Balloon Catheter Capacitive Sensing for Real-Time Diameter Monitoring
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Solution Overview
Problem
Existing balloon catheters lack a simple and efficient method to monitor the diameter of the balloon during inflation and deflation, particularly in angioplasty procedures, often requiring additional electrical lines and sensors that complicate the design.
Innovation Solution
A balloon catheter equipped with a capacitive sensor using a hydrophilic coating on the balloon wall that becomes electrically conductive with blood, forming a capacitor with the inflation medium as electrodes, allowing the diameter to be determined by measuring capacitance changes due to balloon wall thickness variations during inflation and deflation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional electrical lines and sensors are added to the balloon catheter to measure diameter, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the measurement function with the existing balloon structure by using the balloon wall itself as part of the sensing system. The capacitive sensor integrates the hydrophilic coating on the outer surface with the balloon wall as dielectric, eliminating the need for separate sensor components and electrical lines running along the catheter shaft.
Solution Approach 2:
The balloon wall serves dual purposes: it maintains structural integrity during inflation while simultaneously acting as the dielectric component of the capacitive sensor. The system uses the balloon's own materials (wall and inflation medium) to create the measurement function, rather than requiring additional dedicated components.
2Measurement precision
If printed sensors or strain gauges are placed on the balloon surface, then diameter measurement is enabled, but additional electrical lines are required along the catheter shaft
Solution Approach 1:
The patent extracts the electrical line requirement from the system by using the inflation medium itself as one electrode of the capacitor. This eliminates the need for electrical lines to run from the catheter shaft to the sensor, as the measurement can be performed through the balloon wall using the conductive inflation medium already present in the balloon interior.
Solution Approach 2:
The balloon wall acts as an intermediary dielectric layer between the hydrophilic coating on the outer surface and the conductive inflation medium on the inner surface. This intermediary structure enables capacitive measurement without requiring direct electrical contact or additional wiring through the catheter shaft.
3Measurement precision
If the balloon wall thickness decreases during inflation, then diameter measurement sensitivity is improved, but balloon structural integrity may be compromised
Solution Approach 1:
The patent utilizes the natural parameter change of balloon wall thickness during inflation as the measurement mechanism. The thinning of the wall during expansion increases capacitance sensitivity to diameter changes, while the balloon material and design maintain sufficient structural integrity to withstand inflation pressures up to 40 atm.
Solution Approach 2:
The balloon employs a composite structure with a hydrophilic coating on the outer surface and a dielectric balloon wall material, creating a multi-layer composite that maintains structural strength while enabling capacitive sensing. The combination of materials provides both mechanical integrity during high-pressure inflation and electrical properties for measurement.
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 precise and contactless monitoring of the balloon diameter without additional electrical lines, providing a robust and efficient means to determine the instantaneous diameter during angioplasty procedures.
Implementation Method 1
the sensor uses a hydrophilic coating arranged on an outer side of the balloon wall, which becomes electrically conductive upon contact with blood of the patient
Implementation Method 2
the sensor furthermore uses the balloon wall, which is formed by a dielectric, so that a capacitor having a capacitance is formed when the balloon interior is filled with an electrically conductive inflation medium
Implementation Method 3
The capacitance of the capacitive sensor thus formed changes when the balloon is inflated by way of the inflation medium as a result of a changed diameter of the balloon due to the inflation, since the thickness of the balloon wall decreases as the balloon diameter grows
Data Source
Figure 1
AI summary
The application relates to a balloon catheter (1), comprising a balloon (4) having an expandable balloon wall (40), which surrounds a balloon interior (4a) of the balloon (4), which can be filled with a fluid inflation medium (3) for inflating the balloon (4), so that a thickness (S) of the balloon wall (40) decreases as the diameter (D) of the balloon (4) grows during the inflation of the balloon (4), due to an expansion of the balloon wall (40), According to the invention, it is provided: the balloon catheter (1) comprises a capacitive sensor (2) for determining the diameter (D), wherein the sensor (2) comprises a hydrophilic coating (5) arranged on an outer side (40a) of the balloon wall (40), which becomes electrically conductive when wetted with blood of a patient, and wherein the sensor (2) furthermore comprises the balloon wall (40), which is formed from a dielectric, so that a capacitor having a capacitance is formed when the balloon interior (4a) is filled with an electrically conductive inflation medium (3).