Programmable particles patterning by multifrequency excitation radiation force of acoustic resonance modes

Acoustofluidics offers contact-free manipulation of particles and fluids, enabling their uses in various life sciences, such as for biological and medical applications. Recently, there have been extensive studies on acoustic streaming-based acoustofluidics, which are formed inside a liquid agitated by leaky surface acoustic waves (SAWs) through applying radio frequency signals to interdigital transducers (IDTs) on a piezoelectric substrate. This paper aims to describe acoustic streaming-based acoustofluidics and provide readers with an unbiased perspective to determine which IDT structural designs and techniques are most suitable for their research. This review, first, qualitatively and quantitatively introduces underlying physics of acoustic streaming. Then, it comprehensively discusses the fundamental designs of IDT technology for generating various types of acoustic streaming phenomena. Acoustic streaming-related methodologies and the corresponding biomedical applications are highlighted and discussed, according to either standing surface acoustic waves or traveling surface acoustic waves generated, and also sessile droplets or continuous fluids used. Traveling SAW-based acoustofluidics generate various physical phenomena including mixing, concentration, rotation, pumping, jetting, nebulization/atomization, and droplet generation, as well as mixing and concentration of liquid in a channel/chamber. Standing SAWs induce streaming for digital and continuous acoustofluidics, which can be used for mixing, sorting, and trapping in a channel/chamber. Key challenges, future developments, and directions for acoustic streaming-based acoustofluidics are finally discussed.

https://pubs.aip.org/aip/apr/article-pdf/doi/10.1063/5.0134646/16789475/011315_1_online.pdf

Methodologies, technologies, and strategies for acoustic streaming-based acoustofluidics

Simultaneous detection of multiple miRNAs of one disease can greatly reduce misdiagnosis and improve the detection rate, which is helpful for early cancer diagnosis. Here, a programmable microparticle-array-based acoustic microchip for in situ simultaneous multiple miRNAs detection is developed. On this microchip, the multiple probes-labeled microparticle array can be procedurally arranged in a microfluidic reaction chamber when four orthogonally piezoelectric transducers are applied. The probes-labeled microparticle array offers a platform for full molecular contact under dynamic ultrasonic streaming, and the array supplies a multipoint data correction to reduce the false positive of the detection results for more precisely visible fluorescence multiple target miRNAs sensing. We employed miRNA-21, miRNA-210, and miRNA-155 as specific biomarkers of pancreatic cancer and successfully finished the multiple miRNAs simultaneous detection in the microchip with a detection limit of 139.1, 179.9, and 111.4 pM, respectively. Such a device is programmable by adjusting the imputing frequency and voltage, and target biomarkers can be easily collected when the ultrasound force is released for further analysis, which shows great potential in multiple miRNAs enrichment and simultaneous detection for cancer clinical diagnosis.

Programmable Microparticle Array for In Situ Modification and Multiple miRNA Detection.

Single‐cell manipulation technology is an essential method of cell research, with wide applications in biological engineering, medical engineering, agricultural engineering, and other precise manipulation fields. Cell pose adjustment and cell puncture are considered as two basic operations of single‐cell manipulation. Cell pose adjustment can be used for cell sorting, cell trapping, cell orientation, cell transportation, etc. It consists of direct contact manipulation methods and noncontact manipulation methods (e.g., mechanical contact method, electric field, optical field, magnetic field, acoustic field, and hydrodynamic methods). Cell puncture consists of ordinary glass needle puncture methods, piezoelectric‐assisted puncture methods, and rotational oscillatory drill puncture methods. It aims to achieve directional and quantified injection or sampling with minimal damage. Herein, the recent research progress on single‐cell pose adjustment and puncture methods is systematically summarized and discussed, which involves the basic mechanism, characteristics, limitations, and applications. Some potential directions for future research are proposed in accordance with the above analysis. It is hoped that this review can provide a reference for academic research and industrial applications of single‐cell manipulation technology.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/aisy.202200096

A Review of Single‐Cell Pose Adjustment and Puncture

Acoustic tweezers based on surface acoustic waves (SAWs) have raised great interest in the fields of tissue engineering, targeted therapy, and drug delivery. Generally, the complex structure and array layout design of interdigital electrodes would restrict the applications of acoustic tweezers. Here, we present a novel approach by using bisymmetric coherent acoustic tweezers to modulate the shape of acoustic pressure fields with high flexibility and accuracy. Experimental tests were conducted to perform the precise, contactless, and biocompatible cluster manipulation of polystyrene microparticles and yeast cells. Stripe, dot, quadratic lattice, hexagonal lattice, interleaved stripe, oblique stripe, and many other complex arrays were achieved by real-time modulation of amplitudes and phase relations of coherent SAWs to demonstrate the capability of the device for the cluster manipulation of particles and cells. Furthermore, rapid switching among various arrays, shape regulation, geometric parameter modulation of array units, and directional translation of microparticles and cells were implemented. This study demonstrated a favorable technique for flexible and versatile manipulation and patterning of cells and biomolecules, and it has the advantages of high manipulation accuracy and adjustability, thus it is expected to be utilized in the fields of targeted cellular assembly, biological 3D printing, and targeted release of drugs.

Bisymmetric coherent acoustic tweezers based on modulation of surface acoustic waves for dynamic and reconfigurable cluster manipulation of particles and cells.

Acoustic tweezers based on travelling surface acoustic waves (TSAWs) have the potential for contactless trajectory manipulation and motion-parameter regulation of microparticles in biological and microfluidic applications. Here, we present a novel design of a tri-directional symmetrical acoustic tweezers device that enables the precise manipulation of linear, clockwise, and anticlockwise trajectories of microparticles. By switching the excitation combinations of interdigital electrodes (IDTs), various shape patterns of acoustic pressure fields can be formed to capture and steer microparticles accurately according to pre-defined trajectories. Numerical simulations and experimental tests were conducted in this study. By adjusting the input electric signals and the fluid's viscosity, the device is able to manipulate microparticles of various forms as well as brine shrimp egg cells with the accurate modulation of motion parameters. The results show that the proposed programmable design possesses low-cost, compact, non-contact, and high biocompatibility benefits, with the capacity to accurately manage microparticles in a range of motion trajectories, independent of their physical and/or chemical characteristics. Thus, our design has strong potential applications in chemical composition analysis, drug delivery, and cell assembly.

Programmable motion control and trajectory manipulation of microparticles through tri-directional symmetrical acoustic tweezers.

Multifunctional composites have been widely utilized in soft robots, electronics, batteries, and biomedicine. Meanwhile, several fabrication processes have been proposed to fabricate these functional composites with desired mechanical, electrical, magnetic, and thermal properties. However, patterning functional micro/nanomaterials such as particles, dots, wires, and fibers into complex designs with high spatial resolutions in a matrix remains a technical challenge. Herein, we present an acoustic-assisted 3D printing method enabled by standing surface acoustic waves (SSAWs). The proposed SSAWs-assisted patterning method produces diverse patterning forms of micro/nanomaterials and has almost no special requirements on micro/nanomaterials properties, indicating its great versatility and compatibility. Functional materials are assembled into desired stripe-like, net-like, and dot-like patterns. Multilayer composites with different patterns in each layer are even fabricated through a layer-by-layer printing process. To further demonstrate the potential of this 3D printing method, conductive polymer composite films with programmed electrical anisotropies are printed, yielding a maximum electrical conductivity of 827 S/m. The proposed acoustic-assisted patterning method makes the 3D printing of complex functional composites with customized properties possible, pushing the wide application of functional composites forward. 

Chengyao Xu

Papers

Programmable motion control and trajectory manipulation of microparticles through tri-directional symmetrical acoustic tweezers.

Bisymmetric coherent acoustic tweezers based on modulation of surface acoustic waves for dynamic and reconfigurable cluster manipulation of particles and cells.

Acoustic-assisted 3D Printing Based on Acoustofluidic Microparticles Patterning for Conductive Polymer Composites Fabrication

Acoustic tweezers using bisymmetric coherent surface acoustic waves for dynamic and reconfigurable manipulation of particle multimers.

Multifunctional Acoustofluidic Centrifuge Device Using Tri-Symmetrical Design for Particle Enrichment and Separation and Multiphase Microflow Mixing