Implantable SAW Pressure Sensor With Hermetic Membrane Sealing
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Solution Overview
Problem
Conventional ICP monitoring systems are invasive, prone to infection, and have limitations due to large device sizes and wireless transmission methods, while current shunts are prone to failures and require improvements for reliable, precise, and long-term monitoring.
Innovation Solution
A pressure sensing apparatus with a flexible membrane and SAW resonators, supported by a rigid structure, is designed for wireless operation, allowing small size and high sensitivity, and can be implanted via a catheter, featuring a hermetically sealed envelope and a flexible membrane that deflects under pressure to measure ICP accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional invasive ICP monitoring systems are used, then ICP can be monitored, but the system size is large and risk of infection is high
Solution Approach 1:
The monitoring system is divided into two separate components: an implantable pressure sensor unit that remains inside the body, and an external reader unit. This segmentation eliminates the need for large external coils, reducing infection risk while maintaining wireless functionality
Solution Approach 2:
A hermetically sealed envelope acts as an intermediary barrier between the implantable sensor and the external environment, providing protection against infection while allowing wireless signal transmission through the membrane
2Reliability
If wired ICP monitoring systems are used, then continuous monitoring is achieved, but patient movement is limited and infection risk increases
Solution Approach 1:
The mechanical wired connection is replaced with wireless electromagnetic coupling for data transmission, eliminating physical constraints on patient movement while maintaining continuous monitoring capability
Solution Approach 2:
The external reader periodically interrogates the implantable sensor to obtain pressure measurements, enabling continuous monitoring through periodic wireless communication without requiring physical connections
3Reliability
If current shunt technology is used, then CSF drainage is achieved, but the system is prone to failures due to obstruction and disconnection
Solution Approach 1:
The implantable pressure sensor provides continuous feedback on intracranial pressure levels, enabling monitoring of shunt performance and early detection of obstruction or malfunction, thereby improving reliability
Solution Approach 2:
The shunt system incorporates an integrated pressure sensor that autonomously monitors pressure without requiring external intervention, enabling self-diagnosis of shunt status and reducing the need for manual checks
4Reliability
If implantable pressure sensors with wireless reading are used, then infection risk is reduced, but the device size increases due to large coils
Solution Approach 1:
The wireless communication function is segmented into a separate external reader device, allowing the implantable sensor to be miniaturized without large coils while maintaining wireless reading capability
Solution Approach 2:
The wireless coupling is moved from the implantable side to the external side, with the external reader positioned in a different spatial dimension outside the body, eliminating the need for large coils within the constrained implantable volume
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 apparatus enables continuous, accurate, and wireless ICP monitoring with reduced infection risk, improved patient mobility, and enhanced reliability by converting a shunt into a smart device with pressure measurement and valve control capabilities.
Implementation Method 1
Inward pressure applied to the flexible membrane at the second face causes inward deflection of the flexible membrane disposed over the deflectable portion of the first sensor device
Implementation Method 2
a flexible membrane disposed over and coupled to a second, externally-facing, face of the first sensor device
Implementation Method 3
surface acoustic wave resonators
Implementation Method 4
surface acoustic wave resonators
Implementation Method 5
an envelope hermetically sealing the first sensor device and chamber from an ambient environment
Data Source
AI summary
A pressure sensing apparatus comprises an elongate first sensor device in a beam configuration supported at at least one longitudinal end by a rigid support structure and having a deflectable portion. A chamber is disposed adjacent a first, internally-facing, face of the first sensor device. An envelope hermetically seals the first sensor device and the chamber from an ambient environment external to the pressure sensing apparatus. The envelope comprises a flexible membrane disposed over and coupled to a second, externally-facing, face of the first sensor device and extending along at least one or two sides of the first sensor device and the chamber. The sensor device may be a surface acoustic wave device coupled to an RF antenna.