CMUT Array Broadband Imaging via Segmented Pulse Sequences
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Solution Overview
Problem
Current ultrasound systems with CMUT transducers face challenges in maintaining high-quality imaging over large bandwidths due to signal attenuation, frequency-dependent acoustic speeds, and increased noise and energy dissipation, which affect image quality and cost-effectiveness.
Innovation Solution
The ultrasound system employs a CMUT transducer array with a voltage supply generating temporally distinct transmit pulses and bias voltages to operate in narrowband modes, allowing for broadband imaging by superimposing echoes, and includes programmable filters and delay stages to compensate for frequency-dependent effects, thereby reducing noise and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If broadband transmit pulses are used for ultrasonic imaging, then imaging bandwidth and resolution are improved, but signal attenuation and noise increase significantly
Solution Approach 1:
The broadband frequency spectrum is segmented into multiple narrowband frequency ranges. The transmit pulse sequence is divided into multiple pulses, each centered at a different frequency within the broadband range. This segmentation allows each pulse to operate in a narrowband mode where signal attenuation is lower and more predictable, while collectively covering the full broadband imaging range through frequency compounding.
Solution Approach 2:
The system transmits a periodic sequence of narrowband pulses at different frequencies rather than a single broadband pulse. Each pulse is transmitted at a specific frequency, and the sequence is repeated over time. This periodic transmission allows the system to maintain narrowband operation for each pulse while achieving broadband imaging capability through the combination of multiple frequency components.
2Adaptability or versatility
If broadband transmit pulses are used, then imaging bandwidth is improved, but energy dissipation and noise increase
Solution Approach 1:
The broadband frequency spectrum is segmented into multiple narrowband frequency ranges. The transmit pulse sequence is divided into multiple pulses, each centered at a different frequency within the broadband range. This segmentation allows each pulse to operate in a narrowband mode where signal attenuation is lower and more predictable, while collectively covering the full broadband imaging range through frequency compounding.
Solution Approach 2:
Instead of transmitting a single high-power broadband pulse that would cause excessive energy dissipation, the system transmits multiple lower-power narrowband pulses that collectively cover the broadband range. Each individual pulse uses less energy, but the cumulative effect of multiple pulses achieves the desired broadband imaging capability with reduced overall energy dissipation and noise.
3Adaptability or versatility
If frequency-dependent acoustic speed variations are present, then broadband imaging capability is maintained, but image quality degrades due to aberrations
Solution Approach 1:
The system applies frequency-specific processing to compensate for local variations in acoustic speed at different frequencies. Each frequency component in the pulse sequence is processed independently with frequency-dependent delay and weighting factors that account for the specific acoustic speed variations at that frequency. This local quality adjustment ensures that each frequency component maintains optimal image quality while the combined broadband signal provides comprehensive imaging capability.
Solution Approach 2:
The system uses feedback from measured or estimated acoustic speed variations to adjust the transmit and receive parameters for each frequency component. By monitoring the actual acoustic performance and adjusting the frequency-dependent delays and weights accordingly, the system compensates for aberrations caused by frequency-dependent acoustic speed variations, maintaining high image quality across the broadband range.
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 enhances noise reduction, energy efficiency, and image quality while maintaining broad bandwidth capabilities, optimizing the CMUT transducer array's performance for improved ultrasound imaging.
Implementation Method 1
each cell comprising a substrate carrying a first electrode of an electrode arrangement, the substrate being spatially separated from a flexible membrane including a second electrode of said electrode arrangement by a gap
Implementation Method 2
CMUT transducers are tiny diaphragm-like devices with electrodes that convert the sound vibration of a received ultrasound signal into a modulated capacitance
Implementation Method 3
providing a second set of CMUT cells with a sequence of temporally distinct bias voltages, wherein each temporally distinct bias voltage is provided in a receive mode following one of said transmit modes and is for setting the second set of CMUT cells to a resonance frequency corresponding to the pulse frequency
Data Source
AI summary
An ultrasound system (1) is disclosed that comprises a probe (10) including an array (110) of CMUT (capacitive micromachined ultrasound transducer) cells (100), each cell comprising a substrate (112) carrying a first electrode (122) of an electrode arrangement, the substrate being spatially separated from a flexible membrane (114) including a second electrode (120) of said electrode arrangement by a gap (118); a voltage supply (45) coupled to said probe and adapted to provide a first set of said CMUT cells with a sequence of drive voltages each including a bias voltage component and a stimulus component of different frequency for generating a series of temporally distinct pulses each having a different frequency, wherein each pulse is generated in a separate transmit mode and provide a second set of said CMUT cells with a sequence of temporally distinct bias voltages, wherein each temporally distinct bias voltage is provided in a receive mode following one of said transmit modes and is for setting the second set of CMUT cells to a resonance frequency corresponding to the pulse frequency of said transmit mode; and a signal processing unit (22) communicatively coupled to said array and adapted to superimpose the echo signals received by the second set of CMUT cells during the respective receive modes. An ultrasonic imaging method using such a system is also disclosed.