid rate is uniform.

14. The method of claim 12 , wherein the time varying field is an electric field created by a scanning voltage on one of the permeable walls.

15. The method of claim 12 , wherein a shape of a system performing the method is radial.

16. The method of claim 12 , wherein a shape of a system performing the method is defined using parallel plates.

17. The method of claim 12 , wherein a shape of a system performing the method is defined by a coaxial cylinder.

Assignees

• California Inst Of Techn

Inventors

• Mai Huajun
• Flagan Richard C

Classifications

• B01D21/00

  Separation of suspended solid particles from liquids by sedimentation ({separation of ores or the like by sedimentation B03B5/48 - B03B5/60} ; differential sedimentation B03D3/00; {purification of water, waste water, sewage or sludge C02F, e.g.} devices for separating or removing fatty or oily substances or similar floating material from water, waste water or sewage C02F1/40) · CPC title

• G01N15/02

  Investigating particle size or size distribution (by measuring osmotic pressure G01N7/10; investigating sedimentation of particle suspensions G01N15/04; investigating individual particles G01N15/10) · CPC title

• G01N2015/0046

  in gas, e.g. smoke · CPC title

• G01N15/0266 Primary

  with electrical classification · CPC title

• B03C3/014 Primary

  Addition of water; Heat exchange, e.g. by condensation · CPC title