Resonant Magnetic Pressure Sensor for Miniaturized Remote Readout
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Solution Overview
Problem
Current wireless pressure sensing solutions for medical applications, such as coronary catheterization and aneurysm pressure monitoring, are limited by the lack of a true wireless solution, sensor miniaturization, and precise localization, with existing technologies being too large or requiring direct skin contact.
Innovation Solution
A wireless pressure sensing unit utilizing two permanent magnets with one movable and one fixed, where the separation distance between them is influenced by external pressure, causing a change in their magnetic interaction and resonant frequency, allowing for miniaturized and remotely readable sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If induction coils are used for wireless communication in implanted sensors, then wireless communication is enabled, but the sensor size becomes too large (about 1 mm diameter) for some delivery types and implantation sites
Solution Approach 1:
The patent replaces traditional induction coils with a magnetic field-based sensing mechanism using permanent magnets and magnetically soft material. This substitution eliminates the need for large coils while maintaining wireless communication capability through magnetic field modulation, directly resolving the size constraint for implantable sensors
Solution Approach 2:
The patent changes the operating parameters by using permanent magnets with specific remanence values and magnetically soft material with controlled permeability. This allows the system to achieve wireless communication at much smaller dimensions by optimizing the magnetic properties rather than relying on coil geometry
2Measurement precision
If ultrasound based sensors are used, then pressure sensing is enabled, but direct skin contact is required which is often not practical, and they do not work in every body location (e.g. lung)
Solution Approach 1:
The patent replaces ultrasound-based mechanical contact sensing with a magnetic field-based sensing system. The permanent magnets and magnetically soft material create a magnetic signature that can be detected wirelessly without requiring skin contact or direct coupling, enabling operation in locations like the lung where contact is impractical
Solution Approach 2:
The patent introduces magnetically soft material as an intermediary between the permanent magnet and the external environment. This intermediary modulates the magnetic field in response to pressure changes while allowing wireless detection without direct contact, bridging the gap between the sensing element and external detectors
3Measurement precision
If magnetic signature methods using magnetically soft material and permanent magnet strip are used, then pressure sensing is enabled, but the signal is weak (due to demagnetization factor) and hence not easy to miniaturize
Solution Approach 1:
The patent optimizes the magnetic parameters by selecting permanent magnets with high remanence (e.g., 1.2-1.4 T) and controlling the geometry and material properties of the magnetically soft component. This enhances the magnetic signal strength while enabling miniaturization, overcoming the weak signal problem in previous designs
Solution Approach 2:
The patent uses a composite structure combining permanent magnet material with magnetically soft material having specific permeability characteristics. This composite approach strengthens the magnetic interaction and signal output while maintaining a compact form factor suitable for 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
Enables highly sensitive pressure sensing with miniaturized sensors that can be implanted or used in catheters, providing precise localization and remote read-out without the need for local power sources.
Implementation Method 1
a first permanent magnet inside the cavity and coupled to the at least one membrane; and a second permanent magnet inside the cavity
Implementation Method 2
The separation is changed by the pressure being sensed. This produces a weak signal (as a result of a demagnetization factor)
Implementation Method 3
at least one of the first and second permanent magnets can perform a rotational movement about a rotation axis
Implementation Method 4
the readout is based on rotational oscillation of the non-fixed permanent magnet
Data Source
AI summary
A pressure sensing unit comprises a membrane and two permanent magnets inside the cavity. One magnet is coupled to the membrane, and at least one magnet is free to oscillate with a rotational movement. At least one magnet is free to oscillate with a rotational movement. The oscillation takes place at a resonance frequency, which is a function of the sensed pressure, which pressure influences the spacing between the two permanent magnets. This oscillation frequency can be sensed remotely by measuring a magnetic field altered by the oscillation. The pressure sensing unit may be provided on a catheter or guidewire.