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Wei Z, Bai Y, Cheng R, Hu H, Wang P, Zhang W, Zhang G. Improved sparse domain super-resolution reconstruction algorithm based on CMUT. PLoS One 2023; 18:e0290989. [PMID: 37651438 PMCID: PMC10470967 DOI: 10.1371/journal.pone.0290989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 08/20/2023] [Indexed: 09/02/2023] Open
Abstract
A novel breast ultrasound tomography system based on a circular array of capacitive micromechanical ultrasound transducers (CMUT) has broad application prospects. However, the images produced by this system are not suitable as input for the training phase of the super-resolution (SR) reconstruction algorithm. To solve the problem, this paper proposes an improved medical image super-resolution (MeSR) method based on the sparse domain. First, we use the simultaneous algebraic reconstruction technique (SART) with high imaging accuracy to reconstruct the image into a training image in a sparse domain model. Secondly, we denoise and enhance the contrast of the SART images to obtain improved detail images before training the dictionary. Then, we use the original detail image as the guide image to further process the improved detail image. Therefore, a high-precision dictionary was obtained during the testing phase and applied to filtered back projection SR reconstruction. We compared the proposed algorithm with previously reported algorithms in the Shepp Logan model and the model based on the CMUT background. The results showed significant improvements in peak signal-to-noise ratio, entropy, and average gradient compared to previously reported algorithms. The experimental results demonstrated that the proposed MeSR method can use noisy reconstructed images as input for the training phase of the SR algorithm and produce excellent visual effects.
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Affiliation(s)
- Zhiqing Wei
- School of Mathematics, North University of China, Taiyuan, China
| | - Yanping Bai
- School of Mathematics, North University of China, Taiyuan, China
| | - Rong Cheng
- School of Mathematics, North University of China, Taiyuan, China
| | - Hongping Hu
- School of Mathematics, North University of China, Taiyuan, China
| | - Peng Wang
- School of Mathematics, North University of China, Taiyuan, China
| | - Wendong Zhang
- Key Laboratory of Dynamic Testing Technology, School of Instrument and Electronics, North University of China, Taiyuan, China
| | - Guojun Zhang
- Key Laboratory of Dynamic Testing Technology, School of Instrument and Electronics, North University of China, Taiyuan, China
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Gao B, Zhang S, He C, Wang R, Yang Y, Jia L, Wang Z, Wu Y, Hu S, Zhang W. Research on Broadband Matching Method for Capacitive Micromachined Ultrasonic Transducers Based on PDMS/TiO 2 Particles. MICROMACHINES 2022; 13:1827. [PMID: 36363848 PMCID: PMC9695076 DOI: 10.3390/mi13111827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 10/23/2022] [Accepted: 10/23/2022] [Indexed: 06/16/2023]
Abstract
The study of impedance matching between a transducer and its working medium is an important part of acoustic transducer design. The traditional quarter wavelength matching (Q-matching) scheme is not suitable for broadband capacitive micromachined ultrasonic transducers. To mitigate this issue, a 0-3 composite broadband matching layer based on polydimethylsiloxane (PDMS) substrate/TiO2 particles is designed to achieve electrical insulation and efficient acoustic energy transfer of underwater capacitive micromachined ultrasonic transducer (CMUT) devices. In this work, the coherent potential approximation model is used to analyze the properties of 0-3 composite materials. Samples are prepared for performance testing to determine the proportion of TiO2 particles that enable the 0-3 composite materials to have the same longitudinal acoustic impedance as water. The CMUT device is packaged by a spin coating and pouring process, and its performance tests are carried out. The experimental results show that the central frequency of the transducer remains at 1.74 MHz, the -6 dB fractional bandwidth increases from 97.3% to 100.3%, the 3 dB directional main beam width increases from 8.3° to 10.3°, the side lobes decrease significantly, and the device has good reception sensitivity. These values imply that the 0-3 composite material has good matching performance, and this matching scheme has the advantages of high efficiency and wide bandwidth. This broadband matching method endows CMUTs with great advantages in underwater detection systems, and it facilitates underwater ultrasonic imaging of CMUT.
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Affiliation(s)
- Bizhen Gao
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Sai Zhang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
- Department of Physics, The Institute of Ultrasonic Testing, Jiangsu University, Zhenjiang 212013, China
| | - Changde He
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Renxin Wang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Yuhua Yang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Licheng Jia
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Zhihao Wang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Yang Wu
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Shumin Hu
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
| | - Wendong Zhang
- State Key Laboratory of Dynamic Measurement Technology, School of Instrumentand Electronics, North University of China, Taiyuan 030051, China
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Ultra-Low-Voltage Capacitive Micromachined Ultrasonic Transducers with Increased Output Pressure Due to Piston-Structured Plates. MICROMACHINES 2022; 13:mi13050676. [PMID: 35630143 PMCID: PMC9144194 DOI: 10.3390/mi13050676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/22/2022] [Accepted: 04/24/2022] [Indexed: 02/01/2023]
Abstract
Capacitive micromachined ultrasonic transducers (CMUTs) represent an accepted technology for ultrasonic transducers, while high bias voltage requirements and limited output pressure still need to be addressed. In this paper, we present a design for ultra-low-voltage operation with enhanced output pressure. Low voltages allow for good integrability and mobile applications, whereas higher output pressures improve the penetration depth and signal-to-noise ratio. The CMUT introduced has an ultra-thin gap (120 nm), small plate thickness (800 nm), and is supported by a non-flexural piston, stiffening the topside for improved average displacement, and thus higher output pressure. Three designs for low MHz operation are simulated and fabricated for comparison: bare plate, plate with small piston (34% plate coverage), and big piston (57%). The impact of the piston on the plate mechanics in terms of resonance and pull-in voltage are simulated with finite element method (FEM). Simulations are in good agreement with laser Doppler vibrometer and LCR-meter measurements. Further, the sound pressure output is characterized in immersion with a hydrophone. Pull-in voltages range from only 7.4 V to 25.0 V. Measurements in immersion with a pulse at 80% of the pull-in voltage present surface output pressures from 44.7 kPa to 502.1 kPa at 3.3 MHz to 4.2 MHz with a fractional bandwidth of up to 135%. This leads to an improvement in transmit sensitivity in pulsed (non-harmonic) driving from 7.8 kPa/V up to 24.8 kPa/V.
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Chen D, Cui X, Zhang Q, Li D, Cheng W, Fei C, Yang Y. A Survey on Analog-to-Digital Converter Integrated Circuits for Miniaturized High Resolution Ultrasonic Imaging System. MICROMACHINES 2022; 13:mi13010114. [PMID: 35056279 PMCID: PMC8779678 DOI: 10.3390/mi13010114] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 12/31/2021] [Accepted: 01/05/2022] [Indexed: 01/27/2023]
Abstract
As traditional ultrasonic imaging systems (UIS) are expensive, bulky, and power-consuming, miniaturized and portable UIS have been developed and widely utilized in the biomedical field. The performance of integrated circuits (ICs) in portable UIS obviously affects the effectiveness and quality of ultrasonic imaging. In the ICs for UIS, the analog-to-digital converter (ADC) is used to complete the conversion of the analog echo signal received by the analog front end into digital for further processing by a digital signal processing (DSP) or microcontroller unit (MCU). The accuracy and speed of the ADC determine the precision and efficiency of UIS. Therefore, it is necessary to systematically review and summarize the characteristics of different types of ADCs for UIS, which can provide valuable guidance to design and fabricate high-performance ADC for miniaturized high resolution UIS. In this paper, the architecture and performance of ADC for UIS, including successive approximation register (SAR) ADC, sigma-delta (Σ-∆) ADC, pipelined ADC, and hybrid ADC, have been systematically introduced. In addition, comparisons and discussions of different types of ADCs are presented. Finally, this paper is summarized, and presents the challenges and prospects of ADC ICs for miniaturized high resolution UIS.
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Affiliation(s)
| | | | | | - Di Li
- Correspondence: (D.L.); (W.C.); Tel.: +86-137-0925-0163 (D.L.); +86-152-3193-6291 (W.C.)
| | - Wenyang Cheng
- Correspondence: (D.L.); (W.C.); Tel.: +86-137-0925-0163 (D.L.); +86-152-3193-6291 (W.C.)
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