Shape Memory Alloy Pressure Sensor with Elastomeric Diaphragm

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Solution Overview

Problem

Existing pressure transducers for measuring blood pressure face challenges such as inaccurate readings due to improper diaphragm thickness, lack of sensitivity, and the presence of hazardous hardware within blood vessels, which can lead to complications like blood flow obstructions and thrombus formation.

Innovation Solution

A pressure sensitive device featuring a shape memory alloy body with a flexible elastomeric diaphragm and non-compressible silicone fluid, configured to expand within a blood vessel, allowing for accurate hydraulic pressure measurement via a MEMS device outside the vessel, minimizing hardware presence and improving sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a metal diaphragm is used in a pressure transducer, then the device can measure pressure, but the diaphragm deflection exceeds acceptable limits leading to inaccurate readings

Engineering Contradiction:

Improvepressure measurement accuracyVSAvoidreading accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the material parameter of the diaphragm from metal to elastomeric material, which fundamentally alters the mechanical properties including elasticity, compliance, and deflection characteristics. This material substitution enables the diaphragm to maintain proper thickness while achieving acceptable deflection limits for accurate pressure measurement.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If a metal diaphragm with small diameter is used, then the device structure is compact, but the device lacks sensitivity to detect small pressure variations

Engineering Contradiction:

Improvedevice sizeVSAvoidpressure variation detection sensitivity

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent changes the material parameter from metal to elastomeric material, which fundamentally alters the mechanical properties including elasticity, compliance, and deflection characteristics. This material substitution enables the diaphragm to maintain proper thickness while achieving acceptable deflection limits for accurate pressure measurement.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If significant hardware is present inside the blood vessel, then the pressure measuring system can function, but the hardware causes blood flow obstructions and thrombus formation

Engineering Contradiction:

Improvepressure measurement functionVSAvoidblood flow obstruction and thrombus formation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the hazardous metal components from the blood vessel environment by using a fully biocompatible elastomeric construction. The entire pressure sensing device including diaphragm, housing, and internal components are made from medical-grade elastomers that are inert to blood, eliminating the risk of thrombus formation and blood flow obstructions while maintaining pressure measurement functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs composite elastomeric materials that combine multiple properties: mechanical strength for structural integrity, flexibility for diaphragm compliance, and biocompatibility for safe blood vessel contact. This composite material approach allows the device to function reliably while minimizing harmful effects on blood flow.

Inventive Principle:

Principle #40Composite materials

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 device provides accurate and sensitive blood pressure measurements with reduced risk of complications by using a shape memory alloy body and elastomeric diaphragm, ensuring minimal obstruction and improved patient safety.

Implementation Method 1

the distal portion is made of a shape memory alloy... a constrained configuration including the plurality of arms being parallel to the axis and the expanded configuration including the plurality of arms being disposed transverse with respect to the axis

Methodology Applied

Scientific EffectShape memory alloy phase transition: Shape Memory Alloy

Implementation Method 2

a non-compressible fluid disposed within the flexible diaphragm and exhibiting a hydraulic pressure in communication with the flexible diaphragm... fluidly coupled to a pressure measuring system remote from the body

Methodology Applied

Scientific EffectHydraulic pressure transmission: Pascal's Law

Data Source

PatentUS11529100B2Pressure sensitive device

Publication Date: 2022.12.20 RTM VITAL SIGNS LLC

AI summary

A pressure sensitive device including a body having a proximal portion and a distal portion opposite the proximal portion, the distal portion being made of a shape memory alloy, a flexible diaphragm at least partially surrounding the body and defining a fluid chamber between the flexible diaphragm and the distal portion of the body, and a non-compressible fluid disposed within the flexible diaphragm and exhibiting a hydraulic pressure in communication with the flexible diaphragm.