pMUT Array Segmentation for Ultrasound Sensitivity
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Solution Overview
Problem
Conventional ultrasound probes using piezoelectric micromachined ultrasound transducers (pMUTs) face limitations in frequency range and sensitivity due to shared deflection vibration for transmission and reception, leading to narrowed frequency bands and reduced image quality.
Innovation Solution
An ultrasound probe design featuring a pMUT array with separate first pMUTs for transmission and second pMUTs for reception, each with distinct structures and non-overlapping cell regions, utilizing MEMS technology to achieve high sensitivity and wide frequency bands by optimizing piezoelectric materials and configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pMUT structure is used for both transmission and reception, then the device complexity is reduced, but the frequency band is narrowed and sensitivity is reduced
Solution Approach 1:
The pMUT array is segmented into two distinct groups: first pMUTs optimized for transmission and second pMUTs optimized for reception. Each group has different structural parameters (diaphragm thickness, piezoelectric layer thickness, cavity depth) tailored to their specific function, allowing independent optimization of transmission and reception frequency bands without compromising the other.
Solution Approach 2:
Different regions of the pMUT array have different local structures. The first pMUTs have structural characteristics (thinner diaphragm, smaller cavity) suited for transmission at higher frequencies, while the second pMUTs have characteristics (thicker diaphragm, larger cavity) suited for reception at lower frequencies. This local differentiation allows each region to excel at its designated function.
2Adaptability or versatility
If multiple pMUTs with different resonance frequencies are arranged, then the frequency band is widened, but deep alleys form between resonance peaks deteriorating image quality
Solution Approach 1:
The array is segmented into transmission-optimized pMUTs and reception-optimized pMUTs with non-overlapping frequency bands. The transmission pMUTs operate at higher frequencies while reception pMUTs operate at lower frequencies, creating complementary frequency coverage without the deep nulls that occur when multiple resonance peaks are mixed.
Solution Approach 2:
The system dynamically switches between transmission and reception modes, activating only the appropriate pMUT group for each operation. During transmission, only first pMUTs are activated; during reception, only second pMUTs are activated. This dynamic operation ensures consistent, high-quality signals without the interference of mixed resonance frequencies.
3Device complexity
If the same deflection vibration is used for transmission and reception, then the device structure is simplified, but the usable frequency is limited to the range around the resonance frequency
Solution Approach 1:
The vibration mechanism is segmented into two types: first pMUTs using deflection vibration for transmission and second pMUTs using thickness vibration for reception. This segmentation allows each vibration type to be optimized for its specific frequency range, with deflection vibration suited for higher frequencies and thickness vibration suited for lower frequencies, thereby expanding the overall usable frequency range.
Solution Approach 2:
The vibration mode parameter is changed between the two pMUT groups. First pMUTs are designed with structural parameters that favor deflection vibration at higher frequencies, while second pMUTs are designed with parameters that favor thickness vibration at lower frequencies. This parameter change enables the system to operate across a broader frequency spectrum.
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 design enhances transmission and reception sensitivity while expanding the frequency band, resulting in improved ultrasound image quality and resolution.
Implementation Method 1
an ultrasound transducer, an ultrasound probe employing a piezoelectric element produced by micro electro mechanical systems (MEMS) (so-called piezoelectric micromachined ultrasound transducer (pMUT)) has been increasingly developed
Implementation Method 2
The pMUT can transmit and receive ultrasound waves by vibrating (deflection vibration) a diaphragm including a piezoelectric body like a drum
Data Source
AI summary
An ultrasound probe and ultrasound diagnostic apparatus that achieve high transmission/reception sensitivity and wide frequency band are provided. The ultrasound probe includes a pMUT array in which a plurality of pMUTs are arranged. The pMUTs include first pMUTs for ultrasound transmission and pMUTs for ultrasound wave reception having a structure different from that of the first pMUTs. The cell region of each first pMUT and the cell region of each second pMUT are separated from each other in the ultrasound wave radiation plane.