Flexible Membrane Housing for Implantable Pressure Sensor Thermal Compensation
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Solution Overview
Problem
Implantable pressure sensors face challenges in maintaining measurement accuracy due to temperature-induced volume changes in the housing liquid, leading to high pressure levels that can cause nonreversible deformations and damage, especially in miniaturized devices for cardiac implants.
Innovation Solution
The pressure sensor device features a housing made predominantly or entirely of a flexible pressure transmitting membrane, with an irregular geometry that allows reversible deformation, reducing tensile stress and compensating volume changes, thereby minimizing temperature-induced pressure errors and maintaining accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid housing with a small membrane window is used, then the housing provides structural stability and protection, but the membrane surface area is limited and cannot compensate for thermal volume expansion, leading to high pressure levels and measurement errors
Solution Approach 1:
The housing is constructed from a flexible membrane material that can deform to compensate for thermal volume expansion of the liquid. This flexible housing acts as the pressure-sensing element itself, eliminating the need for a separate small membrane window while providing both structural integrity and thermal compensation capability.
Solution Approach 2:
The housing material properties are selected to change flexibly with temperature, allowing the housing volume to expand or contract in response to thermal changes. This parameter change in the housing itself compensates for the liquid's thermal expansion, maintaining constant pressure conditions for accurate measurements.
2Volume of moving object
If the housing is miniaturized for cardiac implants, then the device size is reduced for better biocompatibility and implantability, but the membrane surface area is further reduced, worsening the ability to compensate for thermal effects
Solution Approach 1:
The housing structure and the thermal compensation mechanism are merged into a single flexible membrane component. The housing itself performs the compensation function through its flexibility, eliminating the need for separate compensation mechanisms that would increase device size. This integration allows miniaturization without sacrificing temperature compensation capability.
3Volume of moving object
If a small membrane window is used in the housing, then the housing can be miniaturized, but the membrane surface area is limited, reducing the system capacity to compensate for internal volume expansions and increasing the temperature coefficient
Solution Approach 1:
The flexible membrane housing serves multiple functions simultaneously: it provides structural containment, acts as the primary pressure-sensing element, and performs thermal volume compensation. This multi-functionality eliminates the need for separate components, allowing the device to maintain low temperature coefficient despite miniaturization.
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 design achieves a significantly reduced temperature coefficient, ensuring accurate pressure measurements with minimal recalibration needs, even under thermal sterilization, and is tolerant to manufacturing tolerances and air bubbles, maintaining precision below 10 mbar/K for miniaturized devices.
Implementation Method 1
The interior volume comprises an incompressible liquid, such as oil, as a medium for transmitting pressure from outside the housing to the inside of the housing and the pressure sensor located therein
Implementation Method 2
The flexible membrane compensates changes of the volume of the liquid in the housing caused by temperature variations during operation and manufacture without creating high pressure levels in the incompressible liquid
Implementation Method 3
the membrane comprises one or more regions which allow for reversible deformation or back-formation while maintaining a size of the membrane's surface area when a volume is changed inside the housing
Data Source
Figure 1~3
Figure 4~5
AI summary
The invention relates to an implantable pressure sensor device (100), having a housing (10) which is at least partially made of a pressure transmitting membrane (20), wherein the housing (10) comprises one or more regions which allow for reversible deformation or back-formation while maintaining a size of the membrane's (20) surface area when a volume is changed inside the housing (10).