Wireless Cylindrical Shell LC Sensor for Blood Pressure Monitoring
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Solution Overview
Problem
Existing passive LC sensors for monitoring blood pressure within blood vessels face challenges such as water penetration, signal drift, and mechanical stress due to their size and rigidity, which affect their accuracy and longevity, and they struggle to maintain flexibility and biocompatibility.
Innovation Solution
A coaxial RF shielding structure with partially enclosed shells and electrically conductive coaxial coils, encapsulated in a water barrier, forms a flexible and wireless LC sensor that maintains signal integrity and biocompatibility, allowing for increased sensing depth without blocking blood flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick water-tight electrical insulation layer is used to encapsulate the sensor, then water penetration is prevented and circuit stability is improved, but the sensor becomes bulky and attachment to stent or graft is impeded
Solution Approach 1:
The patent employs a thin flexible membrane as the water-tight encapsulation layer instead of thick rigid insulation. This membrane is sufficiently thin to maintain sensor flexibility and enable attachment to stents or grafts, yet sufficiently impermeable to prevent water penetration and protect the circuit from degradation
Solution Approach 2:
The patent uses composite material structures combining hydrophobic coatings with biocompatible membranes. This composite approach provides both water resistance and mechanical flexibility, resolving the contradiction between protection and flexibility
2Strength
If a rigid housing is used to encapsulate the sensor, then structural protection is improved, but the sensor's ability to flex is limited, creating difficulties when inserting and/or attaching the sensor
Solution Approach 1:
The patent replaces rigid housing with flexible membrane structures that can bend and conform to the geometry of stents or grafts. These flexible membranes provide sufficient structural protection while maintaining the sensor's ability to flex during insertion and attachment procedures
Solution Approach 2:
The patent employs dynamic flexible structures that can adapt their shape during insertion and then maintain stability during operation. The flexible membrane allows the sensor to deform during catheter delivery and then conform to the final implantation site
3Length of stationary object
If a large antenna is used in the sensor, then sensing depth is increased, but inserting the sensor and/or attaching to stent or graft is impeded
Solution Approach 1:
The patent segments the antenna into multiple smaller elements arranged in a distributed configuration along the sensor body. This segmentation allows the sensor to maintain a large effective antenna area for deep sensing while keeping the overall sensor profile thin and flexible for easy insertion
Solution Approach 2:
The patent transitions from a single large planar antenna to a three-dimensional distributed antenna structure. By arranging multiple smaller antenna elements in three-dimensional space, the sensor achieves large effective sensing depth while maintaining a compact form factor that facilitates insertion
4Reliability
If electrical connections are used between inductor and capacitor in LC circuit, then circuit functionality is achieved, but stress from movement and pressure waves causes connection failure
Solution Approach 1:
The patent replaces mechanical electrical connections with a purely electromagnetic coupled circuit design. The inductor and capacitor are electrically isolated but maintain functional connection through magnetic coupling, eliminating mechanical stress points that would fail under movement and pressure wave conditions
Solution Approach 2:
The patent introduces magnetic field coupling as an intermediary between the inductor and capacitor. This magnetic coupling allows energy and signal transfer without direct electrical contact, protecting the circuit from mechanical stress while maintaining full functionality
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 provides a stable, flexible, and biocompatible LC sensor with improved sensing distance and longevity, capable of accurately monitoring blood pressure without significant signal drift, even in harsh environments.
Implementation Method 1
The wireless sensing operates through magnetic induction between the sensor antenna and the external reader antenna
Implementation Method 2
A typical LC sensor connects an inductor (L) and a capacitor (C) to form an LC resonant circuit. The capacitor may be configured to vary its capacitance in response to external pressure changes, with the LC circuit's resonant frequency changing accordingly
Data Source
AI summary
A sensor includes two coaxial RF shielding members arranged to create a coaxial RF shielding structure that is electrically open and is formed from partially enclosed cylindrical shells. The RF shielding members are spaced from one another. The sensor also includes one or multiple electrically conductive coaxial coils between the coaxial RF shielding members. This configuration creates an LC circuit without requiring a separate capacitor electrically connected to the inductor. The RF shielding structure minimizes the surrounding tissue effects (e.g., parasitic capacitance), which improves the overall accuracy of the sensor. The LC circuit also can be remotely interrogated by external reader.