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Abstract Leveraging robot-assisted technology to manipulate tiny objects has shown significant potential in the fields of engineering, chemistry, and biology. However, achieving high-resolution, non-invasive manipulation of objects shielded by biological barriers remains a major challenge. In this work, we present a robot-assisted acoustic vortex end effector system capable of generating acoustic vortex beams for contactless manipulation of small objects. First, instead of generating a fixed acoustic vortex beam, our acoustic end effector can tune the chirality of the vortex beam by adjusting the topological charge number encoded in the holographic lens, allowing for customization of the size of the corresponding potential well to accommodate various sizes of trapped particle. Second, by leveraging acoustic vortex beams as a non-invasive manipulator, we successfully achieved acoustic manipulation through biomimetic barriers. In a proof-of-concept experiment, we demonstrated the high-resolution contactless acoustic manipulation of a plastic ball (3 mm diameter) within a straight phantom mimic-vessel. Third, by combining the acoustic vortex end effector with a real time ultrasound imaging system, our approach enables continuous, real-time monitoring of the entire acoustic manipulation process. This integration paves the way for acoustic trapping and manipulation in non-transparent environments. Overall, our research demonstrates the advantages of acoustic manipulation technologies in biomedical and clinical applications, offering a biocompatible solution for medical interventions in the future. 

Abstract Ultrasonics structural health monitoring (SHM) is widely recognized as an effective technique that enables early damage detection in large-scale structures and helps prevent potential catastrophic failures. Ultrasonic phased array technology has gained prominence in SHM due to its ability to inspect a large area with high spatial resolution. However, conventional systems often rely on physical wired sensor networks, limiting their deployment for hard-to-access regions. In this study, we present a wireless ultrasonic phased array system capable of dual-mode operation for both wall thickness measurement and structural damage detection. The system integrates wireless power transfer (WPT) modules and customized matching circuits, enabling efficient and flexible deployment. Proof-of-concept experiments demonstrate successful wall thickness evaluation and accurate defect localization in metallic structures using both delay-and-sum (DAS) and minimum variance (MV) imaging methods, with the MV algorithm offering improved imaging resolution. Future work will focus on advancing real-time monitoring through machine learning, enabling 3D imaging, and extending system applicability to anisotropic composite materials. 

Abstract The development of smart materials capable of dynamic shape morphing and rapid responsiveness has garnered significant interest for applications in soft robotics, tissue engineering, programmable materials, and adaptive structures. Hydrogels, owing to their intrinsic biocompatibility and flexibility, are promising candidates for such systems. Embedding micro-scale materials within hydrogel networks can further enhance their mechanical and functional properties. In this study, we present a hybrid fabrication platform that integrates surface acoustic wave (SAW)-based acoustofluidics with digital light processing (DLP) photopolymerization to fabricate smart hydrogel composites with programmable shape-memorable behavior. Using the SAW-induced acoustic potential field, silicon carbide (SiC) micro-whiskers are aligned within a custom UV-curable hydrogel ink and subsequently fixed via high-resolution DLP photopolymerization. This dual-control approach enables independent manipulation of micro-whisker orientation and structural geometry. Numerical simulations and Laser Doppler vibrometry-based validation were employed to characterize the acoustic field. To evaluate shape-memory behavior, the fabricated hydrogels were subjected to dehydration and rehydration cycles. The resulting shape transformations, driven by internal stress gradients within the aligned microparticle framework, enabled humidity-responsive actuation. This work establishes a novel strategy for constructing 4D-printed smart hydrogels, offering a versatile platform for the development of next-generation programmable materials and adaptive structures. 

Abstract Precise manipulation of nanomaterials has shown great potential in facilitating the fabrication of functional hydrogel nanocomposites in applications such as soft robotics, biomedicine, structural health monitoring, and wearable sensing. Surface acoustic wave (SAW)-based acoustofluidics offers a contactless approach for nanoparticle manipulation. Meanwhile, digital light processing (DLP) has been extensively utilized in the hydrogel printing process due to its high-resolution fabrication capabilities. This study presents an innovative SAW acoustofluidics-assisted DLP system, enabling the patterning of nanoparticles embedded in matrix materials while facilitating programmed light exposure for the controllable photopolymerization of customized hydrogel nanocomposites. Instead of utilizing the acoustic potential field generated by SAWs, we leverage the accompanying electric field due to the piezoelectric effect of the lithium niobate (LiNbO3) substrate to generate electric field, enabling the electric field-driven patterning of multi-walled carbon nanotubes (MWCNTs) Laser Doppler vibrometry confirms the SAW-generated acoustic intensity fields. The analytical simulation together with the scanned data predicted the co-current electric field predicted the distribution of MWCNTs. By applying a programmed light pattern, we successfully fabricated hydrogel nanocomposites in the shape of a VT logo and produced hydrogel nanocomposite sensors. The capabilities of printed hydrogel nanocomposite sensors were demonstrated through beam vibration sensing, proving its potential application in structural health monitoring. The fabricated sensors demonstrated the capability to track finger movements, indicating their potential for wearable sensing applications. In summary, this study offers a unique approach for nanocomposites fabricating multi-material integration and material anisotropy control, thereby facilitating advanced smart material development. Future work will focus on exploring the fabrication of hydrogels containing other types of nanomaterials to enhance material conductivity and achieve other functions, aiming with the goal of developing nanocomposite sensors for applications in soft robotics, biomedicine, structural health monitoring, and wearable sensing. 

This study presents a facile strategy for fabricating chitosan/polyurethane nanoparticle (PU NP) bioplastic films that simultaneously enhance both ductility and strength due to their unique elastic node-grid structure. 

The graphic illustrates how an external acoustic field stabilizes the SEI layer by enhancing lithium-ion mass transfer at slip lines and kinks, reducing pit formation and promoting a more uniform SEI, ultimately improving battery performance. 

Abstract Cell patterning techniques play a pivotal role in the development of three-dimensional (3D) engineered tissues, holding significant promise in regenerative medicine, drug screening, and disease research. Current techniques encompass various mechanisms, such as nanoscale topographic patterning, mechanical loading, chemical coating, 3D inkjet printing, electromagnetic fields, and acoustic waves. In this study, we introduce a unique standing bulk waves-based acoustic cell patterning device designed for constructing anisotropic-engineered glioma tissues containing acoustically patterned human glioblastoma cell U251. Our device features two orthogonal pairs of piezoelectric transducers securely mounted on a customized holder. The energy of standing bulk waves generated from these transducers can be transmitted into the medium in a Petri dish through its bottom wall. Cells in the medium can be directed to the local minima of Gor’kov potential fields and trapped by the resultant acoustic radiation force. Through proof-of-concept experiments, we validate the functionality of our acoustic patterning device and assess the morphology and differentiation of U251 cells within the engineered glioma tissues. Our findings reveal that cells can be arranged in different distributions, such as parallel-line-like and lattice-like patterns. Moreover, the aligned cells exhibit more obvious elongation along the cell alignment orientation compared to the result of a control group. We anticipate that this study will catalyze the advancement in contactless cell patterning technologies within tissue engineering, facilitating the development of engineered tissues for applications in regenerative medicine and disease research. 

Abstract Cellulose nanofibers (NFCs) have emerged as a preferred choice for fabricating nanomaterials with exceptional mechanical properties. At the same time, boron nitride nanotubes (BNNTs) have long been favored in thermal management devices due to their superior thermal conductivity (k). This study uses reverse non-equilibrium molecular dynamics (MD) simulations to investigatekfor a hybrid material based on NFCs and BNNTs. The result is then compared with pure NFC and BNNT-based structures with equivalent total weight content to elucidate how incorporating BNNT fillers enhanceskfor the hybrid system. Furthermore, the fundamental phonon vibration modes responsible for driving thermal transport in NFC-based materials upon incorporating BNNTS are identified by computing the vibrational density of states from the Fourier transform analysis of the averaged mass-weighted velocity autocorrelation function. Additionally, MD simulations demonstrate how both NFCs and BNNTs synergistically improve the constituting hybrid structure’s mechanical properties (e.g. tensile strength and stiffness). The overarching aim is to contribute towards the engineered design of novel functional materials based on nanocellulose that simultaneously improve crucial physical properties pertaining to thermal transport and mechanics.