Piezoelectric MUT Electrode Layout for Resonance-Aligned Sensitivity
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Solution Overview
Problem
Existing micromachined ultrasound transducers (MUTs) face a trade-off between electrical and acoustic performance due to the size and shape of their electrodes, where increasing electrode size improves acoustic performance but degrades electrical performance, and vice versa.
Innovation Solution
Designing micromachined ultrasound transducers with asymmetric or symmetric top electrodes that have areal density distributions with local maxima coinciding with anti-nodal points at vibrational resonance frequencies to enhance both acoustic and electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ultrasonic transducer with uniform electrode distribution is used, then the manufacturing process is simple, but the transmit and receive sensitivity are insufficient and beamforming capabilities are limited
Solution Approach 1:
The patent applies local quality by creating non-uniform electrode density distributions on the membrane surface. Different regions of the membrane have different electrode densities, with higher density at anti-nodal points and lower density at nodal points. This localized variation in electrode properties optimizes the transmit and receive sensitivity at specific locations while maintaining overall transducer functionality.
Solution Approach 2:
The patent implements asymmetry by using different electrode density patterns for transmit and receive operations. The electrode distribution is specifically designed to be asymmetric relative to the membrane vibration modes, creating optimized patterns for each operational mode. This asymmetric design enables superior beamforming capabilities and directional control compared to symmetric uniform distributions.
2Measurement precision
If the ultrasonic transducer operates at higher frequencies, then the imaging resolution improves, but the tissue attenuation increases and reduces penetration depth
Solution Approach 1:
The patent applies dynamics by enabling the transducer to operate across a broad frequency range rather than being limited to a single resonant frequency. The non-uniform electrode distribution allows the transducer to dynamically adjust its effective operating characteristics across multiple frequencies, optimizing the balance between resolution and penetration for different imaging scenarios.
Solution Approach 2:
The patent implements parameter changes by varying the electrode density parameters across the membrane surface. This parameter variation enables the transducer to maintain efficient energy coupling across a broader frequency spectrum, reducing energy loss at higher frequencies while preserving imaging resolution through controlled parameter optimization.
3Power
If a large aperture transducer is used to improve signal strength, then the transmit power increases, but the device size and complexity increase
Solution Approach 1:
The patent applies local quality by concentrating electrode density at specific locations (anti-nodal points) rather than uniformly distributing it across the entire aperture. This localized concentration of electroactive material increases transmit power and receive sensitivity without requiring a proportionally larger overall aperture, thus maintaining compact transducer dimensions.
Solution Approach 2:
The patent implements a composite structure combining regions of high electrode density with regions of low or zero electrode density on the membrane surface. This composite electrode distribution optimizes power output by concentrating active elements where they are most effective while reducing overall device complexity by minimizing the total electroactive material required.
4Adaptability or versatility
If conventional transducers with simple electrode patterns are used, then the manufacturing process is straightforward, but the beamforming capabilities and focal control are insufficient
Solution Approach 1:
The patent applies local quality by assigning different electrode density characteristics to different spatial locations on the membrane. This localized differentiation enables independent control of beamforming parameters at different regions, providing superior focal control and adaptability for various imaging scenarios without requiring complex external control systems.
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 proposed design allows for improved acoustic pressure performance and frequency tuning by optimizing electrode geometry, resulting in enhanced imaging capabilities.
Implementation Method 1
a piezoelectric layer (410) disposed on the bottom electrode (408)
Implementation Method 2
The areal density distribution of the asymmetric electrode (722) along an axis (742) has a plurality of local maxima (702), wherein locations of the plurality of local maxima (735, 737) coincide with locations (726, 728) where a plurality of anti-nodal points (516, 517) at a vibrational resonance frequency is located
Implementation Method 3
a membrane (406) suspending from the substrate (402)... at a vibrational resonance frequency
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
A micromachined ultrasonic transducer (MUT) (400). The MUT (400) includes: a substrate (402); a membrane (406) suspending from the substrate (402); a bottom electrode (408) disposed on the membrane (406); a piezoelectric layer (410) disposed on the bottom electrode (408) and an asymmetric top electrode (412, 722) is disposed on the piezoelectric layer (410). The areal density distribution of the asymmetric electrode (722) along an axis (742) has a plurality of local maxima (702), wherein locations of the plurality of local maxima (735, 737) coincide with locations (726, 728) where a plurality of anti-nodal points (516, 517) at a vibrational resonance frequency is located.