Micromachined Wireless Pressure Sensor for Catheter Delivery
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Solution Overview
Problem
Existing methods for manufacturing implantable wireless pressure sensors for monitoring blood pressure within the heart or vasculature face challenges such as the need for miniaturization, biocompatibility, and the absence of a power source or physical connections, limiting their use to acute settings and accessibility through surgical implantation.
Innovation Solution
A method involving the fabrication of a wireless, un-powered, micromachined pressure sensor using a hermetically sealed LC circuit with a pressure-sensitive capacitor and inductor coil, allowing for wireless communication and operation without external power or connections, utilizing micro-machining techniques to achieve miniaturization suitable for catheter-based delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional capacitor-based pressure sensor fabrication methods are used, then the sensor can measure pressure, but the sensor size is too large to be delivered via catheter-based techniques
Solution Approach 1:
The patent divides the sensor into separate functional modules: a pressure-sensitive capacitor assembly and an inductor assembly, which can be fabricated independently using different processes and then assembled. This segmentation allows each component to be optimized for miniaturization while maintaining manufacturability.
Solution Approach 2:
The patent replaces traditional mechanical pressure sensing mechanisms with a capacitive sensing approach, where pressure changes are detected through capacitance variations of a parallel-plate capacitor. This substitution enables miniaturization while maintaining measurement capability.
2Duration of action of stationary object
If the sensor is made wireless and un-powered to eliminate physical connections, then long-term monitoring is enabled, but the device complexity increases due to the need for hermetic sealing and wireless communication components
Solution Approach 1:
The sensor uses the body's own electrical field to power the capacitive sensing mechanism, eliminating the need for external power sources or batteries. The pressure-induced capacitance changes are detected through electromagnetic coupling with external electronics, enabling wireless operation without adding significant complexity.
3Ease of operation
If the sensor is miniaturized for catheter-based delivery, then non-surgical implantation is possible, but the manufacturing precision requirements increase significantly
Solution Approach 1:
The patent performs preliminary actions by pre-assembling the capacitor plates and inductor components on separate substrates before final assembly. This allows for quality control and precision adjustment at intermediate stages, making the overall manufacturing process more manageable despite the miniaturization requirements.
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 accurate, safe, and easy monitoring of pressure within the heart or vasculature using catheter-based techniques, providing a biocompatible, durable, and reliable sensor that can be implanted non-surgically, facilitating long-term monitoring without the need for external power or connections.
Implementation Method 1
one of the capacitive plates will be displaced with respect to the other as a result of exposure to externally applied stress. This displacement will result in a change in the capacitance that is proportional to the applied stress.
Implementation Method 2
a pressure sensitive capacitor placed in series with an inductor coil provides the basis for a wireless, un-powered pressure sensor
Implementation Method 3
an externally modulated LC circuit has been applied to development of implantable pressure sensors... variations of resonant frequency correlate to changes in measured pressure and in which these variations can be detected remotely through the use of electromagnetic coupling
Implementation Method 4
The device must be hermetically sealed to protect the internal components from the body environment while allowing pressure transmission to the sensing element.
Data Source
AI summary
A method of manufacturing a sensor for in vivo applications includes the steps of providing two wafers of an electrically insulating material. A recess is formed in the first wafer, and a capacitor plate is formed in the recess of the first wafer. A second capacitor plate is formed in a corresponding region of the second wafer, and the two wafers are affixed to one another such that the first and second capacitor plates are arranged in parallel, spaced-apart relation.