Flexible Circuit Electromagnet for Medical Instrument Position Tracking
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Solution Overview
Problem
Accurately tracking the position of medical instruments with electromagnet structures deep within a patient's body is challenging due to interference from the Earth's magnetic field and other medical equipment, and existing methods struggle to generate strong and stable magnetic fields without disrupting body tissues.
Innovation Solution
A medical instrument system featuring a flexible printed circuit with an electromagnet structure, where a conductive coil is driven by a low-frequency excitation signal, allowing for precise tracking of the instrument's position within the body by generating a detectable magnetic field that can be sensed and interpreted by a control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic field is generated for tracking the medical instrument, then the position tracking capability is improved, but the Earth's magnetic field and other interference cause measurement errors
Solution Approach 1:
The patent applies periodic action by using a low-frequency excitation signal (e.g., 100 Hz) to drive the electromagnet coil, causing it to generate an oscillating magnetic field. This periodic magnetic field allows the tracking system to distinguish the instrument's signal from static interference sources like the Earth's magnetic field through frequency discrimination, thereby improving position tracking accuracy in the presence of magnetic interference.
Solution Approach 2:
The patent uses an intermediary approach by introducing a ferromagnetic core into the electromagnet structure. This core concentrates and amplifies the magnetic field generated by the coil, creating a stronger and more localized magnetic field signature that can be detected more accurately despite background interference. The core acts as a mediator that enhances the signal-to-noise ratio for position tracking.
2Strength
If a strong magnetic field is generated to improve tracking signal strength, then the detection range is improved, but body tissues may be disrupted
Solution Approach 1:
The patent applies parameter changes by using a low-frequency excitation signal instead of high-frequency or DC signals. This parameter change allows the generation of a sufficiently strong magnetic field for tracking while minimizing induced currents in body tissues, thereby reducing the risk of tissue disruption. The low frequency ensures the magnetic field is strong enough for detection without reaching frequencies that would cause harmful heating or nerve stimulation.
Solution Approach 2:
The patent replaces a potentially harmful strong static magnetic field with a low-frequency oscillating magnetic field. This substitution maintains the tracking functionality while reducing the harmful effects on body tissues, as the oscillating nature at low frequency avoids the thermal and neurological effects associated with stronger or higher-frequency magnetic fields.
3Adaptability or versatility
If the medical instrument is placed deep within the body, then the treatment capability is improved, but the tracking accuracy deteriorates due to increased distance from external sensors
Solution Approach 1:
The patent uses an intermediary ferromagnetic core within the electromagnet structure to concentrate and extend the magnetic field. This core acts as a mediator that projects the magnetic field signature further from the instrument, allowing external sensors to detect the field strength at greater distances while maintaining sufficient accuracy for tracking the instrument's position deep within the body.
Solution Approach 2:
The patent employs periodic action by using a low-frequency excitation signal that generates an oscillating magnetic field with sufficient amplitude and penetration depth. This periodic field can be detected by external sensors even when the instrument is placed deep within the body, as the oscillating nature maintains signal distinguishability from background noise over greater distances.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and reliable tracking of medical instruments deep within the body, minimizing tissue disruption and effectively distinguishing the magnetic field from noise and interference, thereby improving the precision of medical procedures.
Implementation Method 1
the conductive coil electrically coupled to the first end of the first metal trace and the first end of the second metal trace... ancillary circuitry configured to drive an excitation signal through the conductive coil via the first and second metal traces to generate a magnetic field about the electromagnet structure
Data Source
AI summary
A medical system tracks the position of a medical instrument within a body of a patient. The medical instrument includes an elongated flexible printed circuit and an electromagnet structure having a conductive coil wound around a core. A control circuit applies an excitation signal across the conductive coil. Electrical current running through the conductive coil (wound around the core) generates a magnetic field. A plurality of sensors sense parameters of the magnetic field and output sensor signals. The control circuit calculates the position of the medical instrument based on the sensor signals.