Guided Wave Piezoelectric Layer Layout for Selective Loading
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Solution Overview
Problem
Existing MEMS guided wave devices face challenges in manufacturing efficiency and utility due to limitations in accessing exposed portions of piezoelectric layers, difficulty in adjusting properties like frequency and coupling coefficient, and integration of functional structures without interfering with electrodes such as IDTs.
Innovation Solution
A MEMS guided wave device design where electrodes are arranged below the piezoelectric layer, allowing for transduction of lateral acoustic waves, with a slow wave propagation layer and guided wave confinement structures to confine the waves, enabling adjustments to frequency and properties through selective trimming and loading materials, and integration of sensing or functional layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrodes are arranged above the piezoelectric layer (conventional IDT configuration), then transduction of lateral acoustic waves is achieved, but access to exposed portions of the piezoelectric layer is limited and manufacturing flexibility is reduced
Solution Approach 1:
The patent inverts the conventional electrode arrangement by placing electrodes below the piezoelectric layer instead of above it. This inversion exposes the top surface of the piezoelectric layer for modifications while maintaining transduction functionality through the substrate, directly resolving the contradiction between manufacturing access and device structure.
Solution Approach 2:
The patent transitions the electrode arrangement from a planar configuration above the piezoelectric layer to a vertical configuration below it, utilizing the third dimension (depth/substrate layer) to achieve both transduction and improved access to the piezoelectric layer surface for modifications.
2Manufacturing precision
If properties like frequency and coupling coefficient are adjusted through trimming and loading materials, then device performance is optimized, but manufacturing steps and device complexity increase
Solution Approach 1:
The patent employs parameter changes by introducing loading materials with different physical properties (density, elasticity) and varying piezoelectric layer thickness through selective trimming to precisely control frequency and coupling coefficient, transforming qualitative performance optimization into quantitative parameter adjustment.
Solution Approach 2:
The patent applies local quality by selectively trimming specific regions of the piezoelectric layer and placing loading materials at specific locations to achieve desired frequency and coupling characteristics in different device regions, allowing localized optimization without affecting the entire device.
3Adaptability or versatility
If functional structures are integrated into the device, then device utility is enhanced, but integration difficulty increases due to interference with electrodes
Solution Approach 1:
The patent extracts the electrodes from their conventional position above the piezoelectric layer and relocates them below, removing the conflict between electrodes and functional structures that would be integrated on or above the piezoelectric layer surface, thereby enabling easier integration of sensors, antennas, and other functional elements.
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 design enhances manufacturing efficiency and device utility by exposing the piezoelectric layer for modifications, allowing for precise adjustments and integration of functional elements without interfering with electrodes, thereby improving frequency control and wave propagation properties.
Implementation Method 1
Piezoelectric materials acquire a charge when compressed, twisted, or distorted. This property provides a transducer effect between electrical and mechanical oscillations or vibrations.
Implementation Method 2
Confinement may be provided on at least one surface, such as by reflection at a solid/air interface, or by way of an acoustic mirror (e.g., a stack of layers referred to as a Bragg mirror) capable of reflecting acoustic waves.
Implementation Method 3
an acoustic wave may be excited in a piezoelectric layer in the presence of an alternating electrical signal, or propagation of an elastic wave in a piezoelectric material may lead to generation of an electrical signal
Data Source
AI summary
A micro-electrical-mechanical system (MEMS) guided wave device includes a plurality of electrodes arranged below a piezoelectric layer (e.g., either embedded in a slow wave propagation layer or supported by a suspended portion of the piezoelectric layer) and configured for transduction of a lateral acoustic wave in the piezoelectric layer. The piezoelectric layer permits one or more additions or modifications to be made thereto, such as trimming (thinning) of selective areas, addition of loading materials, sandwiching of piezoelectric layer regions between electrodes to yield capacitive elements or non-linear elastic convolvers, addition of sensing materials, and addition of functional layers providing mixed domain signal processing utility.