pMUT Top Electrode Layout for Acoustic Pressure and Capacitance
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Solution Overview
Problem
Existing micromachined ultrasound transducers (MUTs) face a trade-off between electrical and acoustic performance, where increasing electrode size improves acoustic pressure but degrades electrical performance, and the shape of electrodes affects vibrational resonance frequency.
Innovation Solution
Designing micromachined ultrasonic transducers with asymmetric or symmetric top electrodes, where the areal density distribution has local maxima coinciding with anti-nodal points at vibrational resonance frequencies, optimizing both acoustic and electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the size of the electrodes increases, then the amplitude of acoustic pressure generated by the pMUT increases, but the capacitance increases which degrades the electrical performance
Solution Approach 1:
The patent applies local quality by creating non-uniform areal density distribution in the top electrode, with local maxima positioned at anti-nodal points of the vibrational mode. This allows different regions of the electrode to have different densities - higher density at anti-nodal points to maximize acoustic pressure generation, and lower density elsewhere to minimize overall capacitance. This resolves the contradiction by optimizing acoustic performance locally without proportionally increasing electrical capacitance.
2Stress or pressure
If the shape of the electrodes is modified to improve acoustic pressure at vibrational resonance frequency, then the electrical performance may be affected
Solution Approach 1:
The patent employs asymmetry by designing top electrodes with non-uniform areal density distribution that does not follow conventional symmetric patterns. The density varies across the electrode surface with local maxima at specific anti-nodal points, creating an asymmetric density profile that optimizes acoustic coupling at resonance frequencies while controlling overall capacitance through strategic placement of high-density regions.
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
Enhances acoustic pressure performance while maintaining electrical performance by aligning electrode density with anti-nodal points, allowing for improved imaging and tissue analysis.
Implementation Method 1
transducers, such as capacitive transduction (cMUTs) or piezoelectric transduction (pMUTs)
Implementation Method 2
micromachined ultrasonic transducers (MUTs)
Implementation Method 3
transducers, such as capacitive transduction (cMUTs) or piezoelectric transduction (pMUTs)
Data Source
AI summary
A micromachined ultrasonic transducer (MUT). The MUT includes: a substrate; a membrane suspending from the substrate; a bottom electrode disposed on the membrane; a piezoelectric layer disposed on the bottom electrode and an asymmetric top electrode is disposed on the piezoelectric layer. The areal density distribution of the asymmetric electrode along an axis has a plurality of local maxima, wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency is located.