Segmented PMUT Membrane for Broadband Ultrasonic Imaging
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Solution Overview
Problem
Existing ultrasonic transducers, particularly piezoelectric micromechanical ultrasonic transducers (PMUTs), face limitations in efficiently spanning a broad frequency range within a single device, requiring multiple transducer heads and complex drive electronics, which complicates their application in medical imaging and other applications where compactness and versatility are essential.
Innovation Solution
The development of segmented piezoelectric micromechanical ultrasonic transducer (PMUT) elements with a membrane divided into segments corresponding to nodal lines, allowing for resonance at various frequency modes, including first-order and second-order modes, enabling a single array to cover a wide frequency range without the need for multiple transducer sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple transducer heads are used to span a broad frequency range, then the frequency coverage is improved, but the device complexity and size increase
Solution Approach 1:
The membrane is divided into multiple segments by boundary portions that correspond to nodal lines of different harmonic modes. Each segment can be independently controlled by separate electrode layers, allowing the transducer to operate at multiple frequency modes (fundamental, first-order, second-order, and higher-order harmonics) using a single integrated device rather than multiple separate transducer heads
2Adaptability or versatility
If multiple transducer heads are used to span a broad frequency range, then the frequency coverage is improved, but the array size increases
Solution Approach 1:
A single PMUT element with segmented membrane and multiple electrode layers serves multiple functions by operating at different harmonic modes (fundamental, first-order, second-order, and higher-order). This multi-functional design allows one transducer to replace what would traditionally require multiple separate transducers, thereby reducing the overall array size while maintaining broad frequency coverage from 2 MHz to 20 MHz
3Adaptability or versatility
If multiple transducer heads are used, then the frequency coverage is improved, but the drive electronics complexity increases
Solution Approach 1:
The transducer employs dynamic control of the segmented membrane through independently addressable electrode layers, allowing switching between different operational modes (fundamental and various harmonic modes) by applying appropriate drive signals to specific segment groups. This dynamic reconfigurability enables a single device to adapt its frequency response without requiring complex external electronics for multiple fixed-frequency transducers
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 allows for a compact, portable ultrasonic imaging system capable of spanning frequencies from 2 MHz to 20 MHz with reduced array size and complexity, enhancing versatility and efficiency by enabling multiple transmit/receive frequencies with the same diameter or radius, thus simplifying drive electronics and improving device portability.
Implementation Method 1
The piezoelectric layer stack may include a piezoelectric layer, a first electrode layer disposed on a first side of the piezoelectric layer, and a second electrode layer disposed on a second side of the piezoelectric layer
Implementation Method 2
The boundary portions correspond to nodal lines of the entire membrane. The membrane includes a membrane segment disposed proximate each segment cavity. The membrane is configured to undergo one or both of flexural motion and vibration when the segmented PMUT element receives or transmits ultrasonic signals
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
An apparatus may include one or more segmented piezoelectric micromechanical ultrasonic transducer (PMUT) elements. Each segmented PMUT element may include a substrate, an anchor structure disposed on the substrate and a membrane disposed proximate the anchor structure. The membrane may include a piezoelectric layer stack and a mechanical layer. The anchor structure may include boundary portions that divide the segmented PMUT element into segments. Each segment may have a corresponding segment cavity. The boundary portions may correspond to nodal lines of the entire membrane. The membrane may include a membrane segment disposed proximate each segment cavity. The membrane may be configured to undergo one or both of flexural motion and vibration when the segmented PMUT element receives or transmits signals.