CMUT Array with Variable Sub-Element Frequencies
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ultrasound transducers face limitations due to impedance mismatch between piezoelectric materials and human tissues, and their fixed elevation aperture compromises imaging performance with depth, leading to restricted bandwidth and compromised imaging quality.
Innovation Solution
The development of capacitive micromachined ultrasonic transducers (CMUTs) with multiple sub-elements in the elevation dimension, allowing for ultra-wide bandwidth, variable pitch, and continuous elevation apodization, which enables dynamic aperture adjustment and improved imaging performance across varying depths without the need for matching layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If matching layers are added to reduce impedance mismatch, then bandwidth is improved, but device complexity increases
Solution Approach 1:
The patent changes the fundamental operating parameters of the transducer by using CMUT technology with variable capacitance. The capacitance ratio between the first and second capacitive elements can be adjusted to match different impedance values, eliminating the need for physical matching layers while achieving broadband operation across multiple frequency ranges.
2Measurement precision
If aperture size is increased to maintain uniform elevation slice thickness, then imaging performance at depth is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic aperture control where the effective aperture size changes based on imaging depth. The system selectively activates different combinations of capacitive elements in the elevation dimension, allowing the aperture to dynamically adapt to maintain uniform slice thickness across varying penetration depths without requiring a physically larger fixed aperture.
Solution Approach 2:
The transducer array is segmented into multiple independently controllable capacitive elements in the elevation dimension. This segmentation allows selective activation of subsets of elements to create variable aperture sizes, enabling the system to optimize elevation slice thickness for different imaging depths by activating appropriate numbers of sub-elements.
3Measurement precision
If number of sub-elements is increased for optimal near field to far field imaging, then imaging performance is improved, but device complexity and channel requirements increase
Solution Approach 1:
The patent combines multiple capacitive elements into integrated CMUT elements with integrated capacitance values. By merging the functionality of multiple smaller elements into fewer larger elements with variable capacitance ratios, the system achieves the same imaging performance benefits while reducing the total number of channels and control 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
CMUTs achieve enhanced imaging quality by maintaining high image resolution and penetration depth with increased bandwidth and adjustable aperture, effectively addressing the impedance mismatch and fixed aperture limitations of traditional transducers.
Implementation Method 1
capacitive micromachined ultrasonic transducers (CMUTs)
Implementation Method 2
ultrasound imaging
Data Source
AI summary
In some examples, a CMUT array may include a plurality of elements, and each element may include a plurality of sub-elements. For instance, a first sub-element and a second sub-element may be disposed on opposite sides of a third sub-element. In some cases, the third sub-element may be configured to transmit ultrasonic energy at a higher center frequency than at least one of the first sub-element or the second sub-element. Further, in some instances, the sub-elements may have a plurality of regions in which different regions are configured to transmit ultrasonic energy at different resonant frequencies. For instance, the resonant frequencies of a plurality of CMUT cells in each sub-element may decrease in an elevation direction from a center of each element toward the edges of the CMUT array.