Solid State Pressure Sensor Air Gap Design
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Solution Overview
Problem
Current pressure sensing catheters are cumbersome, expensive, and technically challenging to use, with limited ability to resolve spatial characteristics of pressure waves in elongate organs due to their water-perfused pneumohydraulic designs, which are not solid state and unreliable in regions of physiological asymmetry.
Innovation Solution
A solid state pressure sensing catheter with multiple closely spaced sensors connected via a multiplexed logic system, using air gap pressure sensors and a deformable membrane on a rigid structure, allowing for high axial rigidity and easy sterilization, and incorporating a biocompatible outer sleeve for enhanced reliability and patient comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-perfused pneumohydraulic designs are used in pressure sensing catheters, then pressure measurement capability is achieved, but device complexity and ease of operation deteriorate due to cumbersome design and technical challenges
Solution Approach 1:
The patent replaces water-perfused pneumohydraulic mechanical systems with solid-state pressure sensors that use electrical or optical measurement principles. This substitution eliminates the need for fluid-filled channels, pumps, and hydraulic mechanisms, thereby reducing device complexity while maintaining pressure measurement capability.
Solution Approach 2:
The patent eliminates the need for water perfusion and pneumatic-hydraulic transmission by using direct solid-state sensing elements. This removes the complex fluid management system including inflow/outflow channels, perfusion pumps, and hydraulic coupling mechanisms, simplifying the overall device architecture.
2Measurement precision
If multiple pressure sensors are closely spaced to resolve spatial characteristics, then measurement precision improves, but device complexity increases due to more sensors and connections
Solution Approach 1:
The patent combines multiple pressure sensing elements into an integrated solid-state array where sensors are closely spaced and electrically connected through shared conductors. This merging approach allows high spatial resolution without proportionally increasing connection complexity, as multiple sensors can share common signal lines and power supplies.
Solution Approach 2:
The patent employs a multiplexed logic system where a single conductor or signal line serves multiple sensors sequentially or simultaneously. This multi-functional approach allows one communication channel to handle data from multiple closely-spaced sensors, reducing the overall number of required connections and wiring complexity.
3Ease of manufacture
If solid state sensors are used instead of water-perfused designs, then ease of manufacture and sterilization improve, but measurement precision may deteriorate in regions of physiological asymmetry
Solution Approach 1:
The patent employs multiple closely-spaced pressure sensors distributed along the catheter length, with each sensor providing localized pressure measurement. This spatial distribution allows the system to capture pressure gradients and asymmetric pressure patterns in different anatomical regions, maintaining measurement precision while enabling easy sterilization through solid-state construction.
Solution Approach 2:
The patent replaces water-perfused mechanical sensing systems with solid-state sensors that have no moving parts or fluid channels. This substitution provides inherent sterilization capability through standard autoclaving or chemical sterilization processes while maintaining measurement accuracy through direct electrical or optical transduction of pressure signals.
4Ease of operation
If catheter diameter is reduced for patient tolerance, then ease of operation improves, but measurement precision deteriorates due to limited space for sensors
Solution Approach 1:
The patent uses thin-film solid-state pressure sensors that can be fabricated with minimal thickness and integrated directly onto the catheter shaft. These thin-film sensors occupy minimal space, allowing multiple sensors to be closely spaced along a thin catheter, thereby maintaining high spatial resolution while keeping the catheter diameter small for patient comfort.
Solution Approach 2:
The patent integrates multiple sensing elements, conductors, and structural components in a nested or layered configuration within the catheter shaft. This compact arrangement allows multiple functional elements to coexist in a minimal cross-sectional area, enabling high sensor density and spatial resolution within a thin catheter profile that is well-tolerated by patients.
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 solution enables accurate, repeatable, and reliable measurement of pressure changes along the gastrointestinal tract, improving diagnostic capabilities and simplifying sterilization processes, while maintaining a small diameter for patient tolerance.
Implementation Method 1
a capacitive pressure sensor that includes a rigid structure and a deformable membrane mounted on the rigid structure such that an air gap is formed between an inward facing electrode on the deformable membrane and a metalized electrode surface on the rigid structure
Implementation Method 2
the deformable membrane may be caused to deflect toward the inward facing electrode by pressure applied to an outer surface of the deformable membrane
Data Source
AI summary
A pressure sensor and pressure-sensing catheter in which a deformable pressure sensing membrane is separated from an inner metalized surface on a rigid support by an air gap. An input allows a voltage to be applied to an electrode on the sensing membrane and an output allows reading of the signal modulation from the support surface. An outer sleeve overlays the membrane and a wire bus transmits the signals to a terminal connector. The catheter may include a vented air gap, a multiplexing wire bus, and an internal cable to maintain tension.