Elliptical pMUT Arrays for Wideband Ultrasonic Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional piezoelectric micromachined ultrasonic transducer (pMUT) arrays face limitations in bandwidth, which affects axial resolution, and suffer from undesirable crosstalk due to mechanical and acoustic coupling between transducer elements, impacting signal-to-noise ratios in applications like fetal heart monitoring and arterial imaging.
Innovation Solution
The design incorporates independently addressable drive/sense electrode rails and piezoelectric transducer element populations with elliptical membranes of differing semi-principal axes, which increases bandwidth by providing separate resonant frequencies and reduces crosstalk through controlled electromechanical and acoustic coupling between elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional pMUT arrays use standard piezoelectric membranes, then the device structure is simple, but the bandwidth is limited
Solution Approach 1:
The patent applies asymmetry by using elliptical piezoelectric membranes instead of circular or rectangular ones. The elliptical shape has different semi-principles axes (first semi-principle axis and second semi-principle axis of different lengths), which creates different resonant frequencies along each axis. This asymmetric geometry enables the transducer array to achieve wider bandwidth by providing multiple separate resonant frequencies from a single membrane structure, thereby improving adaptability without significantly increasing device complexity.
2Productivity
If transducer elements are placed close together to increase array density, then the array size is reduced, but crosstalk between elements increases
Solution Approach 1:
The patent applies local quality by making each piezoelectric membrane's resonant frequency dependent on its specific geometric dimensions (first and second semi-principle axes). By locally varying the membrane dimensions across different transducer elements, each element operates at a unique resonant frequency. This local differentiation in geometric quality allows close spacing of elements while maintaining reduced crosstalk, as elements with different resonant frequencies experience less mechanical and acoustic coupling interference.
3Measurement precision
If the pulse length is shortened to improve axial resolution, then the bandwidth must be enhanced, but this increases the difficulty of achieving wide bandwidth in conventional arrays
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters (semi-principle axes lengths) of the piezoelectric membranes to create multiple distinct resonant frequencies. By varying these geometric parameters across different elements or within the same element structure, the system achieves wide bandwidth without requiring complex external tuning mechanisms. This direct modification of physical parameters enables the transducer array to provide the necessary bandwidth for short pulse lengths, thereby improving axial resolution while keeping the bandwidth enhancement approach relatively simple.
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 approach enhances the bandwidth of pMUT arrays, improving axial resolution and reducing crosstalk, leading to better signal-to-noise ratios and more effective ultrasonic imaging capabilities.
Implementation Method 1
a piezoelectric membrane capable of vibrating in response to a time-varying driving voltage to generate a high frequency pressure wave
Implementation Method 2
The same piezoelectric membrane can also receive reflected pressure waves from the propagation media and convert the received pressure waves into electrical signals
Implementation Method 3
each of the first piezoelectric membrane and the second piezoelectric membrane having an elliptical geometry with at least first and second semi-principle axes of differing nominal length to provide a plurality of separate resonant frequencies and increase a bandwidth of the pMUT array
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
Piezoelectric micromachined ultrasonic transducer (pMUT) arrays and systems comprising pMUT arrays are described. A piezoelectric micromachined ultrasonic transducer (pMUT) array, comprises a plurality of drive/sense electrode rails disposed over an area of a substrate and electrically addressable independently and a plurality of piezoelectric transducer element populations. Every drive/sense electrode within a piezoelectric transducer element population is coupled to one of the drive/sense electrode rails. At least one piezoelectric transducer element in each of the element populations comprises a piezoelectric membrane having an elliptical geometry with at least first and second semi-principal axes (a,b,c) of differing nominal length.