Actuator-Based Calibration for Pressure-Sensitive Catheter Tips
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Solution Overview
Problem
Existing invasive probes with pressure sensors face challenges in accurately measuring contact pressure between the distal tip and body tissue due to varying relationships between actual pressure and sensor readings, which can lead to inaccurate readings across different catheters.
Innovation Solution
A calibration apparatus comprising a fixture, actuator, and sensing device that applies multiple force vectors to the distal tip of a medical probe, measuring deformations and force magnitudes to compute calibration coefficients, ensuring accurate pressure measurements by accounting for various angles and asymmetries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure sensor is embedded in the catheter to measure contact pressure, then contact pressure measurement capability is improved, but measurement precision deteriorates due to varying relationships between actual pressure and sensor readings across different catheters
Solution Approach 1:
The patent applies parameter changes by measuring multiple parameters (deflection magnitude, deflection direction, and orientation angles) rather than relying on a single pressure sensor reading. By changing from a single-parameter measurement to multi-parameter measurement, the system compensates for variations in sensor characteristics across different catheters and achieves more consistent and accurate pressure measurements.
2Device complexity
If a single pressure sensor reading is used, then device complexity is reduced, but measurement precision deteriorates due to inability to account for asymmetries and angle variations
Solution Approach 1:
The patent segments the pressure measurement into multiple independent components: deflection magnitude, deflection direction, and orientation angles. Each component is measured separately by the magnetic position sensing system, allowing comprehensive characterization of the catheter-tip deformation without requiring a complex array of pressure sensors. This segmentation approach maintains relative system simplicity while achieving high measurement precision.
Solution Approach 2:
The patent transitions from one-dimensional pressure sensing to three-dimensional measurement by capturing deflection in multiple spatial dimensions and orientation angles. The magnetic position sensing system measures the catheter-tip position in 3D space, providing comprehensive data about deformation magnitude and direction, thereby achieving accurate pressure measurement while accounting for asymmetries and angle variations.
3Ease of manufacture
If calibration is performed using only axial forces, then calibration process simplicity is improved, but manufacturing precision deteriorates due to inability to detect axial asymmetries
Solution Approach 1:
The patent applies dynamics by rotating the catheter during calibration to dynamically test the catheter response from multiple orientations. Rather than performing static calibration in a single orientation, the system dynamically changes the catheter's angular position and measures deflection at each angle, enabling detection of axial asymmetries and ensuring accurate calibration across all operating conditions.
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
The calibration system enables precise pressure measurement by determining calibration coefficients that accurately translate deflection measurements into actual pressure readings, ensuring consistent and accurate pressure sensing across different catheters and tissue contact conditions.
Implementation Method 1
The actuator is configured to press against the distal tip of the probe and apply to the distal tip multiple force vectors having respective magnitudes and angles
Implementation Method 2
the distal end of the probe includes a field generator that generates a magnetic field, and the distal tip includes a field sensor that senses the magnetic field and produces the first measurements
Data Source
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AI summary
A calibration apparatus includes a fixture coupled to hold a distal end of a medical probe. An actuator is configured to press against the distal tip of the probe and apply to the distal tip multiple force vectors having respective magnitudes and angles with respect to the distal end, so as to cause a deformation of the distal tip relative to the distal end. A sensing device is configured to measure the magnitudes of the force vectors applied by the actuator. A calibration processor is configured to receive from the probe first measurements indicative of the deformation of the distal tip in response to the force vectors, to receive from the sensing device second measurements indicative of the magnitudes of the force vectors, and to compute, based on the angles and the first and second measurements, calibration coefficients for assessing the force vectors as a function of the first measurements.