CMUT Compression Post Structure for Translational Displacement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional capacitive micromachined ultrasonic transducers (CMUTs) rely on deflection or bending of the top plate, which limits the average displacement of the top plate and surrounding medium, whereas a device that utilizes a substantially translational (piston-like) movement of the top plate is needed to enhance displacement.
Innovation Solution
A compression post capacitive micromachined ultrasonic transducer (CMUT) is designed with a pattern of compression posts that provide a restoring force perpendicular to the moveable mass, allowing for translational movement without deflection or bending, utilizing a silicon on insulator (SOI) wafer and electronically insulating layers to isolate electrodes and optimize stiffness for improved frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional CMUT uses deflection or bending of the top plate, then the device can be manufactured using well-established fabrication techniques, but the average displacement of the top plate and surrounding medium is limited
Solution Approach 1:
The top plate is segmented into multiple compression posts that can move independently in the vertical direction. This segmentation allows each post to contribute to the overall displacement, achieving greater average displacement while maintaining compatibility with standard fabrication techniques for creating arrays of discrete structures.
Solution Approach 2:
Instead of allowing the top plate to deflect or bend laterally as in conventional CMUTs, this invention inverts the approach by constraining lateral movement and allowing only vertical compression of the posts. This inversion of the movement mode enables piston-like translational motion that generates greater average displacement of the surrounding medium.
2Ease of operation
If compression posts are used to provide restoring force perpendicular to the moveable mass, then translational movement without deflection is achieved, but the device complexity increases
Solution Approach 1:
The compression posts are implemented as slender, flexible structures that can compress axially while maintaining their structural integrity. These thin-film-like posts provide the necessary restoring force through their elastic compliance, enabling the desired translational movement mode without requiring complex mechanical assemblies.
Solution Approach 2:
The stiffness of the compression posts is carefully controlled by adjusting their geometric parameters (length, cross-sectional area, material properties) to match the stiffness of the moveable mass. This parameter optimization ensures that the posts provide adequate restoring force while minimizing the added structural complexity.
3Speed
If the compression post stiffness is optimized for frequency response, then ultrasound generation is improved, but the restoring force may not adequately support the moveable mass
Solution Approach 1:
The stiffness of the compression posts is precisely controlled by adjusting their geometric parameters (length, cross-sectional area, material properties) to match the stiffness of the moveable mass. This optimization ensures that the posts provide adequate restoring force to support the moveable mass while achieving the desired frequency response for ultrasound generation.
Solution Approach 2:
The compression posts are designed to vibrate at specific resonant frequencies that match the operating frequency of the ultrasound transducer. By tuning the mechanical properties of the posts, they provide both adequate restoring force and optimized frequency response, eliminating the trade-off between these two parameters.
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 compression post CMUT achieves greater average displacement of the moveable mass and surrounding medium compared to conventional CMUTs, enabling enhanced ultrasound wave generation and detection through the compression of posts within post ports, with adjustable stiffness and frequency optimization.
Implementation Method 1
the pattern of compression posts compress to provide a restoring force in a direction that is normal to the bottom surface of the moveable mass
Implementation Method 2
an electrostatic force applied across a first and a second electrodes, where the first electrode is included in the moveable mass, that generates translational movement in the moveable mass
Implementation Method 3
enabling enhanced ultrasound wave generation and detection through the compression of posts within post ports
Data Source
AI summary
A compression post capacitive micromachined ultrasonic transducer (CMUT) is provided. The compression post CMUT includes a first electrode, a top conductive layer having a pattern of post holes, a moveable mass that includes the first electrode. The compression post CMUT further includes an operating gap disposed between the top surface of the top conductive layer and a bottom surface of the moveable mass, a pattern of compression posts, where a proximal end the compression post is connected perpendicularly to a bottom surface of the moveable mass, where the pattern of compression posts span through the pattern of post holes. The top conductive layer includes the second electrode that is electronically insulated from the first electrode, where the pattern of compression posts compress to provide a restoring force in a direction that is normal to the bottom surface of the moveable mass.