Tracking a sensor that includes a ferrofluid
Inventors
Assignees
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Publication Number
US-12257005-B2
Publication Date
2025-03-25
Expiration Date
Abstract
A system comprising: one or more field generating coils configured to generate a magnetic field; a sensor comprising a shell that contains a ferrofluid, the sensor configured to be introduced in proximity to the magnetic field, wherein the ferrofluid causes distortion of the magnetic field when the ferrofluid is in proximity to the magnetic field; and one or more field measuring coils configured to: measure a characteristic of the magnetic field when the ferrofluid is in proximity to the magnetic field; and provide, to a computing device, a signal representative of the measured characteristic of the magnetic field, wherein the computing device is configured to determine one or both of a position and an orientation of the sensor based on the measured characteristic of the magnetic field.
Core Innovation
The disclosed invention relates to an electromagnetic tracking system for use with a sensor introduced into a patient's body. One or more field generating coils generate a magnetic field, and a sensor includes a shell comprising one or more flexible walls that contains a ferrofluid. When the sensor is in proximity to the magnetic field, the ferrofluid causes distortion of the magnetic field.
Magnetic field measuring coils measure characteristics of the magnetic field at a first position located remote from the magnetic field and at a second position that is in proximity to the magnetic field. The sensor is in different orientations when located at the first and second positions, and one or more additional characteristics are measured when the sensor is at one or more other positions with a second orientation different from the first.
A computing device receives one or more signals representative of the measured characteristics and determines a distortion of the magnetic field by comparing field intensities from the first measured characteristic, the second measured characteristic, and the one or more additional measured characteristics. Based on the distortion, the computing device determines a position and an orientation of the sensor containing the ferrofluid, and the ferrofluid is configured to be removed from the shell by piercing the shell and introducing a magnetic force in proximity to the shell.
The document also addresses baseline measurement when the ferrofluid is not proximate or not present, and it describes sensor flexibility and mechanical-stress robustness. It further discloses biocompatible/biodegradable shell and ferrofluid options and ferrofluid compositions using superparamagnetic iron oxide nanoparticles (SPIONs), including magnetite (Fe3O4) and maghemite (γ-Fe2O3) with diameters in the range of about 1–100 nm. The disclosure additionally provides example sensor geometries for the shell and indicates possible wireless operation of the sensor.
Claims Coverage
The document includes three independent claims: a system claim, a sensor claim, and a method claim. Across these claims, the inventive features center on a flexible-shell ferrofluid sensor that magnetically distorts a generated magnetic field, measurement of field characteristics at multiple remote/proximate sensor positions and orientations, comparison of field intensities to determine field distortion, and computing a sensor position and orientation, with ferrofluid removal by piercing and magnetic force.
Ferrofluid-distorting flexible-shell electromagnetic tracking system
A system comprising one or more field generating coils configured to generate a magnetic field; a sensor with a shell comprising one or more flexible walls, the shell containing a ferrofluid and configured to be introduced into a patient's body; wherein the ferrofluid causes distortion of the magnetic field when the sensor is in proximity to the magnetic field; and wherein the ferrofluid is configured to be removed from the shell by piercing the shell and introducing a magnetic force in proximity to the shell.
Multi-position remote/proximate magnetic-field characteristic measurement
One or more magnetic field measuring coils configured to measure a first characteristic of the magnetic field when the sensor containing the ferrofluid is at a first position that is located remote from the magnetic field; measure a second characteristic when the sensor is at a second position in proximity to the magnetic field with the sensor in a first orientation; and measure one or more additional characteristics when the sensor is at one or more positions relative to the magnetic field with the sensor in a second orientation different from the first orientation.
Distortion by comparing field intensities to determine sensor pose
A computing device receiving one or more signals representative of the first measured characteristic, the second characteristic, and the one or more additional measured characteristics; determining a distortion of the magnetic field by comparing field intensities from the first measured characteristic, the second measured characteristic, and the one or more additional measured characteristics; and determining, based on the distortion of the magnetic field, a position and an orientation of the sensor containing the ferrofluid.
Bodily-implantable ferrofluid sensor for electromagnetic tracking with removable ferrofluid
A sensor configured for use in an electromagnetic tracking system, comprising a shell comprising one or more flexible walls and configured to be introduced into a patient's body, and a ferrofluid contained within the shell; wherein the ferrofluid causes measurable distortion of a magnetic field comparable to one or more other measured characteristics of one or more magnetic fields by a computing device; and wherein the computing device determines a position and an orientation of the sensor by determining a distortion by comparing a first measured characteristic at a first remote position, a second measured characteristic at a second proximate position with a first orientation, and one or more additional measured characteristics at one or more other positions with a second orientation different from the first orientation; and wherein the ferrofluid is configured to be removed from the shell by piercing the shell and introducing a magnetic force in proximity to the shell.
Tracking method using remote/proximate measured characteristics and intensity comparison
A method of tracking a sensor with an electromagnetic tracking system comprising initiating generation of a magnetic field; receiving from one or more magnetic field measuring coils one or more signals representative of a first measured characteristic, a second characteristic, and one or more additional measured characteristics for a sensor with a flexible-shell ferrofluid configuration; determining, by the one or more signals and a computing device, a distortion of the magnetic field by comparing field intensities from the first measured characteristic, the second measured characteristic, and the one or more additional measured characteristics; and determining, by the computing device and the distortion of the magnetic field, a position and an orientation of the sensor.
Across the independent claims, the core inventive approach is to introduce a flexible-shell sensor containing ferrofluid into a patient's body so that the ferrofluid causes distortion of a magnetic field, measure magnetic field characteristics at remote and proximate sensor positions in specified orientations and additional positions or orientations, compare field intensities to determine the distortion, and compute the sensor position and orientation, with ferrofluid removal enabled by piercing the shell and applying magnetic force near the shell.
Stated Advantages
Enables determining a position and an orientation of the sensor containing the ferrofluid based on distortion of the magnetic field.
Provides measurable distortion of the magnetic field using ferrofluid for electromagnetic tracking.
Supports removal of the ferrofluid from the shell by piercing the shell and introducing a magnetic force in proximity to the shell.
Allows baseline measurement when the ferrofluid is not proximate or not present.
Provides sensor flexibility and mechanical-stress robustness.
Enables use of biocompatible/biodegradable shell and ferrofluid options.
Documented Applications
Electromagnetic tracking of a sensor introduced into a patient's body (including position and orientation tracking).
Medical electromagnetic tracking with a sensor suitable for insertion into a patient's body.
VR/AR use in the context of electromagnetic tracking as described in the document summary.
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