Catheter Pressure Sensor Using Liquid Column Isolation
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Solution Overview
Problem
Existing pressure sensors, especially electrical and electronic ones, face challenges when monitoring pressure in electrically conductive liquids due to limitations such as reduced accuracy and increased response time caused by the need for a physical membrane to isolate the sensor, which also restricts the pressure range in confined spaces.
Innovation Solution
A pressure monitoring apparatus with a catheter featuring a balloon-mounted pressure sensor where a communicating bore with a specific cross-sectional area and length allows a liquid/gas interface meniscus to travel, preventing liquid or gas passage, enabling direct gas communication with the pressure sensor and maintaining accuracy and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diaphragm or physical membrane is placed between the liquid and the pressure sensor to isolate the sensor from the electrically conductive liquid, then the sensor protection is improved, but the response time is reduced and accuracy is reduced
Solution Approach 1:
The patent uses a liquid column as an intermediary medium between the electrically conductive liquid and the pressure sensor. This liquid column transmits pressure mechanically while maintaining electrical isolation, avoiding the use of a diaphragm that would slow response time. The liquid intermediary allows direct pressure coupling without mechanical deformation delays.
Solution Approach 2:
The patent replaces the traditional diaphragm-based mechanical isolation system with a liquid-column-based pressure transmission system. Instead of using a flexible membrane that must deform to transmit pressure, the system uses the incompressible liquid column to transmit pressure directly, eliminating the deformation delay inherent in diaphragm systems.
2Reliability
If a diaphragm or physical membrane is placed between the liquid and the pressure sensor to isolate the sensor from the electrically conductive liquid, then the sensor protection is improved, but the measurement accuracy is reduced
Solution Approach 1:
The liquid column serves as an intermediary that faithfully transmits pressure from the electrically conductive liquid to the pressure sensor without the signal loss or distortion that occurs when using a diaphragm. The liquid intermediary maintains a direct pressure coupling path, ensuring accurate measurement while providing electrical isolation.
3Reliability
If a diaphragm or physical membrane is used to separate the gas chamber from the liquid, then electrical isolation is achieved, but the pressure range is restricted in confined spaces
Solution Approach 1:
The patent replaces the diaphragm-based pressure transmission mechanism with a liquid-column-based mechanism. This substitution eliminates the need for a flexible membrane that would consume valuable space in confined environments, allowing for a greater pressure range to be monitored within the same physical constraints.
4Measurement precision
If electrical and electronic pressure sensors are used to monitor pressure in electrically conductive liquids, then measurement accuracy is improved, but direct contact with the liquid is not possible
Solution Approach 1:
The patent introduces a liquid column as an intermediary that enables electrical and electronic pressure sensors to measure pressure in electrically conductive liquids indirectly. The liquid intermediary transmits pressure from the conductive liquid to the sensor while maintaining electrical isolation, allowing accurate measurement without direct contact between the sensor and conductive liquid.
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 solution allows for accurate and instantaneous pressure monitoring of electrically conductive liquids without the delays and inaccuracies associated with traditional methods, ensuring safe and precise pressure readings, especially in medical applications like balloon catheters.
Implementation Method 1
the transverse cross-sectional area of the communicating bore along the working length thereof being such as to prevent the passage of liquid past or through the liquid/gas interface meniscus, and to prevent the passage of gas past or through the liquid/gas interface meniscus
Data Source
AI summary
A pressure monitoring apparatus (1) for monitoring pressure of a liquid (4) in a vessel (2) comprises a housing (3) within which an airtight gas chamber (6) is formed. A pressure sensor (8) is located in the housing (3) monitors the pressure of a gas in the gas chamber (6). A conduit (12) having a communicating bore (16) of total length Lt communicates the gas chamber (6) with the vessel (2). As the pressure of the liquid in the vessel (2) increases, a liquid/gas interface meniscus (20) travels along a working length Lw of the communicating bore (16) from the second end (15) thus increasing the pressure in the gas chamber (6) to the pressure of the liquid, which is monitored by the pressure sensor (8). The total length Lt of the conduit (12) is greater than the working length Lw of the conduit (12) to avoid the liquid/gas interface meniscus (20) reaching the first end (14) of the communicating bore (16). The pressure monitoring apparatus (1) may also be mounted at the distal end (33) of a balloon catheter (30) for monitoring the pressure of a liquid inflating medium inflating the balloon (35) of the balloon catheter (30), which may be an electrically conductive liquid, with the gas isolating the pressure sensor (8) from the liquid inflating medium.