Ultrasound Source Research Articles

Ultrasound-compatible 3D-printed Franz diffusion system for sonophoresis with microbubbles.

Sonophoresis is a topical drug delivery approach that utilises ultrasound as a physical stimulus to enhance permeation of active pharmaceutical ingredients through the skin. Only limited research has however been conducted to evaluate the potential of ultrasound-responsive drug carriers, such as gas microbubbles, in sonophoresis. Franz diffusion cells have been extensively used for measuring drug permeation in vitro; however, traditional systems lack compatibility with ultrasound and only limited characterisation of their acoustical behaviour has been carried out in previous research. To overcome this limitation, we designed and manufactured a novel Franz cell donor compartment coupled with a conventional glass receptor, and performed a functional characterisation of the assembly for application in sonophoresis with ultrasound-responsive agents (specifically imiquimod-loaded gas microbubbles). The donor was fabricated using a photoreactive resin via 3D printing and was designed to enable integration with a therapeutically relevant ultrasound source. The assembly was capable of effectively retaining liquids during prolonged incubation and the absorption of imiquimod onto the 3D-printed material was comparable to the one of glass. Moreover, a predictable ultrasound field could be generated at a target surface without any significant spatial distortion. Finally, we demonstrated applicability of the developed assembly in sonophoresis experiments with StratM®, wherein ultrasound stimulation in the presence of microbubbles resulted in significantly enhanced drug permeation through and partitioning within the membrane (2.96 ± 0.25 μg and 3.84 ± 0.39 μg) compared to passive diffusion alone (1.74 ± 0.29 μg and 2.29 ± 0.32 μg), over 24 h.

How safe is high-intensity focused ultrasound? An intriguing solution for obstetric and gynecological diseases: A systematic review.

High-intensity focused ultrasound (HIFU) is a non-surgical and noninvasive treatment modality that depends on external ultrasound energy sources that induce focused mass ablation and protein degeneration in the treatment area via thermal energy penetration under the intact skin. We aim in our study to collectively evaluate the safety of HIFU for the treatment of different obstetric and gynecological diseases in the literature. We searched PubMed, Scopus, and Science Direct databases, without restriction on date or language, from the inception of these databases until January 20, 2024. We also examined the references of the included studies in the Mendeley archive for eligible articles. We found a total of 706 studies. After the screening and selection process, 56 participants were included. Our dichotomous outcomes were pooled in our single-arm meta-analysis as risk ratio (RR) and with 95% confidence interval (CI) while our continuous outcomes were pooled as mean change and 95% CIs. Fixed- or random-effects models were applied depending on the heterogeneity detected. Our systematic review and meta-analysis included 56 studies including 11.740 patients. Depending on the Society of Interventional Radiology (SIR) classification for adverse effects. The results of this meta-analysis for the type A category that did not require clinical intervention found that pain in the treatment site estimated RR with 95% CI: 0.61 (0.33, 0.89), abnormal vaginal discharge 0.16 (0.073, 0.24), low-grade fever (<38 °C) 0.005 (0.002, 0.009). Sensory abnormalities of the lower limbs were examined in 3390 individuals and observed in only 19 patients who experienced gradual relief of symptoms within one month after treatment. Regarding SIR type B, 99 of a total of 6.437 patients had small vesicles and superficial burns with pooled RR and 95% CI: 0.012 (0.007, 0.018). In terms of groin or perianal and lower abdominal pain, our RRs with 95% CIs were 0.1 (0.067, 0.13) and 0.38 (0.25, 0.51). However, vaginal bleeding was detected in only 32 out of a total of 3.017. Major adverse events like lumber disc herniation, thrombocytopenia, and renal failure, were unmentionable. Additionally, our included studies did not record any deaths. HIFU, either alone or in combination with oxytocin or any other enhancing agent, is safe for patients with different gynecological and obstetric diseases. In terms of efficacy, it showed promising results compared with traditional treatment lines. To our knowledge, we are the first and most comprehensive meta-analysis in the literature that has studied the different safety outcomes related to HIFU as a treatment modality for different obstetric and gynecological diseases with a very large sample size, making our evidence strong and less attributed to errors.

Multimodal optical ultrasound imaging: Real-time imaging under concurrent CT or MRI

Optical ultrasound (OpUS) imaging is an ultrasound modality that utilizes fiber-optic ultrasound sources and detectors to perform pulse-echo ultrasound imaging. These probes can be constructed entirely from glass optical fibers and plastic components, and as such, these devices have been predicted to be compatible with computed tomography (CT) and magnetic resonance imaging (MRI), modalities that use intense electromagnetic fields for imaging. However, to date, this compatibility has not been demonstrated. In this work, a free-hand OpUS imaging system was developed specifically to investigate the compatibility of OpUS systems with CT and MRI imaging systems. The OpUS imaging platform discussed in this work was used to perform real-time OpUS imaging under (separately) concurrent CT and MRI. CT and MRI imaging of the OpUS probe was used to determine if the probe itself would induce artifacts in the CT and MRI imaging, and ultrasound resolution targets and background measurements were used to assess any impact of CT and MRI on the OpUS signal fidelity. These measurements demonstrate that there was negligible interaction between the OpUS system and both the CT and MRI systems, and to further demonstrate this capability, concurrent OpUS-CT and OpUS-MRI imaging was conducted of a tissue-mimicking phantom and a dynamic motion phantom. This work presents a comprehensive demonstration of an OpUS imaging system operating alongside CT and MRI, which opens up new applications of ultrasound imaging in electromagnetically challenging settings.

Mid-Infrared Photoacoustic Stimulation of Neurons through Vibrational Excitation in Polydimethylsiloxane.

Photoacoustic (PA) emitters are emerging ultrasound sources offering high spatial resolution and ease of miniaturization. Thus far, PA emitters rely on electronic transitions of absorbers embedded in an expansion matrix such as polydimethylsiloxane (PDMS). Here, it is shown that mid-infrared vibrational excitation of C─H bonds in a transparent PDMS film can lead to efficient mid-infrared photoacoustic conversion (MIPA). MIPA shows 37.5 times more efficient than the commonly used PA emitters based on carbon nanotubes embedded in PDMS. Successful neural stimulation through MIPA both in a wide field with a size up to a 100µm radius and in single-cell precision is achieved. Owing to the low heat conductivity of PDMS, less than a 0.5°C temperature increase is found on the surface of a PDMS film during successful neural stimulation, suggesting a non-thermal mechanism. MIPA emitters allow repetitive wide-field neural stimulation, opening up opportunities for high-throughput screening of mechano-sensitive ion channels and regulators.

Effect of organic solvent additives on the enhancement of ultrasonic cavitation effects in water for lithium-ion battery electrode delamination

Ultrasonic delamination is a low energy approach for direct recycling of spent lithium-ion batteries. The efficiency of the ultrasonic delamination relies both on the thermophysical properties (such as viscosity, surface tension, and vapour pressure) of the solvent in which the delamination process is carried out, and the properties of the ultrasound source as well as the geometry of the containment vessel. However, the effect of tailoring solutions to optimise cavitation and delamination of battery cathode coatings has not yet been sufficiently investigated. Acoustic detection, high-speed imaging, and sonochemiluminescence (SCL) are employed to study the cavitation processes in water-glycol systems and identify the effect of tailoring solvent composition on cavitation strength. The addition of small volume fractions of organic solvent (ca. 10–30 vol%), including ethylene glycol or glycerol, to the aqueous delamination solution were found to significantly improve the delamination efficiency of lithium-ion battery cathode coatings due to the alteration of these thermophysical properties. However, greater volume fractions of glycol decrease delamination efficiency due to the signal-dampening effect of viscosity on the ultrasonic waves. The findings of this study offer valuable insights for optimising ultrasonic bath solution composition to enhance film delamination processes.

Towards clinical application of freehand optical ultrasound imaging

Freehand optical ultrasound (OpUS) imaging is an emerging ultrasound imaging paradigm that uses an array of fibre-optic, photoacoustic ultrasound sources and a single fibre-optic ultrasound detector to perform ultrasound imaging without the need for electrical components in the probe head. Previous freehand OpUS devices have demonstrated capability for real-time, video-rate imaging of clinically relevant targets, but have been hampered by poor ultrasound penetration, significant imaging artefacts and low frame rates, and their designs limited their clinical applicability. In this work we present a novel freehand OpUS imaging platform, including a fully mobile and compact acquisition console and an improved probe design. The novel freehand OpUS probe presented utilises optical waveguides to shape the generated ultrasound fields for improved ultrasound penetration depths, an extended fibre-optic bundle to improve system versatility and an overall ruggedised design with protective elements to improve probe handling and protect the internal optical components. This probe is demonstrated with phantoms and the first multi-participant in vivo imaging study conducted with freehand OpUS imaging probes, this represents several significant steps towards the clinical translation of freehand OpUS imaging.

Ultrahigh energy efficiency from a supersonic underwater ultrasound source

The present work is dedicated to an experimental and theoretical study of an innovative underwater ultrasound source. The source works using a technique in which a pulsed power generator using the impedance mismatch of a long high-voltage coaxial cable generates a train of voltage impulses with a very high pulse repetition frequency of the order of a few MHz. Applying this train of voltage impulses to a pair of underwater electrodes generates a streamer-initiated breakdown of water and, subsequently, a plasma column connecting the electrodes over a very large inter-electrode gap of 55 mm. The interaction of the long plasma column thus formed with the surrounding water produces a rapidly expanding vapor bubble, an “instrument” producing a strong pressure wave with an overall energy efficiency of 24%, an order of magnitude higher than most underwater pressure sources reported in the literature.

Visualization of slit defect by scanning nonlinear airborne ultrasound source technique using compressed sensing

A high-speed, non-contact non-destructive testing method using a scanning airborne ultrasound source and a nonlinear harmonic method has been developed for plate-like structures. The testing time depends on the scanning speed and the number of measurement points. To solve this problem, we propose using compressed sensing with this method. In this paper, we investigated visualizing Lamb wave propagation using the proposed compressed sensing method. In addition, we detected a slit defect by using the Lamb wave propagation image. Our results demonstrated that compressed sensing could be used to reduce the testing time.

Model-based investigation of a novel decontamination technology: Ultrasound assisted aerosolized hydrogen peroxide

This work investigates the feasibility of a novel decontamination technology that employs ultrasonic acoustic streaming to improve aerosol distribution inside isolator chambers. For this purpose, a numerical model consisting of three simulations (i) acoustic pressure, (ii) fluid flow, and (iii) particle tracing, is developed. Acoustic air streaming is examined for ultrasound source pressure levels between 131 and 136 dB. Maximum streaming velocity reached values of the order 10−3 and 10−2m/s which agrees with previous experimental and numerical investigations. The effect of air velocity field on the deposition of the decontamination agent on the isolator floor was assessed for aerosol with droplet diameter between 10 and 20μm. The results show that a more homogeneous distribution of deposited droplets is obtained with configurations that have sound sources placed at a distance from each other. Designs with a homogeneous aerosol deposition are expected to have a better decontamination outcome.

Utilizing Shear Piezoelectricity of Chiral Lead‐Free Metal Halides for Electromechanical Sensing

AbstractChiral hybrid metal halides have emerged as a promising class of piezoelectric materials owing to their ease of synthesis, low acoustic impedance, and solution processibility. However, many known chiral halides crystalize in structures with only shear piezoelectricity which is less facile to be utilized compared with the longitudinal piezoelectricity, largely preventing their practical utility. In addressing this problem, chiral lead‐free S‐MPBiCl5 and R‐MPBiCl5 (MP = 2‐methylpiperazinium) with shear piezoelectricity are synthesized and the thin films orientating along the polarization direction are fabricated. These orientated films, characterized by numerous grains and compact grain boundaries, can effectively facilitate the grain boundary sliding to convert normal stress into shear stress, thus facilely activating the shear piezoelectricity. The resulting devices can accurately identify the position and type of ultrasound sources without the need for a complex acoustic impedance matching layer. Moreover, these devices can successfully sense delicate variations in momentum caused by table tennis balls. The findings open up a new pathway to utilize shear piezoelectricity that is normally considered unuseful of metal halides and other molecular piezoelectrics.

ANALIZA NUMERICĂ A UNUI TRADUCTOR PIEZOELECTRIC DE ULTRASUNET

The paper presents the numerical analysis of a piezoelectric ultrasound transducer intended for biological micro cavitation applications. The ultrasound source in a two-dimensional, simplified variant with axial symmetry is analyzed numerically. The natural frequencies and the eigenmodes of the deformation associated with these natural frequencies, respectively, the resonance frequency, are determined. For the study in dynamic mode, the piezoceramic layers are considered to be supplied with a sinusoidal voltage at the previously determined resonance frequency.

Active osseointegration in an ex vivo porcine bone model.

Achieving osseointegration is a fundamental requirement for many orthopaedic, oral, and craniofacial implants. Osseointegration typically takes three to 6months, during which time implants are at risk of loosening. The aim of this study was to investigate whether osseointegration could be actively enhanced by delivering controllable electromechanical stimuli to the periprosthetic bone. First, the osteoconductivity of the implant surface was confirmed using an in vitro culture with murine preosteoblasts. The effects of active treatment on osseointegration were then investigated in a 21-day ex vivo model with freshly harvested cancellous bone cylinders (n = 24; Ø10 mm × 5mm) from distal porcine femora, with comparisons to specimens treated by a distant ultrasound source and static controls. Cell viability, proliferation and distribution was evident throughout culture. Superior ongrowth of tissue onto the titanium discs during culture was observed in the actively stimulated specimens, with evidence of ten-times increased mineralisation after 7 and 14days of culture (p < 0.05) and 2.5 times increased expression of osteopontin (p < 0.005), an adhesive protein, at 21days. Moreover, histological analyses revealed increased bone remodelling at the implant-bone interface in the actively stimulated specimens compared to the passive controls. Active osseointegration is an exciting new approach for accelerating bone growth into and around implants.

Numerical investigation of the effect of bubble properties on the linear resonance frequency shift due to inter-bubble interactions in ultrasonically excited lipid coated microbubbles

Ultrasonically excited microbubbles (MBs) have numerous applications in various fields, such as drug delivery, and imaging. Ultrasonically excited MBs are known to be nonlinear oscillators that generate secondary acoustic emissions in the media when excited by a primary ultrasound wave. The propagation of acoustic waves in the liquid is limited to the speed of sound, resulting in each MB receiving the primary and secondary waves at different times depending on their distance from the ultrasound source and the distance between MBs. These delays are referred to as primary and secondary delays, respectively. A previous study demonstrated that the inclusion of secondary delays in a model describing the interactions between MBs exposed to ultrasound results in an increase in the linear resonance frequency of MBs as they approach each other. This work investigates the impact of various MB properties on the change in linear resonance frequency resulting from changes in inter-bubble distances. The effects of shell properties, including the initial surface tension, surface dilatational viscosity of the shell monolayer, elastic compression modulus of the shell, and the initial radius of the MBs, are examined. MB size is a significant factor influencing the rate of linear resonance frequency increase with increasing concentration. Moreover, it is found that the shell properties of MBs play a negligible role in the rate of change in linear resonance frequency of MBs as the inter-bubble distances change.The findings of this study have implications for various applications of MBs in the biomedical field. By understanding the impact of inter-bubble distances and shell properties on the linear resonance frequency of MBs, the utilization of MBs in applications reliant on their resonant behavior can be optimized.

A cancer cell nanotherapy method based on GHz film bulk acoustic resonator and nanoscale CaO2.

Sonodynamic therapy (SDT) is an emerging cancer treatment method in recent years. However, the ultrasound signal utilized for SDT is usually located at a low-frequency spectrum (<2MHz), and in the field of SDT research, few studies have focused on the exploration and development of ultrasound frequency. Studies have shown that the GHz-level ultrasound can increase cell membrane permeability and have a negligible effect on cell vitality. Herein, we reported the study of a GHz thin film bulk acoustic resonator as an ultrasound source for synergistic treatment with nanoscale calcium peroxide (CaO2). It was discovered that this ultrasound source ultimately achieved an efficient therapeutic outcome on mouse breast cancer cell line 4T1. Such GHz-level ultrasound application in SDT is of high significance to broaden the cognition and application scope of SDT.

Ultrasound-assisted activation of PAW residual radicals in the concurrent elimination of ARB and ARGs: Process efficiency, mechanism and implication

Methicillin-resistant Staphylococcus aureus (MRSA) and antibiotic resistance gene (mecA) are considered emerging contaminants that have been extensively identified in aqueous environments due to their high resistance to disinfectants. Herein, we report for the first time the inactivation of MRSA through a sequential application of plasma-activated water and ultrasound (PAW-SU). While the impact of PAW alone on bacterial culturability and mecA integrity was negligible, the combined PAW-SU treatment outperformed the inactivation method involving PAW with direct US (PAW-DU). It exhibited a shorter lag phase and a higher maximum inactivation rate constant. We numerically demonstrated that sonolysis processes induced by external ultrasound sources considerably improved the intracellular and extracellular reactive oxygen and nitrogen species (RONS) of MRSA in PAW system, thereby increasing the PAW reactivity and applicability. The highest inactivation efficiency of PAW-SU can be attributed to the synergistic effect of enhanced intracellular RONS (i.e., peroxynitrite and singlet oxygen) and membrane disruption induced by US, resulting in irreparable oxidative damage to the Save our Soul response and energy metabolic system. In particular, the elevated arginine metabolites in MRSA cells were primarily responsible for the formation of the viable but nonculturable state (VBNC) bacteria associated with high resistance to PAW system. Surprisingly, a decrease in arginine synthesis capacity was observed to expedite the flow of the tricarboxylic acid cycle, accelerating the detrimental effects of PAW-SU on intracellular components in VBNC bacteria. Finally, the limited regrowth potential of injured MRSA caused by cyclic inactivation of PAW-SU process was further confirmed in wastewater from meat and dairy models and therefore, advocates the possible real-world applications.

Observation of cavitation dynamics in viscous deep eutectic solvents during power ultrasound sonication.

Deep eutectic solvents (DESs) are a class of ionic liquid with emerging applications in ionometallurgy. The characteristic high viscosity of DESs, however, limit mass transport and result in slow dissolution kinetics. Through targeted application of high-power ultrasound, ionometallurgical processing time can be significantly accelerated. This acceleration is primarily mediated by the cavitation generated in the liquid surrounding the ultrasound source. In this work, we characterise the development of cavitation structure in three DESs of increasing viscosity, and water, via high-speed imaging and parallel acoustic detection. The intensity of the cavitation is characterised in each liquid as a function of input power of a commercially available ultrasonic horn across more than twenty input powers, by monitoring the bubble collapse shockwaves generated by intense, inertially collapsing bubbles. Through analysis of the acoustic emissions and bubble structure dynamics in each liquid, optimal driving powers are identified where cavitation is most effective. In each of the DESs, driving the ultrasonic horn at lower input powers (25%) was associated with greater cavitation performance than at double the driving power (50%).

Ультразвуковое формообразование изделий из мелкодисперсных порошков

The article deals with the current state of the physics and technology of the process of ultrasonic molding (USM) of products from finely dispersed metal and non-metal powders. The relevance of a comprehensive consideration of the process is substantiated, structural and technological schemes for its implementation are presented, types of ultrasound sources – ultrasonic transducers and ultrasonic generators, as well as designs and methods for calculating concentrators (transformers) of ultrasonic vibrations are given. The results of experimental studies of the USM process as applied to fine powders of various physical and chemical nature are analyzed. Physical models of the USM process are presented and discussed.

An on-demand bioresorbable neurostimulator

Bioresorbable bioelectronics, with their natural degradation properties, hold significant potential to eliminate the need for surgical removal. Despite notable achievements, two major challenges hinder their practical application in medical settings. First, they necessitate sustainable energy solutions with biodegradable components via biosafe powering mechanisms. More importantly, reliability in their function is undermined by unpredictable device lifetimes due to the complex polymer degradation kinetics. Here, we propose an on-demand bioresorbable neurostimulator to address these issues, thus allowing for clinical operations to be manipulated using biosafe ultrasound sources. Our ultrasound-mediated transient mechanism enables (1) electrical stimulation through transcutaneous ultrasound-driven triboelectricity and (2) rapid device elimination using high-intensity ultrasound without adverse health effects. Furthermore, we perform neurophysiological analyses to show that our neurostimulator provides therapeutic benefits for both compression peripheral nerve injury and hereditary peripheral neuropathy. We anticipate that the on-demand bioresorbable neurostimulator will prove useful in the development of medical implants to treat peripheral neuropathy.

A Miniature Ultrasound Source for Neural Modulation.

This work describes a unique ultrasound (US) exposure system designed to create very localized ( [Formula: see text]) sound fields at operating frequencies that are currently being used for preclinical US neuromodulation. This system can expose small clusters of neuronal tissue, such as cell cultures or intact brain structures in target animal models, opening up opportunities to examine possible mechanisms of action. We modified a dental descaler and drove it at a resonance frequency of 96 kHz, well above its nominal operating point of 28 kHz. A ceramic microtip from an ultrasonic wire bonder was attached to the end of the applicator, creating a 100- [Formula: see text] point source. The device was calibrated with a polyvinylidene difluoride (PVDF) membrane hydrophone, in a novel, air-backed, configuration. The experimental results were confirmed by simulation using a monopole model. The results show a consistent decaying sound field from the tip, well-suited to neural stimulation. The system was tested on an existing neurological model, Drosophila melanogaster, which has not previously been used for US neuromodulation experiments. The results show brain-directed US stimulation induces or suppresses motor actions, demonstrated through synchronized tracking of fly limb movements. These results provide the basis for ongoing and future studies of US interaction with neuronal tissue, both at the level of single neurons and intact organisms.

The influence of bone model geometries on the determination of skull acoustic properties.

In this study, we investigated the impact of various simulated skull bone geometries on the determination of skull speed of sound and acoustic attenuation values via optimization using transmitted pressure amplitudes beyond the bone. Using the hybrid angular spectrum method (HAS), we simulated ultrasound transmission through four model sets of different geometries involving sandwiched layers of diploë and cortical bone in addition to three models generated from CT images of ex-vivo human skull-bones. We characterized cost-function solution spaces for each model and, using optimization, found that when a model possessed appreciable variations in resolvable layer thickness, the predefined attenuation coefficients could be found with low error (RMSE < 0.01 Np/cm). However, we identified a spatial frequency cutoff in the models' geometry beyond which the accuracy of the property determination begins to fail, depending on the frequency of the ultrasound source. There was a large increase in error of the attenuation coefficients determined by the optimization when the variations in layer thickness were above the identified spatial frequency cutoffs, or when the lateral variations across the model were relatively low in amplitude. For our limited sample of three CT-image derived bone models, the attenuation coefficients were determined successfully. The speed of sound values were determined with low error for all models (including the CT-image derived models) that were tested (RMSE < 0.4 m/s). These results illustrate that it is possible to determine the acoustic properties of two-component models when the internal bone structure is taken into account and the structure satisfies the spatial frequency constraints discussed.