Pub Date : 2025-11-09DOI: 10.1016/j.ultras.2025.107885
Gregory J. Anthony , Steffen Sammet, Jeffrey S. Souris, Kenneth B. Bader
Forms of sonodynamic therapy rely on close interactions between microbubbles and agents to generate cytotoxic reactive oxygen species. Microbubbles are inherently intravascular agents, which limits the therapeutic range for effective distribution of reactive oxygen species. Histotripsy is a focused ultrasound therapy that ablates tissue via the generation of a dense cloud of bubbles spontaneously without the need for microbubbles. This study investigated the capacity of histotripsy to generate the hydroxyl radical with and without sonodynamic agents. In the absence of sonodynamic agents, histotripsy produced the hydroxyl radical at rate that was increased by a factor of three relative to other forms of therapeutic ultrasound. These sonochemical reactions were found to correlate strongly with acoustic emissions tracked with passive cavitation imaging. Histotripsy bubble activity was found to increase the rate of hydroxyl radical production for multiple sonosensitizers relative to controls, particularly for ultrasound pulses longer than 20 cycles (i.e., 20 μs) in duration. Overall, these data indicate histotripsy may be a viable approach for activating sonosensitve agents, and this activation may be tracked based on acoustic emission.
{"title":"Histotripsy-mediated reactive oxygen species generation in vitro","authors":"Gregory J. Anthony , Steffen Sammet, Jeffrey S. Souris, Kenneth B. Bader","doi":"10.1016/j.ultras.2025.107885","DOIUrl":"10.1016/j.ultras.2025.107885","url":null,"abstract":"<div><div>Forms of sonodynamic therapy rely on close interactions between microbubbles and agents to generate cytotoxic reactive oxygen species. Microbubbles are inherently intravascular agents, which limits the therapeutic range for effective distribution of reactive oxygen species. Histotripsy is a focused ultrasound therapy that ablates tissue via the generation of a dense cloud of bubbles spontaneously without the need for microbubbles. This study investigated the capacity of histotripsy to generate the hydroxyl radical with and without sonodynamic agents. In the absence of sonodynamic agents, histotripsy produced the hydroxyl radical at rate that was increased by a factor of three relative to other forms of therapeutic ultrasound. These sonochemical reactions were found to correlate strongly with acoustic emissions tracked with passive cavitation imaging. Histotripsy bubble activity was found to increase the rate of hydroxyl radical production for multiple sonosensitizers relative to controls, particularly for ultrasound pulses longer than 20 cycles (i.e., 20 μs) in duration. Overall, these data indicate histotripsy may be a viable approach for activating sonosensitve agents, and this activation may be tracked based on acoustic emission.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"159 ","pages":"Article 107885"},"PeriodicalIF":4.1,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-09DOI: 10.1016/j.ultras.2025.107886
Yinmin Zhu , Wenhao Li , Jing Lin , Fei Gao , Zongyang Liu
Multi-mode damage coupling in composite structures is a key factor preventing accurate classification of different damage types. To address this, this paper presents a damage classification framework for composite structures based on acoustic emission (AE) signal decomposition. The approach begins by generating a Peak Frequency-Normalized Count Spectrum using Pearson correlation, principal component analysis, and hierarchical clustering. This spectrum, combined with electron microscopy observations, allows for quick identification of damage types and their frequency ranges, even with limited understanding of damage mechanisms. A customized wavelet packet decomposition filter is then created to decompose AE signals, enabling precise classification of different damage types. To validate the method, multiple tensile tests on adhesive composite joints were conducted, and the AE data were classified using both the proposed method and the K-means method. The results show that, compared to the K-means method, the energy proportions of the three types of damage classified by our method consistently remain in the range of 30%-40%, with the normalized energy proportion of adhesive debonding reaching or even exceeding 50%. Our method more accurately reflects the true damage state of the specimens. It effectively mitigates the negative impact caused by the coupling of multiple damage modes, providing a new perspective for health monitoring of composite structures.
{"title":"A multi-mode coupling damage classification method for composite structures based on acoustic emission signal decomposition","authors":"Yinmin Zhu , Wenhao Li , Jing Lin , Fei Gao , Zongyang Liu","doi":"10.1016/j.ultras.2025.107886","DOIUrl":"10.1016/j.ultras.2025.107886","url":null,"abstract":"<div><div>Multi-mode damage coupling in composite structures is a key factor preventing accurate classification of different damage types. To address this, this paper presents a damage classification framework for composite structures based on acoustic emission (AE) signal decomposition. The approach begins by generating a Peak Frequency-Normalized Count Spectrum using Pearson correlation, principal component analysis, and hierarchical clustering. This spectrum, combined with electron microscopy observations, allows for quick identification of damage types and their frequency ranges, even with limited understanding of damage mechanisms. A customized wavelet packet decomposition filter is then created to decompose AE signals, enabling precise classification of different damage types. To validate the method, multiple tensile tests on adhesive composite joints were conducted, and the AE data were classified using both the proposed method and the K-means method. The results show that, compared to the K-means method, the energy proportions of the three types of damage classified by our method consistently remain in the range of 30%-40%, with the normalized energy proportion of adhesive debonding reaching or even exceeding 50%. Our method more accurately reflects the true damage state of the specimens. It effectively mitigates the negative impact caused by the coupling of multiple damage modes, providing a new perspective for health monitoring of composite structures.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"160 ","pages":"Article 107886"},"PeriodicalIF":4.1,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-07DOI: 10.1016/j.ultras.2025.107871
Nuomin Zhang , Yang Xiao , Yiyin Su , Xuanhao Wang , Xudong Yang , Junhui Shi
This paper presents a pulse-echo sound speed estimation method for layered media, utilizing prior-constrained coherent analysis. The proposed method addresses the instability in local sound speed estimation caused by phase ambiguities resulting from suboptimal probe configurations. By introducing biologically reasonable sound speed boundary constraints to compensate for errors in average sound speed (ASS) estimation, and integrating sparse interface regularization inversion models, this method suppresses noise amplification during inversion, thereby enhancing robustness. The experimental results demonstrate that using this method significantly improves performance in simulations and in vitro data, reducing the root-mean-square error (RMSE) by 68% compared to existing methods. In in vivo experiments, the average sound speed in the tested regions deviated less than 0.6% from the reference values, while maintaining high repeatability. Furthermore, ablation studies validate the synergistic effect of prior compensation and sparse regularization, confirming their effectiveness in reducing phase sensitivity and enhancing the resolution of stratified structures. This method provides a reliable quantitative sound speed assessment tool for clinical scenarios such as hepatic steatosis, simultaneously relaxing hardware requirements for ultrasound probe parameters.
{"title":"A pulse-echo sound speed estimation approach with prior constraints for layered media","authors":"Nuomin Zhang , Yang Xiao , Yiyin Su , Xuanhao Wang , Xudong Yang , Junhui Shi","doi":"10.1016/j.ultras.2025.107871","DOIUrl":"10.1016/j.ultras.2025.107871","url":null,"abstract":"<div><div>This paper presents a pulse-echo sound speed estimation method for layered media, utilizing prior-constrained coherent analysis. The proposed method addresses the instability in local sound speed estimation caused by phase ambiguities resulting from suboptimal probe configurations. By introducing biologically reasonable sound speed boundary constraints to compensate for errors in average sound speed (ASS) estimation, and integrating sparse interface regularization inversion models, this method suppresses noise amplification during inversion, thereby enhancing robustness. The experimental results demonstrate that using this method significantly improves performance in simulations and in vitro data, reducing the root-mean-square error (RMSE) by 68% compared to existing methods. In in vivo experiments, the average sound speed in the tested regions deviated less than 0.6% from the reference values, while maintaining high repeatability. Furthermore, ablation studies validate the synergistic effect of prior compensation and sparse regularization, confirming their effectiveness in reducing phase sensitivity and enhancing the resolution of stratified structures. This method provides a reliable quantitative sound speed assessment tool for clinical scenarios such as hepatic steatosis, simultaneously relaxing hardware requirements for ultrasound probe parameters.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"160 ","pages":"Article 107871"},"PeriodicalIF":4.1,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-06DOI: 10.1016/j.ultras.2025.107884
Hasan Koruk , Srinath Rajagopal , William Vale , Andrew M. Hurrell
Hydrophones are commonly used to measure the acoustic output of ultrasound transducers and devices. Commonly, only the magnitude response of a hydrophone is quantified, since the direct measurement of phase response requires a complicated calibration procedure, and phase is extremely sensitive to small variations in experimental conditions such as alignment of hydrophone in the ultrasound field, signal-to-noise ratio, and temperature of water. However, for linear, time-invariant systems, phase can be predicted from the magnitude spectrum using the minimum phase approach. Here, a procedure was established to estimate the phase and evaluate the phase uncertainty of a hydrophone. The phase response was calculated using the minimum phase approach and the preconditioned magnitude spectrum. By using the uncertainty in the magnitude spectrum and the propagation of uncertainty, the uncertainty in the subsequently derived phase was calculated. A machine learning model was used to determine the phase uncertainty arising from applying the minimum phase approach to band-limited magnitude spectrum. After the performances of the calculation methods for phase and phase uncertainty were evaluated, the proposed procedure was implemented and assessed using a hydrophone model and two hydrophones with characterised magnitude and phase responses with their associated uncertainties. The predicted phase responses and evaluated uncertainties were comparable to the reference values. The results indicated that the procedure presented in this study could be used in practice to predict the phases and evaluate the phase uncertainties of various hydrophones.
{"title":"Predicting hydrophone phase and evaluating its uncertainty using magnitude data and minimum phase approach","authors":"Hasan Koruk , Srinath Rajagopal , William Vale , Andrew M. Hurrell","doi":"10.1016/j.ultras.2025.107884","DOIUrl":"10.1016/j.ultras.2025.107884","url":null,"abstract":"<div><div>Hydrophones are commonly used to measure the acoustic output of ultrasound transducers and devices. Commonly, only the magnitude response of a hydrophone is quantified, since the direct measurement of phase response requires a complicated calibration procedure, and phase is extremely sensitive to small variations in experimental conditions such as alignment of hydrophone in the ultrasound field, signal-to-noise ratio, and temperature of water. However, for linear, time-invariant systems, phase can be predicted from the magnitude spectrum using the minimum phase approach. Here, a procedure was established to estimate the phase and evaluate the phase uncertainty of a hydrophone. The phase response was calculated using the minimum phase approach and the preconditioned magnitude spectrum. By using the uncertainty in the magnitude spectrum and the propagation of uncertainty, the uncertainty in the subsequently derived phase was calculated. A machine learning model was used to determine the phase uncertainty arising from applying the minimum phase approach to band-limited magnitude spectrum. After the performances of the calculation methods for phase and phase uncertainty were evaluated, the proposed procedure was implemented and assessed using a hydrophone model and two hydrophones with characterised magnitude and phase responses with their associated uncertainties. The predicted phase responses and evaluated uncertainties were comparable to the reference values. The results indicated that the procedure presented in this study could be used in practice to predict the phases and evaluate the phase uncertainties of various hydrophones.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"159 ","pages":"Article 107884"},"PeriodicalIF":4.1,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145496735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study describes the bidirectional excitation and detection of Rayleigh waves using two facing elliptical reflector focusing structures (ELIPS), in contrast to previous studies that have achieved only one-way excitation and did not demonstrate detection. First, the design of a proposed ELIPS surface-acoustic-wave (SAW) device is presented, and the relationship between the design parameters and SAW excitation performance is clarified. Next, finite element method simulations are presented, showing that 40 % of the energy of the incident dilatational wave is converted into a SAW and 60 % of the generated SAW is reconverted into a received dilatational wave. Finally, bidirectional SAW excitation and detection are demonstrated. In the experiment, a 5-cycle, 1 MHz burst signal with an amplitude of 10 Vpp was used to excite Rayleigh waves in both the forward and reverse directions. In the forward direction, a SAW vibration velocity of 5.4 mm/s was obtained and the received voltage reached 21 % of the applied voltage. In the reverse direction, the vibration velocity was 5.8 mm/s and the received voltage reached 22 %. These received voltage ratios are sufficient for sensing applications. Moreover, the response remained linear up to at least 140 Vpp, producing vibration amplitudes of 13 and 12 nm, adequate for high-power applications and with potential for further increase at higher input power.
{"title":"Bidirectional excitation and detection of Rayleigh waves via two facing elliptical reflectors","authors":"Kyohei Yamada , Shoki Ieiri , Shinsuke Itoh , Takashi Kasashima , Chikahiro Imashiro , Takeshi Morita","doi":"10.1016/j.ultras.2025.107883","DOIUrl":"10.1016/j.ultras.2025.107883","url":null,"abstract":"<div><div>This study describes the bidirectional excitation and detection of Rayleigh waves using two facing elliptical reflector focusing structures (ELIPS), in contrast to previous studies that have achieved only one-way excitation and did not demonstrate detection. First, the design of a proposed ELIPS surface-acoustic-wave (SAW) device is presented, and the relationship between the design parameters and SAW excitation performance is clarified. Next, finite element method simulations are presented, showing that 40 % of the energy of the incident dilatational wave is converted into a SAW and 60 % of the generated SAW is reconverted into a received dilatational wave. Finally, bidirectional SAW excitation and detection are demonstrated. In the experiment, a 5-cycle, 1 MHz burst signal with an amplitude of 10 Vpp was used to excite Rayleigh waves in both the forward and reverse directions. In the forward direction, a SAW vibration velocity of 5.4 mm/s was obtained and the received voltage reached 21 % of the applied voltage. In the reverse direction, the vibration velocity was 5.8 mm/s and the received voltage reached 22 %. These received voltage ratios are sufficient for sensing applications. Moreover, the response remained linear up to at least 140 Vpp, producing vibration amplitudes of 13 and 12 nm, adequate for high-power applications and with potential for further increase at higher input power.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"159 ","pages":"Article 107883"},"PeriodicalIF":4.1,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145496718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.ultras.2025.107879
Chuanxin Zhang , Xue Jiang , Dean Ta
Acoustic holograms offer precise three-dimensional control of sound fields with immense potential for non-invasive therapies and contactless manipulation. However, conventional phase-only design methods suffer from a fundamental performance gap between theoretical predictions and physical implementation, especially for creating multi-functional devices. These approaches design idealized phase maps while neglecting complex wave physics within hologram structures and distorting effects of heterogeneous biological tissues. Here, we introduce the End-to-End Heterogeneous Physics-Constrained (E2E-HPC) framework, a deep learning paradigm that resolves this gap by directly designing the physical hologram structure. Our framework is guided by integrated, differentiable models that account for both the hologram’s intricate internal acoustics and wave propagation through complex media like the skull. This heterogeneous physics-constrained approach eliminates the performance limitations of conventional methods, improving the resulting acoustic pattern’s fidelity by over 6 dB in Peak Signal-to-Noise Ratio (PSNR) and recovering ∼16 % of the correlation fidelity lost in physical implementation. Beyond single-target design, we demonstrate the framework’s extensibility for multi-functional controls by creating a single hologram capable of both simultaneous, high-fidelity focusing on multiple axial planes and dynamic pattern switching by modulating the input frequency. As a proof-of-concept for therapeutic applications, we showcase real-time, frequency-specific switching of thermal patterns. These results establish a robust platform for designing physically realizable, multi-functional acoustic holograms for challenging biomedical applications.
{"title":"End-to-end design of multi-functional acoustic holograms via heterogeneous physics constraints","authors":"Chuanxin Zhang , Xue Jiang , Dean Ta","doi":"10.1016/j.ultras.2025.107879","DOIUrl":"10.1016/j.ultras.2025.107879","url":null,"abstract":"<div><div>Acoustic holograms offer precise three-dimensional control of sound fields with immense potential for non-invasive therapies and contactless manipulation. However, conventional phase-only design methods suffer from a fundamental performance gap between theoretical predictions and physical implementation, especially for creating multi-functional devices. These approaches design idealized phase maps while neglecting complex wave physics within hologram structures and distorting effects of heterogeneous biological tissues. Here, we introduce the End-to-End Heterogeneous Physics-Constrained (E2E-HPC) framework, a deep learning paradigm that resolves this gap by directly designing the physical hologram structure. Our framework is guided by integrated, differentiable models that account for both the hologram’s intricate internal acoustics and wave propagation through complex media like the skull. This heterogeneous physics-constrained approach eliminates the performance limitations of conventional methods, improving the resulting acoustic pattern’s fidelity by over 6 dB in Peak Signal-to-Noise Ratio (PSNR) and recovering ∼16 % of the correlation fidelity lost in physical implementation. Beyond single-target design, we demonstrate the framework’s extensibility for multi-functional controls by creating a single hologram capable of both simultaneous, high-fidelity focusing on multiple axial planes and dynamic pattern switching by modulating the input frequency. As a proof-of-concept for therapeutic applications, we showcase real-time, frequency-specific switching of thermal patterns. These results establish a robust platform for designing physically realizable, multi-functional acoustic holograms for challenging biomedical applications.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"159 ","pages":"Article 107879"},"PeriodicalIF":4.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145453084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-31DOI: 10.1016/j.ultras.2025.107882
Shaojie Gong , Shifeng Guo , Yi Xiong , Shiyuan Zhou , Fangsen Cui , Menglong Liu
Ultrasonic non-destructive testing provides an important means to characterize grain size and orientation distribution of polycrystalline materials. Analytical and numerical modeling of ultrasound propagation offer an insight into how ultrasound interacts with polycrystalline materials. However, in highly anisotropic polycrystals, there is still no mature and accurate analytical formulation to describe the strong wave scattering, while the numerical modeling often relies on extremely dense structured meshes to conform to the grain boundary. This study proposes to use a high-order unstructured mesh with added internal nodes to obtain diagonal mass matrices, in order to accurately model wave propagation in strongly anisotropic polycrystals with complex grain boundary. Firstly, polycrystalline geometry was constructed with the Voronoi-based tessellation. Then an explicit dynamics solution was to simulate ultrasonic propagation with the improved element and several typical structured and unstructured elements. The influence of mesh type on calculation accuracy and convergence rate shows that the improved high-order mass-lumped elements, by retaining the true geometry of grain boundaries with unstructured meshes, significantly enhance both computational efficiency and accuracy. Lastly, the simulated results of ultrasonic attenuation and phase velocity in polycrystals show good agreement with both modified analytical models and results obtained with structured meshes. This confirms the effectiveness of the proposed high-order mass-lumped unstructured meshes for accurately simulating wave propagation in polycrystals for the characterization of grain features.
{"title":"Wave propagation in highly anisotropic polycrystals: a numerical perspective from an unstructured-mesh-based high-order finite element method","authors":"Shaojie Gong , Shifeng Guo , Yi Xiong , Shiyuan Zhou , Fangsen Cui , Menglong Liu","doi":"10.1016/j.ultras.2025.107882","DOIUrl":"10.1016/j.ultras.2025.107882","url":null,"abstract":"<div><div>Ultrasonic non-destructive testing provides an important means to characterize grain size and orientation distribution of polycrystalline materials. Analytical and numerical modeling of ultrasound propagation offer an insight into how ultrasound interacts with polycrystalline materials. However, in highly anisotropic polycrystals, there is still no mature and accurate analytical formulation to describe the strong wave scattering, while the numerical modeling often relies on extremely dense structured meshes to conform to the grain boundary. This study proposes to use a high-order unstructured mesh with added internal nodes to obtain diagonal mass matrices, in order to accurately model wave propagation in strongly anisotropic polycrystals with complex grain boundary. Firstly, polycrystalline geometry was constructed with the Voronoi-based tessellation. Then an explicit dynamics solution was to simulate ultrasonic propagation with the improved element and several typical structured and unstructured elements. The influence of mesh type on calculation accuracy and convergence rate shows that the improved high-order mass-lumped elements, by retaining the true geometry of grain boundaries with unstructured meshes, significantly enhance both computational efficiency and accuracy. Lastly, the simulated results of ultrasonic attenuation and phase velocity in polycrystals show good agreement with both modified analytical models and results obtained with structured meshes. This confirms the effectiveness of the proposed high-order mass-lumped unstructured meshes for accurately simulating wave propagation in polycrystals for the characterization of grain features.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"159 ","pages":"Article 107882"},"PeriodicalIF":4.1,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145514127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-28DOI: 10.1016/j.ultras.2025.107880
Xin Wang , Le Wang , Hanlin Wang , Xiqing Zuo , Rongyang Wang , Xianglei Zhang , Chao Xu
Untethered underwater robots are capable of navigating confined aquatic environments, offering significant potential for applications such as environmental monitoring, pipeline inspection and biological sample collection. However, traditional propeller propulsion systems suffer from limited maneuverability and potential safety risks in confined spaces. To address these challenges, we propose a miniature robotic swimmer (8.5 cm in diameter and 10 cm in height) actuated by a vector acoustic system. Specifically, the robot employs a piezoelectric transducer to generate high-intensity ultrasonic waves, which produce a directional jet in the fluid by acoustic radiation force. By using a miniature electromagnetic motor to adjust the alignment of the piezoelectric actuator, the system can modify the jet direction, achieving full-range propulsion without turning radius limitations. Moreover, the combined implementation of a vectorized propulsion system with a wireless control module enables superior maneuverability. Experiments show that the robot achieves a maximum linear velocity of 79.2 mm/s and can traverse a narrow gap of 1.5 times the body length under remote wireless control, demonstrating excellent maneuverability and obstacle avoidance capability.
{"title":"A miniature wireless robotic swimmer actuated by a vector acoustic system","authors":"Xin Wang , Le Wang , Hanlin Wang , Xiqing Zuo , Rongyang Wang , Xianglei Zhang , Chao Xu","doi":"10.1016/j.ultras.2025.107880","DOIUrl":"10.1016/j.ultras.2025.107880","url":null,"abstract":"<div><div>Untethered underwater robots are capable of navigating confined aquatic environments, offering significant potential for applications such as environmental monitoring, pipeline inspection and biological sample collection. However, traditional propeller propulsion systems suffer from limited maneuverability and potential safety risks in confined spaces. To address these challenges, we propose a miniature robotic swimmer (8.5 cm in diameter and 10 cm in height) actuated by a vector acoustic system. Specifically, the robot employs a piezoelectric transducer to generate high-intensity ultrasonic waves, which produce a directional jet in the fluid by acoustic radiation force. By using a miniature electromagnetic motor to adjust the alignment of the piezoelectric actuator, the system can modify the jet direction, achieving full-range propulsion without turning radius limitations. Moreover, the combined implementation of a vectorized propulsion system with a wireless control module enables superior maneuverability. Experiments show that the robot achieves a maximum linear velocity of 79.2 mm/s and can traverse a narrow gap of 1.5 times the body length under remote wireless control, demonstrating excellent maneuverability and obstacle avoidance capability.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"159 ","pages":"Article 107880"},"PeriodicalIF":4.1,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145425019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dual-frequency or multi-frequency transducers have been proposed to balance deep penetration and high resolution in optoacoustic (OA) imaging, based on the well-established tradeoff that low frequencies provide deeper penetration, while high frequencies offer higher resolution. In practice, conventional transducer designs are primarily guided by the signal’s center frequency and bandwidth, as these parameters fundamentally constrain spatial resolution. However, such criteria alone are insufficient, as they overlook the influence of transducer geometry within the array. To address this limitation, we introduce k-space analysis and a weighted entropy () metric that links transducer design parameters to directional resolution performance. Simulations and phantom experiments validated that the dual-frequency multi-segment transducer array (DF-MSTA), combining 3 and 7.5 MHz, achieved more uniform and enhanced axial resolution (by up to 23.8 %), compared to a single-frequency MSTA operating at 7.5 MHz. The results align with predictions from the k-space analysis and quantification. This work provides a transducer design strategy that jointly considers frequency selection and array geometry, along with a quantitative framework to optimize axial resolution in deep-tissue OA imaging, offering insights beyond conventional approaches.
{"title":"Improving axial resolution uniformity in deep-tissue optoacoustic imaging via entropy-driven design of dual-frequency multi-segment arrays","authors":"Weixia Cheng , Ruochong Zhang , Cristian Ciobanu , Renzhe Bi , Xosé Luís Deán-Ben , Zheng Zesheng , Ghayathri Balasundaram , Yonggeng Goh , Malini Olivo , Daniel Razansky , Zheng Fan","doi":"10.1016/j.ultras.2025.107875","DOIUrl":"10.1016/j.ultras.2025.107875","url":null,"abstract":"<div><div>Dual-frequency or multi-frequency transducers have been proposed to balance deep penetration and high resolution in optoacoustic (OA) imaging, based on the well-established tradeoff that low frequencies provide deeper penetration, while high frequencies offer higher resolution. In practice, conventional transducer designs are primarily guided by the signal’s center frequency and bandwidth, as these parameters fundamentally constrain spatial resolution. However, such criteria alone are insufficient, as they overlook the influence of transducer geometry within the array. To address this limitation, we introduce k-space analysis and a weighted entropy (<span><math><mrow><mi>W</mi><mi>E</mi></mrow></math></span>) metric that links transducer design parameters to directional resolution performance. Simulations and phantom experiments validated that the dual-frequency multi-segment transducer array (DF-MSTA), combining 3 and 7.5 MHz, achieved more uniform and enhanced axial resolution (by up to 23.8 %), compared to a single-frequency MSTA operating at 7.5 MHz. The results align with predictions from the k-space analysis and <span><math><mrow><mi>W</mi><mi>E</mi></mrow></math></span> quantification. This work provides a transducer design strategy that jointly considers frequency selection and array geometry, along with a quantitative framework to optimize axial resolution in deep-tissue OA imaging, offering insights beyond conventional approaches.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"159 ","pages":"Article 107875"},"PeriodicalIF":4.1,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145422840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-28DOI: 10.1016/j.ultras.2025.107881
Suntae Hwang , Jinwoo Kim , Eunji Lee , Jin Ho Chang
Ultrasound imaging modality, which operates by transmitting and receiving short ultrasound pulses, offers a promising approach for real-time, high-resolution diagnostic imaging at relatively low cost. However, the conventional short-pulse approach is inherently limited by signal attenuation with increased imaging depth, leading to reduced penetration and a lower signal-to-noise ratio (SNR), which ultimately degrades diagnostic performance. Golay-coded excitation has been introduced to mitigate these issues by transmitting longer, coded pulses that use a pair of complementary sequences (Codes A and B) to enhance SNR and imaging depth. However, this technique requires two sequential transmissions to acquire two echoes related to the complementary codes, inevitably reducing the frame rate by half. In this work, we propose a novel deep learning framework that overcomes this limitation by generating the echo signal corresponding to Code B from the echo signal obtained after transmitting code A. For this, we developed Golay-Net, based on a 1-D U-Net architecture, which changes the phase of the range sidelobes of the Code A-related echo signals, thereby effectively synthesizing the echo signals that would have been obtained using Code B. In vitro and in vivo experiments demonstrate that the proposed Golay-Net can synthesize code B-related echo signals with high fidelity, enabling the reconstruction of ultrasound images with enhanced SNR and imaging depth, without compromising frame rate.
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