Piezoelectric Membrane Transducer Arrays with Patterned Insulation
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Solution Overview
Problem
Acoustic crosstalk between piezoelectric vibrating membranes in arrays for acoustic/ultrasound applications leads to reduced image quality, poorly defined measurement areas, and larger than expected focus due to lateral vibrations, which existing technologies have not adequately addressed.
Innovation Solution
A patterned stack on a flexible substrate with a piezoelectric layer sandwiched between electrode layers and a patterned insulation layer that electrically and acoustically insulates between transducers, preventing lateral crosstalk by varying flexural rigidity between contact and insulated areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If piezoelectric membranes are closely packed in arrays for acoustic applications, then device productivity and area utilization are improved, but acoustic crosstalk between neighboring transducers increases due to lateral vibrations
Solution Approach 1:
The piezoelectric membrane is segmented into isolated vibrating regions by providing insulating material between adjacent membranes. This segmentation prevents lateral vibrations from propagating between neighboring transducers, thereby reducing acoustic crosstalk while maintaining high array density for improved productivity
Solution Approach 2:
The insulating material is applied locally between specific adjacent membranes rather than uniformly across the entire array. This local quality approach selectively prevents acoustic crosstalk at critical interfaces while maintaining the overall structural integrity and high density of the transducer array
2Object-generated harmful factors
If insulation material is added between electrodes and piezoelectric layer, then acoustic crosstalk is reduced, but device complexity and manufacturing steps increase
Solution Approach 1:
The insulating material serves multiple functions simultaneously: it provides electrical insulation between the electrode and piezoelectric layer, acts as acoustic isolation between adjacent membranes, and defines the boundaries of individual vibrating regions. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity despite adding the insulation layer
3Object-generated harmful factors
If insulation material is used to prevent lateral vibrations, then acoustic crosstalk is alleviated, but manufacturing precision requirements increase for pattern formation
Solution Approach 1:
The insulating material is applied in advance during the manufacturing process, before final assembly and testing. This preliminary action allows for controlled pattern formation using standard lithographic or deposition techniques, reducing the need for high-precision post-processing and thereby limiting the increase in manufacturing precision requirements
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 configuration effectively alleviates in-plane acoustic crosstalk, allowing for improved manufacturability and design freedom of acoustic devices with minimal crosstalk, maintaining membrane dimensions and resonance frequency while reducing interference between transducers.
Implementation Method 1
piezoelectric layer sandwiched between respective bottom and top electrode layers
Implementation Method 2
the insulation material may function as acoustic insulation between the transducers. In this way, acoustic interference or crosstalk can be alleviated
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3D
AI summary
An acoustic device (100) comprises an array of acoustic transducers (10a,10b) formed by a patterned stack (12-15) on a flexible substrate (11). The stack comprises a piezoelectric layer (13) sandwiched between respective bottom and top electrode layers (12,15), and a patterned insulation layer (14) formed by a pattern of insulation material (14m). The pattern comprises insulated areas (A14) where the insulation material (14m) is disposed between one of the electrodes (12,15) and the piezoelectric layer (13), and contact areas (A10) without the insulation material (14m) where both electrodes (12,15) contact the piezoelectric layer (13).