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Ambattu LA, Yeo LY. Sonomechanobiology: Vibrational stimulation of cells and its therapeutic implications. BIOPHYSICS REVIEWS 2023; 4:021301. [PMID: 38504927 PMCID: PMC10903386 DOI: 10.1063/5.0127122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 02/27/2023] [Indexed: 03/21/2024]
Abstract
All cells possess an innate ability to respond to a range of mechanical stimuli through their complex internal machinery. This comprises various mechanosensory elements that detect these mechanical cues and diverse cytoskeletal structures that transmit the force to different parts of the cell, where they are transcribed into complex transcriptomic and signaling events that determine their response and fate. In contrast to static (or steady) mechanostimuli primarily involving constant-force loading such as compression, tension, and shear (or forces applied at very low oscillatory frequencies (≤ 1 Hz) that essentially render their effects quasi-static), dynamic mechanostimuli comprising more complex vibrational forms (e.g., time-dependent, i.e., periodic, forcing) at higher frequencies are less well understood in comparison. We review the mechanotransductive processes associated with such acoustic forcing, typically at ultrasonic frequencies (> 20 kHz), and discuss the various applications that arise from the cellular responses that are generated, particularly for regenerative therapeutics, such as exosome biogenesis, stem cell differentiation, and endothelial barrier modulation. Finally, we offer perspectives on the possible existence of a universal mechanism that is common across all forms of acoustically driven mechanostimuli that underscores the central role of the cell membrane as the key effector, and calcium as the dominant second messenger, in the mechanotransduction process.
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Affiliation(s)
- Lizebona August Ambattu
- Micro/Nanophysics Research Laboratory, School of Engineering, RMIT University, Melbourne VIC 3000, Australia
| | - Leslie Y. Yeo
- Micro/Nanophysics Research Laboratory, School of Engineering, RMIT University, Melbourne VIC 3000, Australia
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2
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Choi H. Harmonic-Reduced Bias Circuit for Ultrasound Transducers. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23094438. [PMID: 37177641 PMCID: PMC10181787 DOI: 10.3390/s23094438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/23/2023] [Accepted: 04/27/2023] [Indexed: 05/15/2023]
Abstract
The gain of class-C power amplifiers is generally lower than that of class-A power amplifiers. Thus, higher-amplitude input voltage signals for class-C power amplifiers are required. However, high-amplitude input signals generate unwanted harmonic signals. Therefore, a novel bias circuit was proposed to suppress the harmonic signals generated by class-C power amplifiers, which improves the output voltage amplitudes. To verify the proposed idea, the input harmonic signals when using a harmonic-reduced bias circuit (-61.31 dB, -89.092 dB, -90.53 dB, and -90.32 dB) were measured and were found to be much lower than those when using the voltage divider bias circuit (-57.19 dB, -73.49 dB, -70.97 dB, and -73.61 dB) at 25 MHz, 50 MHz, 75 MHz, and 100 MHz, respectively. To further validate the proposed idea, the pulse-echo measurements were compared using the bias circuits. The peak-to-peak echo amplitude and bandwidth of the piezoelectric transducer, measured when using a harmonic-reduced bias circuit (27.07 mV and 37.19%), were higher than those achieved with a voltage divider circuit (18.55 mV and 22.71%). Therefore, the proposed scheme may be useful for ultrasound instruments with low sensitivity.
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Affiliation(s)
- Hojong Choi
- Department of Electronic Engineering, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam 13120, Republic of Korea
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3
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Choi H. An Inverse Class-E Power Amplifier for Ultrasound Transducer. SENSORS (BASEL, SWITZERLAND) 2023; 23:3466. [PMID: 37050526 PMCID: PMC10098776 DOI: 10.3390/s23073466] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/23/2023] [Accepted: 03/24/2023] [Indexed: 05/27/2023]
Abstract
An inverse Class-E power amplifier was designed for an ultrasound transducer. The proposed inverse Class-E power amplifier can be useful because of the low series inductance values used in the output matching network that helps to reduce signal distortions. Therefore, a newly designed Class-E power amplifier can obtain a proper echo signal quality. The measured output voltage, voltage gain, voltage gain difference, and power efficiency were 50.1 V, 22.871 dB, 0.932 dB, and 55.342%, respectively. This low voltage difference and relatively high efficiency could verify the capability of the ultrasound transducer. The pulse-echo response experiment using an ultrasound transducer was performed to verify the capability of the proposed inverse Class-E power amplifier. The obtained echo signal amplitude and pulse width were 6.01 mVp-p and 0.81 μs, respectively. The -6 dB bandwidth and center frequencies of the echo signal were 27.25 and 9.82 MHz, respectively. Consequently, the designed Class-E power amplifier did not significantly alter the performance of the center frequency of the ultrasound transducer; therefore, it could be employed particularly in certain ultrasound applications that require high linearity and reasonable power efficiency.
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Affiliation(s)
- Hojong Choi
- Department of Electronic Engineering, Gachon University, Seongnam-daero 1342, Sujeong-gu, Seongnam 13120, Gyeonggi-do, Republic of Korea
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Choi H. A Doherty Power Amplifier for Ultrasound Instrumentation. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23052406. [PMID: 36904610 PMCID: PMC10007245 DOI: 10.3390/s23052406] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/29/2023] [Accepted: 01/30/2023] [Indexed: 05/27/2023]
Abstract
The ultrasound instrumentation uses linear power amplifiers with low power efficiency, generating unwanted heat and resulting in the deterioration of the echo signal quality of measured targets. Therefore, this study aims to develop a power amplifier scheme to increase power efficiency while maintaining appropriate echo signal quality. In communication systems, the Doherty power amplifier has shown relatively good power efficiency while producing high signal distortion. The same design scheme cannot be directly applied to ultrasound instrumentation. Therefore, the Doherty power amplifier needs to be re-designed. To verify the feasibility of the instrumentation, a Doherty power amplifier was designed to obtain high power efficiency. The measured gain, output 1-dB compression point, and power-added efficiency of the designed Doherty power amplifier were 33.71 dB, 35.71 dBm, and 57.24% at 25 MHz, respectively. In addition, the performance of the developed amplifier was measured and tested using the ultrasound transducer through the pulse-echo responses. The output power with 25 MHz, 5-cycle, and 43.06 dBm generated from the Doherty power amplifier was sent through the expander to the focused ultrasound transducer with 25 MHz and 0.5″ diameter. The detected signal was sent via a limiter. Afterwards, the signal was amplified by a 36.8 dB gain preamplifier, and then displayed in the oscilloscope. The measured peak-to-peak amplitude in the pulse-echo response with an ultrasound transducer was 0.9698 V. The data showed a comparable echo signal amplitude. Therefore, the designed Doherty power amplifier can improve the power efficiency used for medical ultrasound instrumentation.
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Affiliation(s)
- Hojong Choi
- Department of Electronic Engineering, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam 13120, Gyeonggi-do, Republic of Korea
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5
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Figarol A, Olive L, Joubert O, Ferrari L, Rihn BH, Sarry F, Beyssen D. Biological Effects and Applications of Bulk and Surface Acoustic Waves on In Vitro Cultured Mammal Cells: New Insights. Biomedicines 2022; 10:biomedicines10051166. [PMID: 35625902 PMCID: PMC9139135 DOI: 10.3390/biomedicines10051166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/09/2022] [Accepted: 05/13/2022] [Indexed: 02/01/2023] Open
Abstract
Medical imaging has relied on ultrasound (US) as an exploratory method for decades. Nonetheless, in cell biology, the numerous US applications are mainly in the research and development phase. In this review, we report the main effects on human or mammal cells of US induced by bulk or surface acoustic waves (SAW). At low frequencies, bulk US can lead to cell death. Under specific intensities and exposure times, however, cell proliferation and migration can be enhanced through cytoskeleton fluidization (a reorganization of the actin filaments and microtubules). Cavitation phenomena, frequencies of resonance close to those of the biological compounds, and mechanical transfers of energy from the acoustic pressure could explain those biological outcomes. At higher frequencies, no cavitation is observed. However, USs of high frequency stimulate ionic channels and increase cell permeability and transfection potency. Surface acoustic waves are increasingly exploited in microfluidics, especially for precise cell manipulations and cell sorting. With applications in diagnosis, infection, cancer treatment, or wound healing, US has remarkable potential. More mechanotransduction studies would be beneficial to understand the distinct roles of temperature rise, acoustic streaming and mechanical and electrical stimuli in the field.
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Affiliation(s)
- Agathe Figarol
- Institut FEMTO-ST, UMR CNRS 6174, Université de Bourgogne Franche-Comté, F-25030 Besançon, France;
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, CNRS, IJL, F-54000 Nancy, France; (L.O.); (O.J.); (L.F.); (B.H.R.); (F.S.)
| | - Lucile Olive
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, CNRS, IJL, F-54000 Nancy, France; (L.O.); (O.J.); (L.F.); (B.H.R.); (F.S.)
| | - Olivier Joubert
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, CNRS, IJL, F-54000 Nancy, France; (L.O.); (O.J.); (L.F.); (B.H.R.); (F.S.)
| | - Luc Ferrari
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, CNRS, IJL, F-54000 Nancy, France; (L.O.); (O.J.); (L.F.); (B.H.R.); (F.S.)
| | - Bertrand H. Rihn
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, CNRS, IJL, F-54000 Nancy, France; (L.O.); (O.J.); (L.F.); (B.H.R.); (F.S.)
| | - Frédéric Sarry
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, CNRS, IJL, F-54000 Nancy, France; (L.O.); (O.J.); (L.F.); (B.H.R.); (F.S.)
| | - Denis Beyssen
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, CNRS, IJL, F-54000 Nancy, France; (L.O.); (O.J.); (L.F.); (B.H.R.); (F.S.)
- Correspondence: ; Tel.: +33-61-448-6182
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Automatic Cancer Cell Taxonomy Using an Ensemble of Deep Neural Networks. Cancers (Basel) 2022; 14:cancers14092224. [PMID: 35565352 PMCID: PMC9100154 DOI: 10.3390/cancers14092224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 04/18/2022] [Accepted: 04/26/2022] [Indexed: 12/24/2022] Open
Abstract
Microscopic image-based analysis has been intensively performed for pathological studies and diagnosis of diseases. However, mis-authentication of cell lines due to misjudgments by pathologists has been recognized as a serious problem. To address this problem, we propose a deep-learning-based approach for the automatic taxonomy of cancer cell types. A total of 889 bright-field microscopic images of four cancer cell lines were acquired using a benchtop microscope. Individual cells were further segmented and augmented to increase the image dataset. Afterward, deep transfer learning was adopted to accelerate the classification of cancer types. Experiments revealed that the deep-learning-based methods outperformed traditional machine-learning-based methods. Moreover, the Wilcoxon signed-rank test showed that deep ensemble approaches outperformed individual deep-learning-based models (p < 0.001) and were in effect to achieve the classification accuracy up to 97.735%. Additional investigation with the Wilcoxon signed-rank test was conducted to consider various network design choices, such as the type of optimizer, type of learning rate scheduler, degree of fine-tuning, and use of data augmentation. Finally, it was found that the using data augmentation and updating all the weights of a network during fine-tuning improve the overall performance of individual convolutional neural network models.
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Choi H. Novel dual-resistor-diode limtier circuit structures for high-voltage reliable ultrasound receiver systems. Technol Health Care 2022; 30:513-520. [PMID: 35124625 PMCID: PMC9028643 DOI: 10.3233/thc-228047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: The limiters have been used to protect the ultrasound receivers because of the inherent characteristic of the transducers which are required to use the high voltage excitation to obtain the reasonable echo signal amplitudes. OBJECTIVE: Among the variety of the limiters, the performances of discharge voltage degradation from the limiters gradually deteriorate the whole ultrasound systems according to the applied voltages of the ultrasonic transducers. This could cause the ultrasound systems to be unreliable for the long-term operations, resulting in possibly breaking the receiver systems. METHODS: Designed limiters were evaluated with insertion loss, total harmonic distortion, and pulse-echo responses with the ultrasound transducer devices. RESULTS: Designed new dual-resistor-diode limiters exhibited greater and faster suppression of the pulse width (1.15 V and 6.1 μs) for high-voltage signals. CONCLUSIONS: Our proposed dual-resistor-diode limiter could be one of the potential candidates for reliable ultrasound receiver system.
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Ryu S, Ryu J, Choi H. Fisheye lens design for solar-powered mobile ultrasound devices. Technol Health Care 2022; 30:243-250. [PMID: 35124601 PMCID: PMC9028671 DOI: 10.3233/thc-228023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: Compared to benchtop ultrasound machines, mobile ultrasound machines require portable batteries when acquiring information regarding human tissues during outdoor activities. OBJECTIVE: A novel fisheye lens type was designed to address the charging issue where it is difficult to constantly track the sun. This method does not require the use of a mechanical motor that constantly tracks the sun to charge the portable batteries. METHODS: To obtain an optical solar power system, the numerical aperture (NA) and field angle must be increased. Therefore, we use the fisheye lens with the largest field angle. RESULTS: The NA of the designed fisheye lens system reaches 0.75, allowing light collection of approximately ± 48∘. Additionally, the efficiency ratio of the central and surrounding areas also satisfies more than 80% at a field angle of 85∘ and more than 70% at field angles of 85∘ to 90∘, respectively. CONCLUSIONS: We designed a novel fisheye lens for solar-powered mobile ultrasound machines used outdoors.
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Affiliation(s)
- Seonho Ryu
- Department of Optical System Engineering, Kumoh National Institute of Technology, Gumi, Korea
| | - Jaemyung Ryu
- Department of Optical System Engineering, Kumoh National Institute of Technology, Gumi, Korea
| | - Hojong Choi
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Korea
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9
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A New Approach to Power Efficiency Improvement of Ultrasonic Transmitters via a Dynamic Bias Technique. SENSORS 2021; 21:s21082795. [PMID: 33921082 PMCID: PMC8071451 DOI: 10.3390/s21082795] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/07/2021] [Accepted: 04/12/2021] [Indexed: 12/17/2022]
Abstract
To obtain a high-quality signal from an ultrasound system through the transmitter, it is necessary to achieve an appropriate operating point of the power amplifier in the ultrasonic transmitter by applying high static bias voltage. However, the power amplifier needs to be operated at low bias voltage, because a power amplifier operating at high bias voltage may consume a large amount of power and increase the temperature of the active devices, worsening the signal characteristics of the ultrasound systems. Therefore, we propose a new method of increasing the bias voltage for a specific period to solve this problem by reducing the output signal distortion of the power amplifier and decreasing the load on the active device. To compare the performance of the proposed method, we measured and compared the signals of the amplifier with the proposed technique and the amplifier only. Notably, improvement was achieved with 11.1% of the power added efficiency and 3.23% of the total harmonic distortion (THD). Additionally, the echo signal generated by the ultrasonic transducer was improved by 2.73 dB of amplitude and 0.028% of THD under the conditions of an input signal of 10 mW. Therefore, the proposed method could be useful for improving ultrasonic transmitter performance using the developed technique.
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Novel Bandwidth Expander Supported Power Amplifier for Wideband Ultrasound Transducer Devices. SENSORS 2021; 21:s21072356. [PMID: 33800641 PMCID: PMC8037455 DOI: 10.3390/s21072356] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/24/2021] [Accepted: 03/25/2021] [Indexed: 01/08/2023]
Abstract
Ultrasound transducer devices have their own frequency ranges, depending on the applications and specifications, due to penetration depth, sensitivity, and image resolution. For imaging applications, in particular, the transducer devices are preferable to have a wide bandwidth due to the specific information generated by the tissue or blood vessel structures. To support these ultrasound transducer devices, ultrasound power amplifier hardware with a wide bandwidth can improve the transducer performance. Therefore, we developed a new bandwidth expander circuit using specially designed switching architectures to increase the power amplifier bandwidth. The measured bandwidth of the power amplifier with the help of the bandwidth expander circuit increased by 56.9%. In addition, the measured echo bandwidths of the 15-, 20-, and 25-MHz transducer devices were increased by 8.1%, 6.0%, and 9.8%, respectively, with the help of the designed bandwidth expander circuit. Therefore, the designed architecture could help an ultrasound system hardware with a wider bandwidth, thus supporting the use of different frequency ultrasound transducer devices with a single developed ultrasound system.
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Kim J, Kim KS, Choi H. Development of a low-cost six-axis alignment instrument for flexible 2D and 3D ultrasonic probes. Technol Health Care 2021; 29:77-84. [PMID: 33682747 PMCID: PMC8150473 DOI: 10.3233/thc-218008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND: The pulse-echo test is used to evaluate the performance of ultrasonic probes before manufacturing ultrasonic systems. However, commercial alignment instruments are very large and use complex programs with long operation times. OBJECTIVE: To develop a low-cost alignment instrument used in the pulse-echo test for evaluating the performance of various 2D and 3D ultrasonic probes. METHODS: The developed alignment instrument can be aligned with the X, Y, Z, azimuth, elevation, and tilt axes with manual structure to support mounting fixtures that hold 2D and 3D ultrasonic probes. Each axis has a manual lever and is designed to have no movement when fixed. In particular, tilt and azimuth directions are designed to move more than 5∘ left and right. RESULTS: The probe mounted in the X, Y, and Z axes can move at above 50 mm. The probe mounted in the azimuth, elevation, and tilt axes can move more than 5∘ in the left and right directions. The pulse-echo test using commercial ultrasonic probes showed maximum error rate of less than 5%. CONCLUSIONS: Our developed alignment instrument can reduce costs by eliminating the need for shortening inspection times for probe manufacturers.
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Affiliation(s)
- Jungsuk Kim
- Department of Biomedical Engineering, Gachon University, Hambakmoe-ro, Incheon 21936, Korea
| | - Kwang Soo Kim
- IMP System, 301-3ho 267-96, Gumi, Gyeongbuk 39373, Korea
| | - Hojong Choi
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi-Daero, Gumi 39253, Korea
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You K, Choi H. Inter-Stage Output Voltage Amplitude Improvement Circuit Integrated with Class-B Transmit Voltage Amplifier for Mobile Ultrasound Machines. SENSORS 2020; 20:s20216244. [PMID: 33147757 PMCID: PMC7662991 DOI: 10.3390/s20216244] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/25/2020] [Accepted: 10/28/2020] [Indexed: 11/16/2022]
Abstract
Piezoelectric transducers are triggered by the output voltage signal of a transmit voltage amplifier (TVA). In mobile ultrasound instruments, the sensitivity of piezoelectric transducers is a critical parameter under limited power supply from portable batteries. Therefore, the enhancement of the output voltage amplitude of the amplifier under limited power supply could increase the sensitivity of the piezoelectric transducer. Several-stage TVAs are used to increase the voltage amplitude. However, inter-stage design issues between each TVA block may reduce the voltage amplitude and bandwidth because the electronic components of the amplifier are nonlinearly operated at the desired frequency ranges. To compensate for this effect, we propose a novel inter-stage output voltage amplitude improvement (OVAI) circuit integrated with a class-B TVA circuit. We performed fundamental A-mode pulse-echo tests using a 15-MHz immersion-type piezoelectric transducer to verify the design. The echo amplitude and bandwidth when using an inter-stage OVAI circuit integrated with a class-B TVA circuit (696 mVPP and 29.91%, respectively) were higher than those obtained when using only the class-B TVA circuit (576 mVPP and 24.21%, respectively). Therefore, the proposed OVAI circuit could be beneficial for increasing the output amplitude of the class-B TVA circuit for mobile ultrasound machines.
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Kim J, You K, Choi H. Post-Voltage-Boost Circuit-Supported Single-Ended Class-B Amplifier for Piezoelectric Transducer Applications. SENSORS 2020; 20:s20185412. [PMID: 32967294 PMCID: PMC7571019 DOI: 10.3390/s20185412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/07/2020] [Accepted: 09/14/2020] [Indexed: 01/18/2023]
Abstract
Piezoelectric transducers are important devices that are triggered by amplifier circuits in mobile ultrasound systems. Therefore, amplifier performance is vital because it determines the acoustic piezoelectric transducer performances. Particularly, mobile ultrasound applications have strict battery performance and current consumption requirements; hence, amplifier devices should exhibit good efficiency because the direct current (DC) voltage in the battery are provided to the supply voltages of the amplifier, thus limiting the maximum DC drain voltages of the main transistors in the amplifier. The maximum DC drain voltages are related with maximum output power if the choke inductor in the amplifier is used. Therefore, a need to improve the amplifier performance of piezoelectric transducers exists for mobile ultrasound applications. In this study, a post-voltage-boost circuit-supported class-B amplifier used for mobile ultrasound applications was developed to increase the acoustic performance of piezoelectric transducers. The measured voltage of the post-voltage-boost circuit-supported class-B amplifier (62 VP-P) is higher than that of only a class-B amplifier (50 VP-P) at 15 MHz and 100 mVP-P input. By performing the pulse-echo measurement test, the echo signal with the post-voltage-boost circuit-supported class-B amplifier (10.39 mVP-P) was also noted to be higher than that with only a class-B amplifier (6.15 mVP-P). Therefore, this designed post-voltage-boost circuit can help improve the acoustic amplitude of piezoelectric transducers used for mobile ultrasound applications.
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Affiliation(s)
- Jungsuk Kim
- Department of Biomedical Engineering, Gachon University, 191 Hambakmoe-ro, Yeonsu-Gu, Incheon 21936, Korea;
| | - Kiheum You
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, 350-27 Gumi-daero, Gumi 39253, Korea;
| | - Hojong Choi
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, 350-27 Gumi-daero, Gumi 39253, Korea;
- Correspondence: ; Tel.: +82-54-478-7782
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Wireless Ultrasound Surgical System with Enhanced Power and Amplitude Performances. SENSORS 2020; 20:s20154165. [PMID: 32726961 PMCID: PMC7435488 DOI: 10.3390/s20154165] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/24/2020] [Accepted: 07/25/2020] [Indexed: 01/20/2023]
Abstract
A wireless ultrasound surgical system (WUSS) with battery modules requires efficient power consumption with appropriate cutting effects during surgical operations. Effective cutting performances of the ultrasound transducer (UT) should be produced for ultrasound surgical knives for effective hemostasis performance and efficient dissection time. Therefore, we implemented a custom-made UT with piezoelectric material and re-poling process, which is applied to enhance the battery power consumption and output amplitude performances of the WUSS. After the re-poling process of the UT, the quality factor increased from 1231.1 to 2418 to minimize the unwanted heat generation. To support this UT, we also developed a custom-made generator with a transformer and developed 2nd harmonic termination circuit, control microcontroller with an advanced reduced instruction set computer machine (ARM) controller, and battery management system modules to produce effective WUSS performances. The generator with a matching circuit in the WUSS showed a peak-to-peak output voltage and current amplitude of 166 V and 1.12 A, respectively, at the resonant frequency. The performance with non-contact optical vibrators was also measured. In the experimental data, the developed WUSS reduced power consumption by 3.6% and increased the amplitude by 20% compared to those of the commercial WUSS. Therefore, the improved WUSS performances could be beneficial for hemostatic performance and dissection time during surgical operation because of the developed UT with a piezoelectric material and re-poling process.
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Kim J, Kim K, Choe SH, Choi H. Development of an Accurate Resonant Frequency Controlled Wire Ultrasound Surgical Instrument. SENSORS 2020; 20:s20113059. [PMID: 32481729 PMCID: PMC7309115 DOI: 10.3390/s20113059] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 05/22/2020] [Accepted: 05/26/2020] [Indexed: 01/28/2023]
Abstract
Our developed wire ultrasound surgical instrument comprises a bolt-clamped Langevin ultrasonic transducer (BLUT) fabricated by PMN-PZT single crystal material due to high mechanical quality factor and electromechanical coupling coefficient, a waveguide in the handheld instrument, and a generator instrument. To ensure high performance of wire ultrasound surgical instruments, the BLUT should vibrate at an accurate frequency because the BLUT’s frequency influences hemostasis and the effects of incisions on blood vessels and tissues. Therefore, we implemented a BLUT with a waveguide in the handheld instrument using a developed assembly jig process with impedance and network analyzers that can accurately control the compression force using a digital torque wrench. A generator instrument having a main control circuit with a low error rate, that is, an output frequency error rate within ±0.5% and an output voltage error rate within ±1.6%, was developed to generate the accurate frequency of the BLUT in the handheld instrument. In addition, a matching circuit between the BLUT and generator instrument with a network analyzer was developed to transfer displacement vibration efficiently from the handheld instrument to the end of the waveguide. Using the matching circuit, the measured S-parameter value of the generator instrument using a network analyzer was −24.3 dB at the resonant frequency. Thus, our proposed scheme can improve the vibration amplitude and accuracy of frequency control of the wire ultrasound surgical instrument due to developed PMN-PZT material and assembly jig process.
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Affiliation(s)
- Jungsuk Kim
- Department of Biomedical Engineering, Gachon University, 534-2, Hambakmoe-ro, Incheon 21936, Korea;
| | - Kyeongjin Kim
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, 350-27 Gumi-daero, Gumi 39253, Korea;
| | - Sun-Ho Choe
- R&D Center, Metabiomed Corporation, 215 Osongsaenmyeong1-ro, Chenongu 28161, Korea;
| | - Hojong Choi
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, 350-27 Gumi-daero, Gumi 39253, Korea;
- Correspondence: ; Tel.: +82-54-478-7782
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Wide Bandwidth Class-S Power Amplifiers for Ultrasonic Devices. SENSORS 2020; 20:s20010290. [PMID: 31947972 PMCID: PMC6982734 DOI: 10.3390/s20010290] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 12/23/2019] [Accepted: 01/01/2020] [Indexed: 01/19/2023]
Abstract
Wide bandwidth ultrasonic devices are a necessity in high-resolution ultrasonic systems. Therefore, constant output voltages need to be produced across the wide bandwidths of a power amplifier. We present the first design of a wide bandwidth class-S power amplifier for ultrasonic devices. The −6 dB bandwidth of the developed class-S power amplifier was measured at 125.07% at 20 MHz, thus, offering a wide bandwidth for ultrasonic devices. Pulse-echo measurement is a performance measurement method used to evaluate the performance of ultrasonic transducers, components, or systems. The pulse-echo signals were obtained using an ultrasonic transducer with designed power amplifiers. In the pulse-echo measurements, time and frequency analyses were conducted to evaluate the bandwidth flatness of the power amplifiers. The frequency range of the ultrasonic transducer was measured and compared when using the developed class-S and commercial class-A power amplifiers with the same output voltages. The class-S power amplifiers had a relatively flat bandwidth (109.7 mV at 17 MHz, 112.0 mV at 20 MHz, and 109.5 mV at 23 MHz). When the commercial class-A power amplifier was evaluated under the same conditions, an uneven bandwidth was recorded (110.6 mV at 17 MHz, 111.5 mV at 20 MHz, and 85.0 mV at 23 MHz). Thus, we demonstrated that the designed class-S power amplifiers could prove useful for ultrasonic devices with a wide frequency range.
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A Macro Lens-Based Optical System Design for Phototherapeutic Instrumentation. SENSORS 2019; 19:s19245427. [PMID: 31835391 PMCID: PMC6960533 DOI: 10.3390/s19245427] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/02/2019] [Accepted: 12/05/2019] [Indexed: 01/07/2023]
Abstract
Light emitting diode (LED) and ultrasound have been powerful treatment stimuli for tumor cell growth due to non-radiation effects. This research is the first preliminary study of tumor cell suppression using a macro-lens-supported 460-nm LED combined with high-frequency ultrasound. The cell density, when exposed to the LED combined with ultrasound, was gradually reduced after 30 min of induction for up to three consecutive days when 48-W DC, 20-cycle, and 50 Vp-p sinusoidal pulses were applied to the LEDs through a designed macro lens and to the ultrasound transducer, respectively. Using a developed macro lens, the non-directional light beam emitted from the LED could be localized to a certain spot, likewise with ultrasound, to avoid additional undesirable thermal effects on the small sized tumor cells. In the experimental results, compared to LED-only induction (14.49 ± 2.73%) and ultrasound-only induction (13.27 ± 2.33%), LED combined with ultrasound induction exhibited the lowest cell density (6.25 ± 1.25%). Therefore, our measurement data demonstrated that a macro-lens-supported 460-nm LED combined with an ultrasound transducer could possibly suppress early stage tumor cells effectively.
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Choi H. Stacked Transistor Bias Circuit of Class-B Amplifier for Portable Ultrasound Systems. SENSORS 2019; 19:s19235252. [PMID: 31795358 PMCID: PMC6929050 DOI: 10.3390/s19235252] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/07/2019] [Accepted: 11/23/2019] [Indexed: 12/17/2022]
Abstract
The performance of portable ultrasound systems is affected by the excessive heat generated by amplifiers, thereby reducing the sensitivity and resolution of the transducer devices used in ultrasound systems. Therefore, the amplifier needs to generate low amounts of heat to stabilize portable ultrasound systems. To properly control the amplifier, the related bias circuit must provide proper DC bias voltages for long time periods in ultrasound systems. To this end, a stacked transistor bias circuit was proposed to achieve a relatively constant amplifier performance irrespective of temperature variance without any cooling systems as the portable ultrasound system structure is limited. To prove the proposed concept, the performance of the gain and DC current consumption at different experimental times was measured and compared to a developed class-B amplifier with different bias circuits. The amplifier with the stacked transistor bias circuit outperformed with regard to the gain and DC current variance versus time (−0.72 dB and 0.065 A, respectively) compared to the amplifier with a typical resistor divider bias circuit (−5.27 dB and 0.237 A, respectively) after a certain time (5 min). Consequently, the proposed stacked transistor bias circuit is a useful electronic device for portable ultrasound systems with limited structure sizes because of its relatively low gain and DC current variance with respect to time.
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Affiliation(s)
- Hojong Choi
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, 350-27 Gumi-daero, Gumi 39253, Korea
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Choi H. Development of a Class-C Power Amplifier with Diode Expander Architecture for Point-of-Care Ultrasound Systems. MICROMACHINES 2019; 10:mi10100697. [PMID: 31615017 PMCID: PMC6843460 DOI: 10.3390/mi10100697] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 12/13/2022]
Abstract
Point-of-care ultrasound systems are widely used in ambulances and emergency rooms. However, the excessive heat generated from ultrasound transmitters has an impact on the implementation of piezoelectric transducer elements and on battery consumption, thereby affecting the system’s sensitivity and resolution. Non-linear power amplifiers, such as class-C amplifiers, could substitute linear power amplifiers, such as class-A amplifiers, which are currently used in point-of-care ultrasound systems. However, class-C power amplifiers generate less output power, resulting in a reduction of system sensitivity. To overcome this issue, we propose a new diode expander architecture dedicated to power amplifiers to reduce the effects of sinusoidal pulses toward the power supply. Thus, the proposed architecture could increase the input pulse amplitudes applied to the main transistors in the power amplifiers, hence increasing the output voltage of such amplifiers. To verify the proposed concept, pulse-echo responses from an ultrasonic transducer were tested with the developed class-C power amplifier using a resistor divider and the designed diode expander architecture. The peak-to-peak amplitude of the echo signals of the ultrasonic transducers when using a class-C power amplifier with a diode expander architecture (2.98 Vp–p) was higher than that for the class-C power amplifier with a resistor divider architecture (2.51 Vp–p). Therefore, the proposed class-C power amplifier with diode expander architecture is a potential candidate for improving the sensitivity performance of piezoelectric transducers for point-of-care ultrasound systems.
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Affiliation(s)
- Hojong Choi
- Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39253, Korea.
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Development of Public Key Cryptographic Algorithm Using Matrix Pattern for Tele-Ultrasound Applications. MATHEMATICS 2019. [DOI: 10.3390/math7080752] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A novel public key cryptographic algorithm using a matrix pattern is developed to improve encrypting strength. Compared to the Rivest–Sharmir–Adleman (RSA) and Elliptic Curve Cryptography (ECC) algorithms, our proposed algorithm has superior encrypting strength due to several unknown quantities and one additional sub-equation during the encrypting process. Our proposed algorithm also provides a faster encoding/decoding speed when the patient’s images for tele-ultrasound applications are transmitted/received, compared to the RSA and ECC encrypting algorithms, because it encodes/decodes the plain memory block by simple addition and multiplication operations of n terms. However, the RSA and ECC algorithms encode/decode each memory block using complex mathematical exponentiation and congruence. To implement encrypting algorithms for tele-ultrasound applications, a streaming server was constructed to transmit the images to the systems using ultrasound machines. Using the obtained ultrasound images from a breast phantom, we compared our developed algorithm, utilizing a matrix pattern, with the RSA and ECC algorithms. The elapsed average time for our proposed algorithm is much faster than that for the RSA and ECC algorithms.
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