In-vivo monitoring of an internal volume of a mammal using magnetic field gradients

Patent metadata

Field	Value
Publication number	US-11944423-B2
Application number	US-202017097421-A
Country	US
Kind code	B2
Filing date	Nov 13, 2020
Priority date	Nov 13, 2019
Publication date	Apr 2, 2024
Grant date	Apr 2, 2024

Abstract

A method for in-vivo monitoring of a target internal volume of a mammal that includes: (a) placing the target internal volume proximal to a three-dimensional magnetic field generator; (b) generating first, second, and third magnetic field gradients along respective first, second, and third axes that are mutually orthogonal; (c) measuring first, second, and third magnetic fields with a three-dimensional magnetic sensor disposed in an ingestible capsule, the ingestible capsule disposed in the target internal volume; (d) with a controller in electrical communication with the three-dimensional magnetic sensor, generating a magnetic sensor output signal that encodes a measurement of the first, second, and third magnetic fields; (e) broadcasting the magnetic sensor output signal from an antenna disposed in the ingestible capsule, and (f) receiving the magnetic sensor output signal with a receiver. The received magnetic field data can be used to determine the three-dimensional position of the ingestible capsule.

First claim

What is claimed is:

1. A method for in-vivo monitoring of a target internal volume of a mammal, comprising:
placing the target internal volume proximal to a three-dimensional magnetic field generator;
using the three-dimensional magnetic field generator to sequentially produce:
a first localization magnetic field gradient along a first axis, a portion of the magnitude of the first localization magnetic field gradient being monotonically-varying along the first axis through the target internal volume and uniquely encoding a position along said first axis corresponding to a strength of said monotonically-varying first localization magnetic field in said target internal volume, the first localization magnetic field gradient produced at a first time;
a second localization magnetic field gradient along a second axis that is orthogonal to the first axis, a portion of the magnitude of the second localization magnetic field gradient being monotonically-varying along the second axis through the target internal volume and uniquely encoding a position along said second axis corresponding to a strength of said monotonically-varying second localization magnetic field in said target internal volume, the second localization magnetic field gradient produced at a second time that is different than the first time; and
a third localization magnetic field gradient along a third axis that is orthogonal to the first and second axes, a portion of the magnitude of the third localization magnetic field gradient being monotonically-varying along the third axis through the target internal volume and uniquely encoding a position along said third axis corresponding to a strength of said monotonically-varying third localization magnetic field in said target internal volume, the third localization magnetic field gradient produced at a third time that is different than the first and second times;

measuring a total magnetic field magnitude at the first, second, and third times with a three-dimensional magnetic sensor disposed in an ingestible capsule disposed in the target internal volume;
with a controller disposed in the ingestible capsule and in electrical communication with the three-dimensional magnetic sensor, generating a magnetic sensor output signal that encodes a first total magnetic field magnitude measurement, a second total magnetic field magnitude measurement, and a third total magnetic field magnitude measurement that correspond to the first, second, and third magnetic field gradients, respectively;
broadcasting the magnetic sensor output signal from an antenna disposed in the ingestible capsule, the antenna electrically coupled to the controller; and
receiving the magnetic sensor output signal with a receiver;
wherein:
the first localization magnetic field gradient is formed by simultaneously producing:
a first magnetic field with a first planar electromagnet coil set, the first magnetic field having a first-axis magnetic field gradient along the first axis, and
a third magnetic field with a third planar electromagnet coil set, the third magnetic field having a third-axis magnetic field gradient along the third axis, and

the first localization magnetic field gradient comprises a first total magnetic field of the first magnetic field and the third magnetic field.

2. The method of claim 1 , further comprising ingesting the ingestible capsule.

3. The method of claim 1 , further comprising measuring the total magnetic field magnitude of the first total magnetic field with the three-dimensional magnetic sensor at the first time while only the first and third magnetic fields are simultaneously produced.

4. The method of claim 3 , further comprising after measuring the total magnetic field magnitude of the first total magnetic field:
turning off the first magnetic field;
turning on a second magnetic field with a second planar electromagnet coil set, the second magnetic field having a second-axis magnetic field gradient along the second axis; and
simultaneously generating only the second and the third magnetic fields, wherein the second localization magnetic field gradient comprises a second total magnetic field of the second magnetic field and the third magnetic field.

5. The method of claim 4 , further comprising measuring the total magnetic field magnitude of the second total magnetic field with the three-dimensional magnetic sensor at the second time while only the second and third magnetic fields are simultaneously produced.

6. The method of claim 5 , further comprising after measuring the total magnetic field magnitude of the second total magnetic field:
turning off the second magnetic field while continuing to produce the third magnetic field, wherein the third localization magnetic field gradient comprises a third total magnetic field of the third magnetic field; and
measuring the total magnetic field magnitude of the third total magnetic field with the three-dimensional magnetic sensor at the third time while only the third magnetic field is turned on.

7. The method of claim 1 , further comprising sending a control signal from the receiver to the controller that causes the three-dimensional magnetic sensor to sequentially measure the total magnetic field magnitude at the first, second, and third times.

8. The method of claim 1 , further comprising determining a three-dimensional spatial location of the ingestible capsule based on the total magnetic field magnitude measurements at the first, second, and third times, the spatial location determined relative to the three-dimensional magnetic field generator.

9. The method of claim 8 , further comprising using a look-up table to determine the spatial location, the look-up table including a plurality of reference total magnetic field measurements taken at known locations relative to the three-dimensional magnetic field generator.

10. A system for in-vivo monitoring of an internal volume of a mammal, comprising:
a three-dimensional magnetic field generator configured to sequentially produce:
a first localization magnetic field gradient along a first axis, a portion of the magnitude of the first localization magnetic field gradient being monotonically-varying along the first axis through the target internal volume and uniquely encoding a position along said first axis corresponding to a strength of said monotonically-varying first localization magnetic field in said target internal volume,
a second localization magnetic field gradient along a second axis that is orthogonal to the first axis, portion of the magnitude of the second localization magnetic field gradient being monotonically-varying along the second axis through the target internal volume and uniquely encoding a position along said second axis corresponding to a strength of said monotonically-varying second localization magnetic field in said target internal volume, and
a third localization magnetic field gradient along a third axis that is orthogonal to the first and second axes, a portion of the magnitude of the third localization magnetic field gradient being monotonically-varying along the third axis through the target internal volume and uniquely encoding a position along said third axis corresponding to a strength of said monotonically-varying third localization magnetic field in said target internal volume; and

an ingestible magnetic sensor comprising:
a three-dimensional magnetic sensor that outputs measurements of respective magnetic fields corresponding to the first, second, and third localization magnetic field gradients, respectively;
a first controller electrically coupled to the three-dimensional magnetic sensor, the controller generating a magnetic sensor output signal that encodes the measu

Assignees

• California Inst Of Techn

Inventors

• Sharma Saransh
• Shapiro Mikhail
• Emami Azita

Classifications

• A61B5/073 Primary

  Intestinal transmitters · CPC title

• A61B5/05 Primary

  Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves (measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24) · CPC title

• A61B5/076

  Permanent implantation · CPC title

• A61B5/6861

  Capsules, e.g. for swallowing or implanting · CPC title

• G01B7/31

  for testing the alignment of axes · CPC title