This work presents three-dimensional (3D) numerical analysis of acoustic radiation force on an elastic microsphere suspended in a viscous fluid. Acoustophoresis of finite-sized, neutrally buoyant, nearly incompressible soft particles may improve by orders of magnitude and change directions when going through resonant vibrations. These findings offer the potential to manipulate and separate microparticles based on their resonance frequency. This concept has profound implications in cell and microparticle handling, 3D printing, and enrichment in lab-on-chip applications. The existing analytical body of work can predict spheroidal harmonics of an elastic sphere and acoustic radiation force based on monopole and dipole scatter in an ideal fluid. However, little attention is given to the complex interplay of resonant fluid and solid bodies that generate acoustic radiation. The finite element method is used to find resonant modes, damping factors, and acoustic forces of an elastic sphere subject to a standing acoustic wave. Under fundamental spheroidal modes, the radiation force fluctuates significantly around analytical values due to constructive or destructive scatter-incident wave interference. This suggests that for certain materials, relevant to acoustofluidic applications, particle resonances are an important scattering mechanism and design parameter. The 3D model may be applied to any number of particles regardless of geometry or background acoustic field.
Optomechanical sensors provide a platform for probing acoustic/vibrational properties at the micro-scale. Here, we used cavity optomechanical sensors to interrogate the acoustic environment of adjacent air bubbles in water. We report experimental observations of the volume acoustic modes of these bubbles, including both the fundamental Minnaert breathing mode and a family of higher-order modes extending into the megahertz frequency range.
Background: The order Rodentia is the largest group of mammals. Diversification of vocal communication has contributed to rodent radiation and allowed them to occupy diverse habitats and adopt different social systems. The mechanism by which efficient vocal sounds, which carry over surprisingly large distances, are generated is incompletely understood.
Analytical solutions for acoustic vortex beams radiated by sources with uniform circular amplitude distributions are derived in the paraxial approximation. Evaluation of the Fresnel diffraction integral in the far field of an unfocused source and in the focal plane of a focused source leads to solutions in terms of an infinite series of Bessel functions for orbital numbers ℓ>-2. These solutions are reduced to closed forms for 0≤ℓ≤4, which correspond to orbital numbers commonly used in experiments.
Objective: Previous studies have reported that the noise generated by dental equipment can interfere with the auscultation of respiratory sounds during sedation. Therefore, this study aimed to identify whether positing the acoustic sensor on the chest or cervical position would be least susceptible to interference from dental suction device noise, a prominent noise noted during respiratory sound monitoring during dental sedation.
Methods: This prospective cohort study was conducted with 30 students.
Ultrasound generates both compressive and shear mechanical forces in soft tissues. However, the specific mechanisms by which these forces activate cellular processes remain unclear. Here we show that low-intensity focused ultrasound can activate the mechanosensitive RET signalling pathway.
