Tracking a sensor that includes a ferrofluid

Inventors

Mikuszeit, Nikolai

Assignees

Northern Digital Inc

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 electromagnetic tracking system includes one or more field generating coils that generate a magnetic field and one or more field measuring coils that measure characteristics of the magnetic field. A sensor includes a shell that contains a ferrofluid and is configured to be introduced into a patient’s body, and the ferrofluid is injected after the shell is introduced into the patient’s body. The ferrofluid causes distortion of the magnetic field when the ferrofluid is in proximity to the magnetic field.

The sensor has a three-dimensional orthogonal geometry and an oval-shaped cross-section in at least two dimensions of the sensor. The system measures a characteristic of the magnetic field when the ferrofluid is in proximity to the magnetic field and provides a signal representative of the measured characteristic to a computing device. The computing device determines a position and an orientation of the sensor by comparing a characteristic measured when the ferrofluid is not in proximity to the magnetic field and a characteristic measured when the ferrofluid is in proximity to the magnetic field.

A wireless sensor is also described for use in an electromagnetic tracking system, including the shell containing the ferrofluid that is injected after the shell is introduced into the patient's body. The wireless sensor is configured to be introduced in proximity to a generated magnetic field and to cause distortion of the generated magnetic field, and characteristics of the distortion are representative of a position and an orientation of the sensor. A method is described that generates the magnetic field, introduces the ferrofluid-containing sensor into proximity of the magnetic field, receives signals from one or more field measuring coils, and determines the sensor position and orientation by comparing measured characteristics of the magnetic field for ferrofluid not in proximity versus in proximity conditions.

Claims Coverage

Independent claim coverage is provided by three independent claims: clm-00001, clm-00015, and clm-00018. The claims focus on ferrofluid-caused distortion and comparison of magnetic-field characteristics to determine position and orientation, with differences in system architecture, sensor form, and method implementation.

Across clm-00001, clm-00015, and clm-00018, the core inventive concept is using ferrofluid-caused distortion of a generated magnetic field and determining sensor position and orientation by comparing magnetic-field characteristics measured under ferrofluid-not-proximate versus ferrofluid-proximate conditions. The sensor is defined by a three-dimensional orthogonal geometry with an oval-shaped cross-section in at least two dimensions, and the ferrofluid is injected after the shell is introduced into the patient’s body.

Stated Advantages

Documented Applications