Electromagnetic Catheter Localization System
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Solution Overview
Problem
Existing catheter position location systems face challenges such as radiation exposure from x-ray-based methods, interference issues with magnetic fields, and limited depth penetration, making them unreliable for accurate three-dimensional localization, especially with smaller diameter catheters.
Innovation Solution
A system utilizing an array of electromagnetic drive coil sets and a sensor coil communicatively connected to an external control and display box, allowing for two- or three-dimensional localization by energizing drive coils in pairs or combinations to calculate the sensor coil's location and orientation, using virtual drive axes to enhance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If x-ray or fluoroscopy is used to indicate catheter location, then reliable location indication is achieved, but patient and caregiver are exposed to undesirable amounts of radiation
Solution Approach 1:
The patent replaces the x-ray/fluoroscopy imaging system with an electromagnetic sensing system consisting of drive coils and sensor coils. The system uses electromagnetic induction to detect catheter position and orientation through measurement of induced voltages in sensor coils, eliminating the need for ionizing radiation while providing continuous real-time feedback.
Solution Approach 2:
The patent introduces sensor coils as intermediary elements that indirectly detect catheter position through electromagnetic coupling. Instead of directly imaging the catheter with x-rays, the system uses sensor coils to sense the magnetic field disturbances caused by the catheter's position and orientation, providing a radiation-free measurement method.
2Measurement precision
If a fixed magnet is placed on the catheter tip with external sensor coils, then location indication is achieved, but the magnet generates significant interference from other magnetic fields and has limited depth penetration
Solution Approach 1:
The patent inverts the conventional magnetic sensing approach by placing the active drive coils outside the patient's body and the passive sensor coils inside the catheter. This reversal eliminates the need for a magnet on the catheter tip, thereby removing the source of magnetic interference and limiting depth penetration, while still enabling precise location detection through electromagnetic coupling.
Solution Approach 2:
The patent employs alternating current (AC) driven coils that generate time-varying magnetic fields at specific frequencies. By using periodic electromagnetic excitation and detecting the induced voltages at these known frequencies, the system can distinguish the catheter signal from background magnetic interference, improving measurement precision in the presence of external magnetic fields.
3Power
If AC driven coils with sensor coil in catheter tip are used, then electromagnetic signal is generated, but heavy or thick wires are needed to carry sufficient drive current, precluding use with smaller diameter catheters
Solution Approach 1:
The patent inverts the conventional approach by placing the heavy-duty AC driven coils outside the patient's body where they can be made large and powerful without constraining the catheter diameter. The catheter itself only needs to contain thin sensor coils that passively detect the electromagnetic field, enabling use with small-diameter catheters while still providing strong electromagnetic signals for accurate positioning.
4Loss of information
If two coils are driven simultaneously at different frequencies, then independent demodulation is achieved, but the system cannot indicate three-dimensional orientation accurately
Solution Approach 1:
The patent transitions from two-dimensional orientation sensing to three-dimensional orientation sensing by utilizing three orthogonal sensor coils (x, y, z axes) instead of two. This dimensional expansion allows the system to resolve the catheter's orientation in all three spatial dimensions by measuring the induced voltages in each orthogonal coil and calculating the orientation angles accordingly.
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
This system provides accurate three-dimensional localization of catheters, improving measurement accuracy and reducing interference, enabling precise placement of medical devices like catheters without the need for heavy wires or radiation, thus enhancing safety and effectiveness.
Implementation Method 1
an array of electromagnetic drive coil sets, each set having two or three dimensionally oriented drive coils; a sensor coil being electromagnetically communicative with the array of electromagnetic drive coil sets
Data Source
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AI summary
A medical device locating system for determining disposition of a sensor coil in a subject, said system comprising an array of three or more triplet drive coil sets, each drive coil set including at least three discrete drive coils, each of the discrete drive coils being electromagnetic coils, at least one sensor coil adapted to provide one or more sensor coil response signals; a first system component that provides AC drive signals energizing said discrete drive coils; wherein the provision of drive signals includes one or both sequentially driving one or a pair or a triplet of said discrete drive coils within a triplet drive coil set and selectively providing phase inversion of the drive signal to any one, two or three of said discrete drive coils within a triplet drive coil set; a second system component for measuring resulting one or more sensor coil response signals, including one or more of sequential single, paired or triplet sensor coil response signals; an electrocardiogram (ECG) operably associated with said triplet drive coil array wherein one or more ECG reference leads are configured to be placed on said subject and a ECG signal lead is provided by a conductive core wire supporting said sensor coil and a computing component for calculating sensor coil disposition in the subject relative to said triplet drive coil sets.