Flexible Capacitive Pressure Sensor Thin Film Design
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Solution Overview
Problem
Existing pressure sensors, particularly capacitive ones, are inflexible and prone to failure when used with stent-grafts due to their rigid nature, which limits their suitability for minimally invasive procedures and long-term implantation in flexible or confined areas, such as blood vessels and joints.
Innovation Solution
A flexible passive capacitance pressure sensor is developed, comprising polymeric substrates with elastic dielectric sensing materials and conductive or non-conductive wires or metallized films, designed to be thin and durable, allowing for increased flexibility and endurance, with a thickness less than 200 microns, enabling placement in constrained spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitive pressure sensors with metal deposition on polyimide backplane are used, then measurement precision is improved, but flexibility and reliability deteriorate due to rigid structure causing breakage and fatigue
Solution Approach 1:
The patent replaces rigid metal deposition on polyimide with a flexible circuit board substrate and flexible printed circuit board traces, allowing the sensor to bend and flex without breaking. The thin film structure maintains capacitive sensing capability while providing the necessary flexibility for implantation in confined spaces and resistance to fatigue from repeated bending.
Solution Approach 2:
The patent uses composite material structures including flexible circuit board substrates combined with conductive traces, and integrates multiple layers (substrate, dielectric, electrodes) to create a sensor that combines the electrical conductivity needed for measurement with the mechanical flexibility required for reliable long-term operation in dynamic environments.
2Reliability
If protective casings or inflexible coatings are added to pressure sensors, then reliability is improved, but flexibility and ease of operation worsen
Solution Approach 1:
The patent eliminates rigid protective casings and inflexible coatings entirely, using only flexible materials throughout the sensor construction. The flexible circuit board substrate and thin film structure provide inherent protection while maintaining the flexibility needed for minimally invasive catheter-based delivery and implantation in confined anatomical spaces.
3Ease of operation
If sensor thickness is reduced for better flexibility, then ease of operation is improved, but manufacturing precision and reliability may worsen
Solution Approach 1:
The patent employs thin film fabrication techniques on flexible circuit board substrates that enable precise layer alignment and controlled thickness. The flexible printed circuit board technology provides inherent dimensional stability and alignment features that maintain manufacturing precision even as overall sensor thickness is reduced to enhance flexibility and conformability.
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 flexible design enhances the sensor's ability to withstand pressure and temperature changes, providing continuous monitoring over extended periods without failure, suitable for both medical and industrial applications.
Implementation Method 1
flexible passive capacitance pressure sensor
Implementation Method 2
elastic dielectric sensing material
Data Source
AI summary
A flexible passive capacitance pressure sensor includes a first polymeric substrate and a second polymeric substrate. An elastic dielectric sensing material is positioned between the inner-facing surface of the first polymeric substrate and the inner-facing surface of the second polymeric substrate. A first plurality of wires are positioned on the outer-facing surface of said first polymeric substrate, and a second plurality of wires positioned on the outer-facing surface of said second polymeric substrate. The plurality of wires form a flexible capacitor. With the reduced profile enabled by such a capacitor, the flexible passive capacitance pressure sensor can have a thickness of less than 200 microns.