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Cell morphology and viability in acoustic hologram‐induced patterns. a,b) Bright‐field mosaic images of acoustically patterned HCT‐116 cells after 1 day (a) and 7 days (b). c) SiR‐actin imaging of live cells after 1 day in culture indicates that living cells are expressing F‐actin within the matrix. d) Cyto‐dye imaging of cells after 7 days shows that HCT‐116 cells can survive extended culture within the acoustically patterned 3D hydrogel matrix. The green fluorescent signal represents viable cells, while the red fluorescent signal represents dead cells. The scale bars are 5 mm. e) The target pattern used in the acoustic hologram design.
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Acoustophoresis is promising as a rapid, biocompatible, noncontact cell manipulation method, where cells are arranged along the nodes or antinodes of the acoustic field. Typically, the acoustic field is formed in a resonator, which results in highly symmetric regular patterns. However, arbitrary, nonsymmetrically shaped cell assemblies are necessar...
Citations
... Particles from nano to supra-millimetric scales can be trapped and manipulated [26,27]. Prior studies have primarily focused on biological cells, assembling particles in continuous flow systems, and assembling polymeric particles [28][29][30][31][32][33][34]. Highly intricate designs can be achieved through several advanced techniques. ...
... Further research is required to identify other material systems and potential applications that can benefit from this adaptable patterning technique. This exploration should be conducted in conjunction with advanced acoustic patterning methods [31,32,36,37] to fully capitalize on its advantages. ...
... Leveraging standing acoustic waves generated from 1 or 2 pairs of transducers, researchers could arrange randomly distributed objects into parallel line-like or rectangular grid-like periodic patterns, separate objects with different sizes, and control cell-cell distances (28,(53)(54)(55)(56). Improving upon this performance, mechanisms based on acoustic arrays with more transducer pairs were developed to better control acoustic interference and arrange particles into more periodic patterns (57)(58)(59). Recently, the acoustic holography mechanism has been introduced to construct even more complex particle patterns (e.g., patterns depicting letters) based on the transformation of incident acoustic fields to desired patterns using three-dimensional (3D) printed or microfabricated holographic lenses (13,60,61). Very recently, holographic transducers with Archimedes spiral-shaped electrodes on flat piezoelectric wafers have been developed to generate a focalized acoustic vortex to enable selective trapping and 2D translation of single microparticles (62,63). ...
Robotic manipulation of small objects has shown great potential for engineering, biology, and chemistry research. However, existing robotic platforms have difficulty in achieving contactless, high-resolution, 4-degrees-of-freedom (4-DOF) manipulation of small objects, and noninvasive maneuvering of objects in regions shielded by tissue and bone barriers. Here, we present chirality-tunable acoustic vortex tweezers that can tune acoustic vortex chirality, transmit through biological barriers, trap single micro- to millimeter-sized objects, and control object rotation. Assisted by programmable robots, our acoustic systems further enable contactless, high-resolution translation of single objects. Our systems were demonstrated by tuning acoustic vortex chirality, controlling object rotation, and translating objects along arbitrary-shaped paths. Moreover, we used our systems to trap single objects in regions with tissue and skull barriers and translate an object inside a Y-shaped channel of a thick biomimetic phantom. In addition, we showed the function of ultrasound imaging–assisted acoustic manipulation by monitoring acoustic object manipulation via live ultrasound imaging.
... Acoustic manipulation based on Rayleigh-type surface acoustic wave (SAW) has aroused widespread interest in life sciences and biomedical and bioanalytical chemistry due to their miniaturization, biocompatibility, energy localization, and contact-free feature. [1][2][3][4][5][6][7][8][9] For satisfying differently predestined applications of acoustic manipulation, multifunctional and precise SAW is crucial, which fundamentally relies on a design of interdigital transducer (IDT). To date, the design of IDTs generating special SAW fields depends on two methods, either structural design or phased array technology. ...
Acoustic manipulation using surface acoustic wave has aroused widespread interest in life sciences, biomedical, and bioanalytical chemistry. Acoustic manipulation for different applications requires different acoustic fields. Bessel beams are non-diffractive and re-constructable, bringing possibility and versatility of acoustic manipulation integrated on microfluidic chips. To date, there are a few studies on constructing Bessel surface acoustic waves. Moreover, there is still a lack of dynamic acoustic manipulation using Bessel surface acoustic waves propagating along a surface of piezoelectric substrate with simple and high-precision devices. Here, we design a device with two omnidirectional equifrequency interdigital transducers to form a quasi-Bessel surface acoustic wave by means of coherent interference. The proposed device avoids influences of anisotropy on its operating frequency, making its quasi-Bessel beam accurately and stably conform to the predetermined design acoustic field. This acoustic field could control micrometer to submicrometer particles and dynamically move particles along lateral direction and axial direction of the propagation of quasi-Bessel beam. A phenomenon similar to negative force appeared when the two-micron spherical particles were manipulated. The quasi-Bessel beam formed by our device can provide a versatile movement for on-chip acoustic manipulation.
... In contrast, acoustic tweezers provide greater forces and the ability to manipulate much larger objects. Achieving high throughput and arbitrary shape patterning of microscopic objects using acoustic waves is a challenging task 31,32 . Some processes have been made in the advancement of holographic acoustic manipulation through a multiemitter phased array, but their applications are still constrained by the necessity of a considerable number of transducers and the intricacy of hardware control 33 . ...
Optical and acoustic tweezers, despite operating on different physical principles, offer non-contact manipulation of microscopic and mesoscopic objects, making them essential in fields like cell biology, medicine, and nanotechnology. The advantages and limitations of optical and acoustic manipulation complement each other, particularly in terms of trapping size, force intensity, and flexibility. We use photoacoustic effects to generate localized Lamb wave fields capable of mapping arbitrary laser pattern shapes. By using localized Lamb waves to vibrate the surface of the multilayer membrane, we can pattern tens of thousands of microscopic particles into the desired pattern simultaneously. Moreover, by quickly and successively adjusting the laser shape, microparticles flow dynamically along the corresponding elastic wave fields, creating a frame-by-frame animation. Our approach merges the programmable adaptability of optical tweezers with the potent manipulation capabilities of acoustic waves, paving the way for wave-based manipulation techniques, such as microparticle assembly, biological synthesis, and microsystems.
... Its phase and amplitude are modulated according to a predetermined algorithm, thereby forming a complex-shaped pressure distribution. In this way, the spatial information of the tangible patterns on the template mask is transmitted to space through invisible acoustic waves [118]. Melde et al. even presented a 3D holographic assembly of cells and microgel beads in liquid in a centrifuge tube, and this is encouraging for tissue engineering and additive manufacturing fields [119][120][121][122][123]. Despite its great promise, to date, there have been few reported applications of this technology in the manipulation of living cells. ...
Acoutofluidics is an increasingly developing and maturing technical discipline. With the advantages of being label-free, non-contact, bio-friendly, high-resolution, and remote-controllable, it is very suitable for the operation of living cells. After decades of fundamental laboratory research, its technical principles have become increasingly clear, and its manufacturing technology has gradually become popularized. Presently, various imaginative applications continue to emerge and are constantly being improved. Here, we introduce the development of acoustofluidic actuation technology from the perspective of related manipulation applications on living cells. Among them, we focus on the main development directions such as acoustofluidic sorting, acoustofluidic tissue engineering, acoustofluidic microscopy, and acoustofluidic biophysical therapy. This review aims to provide a concise summary of the current state of research and bridge past developments with future directions, offering researchers a comprehensive overview and sparking innovation in the field.
... Vibrating structures actuated via BAW, such as resonating micropillars or sharp edges, have also revealed themselves as effective tools for particle trapping 44,45 , transport along complex trajectories 46 , and inchannel pumping 47 and mixing [48][49][50][51] . Similarly, holographic cell patterning has also been demonstrated based on a 3D-printed phase-encoded plate mounted on a single transducer inducing localized acoustic streaming at the pressure nodes 52 . ...
This article presents an in-depth exploration of the acoustofluidic capabilities of guided flexural waves (GFWs) generated by a membrane acoustic waveguide actuator (MAWA). By harnessing the potential of GFWs, cavity-agnostic advanced particle manipulation functions are achieved, unlocking new avenues for microfluidic systems and lab-on-a-chip development. The localized acoustofluidic effects of GFWs arising from the evanescent nature of the acoustic fields they induce inside a liquid medium are numerically investigated to highlight their unique and promising characteristics. Unlike traditional acoustofluidic technologies, the GFWs propagating on the MAWA’s membrane waveguide allow for cavity-agnostic particle manipulation, irrespective of the resonant properties of the fluidic chamber. Moreover, the acoustofluidic functions enabled by the device depend on the flexural mode populating the active region of the membrane waveguide. Experimental demonstrations using two types of particles include in-sessile-droplet particle transport, mixing, and spatial separation based on particle diameter, along with streaming-induced counter-flow virtual channel generation in microfluidic PDMS channels. These experiments emphasize the versatility and potential applications of the MAWA as a microfluidic platform targeted at lab-on-a-chip development and showcase the MAWA’s compatibility with existing microfluidic systems.
... This includes arbitrary beam steering, generating multiple focal spots, or producing complex acoustic images matching the 3D-shape of a target brain structure [22]. Since then, holograms have widely been used in many applications, such as in synthesizing acoustic vortices into the skull [23], cavitation pattern generation [24], cell patterning [25], producing arbitrary and large thermal patterns [26], controlling the thermal dose of high-intensity focused sources [27], and have been tested in vivo to open the blood-brain barrier in small animals, generating either multiple sharp focal spots whose small spherical size approaches the limit imposed by diffraction [28] or wide and elongated focal areas [29]. ...
... Acoustofluidic technologies have proven to be a powerful method to manipulate biological objects because of their high biocompatibility, simplicity, and versatility [30][31][32][33][34][35][36][37][38][39][40] . Acoustic waves can be directly transmitted into a liquid medium to generate an acoustic radiation force or acoustic streaming force that can be used to manipulate extracellular vesicles, cells, spheroids, and even small organisms in a non-contact and label-free manner [41][42][43][44][45][46][47][48][49] . Compared with the technologies mentioned above, acoustofluidics offer a simple, biocompatible, and effective ECM-free method to manipulate MSCs under natural growth conditions. ...
While mesenchymal stem cells (MSCs) have gained enormous attention due to their unique properties of self-renewal, colony formation, and differentiation potential, the MSC secretome has become attractive due to its roles in immunomodulation, anti-inflammatory activity, angiogenesis, and anti-apoptosis. However, the precise stimulation and efficient production of the MSC secretome for therapeutic applications are challenging problems to solve. Here, we report on Acoustofluidic Interfaces for the Mechanobiological Secretome of MSCs: AIMS. We create an acoustofluidic mechanobiological environment to form reproducible three-dimensional MSC aggregates, which produce the MSC secretome with high efficiency. We confirm the increased MSC secretome is due to improved cell-cell interactions using AIMS: the key mediator N-cadherin was up-regulated while functional blocking of N-cadherin resulted in no enhancement of the secretome. After being primed by IFN-γ, the secretome profile of the MSC aggregates contains more anti-inflammatory cytokines and can be used to inhibit the pro-inflammatory response of M1 phenotype macrophages, suppress T cell activation, and support B cell functions. As such, the MSC secretome can be modified for personalized secretome-based therapies. AIMS acts as a powerful tool for improving the MSC secretome and precisely tuning the secretory profile to develop new treatments in translational medicine.
... However, recent trends show an inclination towards the use of sound fields, which exert acoustic forces for assembly, presenting a direct approach without requiring chemical additives such as photoinitiators. Although the acoustic assembly of particles demonstrates potential in rapid prototyping [1] and cell culture applications [2], its capabilities have been limited mainly to 2D assemblies near boundaries [3,4] or point-focused tweezing in both air [5,6] and aquatic settings [7,8]. Using standing waves to assemble cells or colloidal microparticles often results in highly symmetrical patterns [9,10,11]. ...
The existence and stability of steady-state averaged solutions for a strongly over-damped particle in a cosine potential are analytically studied when subjected to harmonic excitation. The stability loss of these solutions, which oscillate near the bottom of the potential well, can be viewed as an escape problem. The harmonic balance method is used for the analysis up to the first order, including a constant bias term. When a massless particle is assumed, the steady-state solutions oscillate around either the potential well's minima or maxima. However, taking the particle's mass into account alters the structure of the steady-state solution. Within certain excitation parameter ranges, a new set of equilibrium positions for the oscillation center arises, linking the equilibria at the potential's extremities. Interestingly , modulating only the force amplitude can continuously bias the steady-state oscillation center.
... In this case, the holographic information becomes encoded in a passive structure, e.g., a 3D-printed lens of rough surface, which modulates the transmitted phase of the ultrasound field generated by a transducer. Among other applications, acoustic holograms have been proposed for ultrasound particle manipulation and trapping [20], acoustic vortex generation for transmitted [21] or reflected wavefronts [22], fast 3D printing via volumetric particle agglomeration [23], cell patterning [24], generation of cavitation patterns [25], producing arbitrary-shaped thermal patterns in tissues using ultrasound [26], tuning the acoustic field to control the total thermal dose on multiple targets for ultrasound hyperthermia [27], or performing 3D acoustic imaging using a single-channel transducer [28]. ...
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, which in many practical situations cannot be estimated by direct hydrophone measurements. In this work, we apply single-plane holographic measurement techniques to experimentally calibrate and measure the full volumetric field produced by holographic lenses. Two ex vivo test cases are presented, a four-foci lens and a preclinical case, both targeting through a macaque skull for potential applications in blood–brain barrier opening (BBBO) studies. Time-reversal and angular spectrum projection methods are compared to direct experimental measurements. Results show that holographic projection methods can reconstruct the complex acoustic images produced by holographic lenses, matching direct measurements in all test cases. However, while direct measurements are restricted to transverse-field cross sections, holographic projection allows estimating the field on the whole targeting volume. In this way, the location and the full three-dimensional shape of all acoustic foci can be obtained. Furthermore, these techniques can provide the field at the surface of the lens to compare it to the design phase distribution. Using this procedure, complex volumetric acoustic fields can be reconstructed, saving significant measurement time and computational resources, and enabling an accurate characterization of phase plates and other holographic lens topologies.
