Noé Jiménez

Universitat Politècnica de València | UPV · Institute for Molecular Imaging Technologies (I3M)

We report three-dimensional (3D)-printed acoustic holographic lenses for the formation of ultrasonic fields of complex spatial distribution inside the skull. Using holographic lenses, we experimentally, numerically, and theoretically produce acoustic beams whose spatial distribution matches target structures of the central nervous system. In partic...

The formation of high-order Bessel beams by a passive acoustic device consisting of an Archimedes' spiral diffraction grating is theoretically, numerically and experimentally reported in this work. These beams are propagation-invariant solutions of the Helmholtz equation and are characterized by an azimuthal variation of the phase along its annular...

Using the concepts of slow sound and critical coupling, an ultra-thin acoustic metamaterial panel for perfect and quasi-omnidirectional absorption is theoretically and experimentally conceived in this work. The system is made of a rigid panel with a periodic distribution of thin closed slits, the upper wall of which is loaded by Helmholtz Resonator...

We present deep-subwavelength diffusing surfaces based on acoustic metamaterials, namely metadiffusers. These sound diffusers are rigidly backed slotted panels, with each slit being loaded by an array of Helmholtz resonators. Strong dispersion is produced in the slits and slow sound conditions are induced. Thus, the effective thickness of the panel...

Perfect, broadband and asymmetric sound absorption is theoretically, numerically and experimentally reported by using subwavelength thickness panels in a transmission problem. The panels are composed of a periodic array of varying cross-section waveguides, each of them being loaded by an array of Helmholtz resonators (HRs) with graded dimensions. T...

Ultrasonic three-dimensional printed holograms are getting increasing interest for transcranial therapies since they can correct skull aberrations and, simultaneously, adapt the acoustic field to particular brain targets. However, evaluating the targeting performance of these systems requires the measurement of complex volumetric acoustic fields, w...

Hyperthermia is currently used to treat cancer due to its ability to radio- and chemo-sensitize and to stimulate the immune response. While ultrasound is non-ionizing and can induce hyperthermia deep within the body non-invasively, achieving uniform and volumetric hyperthermia is challenging. This work presents a novel focused ultrasound hypertherm...

This broad review summarizes recent advances and “hot” research topics in nanophononics and elastic, acoustic, and mechanical metamaterials based on results presented by the authors at the EUROMECH 610 Colloquium held on April 25–27, 2022 in Benicássim, Spain. The key goal of the colloquium was to highlight important developments in these areas, pa...

3D-printed holographic lenses coupled to an ultrasound transducer shape the acoustic field into arbitrary images. Predefined thermal patterns can be created with this technology in absorbing media, which can be used to generate localized and specific hyperthermia treatments. In this work we study how non-linearities in the acoustic field can affect...

The natural diffraction of acoustic vortex beams results in vortices whose bright core is larger than the wavelength, limiting their use for practical applications such as long-range underwater communications. In this work, we synthesize a vortex beam of sub-wavelength size at a distance beyond Rayleigh diffraction length using the nonlinear mixing...

Cuando una superficie vibra comprimiendo el medio que tiene delante, genera ondas acústicas. Este es el caso de los altavoces, que generan ondas acústicas a frecuencias audibles mediante una superficie móvil. En este trabajo presentamos un tutorial para modelizar la radiación acústica de superficies vibrantes, diferenciando entre geometrías circula...

No PDF available ABSTRACT We present acoustic drill beams. These singular beams show a dynamic intensity distribution matching the shape of a helix. The intensity distribution rotates along the axis of the beam with a controlled direction and angular frequency, therefore resembling the shape of a mechanical drill bit. Acoustic drills emerge elegant...

One of the key trends in laser material processing is the usage of structured laser beams. Collimated and focused Gaussian beams are the most common tools; however, more exotic beams can be beneficial too. For instance, Bessel beams with elongated focal area and self-healing properties, or vortex beams with helical wave fronts and a dark area along...

Holograms can shape wavefronts to produce arbitrary acoustic images. In this work, we experimentally demonstrate how acoustic holograms can produce controlled thermal patterns in absorbing media at ultrasonic frequencies. Magnetic resonance imaging (MRI)-compatible holographic ultrasound lenses were designed by time-reversal methods and manufacture...

Acoustic holograms can encode complex wavefronts to compensate the aberrations of a therapeutical ultrasound beam propagating through heterogeneous tissues such as the skull, and simultaneously, they can generate diffraction-limited acoustic images, that is, arbitrary shaped focal spots. In this work, we numerically study the performance of acousti...

The transfer matrix method is a simple but powerful analytical tool used to model acoustic wave propagation in a wide range of one-dimensional problems. In this chapter, we present the method and summarize the most common building blocks encountered in one-dimensional acoustic systems. These include layers of fluids and porous media, ducts and wave...

Porous and fibrous materials provide effective and broadband acoustic absorption at mid/high audible frequencies. However, these traditional treatments result in thick and heavy layers when designed for low frequency audible sound. To overcome these limitations, in the recent years metamaterials have been proposed as an alternative to design sub-wa...

Transcranial focused ultrasound (FUS) in conjunction with circulating microbubbles injection is the sole non-invasive technique that temporally and locally opens the blood-brain barrier (BBB), allowing targeted drug delivery into the central nervous system (CNS). However, single-element FUS technologies do not allow the simultaneous targeting of se...

Most simulations involving metamaterials often require complex physics to be solvedthrough refined meshing grids. However, it can prove challenging to simulate the effect of localphysical conditions created by said metamaterials into much wider computing sceneries due to theincreased meshing load. We thus present in this work a framework for simula...

Most simulations involving metamaterials often require complex physics to be solved through refined meshing grids. However, it can prove challenging to simulate the effect of local physical conditions created by said metamaterials into much wider computing sceneries due to the increased meshing load. We thus present in this work a framework for sim...

Sound diffusion refers to the ability of a surface to evenly scatter sound energy in both time and space. However, omni-directional radiation of sound, or perfect diffusion, can be impractical or difficult to reach under traditional means. This is due to the considerable size required, and the lack of tunability, of typical quarter-wavelength scatt...

We report a method to locally assess the complex shear modulus of a viscoelastic medium. The proposed approach is based on the application of a magnetic force to a millimetre-sized steel sphere embedded in the medium and the subsequent monitoring of its dynamical response. A coil is used to create a magnetic field inducing the displacement of the s...

In this work, we show that scattered acoustic vortices generated by metasurfaces with chiral symmetry present broadband unusual properties in the far-field. These metasurfaces are designed to encode the holographic field of an acoustical vortex, resulting in structures with spiral geometry. In the near field, phase dislocations with tuned topologic...

Acoustic vortices with subwavelength dimensions and tunable topological charge are theoretically and experimentally synthesized at distances far beyond the Rayleigh diffraction length of the source, using self-demodulation. A dual helical acoustic source is used to generate two primary confocal vortex beams at different frequencies and different to...

No PDF available ABSTRACT In this work, we numerically investigate the performance of acoustic holograms created using k-space simulations and a phase-conjugation method at 650 kHz to simultaneously target both thalami through the temporal bone window compared to a curved transducer. Furthermore, we calculate how a misalignment of the acoustic holo...

No PDF available ABSTRACT We present a hybrid technique that combines magnetic forces and ultrasonic waves (MMUS based) to explicitly characterize the complex elastic modulus of soft-solids in the frequency domain. The results show the dependence of the viscoelastic properties with the frequency content of the applied magnetic impulse.

No PDF available ABSTRACT Arrays of acoustic vortices are synthesised using 3D printed holograms in the ultrasound regime. This technique paves the way for simultaneous trapping of multiple particles and such as arrays of cells, microbubbles or drug-delivery carriers using a low-cost device.

No PDF available ABSTRACT Ideal Bessel beams can be useful for ultrasound imaging, biomedical ultrasound and particle manipulation. Since traditional passive methods to generate these beams are not capable of achieving a flat-intensity beam along the axial coordinate, we use acoustic holograms to produce ideal broad depth-of-field Bessel beams at z...

Beamforming enhances the performance of array-based photoacoustic microscopy (PAM) systems for large-area scan. In this study, we quantify the imaging performance of a large field-of-view optical-resolution photoacoustic-microscopy system using an phased-array detector. The system combines a low-cost pulsed-laser diode with a 128-element linear ult...

In this review, we present the results on sub-wavelength perfect acoustic absorption using acoustic metamaterials made of Helmholtz resonators with different setups. Low frequency perfect absorption requires to increase the number of states at low frequencies and finding the good conditions for impedance matching with the background medium. If, in...

We present a 3-dimensional fully natural sonic crystal composed of spherical aggregates of fibers (called Aegagropilae) resulting from the decomposition of Posidonia Oceanica. The fiber network is first acoustically characterized, providing insights on this natural fiber entanglement due to turbulent flow. The Aegagropilae are then arranged on a pr...

This book delivers a comprehensive and up-to-date treatment of practical applications of metamaterials, structured media, and conventional porous materials. With increasing levels of urbanization, a growing demand for motorized transport, and inefficient urban planning, environmental noise exposure is rapidly becoming a pressing societal and health...

Acoustic vortex beams have great potential for contactless particle manipulation and torque-based biomedical applications. However, focusing acoustic waves through highly aberrating layers such as the human skull at ultrasonic frequencies results in strong phase aberrations, which prevent the generation of sharp acoustic images. In the case of a wa...

Mirror-symmetric acoustic metascreens producing perfect absorption independently of the incidence side are theoretically and experimentally reported in this work. The mirror-symmetric resonant building blocks of the metascreen support symmetric and antisymmetric resonances that can be tuned to be at the same frequency (degenerate resonances). The g...

This work presents the prediction of noise generated during the launch of space rockets. A semi- empirical model was applied, using as input data the physical and geometric characteristics of the jet of gases propelled by the rocket, which acts as the primary source of noise. The model is based on the one originally proposed by Eldred back in 1971...

Sound diffusers are structured surfaces designed to control the scattering of acoustic waves, mainly used in room acoustics to improve sound quality. However, as they are mainly based on quarter-wavelength resonators, phase-grating diffusers result in heavy and thick structures. We present a novel approach to design deep-subwavelength sound diffuse...

Demineralization is a process of loss of minerals in the dental hard tissue that affects seriously the health of the patients, as it diminishes the tooth resistance, generating chewing problems by altering the occlusal structure, hypersensitivity and pulpal problems. Demineralization can be produced by pathological processes as erosion or caries, o...

Mirror-symmetric acoustic metascreens producing perfect absorption independently of the incidence side are theoretically and experimentally reported in this work. The mirror-symmetric resonant building blocks of the metascreen support symmetric and antisymmetric resonances that can be tuned to be at the same frequency (degenerate resonances). The g...

We report zero-th and high-order acoustic Bessel beams with broad depth-of-field generated using acoustic holograms. While the transverse field distribution of Bessel beams generated using traditional passive methods is correctly described by a Bessel function, these methods present a common drawback: the axial distribution of the field is not cons...

We report a method to monitor the setting process of bone-graft substitutes (calcium sulphate) using ultrasonic backscattering techniques. Analyzing the backscattered fields using a pulse-echo technique, we show that it is possible to dynamically describe the acoustic properties of the material which are linked to its setting state. Several experim...

The correction of transcranial focused ultrasound aberrations is a relevant topic for enhancing various non-invasive medical treatments. Presently, the most widely accepted method to improve focusing is the emission through multi-element phased arrays; however, a new disruptive technology, based on 3D printed holographic acoustic lenses, has recent...

An acoustic metadiffuser is a subwavelength locally resonant surface relying on slow sound propagation. Its design consists of rigidly backed slotted panels, with each slit being loaded by an array of Helmholtz resonators. Due to the slow sound properties, the effective thickness of the panel can therefore be dramatically reduced when compared to t...

Acoustics metamaterials have recently revolutionized the field of acoustics and mechanics due to their extraordinary functionalities giving rise to breakthroughs in the material design strategy. This chapter discusses two types of acoustic metamaterial, both based on slow sound and critical coupling conditions, showing efficient absorption and diff...

The unusual viscoelastic properties of silica aerogel plates are efficiently used to design subwavelength perfect sound absorbers. We theoretically, numerically, and experimentally report a perfect absorbing metamaterial panel made of periodically arranged resonant building blocks consisting of a slit loaded by a clamped aerogel plate backed by a c...

The unusual viscoelastic properties of silica aerogel plates are efficiently used to design subwavelength perfect sound absorbers. We theoretically, numerically and experimentally report a perfect absorbing metamaterial panel made of periodically arranged resonant building blocks consisting of a slit loaded by a clamped aerogel plate backed by a cl...

We report a method to monitor the setting process of bone-graft substitutes (calcium sulphate) using ultrasonic backscattering techniques. Analyzing the backscattered fields using a pulse-echo technique, we show that it is possible to dynamically describe the acoustic properties of the material which are linked to its setting state. Several experim...

We report 3D-printed acoustic holographic lenses for the formation of ultrasonic fields of complex spatial distribution inside the skull. Using holographic lenses, we experimentally, numerically and theoretically produce acoustic beams whose spatial distribution matches target structures of the central nervous system. In particular, we produce thre...

En este trabajo presentamos la modelización de una cerámica piezoeléctrica vibrando en modo espesor empleando matrices de transferencia. La modelización completa del comportamiento vibratorio de un material piezoeléctrico es un problema complejo. Ello es debido principalmente al carácter tensorial de los esfuerzos junto a la anisotropía de los sóli...

Ultrasonic backscattering techniques are used to monitor the setting process of calcium sulfate. A 3.5 MHz frequency pulse-echo system is used to obtain the acoustic properties of a sample of calcium sulfate. The temperature of the sample and the rf-backscattering signal are measured every two seconds during the whole setting process (53 min; 1590...