Particle concentration and separation using magnets

• US 9,770,600 B1
• Filed: 07/09/2014
• Issued: 09/26/2017
• Est. Priority Date: 07/09/2014
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Verily Life Sciences LLC (Alphabet Inc.)
• Inventors: Demas, Vasiliki, Bajaj, Vikram Singh
• Primary Examiner(s): Winakur, Eric
• Application Number:
  US14/326,983
• Time in Patent Office: 1,175 Days
• CPC Class Codes: A61B 5/0515 Magnetic particle imaging
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/15003 for venous or arterial blood
• CPC Class Codes: A61B 5/150755 Blood sample preparation for further analysis, e.g. by separating blood components or by mixing
• CPC Class Codes: A61B 5/153 Devices specially adapted for taking samples of venous or arterial blood, e.g. with syringes
• CPC Class Codes: A61B 5/157 Devices characterised by integrated means for measuring characteristics of blood
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61N 2/002 in combination with another treatment
• CPC Class Codes: A61N 2/02 using magnetic fields produced by coils, including single turn loops or electromagnets A61N2/12 takes precedence
• CPC Class Codes: A61N 2/06 using magnetic fields produced by permanent magnets A61N2/12 takes precedence

Abstract

A variety of wearable magnetic assemblies are provided that are configured to produce magnetic fields having high field magnitudes and/or high field gradients. These wearable magnetic assemblies are configured to exert forces on magnetic particles disposed in a portion of subsurface vasculature (e.g., a portion of the ulnar artery near the wrist) proximate to the magnetic assemblies. These magnetic assemblies include a plurality of dipolar permanent magnets. The forces can act to attract, slow, speed, separate, or otherwise influence the magnetic particles in various applications. In some embodiments, the magnetic particles are configured to bind to an analyte of interest. The collection, separation, and/or concentration of the magnetic particles can enable detection of one or more properties of the analyte, modification of the analyte, and/or extraction of the analyte bound to the magnetic particles.

Claims

1. A device comprising:

a magnetic assembly comprising a plurality of magnetic elements and a layer of high-permeability magnetic material, wherein the magnetic assembly has a first side and a second side opposite the first side, wherein the layer of high-permeability magnetic material is disposed on the second side,

wherein the plurality of magnetic elements includes at least a first magnetic element to provide a first magnetic moment and a second magnetic element to provide a second magnetic moment, wherein the first and second magnetic moments have different orientations, such that when the first side of the magnetic assembly is positioned proximate to an external body surface (i) the first magnetic moment is oriented toward a portion of subsurface vasculature proximate to the external body surface and the second magnetic moment has a different orientation than the first magnetic moment and (ii) the magnetic assembly exerts a magnetic force on magnetic particles adapted to be placed in the portion of subsurface vasculature, wherein the magnetic particles are configured to bind to an analyte; and

a detector, wherein the detector is configured to detect one or more properties of the analyte bound to the magnetic particles.

2. The device of claim 1, wherein the first magnetic element is either a permanent magnet or an electromagnet and the second magnetic element is either a permanent magnet or an electromagnet.

3. The device of claim 2, wherein the magnetic force is an attractive magnetic force, and wherein the attractive magnetic force is sufficient to collect the magnetic particles in the subsurface vasculature proximate to the magnetic assembly.

4. The device of claim 1, wherein the magnetic particles include first magnetic particles and second magnetic particles, wherein the magnetic assembly exerts a magnetic force on magnetic particles that are disposed in the portion of subsurface vasculature including a first magnetic force on the first magnetic particles and a second magnetic force on the second magnetic particles, and wherein the first magnetic force and the second magnetic force are sufficiently different to cause separation of the first magnetic particles and the second magnetic particles.

5. The device of claim 1, wherein the plurality of magnetic elements comprises at least three magnetic elements, wherein the first magnetic element is adjacent to the second magnetic element, wherein the second magnetic element is adjacent to a third magnetic element of the at least three magnetic elements, wherein the third magnetic element has a third magnetic moment, wherein the second magnetic moment is perpendicular to the first magnetic moment, wherein the third magnetic moment is perpendicular to the second magnetic moment, wherein the third magnetic moment is antiparallel to the first magnetic moment, and wherein at least one of the at least three magnetic elements has a magnetic moment that is oriented perpendicularly to the external body surface when positioned proximate the external body surface.

6. The device of claim 5, wherein the at least three magnetic elements are permanent magnets, and wherein the at least three magnetic elements have a cross-sectional shape, wherein the cross-sectional shape is narrower proximate to the external body surface.

7. The device of claim 1, wherein the magnetic assembly further comprises a focusing pole comprising a high-permeability magnetic material, wherein the focusing pole is disposed on the first side of the magnetic assembly, wherein the focusing pole has a first cross-sectional area proximate to a first side of the first magnetic element, wherein the focusing pole has a second cross-sectional area farther from the first side of the first magnetic element, and wherein the second cross-sectional area is less than the first cross-sectional area.

8. The device of claim 7, wherein the focusing pole has a cross-sectional shape, wherein the cross-sectional shape is trapezoidal.

9. The device of claim 1, wherein the magnetic assembly has a concave surface, the external body surface has a convex surface, and the concave surface is configured to at least partially enclose the convex surface.

10. The device of claim 9, wherein at least two of the plurality of magnetic elements are disposed on the concave surface.

11. The device of claim 10, wherein the plurality of magnetic elements includes four magnetic elements disposed on the concave surface, wherein each of the four magnetic elements has a respective magnetic moment that is perpendicular to a respective local external body surface, wherein a first magnetic element of the four magnetic elements has a magnetic moment pointing into the respective local external body surface, wherein a second magnetic element of the four magnetic elements has a magnetic moment pointing away from the respective local external body surface, wherein the second magnetic element is proximate to the first magnetic element, wherein a third magnetic element of the four magnetic elements has a magnetic moment pointing into the respective local external body surface, wherein the third magnetic element is proximate to the second magnetic element, wherein the third magnetic element is disposed opposite the first magnetic element relative to the second magnetic element, wherein the magnetic moment of the third magnetic element is antiparallel to the magnetic moment of the second magnetic element, wherein a fourth magnetic element of the four magnetic elements has a magnetic moment pointing away from the respective local external body surface, wherein the fourth magnetic element is proximate to the third magnetic element, wherein the fourth magnetic element is disposed opposite the second magnetic element relative to the third magnetic element.

12. The device of claim 1, wherein the layer of high-permeability magnetic material comprises mu-metal, iron, steel, metglas, Permalloy, or ferrite.