Catheter Distal Tilt Detection with Magnetic Interference Cancellation
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Solution Overview
Problem
Existing catheters with deflectable distal assemblies face inaccuracies in position sensing due to strong magnetic interference from force sensors, leading to incorrect readings when the distal part deflects significantly.
Innovation Solution
Implement a control circuitry that cancels interference at the frequency of the force sensor using an interference cancellation signal of the same amplitude but opposite phase, allowing accurate position coordinates to be calculated by processing signals from magnetic transducers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic transducers are used to sense position in deflectable catheter assemblies, then position coordinates can be calculated, but strong magnetic fields from force sensors cause signal saturation and interference that reduces measurement precision
Solution Approach 1:
The patent converts the harmful magnetic field interference from the force sensor into a useful signal by using the same magnetic transducer to detect both the position information (from the external magnetic field generator) and the force information (from the transducer's own field). The control circuitry processes the transducer output to extract both position coordinates and force magnitude, transforming what was previously interference into valuable dual-function data.
Solution Approach 2:
The magnetic transducer serves multiple functions: it acts as both a position sensor (detecting the external magnetic field for coordinate calculation) and a force sensor (detecting the magnetic field it generates itself for force measurement). This multi-functionality eliminates the need for separate sensors and allows the system to overcome the interference problem by intelligently processing the combined signal.
2Device complexity
If a single magnetic transducer is used for both position sensing and force sensing, then device complexity is reduced, but signal interference from the force sensor's magnetic field saturates the position sensing signal
Solution Approach 1:
The control circuitry uses feedback processing to distinguish between the position signal and force signal from the single magnetic transducer. By analyzing the characteristics of the magnetic field interactions (the transducer detecting the external field for position versus the transducer detecting its own field for force), the system separates the combined output into distinct position coordinates and force magnitude measurements, maintaining precision despite using a single sensor.
Solution Approach 2:
The system changes the interpretation parameters of the magnetic transducer output based on the operating context. The same transducer signal is processed differently depending on whether it's responding to the external magnetic field generator (position mode) or its own generated field (force mode), allowing accurate extraction of both parameters from a single sensor source.
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
Ensures precise and accurate position sensing of the distal part of the catheter, even when the distal assembly deflects, by effectively mitigating signal saturation from force sensor interference.
Implementation Method 1
A first magnetic transducer of the pair is driven to generate a first AC magnetic field at a first frequency
Implementation Method 2
The magnetic field generator is driven to generate a second AC magnetic field at a second frequency
Implementation Method 3
a second signal output by the second magnetic transducer at the first frequency, to calculate a disposition of the distal part of the probe
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Medical apparatus includes a probe including a distal part adapted for insertion into a body of a living subject and first and second magnetic transducers in the distal part of the probe. Control circuitry drives the first magnetic transducer to generate a first AC magnetic field at a first frequency and drives a magnetic field generator in proximity to the body to generate a second AC magnetic field within the body at a second frequency, calculates a disposition of the distal part of the probe by processing a first signal output by the second magnetic transducer at the first frequency, and calculates position coordinates of the distal part of the probe by processing a component of a second signal output by one of the first and second magnetic transducers at the second frequency while canceling from the second signal interference at the first frequency.