CMUT Aperture Geometry for Acoustic Beam Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ultrasonic transducers, particularly capacitive micromachined ultrasonic transducers (CMUTs), face challenges such as spurious boundary effects, fragility, biased voltage requirements, long prototyping cycles, and high production costs, which affect their performance and image quality, especially in array designs where precise geometric control is necessary for high-quality imaging.
Innovation Solution
The implementation of customized surface mapping and apodization techniques for CMUTs, including amplitude and frequency apodization, to optimize the geometry and electrical impedance of capacitive micromachined membranes (CMMs), reducing side lobes and improving the acoustical beam pattern, and enabling better integration with electronics for enhanced imaging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If piezoelectric material is slotted into narrow independent blocks for array transducers, then angular directivity control is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the geometric parameters of the piezoelectric elements, specifically using rectangular blocks with dimensions (width w, length l, thickness t) that satisfy specific ratio relationships (w/l < 0.5, t/w < 0.5). These parameter changes enable control of the acoustic beam pattern and reduction of side lobes while maintaining manufacturability.
Solution Approach 2:
The patent applies different geometric characteristics to different parts of the transducer array. Each piezoelectric block has specific dimensional ratios optimized for its position and function, allowing local optimization of acoustic radiation patterns while maintaining overall array performance.
2Reliability
If piezoelectric material thickness is predetermined for resonant frequency, then frequency performance is improved, but geometric modification capability deteriorates
Solution Approach 1:
The patent introduces adjustability into the transducer design by making the geometric parameters (width, length, thickness) modifiable after the initial resonant frequency is established. This allows the transducer to adapt to different application requirements while maintaining its fundamental resonant frequency performance.
3Ease of manufacture
If CMUT devices use mass production processes, then manufacturing cost is reduced, but device fragility and biased voltage requirements remain
Solution Approach 1:
The patent addresses device fragility by designing the CMUT structure with inherent mechanical robustness considerations during the manufacturing process. The capacitive membrane structure and support mechanisms are designed to withstand handling and operational stresses despite the miniaturized dimensions enabled by mass production processes.
4Manufacturing precision
If transducer aperture geometry is optimized for acoustic beam pattern, then image quality is improved, but electrical impedance characteristics may deteriorate
Solution Approach 1:
The patent optimizes the geometric parameters of the piezoelectric elements (width, length, thickness ratios) to simultaneously achieve desired acoustic beam patterns and acceptable electrical impedance characteristics. The specific dimensional relationships (w/l < 0.5, t/w < 0.5) are derived to balance acoustic and electrical performance.
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
This approach significantly enhances the acoustical and electrical behavior of CMUTs, improving the quality of acoustic beam patterns and frequency response, allowing for customized acoustical output and reduced edge effects, while maintaining the intrinsic performance of the devices without compromising their design.
Implementation Method 1
the transducer is governed by a voltage oscillation over an electrostatic field (bias voltage). This oscillation causes the membranes over the cavity to vibrate and to therefore produce output ultrasonic waves
Implementation Method 2
when a pressure force acts on the surfaces of the biased membranes, this results in mechanical bending of the membranes and, thus, in creation of an output voltage oscillation
Implementation Method 3
Ultrasonic transducers are typically formed with one vibrating surface or a plurality of vibrating surfaces capable of converting electrical energy into mechanical displacements and vice-versa
Data Source
AI summary
A capacitive micro-machined ultrasonic transducer (CMUT) array includes an improved elementary aperture for imaging operations. The transducer can be of a linear, curved linear, annular, matrix or even single surface configuration. The elementary apertures thereof are formed by a specific arrangement of capacitive micromachined membranes (CMM) so as to exhibit ideal acoustical and electrical behavior when operated with imaging systems. The CMM arrangements can be either conventional where the element transducers of the array are uniformly shaped by predefined CMMs in a manner such as to exhibit acoustic behavior similar to a piezoelectric transducer, or can be more sophisticated, wherein each element transducer is formed by a specific combination of different CMMs (i.e., of a different size and/or shape) so as to provide the transducer with built-in acoustic apodization that can be implemented in the azimuth and/or elevation dimension of the device.