Surface-Guided Bulk Wave Transducer with Interlaced Piezoelectric Combs
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Solution Overview
Problem
Conventional transducers for guided surface wave components have a modest electromechanical coupling coefficient, limiting their effectiveness in radiofrequency filtering and other applications, due to the nature of electrostatic field deployment and substrate-driven acousto-electric energy distribution.
Innovation Solution
A surface-guided bulk wave transducer is designed with a network of synchronous acoustic excitation sources on an acoustic substrate and electric ground plane, featuring interlaced piezoelectric transducers to enhance electromechanical coupling, allowing propagation of bulk elastic waves with high coupling coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional transducer structures with interdigitated combs are used on piezoelectric substrates, then the device can be manufactured with proven technological feasibility, but the electromechanical coupling coefficient remains modest and limits effectiveness in radiofrequency filtering applications
Solution Approach 1:
The transducer is segmented into distinct functional layers: a non-piezoelectric acoustic substrate for wave propagation, and a separately deposited piezoelectric layer for excitation and detection. This segmentation allows optimization of each layer's properties independently, enabling high electromechanical coupling while maintaining manufacturing feasibility through standard deposition techniques
Solution Approach 2:
A ground plane is introduced as an intermediary element between the piezoelectric layer and the substrate. This ground plane serves as a reference for the electrostatic field deployment, improving the coupling efficiency by providing a controlled electrical environment that enhances the interaction between the piezoelectric material and the acoustic waves
2Reliability
If materials with high acoustic quality such as sapphire or diamond are used to reduce losses and increase propagation velocity, then acoustic performance is improved, but these materials are not piezoelectric and require additional deposited piezoelectric layers for excitation and detection
Solution Approach 1:
The transducer structure is divided into an acoustic substrate layer optimized for wave propagation (sapphire, diamond, or other high-quality materials) and a separate piezoelectric functional layer deposited on top. This segmentation allows each material to be selected and optimized for its specific function without compromising the other, achieving high acoustic quality while maintaining excitation and detection capabilities
Solution Approach 2:
The deposited piezoelectric layer serves multiple functions simultaneously: it provides the necessary piezoelectric effect for excitation and detection, and when combined with the ground plane, creates a controlled electrostatic field environment that enhances coupling efficiency. This multi-functionality reduces the need for additional specialized components
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 transducer achieves significantly improved electromechanical coupling, enabling more effective conversion of electric signals to surface-guided bulk waves and vice versa, with reduced losses and enhanced performance in radiofrequency applications.
Implementation Method 1
A surface-guided bulk wave transducer... featuring interlaced piezoelectric transducers to enhance electromechanical coupling, allowing propagation of bulk elastic waves
Implementation Method 2
enabling more effective conversion of electric signals to surface-guided bulk waves and vice versa, with reduced losses
Data Source
AI summary
A surface-guided bulk wave transducer includes a stack of an acoustic substrate, an electric ground plane, and a network of synchronous acoustic excitation sources with two combs of elementary piezoelectric transducers alternately interlaced two-by-two according to a periodic network step corresponding to a propagation mode of a surface-guided bulk wave of the acoustic substrate. Each elementary piezoelectric transducer includes a single and different rod with a parallelepipedal shape for which the nature, the cut of the piezoelectric material, the height h, and the width are selected for increasing the electromechanical coupling coefficient of the transducer assembly to a high level.