Noncontact manipulation of soft micro-fibers has great potential in advanced manufacturing, materials science, and biomedical engineering. However, current noncontact manipulation techniques primarily focus on objects with regular shapes, e.g., solid particles, cells, or droplets, with fewer solutions available for manipulating flexible and elongated structures. In this paper, an automated ultrasonic manipulation system is introduced for in-plane soft micro-fiber manipulation, which mainly consists of an ultrasonic transducer array and a microscope. A real-time trap generation algorithm is designed to manipulate the micro-fibers by the visual feedback from microscope. An adequate theoretical analysis is also provided for explanation of the deformation behavior of micro-fiber under external forces. The system is capable of precise in-plane positioning and motion trajectory planning to micro-fiber end, and in-plane morphological reshaping to the micro-fiber. Experiments validated the effectiveness of the proposed system for the in-plane manipulation of soft micro-fibers. Finally, the system was showcased by the practical application of material property characterization.

Noncontact trapping of micro objects has great application potential in fields like material science and biomedical engineering due to its label-freeness and biocompatibility. In this paper, an automated acoustic micro-particle trapping system implemented with phased transducer array (PTA) is prototyped. The system is incorporated with a stereo vision to provide visual feedback benefited from localization of the invisible acoustic field through hydrophone scanning. Binocular vision calibration and stereo matching are realized using image Jacobian matrix. An efficient phase modulation algorithm is proposed for the calculation of desired PTA phase profile in real-time and a spatiotemporal multiplexing control strategy is adopted to dynamically generate multiple trappings. Experimental results well demonstrated that the stable trapping of multiple particles can be robustly realized by the system, leading to the improvements of robotic noncontact manipulation with invisible acoustic end-effector. Note to Practitioners—This paper is motivated by the problem that previous classic acoustic trapping was achieved as a physical phenomenon that particles within the trapping zone would be automatically trapped and thus required people to place the particle into the invisible trapping zone, which is neither precision nor efficient. Such problem is a crucial factor that limits acoustic tweezer to be further readily usable in bioengineering, surface manufacturing, and quantitative micromechanical characterization. In this work, automated acoustic trapping is presented in the context of robotics, as grasping task in conventional industrial robots, that can generate the acoustic trap exactly in the location where particles are detected (by microscopic vision, or micro-CT or acoustic imaging, etc.). This paper proposes a full pipeline to automatically trap multiple particles using ultrasonic transducer array and binocular microscopic vision. The experiments verified the ability of proposed method in simultaneously trapping three micro particles with opposite acoustic properties. Such trapping method is the foundational technology for further acoustic manipulation such as arraying and sorting, which will be the tasks in our future work.

The noncontact acoustic manipulation of particles, biosamples, droplets, and air bubbles has emerged as a promising technology in the fields of biology, chemistry, medicine, etc. The noncontact nature offers significant advantages in terms of biocompatibility, contamination free, and material versatility. However, current noncontact acoustic manipulation techniques still lack adequate selectivity, robustness, and precision controllability in complex environments. To this end, in this article, we propose an automated noncontact manipulation system that leverages a high-density ultrasonic phased transducer array in combination with a microscope to further optimize and enhance the controllability and flexibility of noncontact particle manipulation. This work presents several notable contributions. First, we successfully realized selective particle manipulation, allowing instantaneous interaction with users to perform user-designated and objective-oriented manipulation tasks. Second, we integrated a closed-loop control strategy into the system that effectively mitigates misalignment errors induced by the trapping stiffness heterogeneity of acoustic trap and enables automated precision position control of particles in complex environments (in 30-mm-wide workspace, positioning precision is 1/40 of the wavelength). Third, we proposed a reconfigurable acoustic trap design method, named pseudovortex trap, featuring real-time computing and trapping particles larger than the wavelength. The system setup, the calibration specifics, the acoustic trap design methodology, and the corresponding visual servo control scheme (in terms of selective trapping, precision positioning, and dynamic trajectory planning) are given in detail in the article. Meanwhile, the trapping stiffness and the manipulation stability are also analyzed in this work. Experimental results well demonstrated the effectiveness of the proposed system.

Non-contact particle cluster manipulation holds significant promise in the realms of advanced manufacturing, chemistry, and pharmacy. However, achieving precise and dynamic control over the spatial kinematics of particle clusters remains a significant challenge, necessitating real-time and accurately programmable robotic end-effector. To this end, we develop an innovative non-contact, precise particle cluster manipulation system with ultrasonic phased array transducer (PAT) under microscope. This system combines a physics-based deep learning algorithm for real-time calculation of phase-only holograms (POHs), supporting PAT to dynamically form acoustic fields, namely holographic acoustic end-effector (HAE). Leveraging the dynamically and accurately generated HAEs by our system, kinematics control of particle clusters including aggregation, rotation, and translation is yielded. The extensive experiments well demonstrated the effectiveness of proposed system for particle cluster manipulation.

The pursuit of 3D reconstruction from 2D images for nanomanipulation under scanning electron microscopy stands as a critical research endeavor. Previous methods either necessitates additional lighting which is difficult in standard SEM devices or relies on feature matching with low resolution and precision, further constraining reconstruction performance. In this paper, we propose a novel robot-assisted nanoscale 360° reconstruction approach, which simplifies SEM setups and maximizes the utilization of robot motion and feedback. By harnessing a nanorobotic system, we capture 360°multi-view images automatically with precise mapping information and camera postures. Sequentially, neural radiance field reconstruct the pixel-wise structure and synthesizing images from diverse perspectives. Experimental results using two real datasets demonstrates our approach’s efficacy, achieving PSNR of 28.1 and SSIM of 0.93 for nanotube reconstruction, and PSNR of 32.8 and SSIM of 0.98 for AFM cantilever reconstruction. These results validate the reliability and robustness of our proposed robot-assisted reconstruction method.

Acoustic holography has emerged as a cutting-edge technique for constructing a micro-robot acoustic end-effector for non-contact manipulation. As one of typical implementations of acoustic holography, Binary Amplitude-Only Hologram (BAOH) featured with a simple structure provides an efficient alternative for modulating acoustic fields that support micro-robotic manipulation. In the present study, we propose a deep learning based BAOH generation method for constructing precise and high-resolution end-effector based on acoustic field. Specifically, we model the BAOH generation problem into an optimization framework. The framework combines an acoustic wave propagation model with the deep neural network, in favor of bypassing the laborious collection of labeled data and facilitating the model to learn the inverse mapping. Additionally, to address the issues of gradient invalidation and information loss caused by binarization, the framework uses an adaptive binarization layer consisting of differentiable binarization and adaptive threshold automatically learned during training, which facilitates to realize end-to-end optimization and increase the non-linear capacity of the model. The simulation experiments show that the proposed method is capable to predict BAOH that supports precise, robust, versatile and real-time construction of acoustic end-effector, enjoying broad prospects in various applications related to micro-robotic manipulation.

Acoustic holography (AH) is a promising technique for precise noncontact micro-nano robotic manipulation. It encodes a three-dimensional (3D) acoustic field acting as a virtual end-effector into a two-dimensional (2D) hologram, whereby the desired acoustic field reconstruction is made possible. Most traditional methods to implement AH, such as 3D printed holographic lens and phased array of transducers (PAT), have limitations of dynamic and dexterous manipulation. Furthermore, existing iterative optimization algorithms to calculate 2D holograms have inadequate accuracy and real-time performance. To address these issues, this paper proposes a physics-based deep learning method with a novel training framework for phase-only hologram (POH) calculation enabling further pushing forward the PAT-based AH for noncontact robotic manipulation. By implementing independent control of each channel on PAT referring real-time calculated POH by a well-trained network, the desired acoustic field can be reconstructed in real-time with high fidelity. The results both on a simulated dataset and a real dataset demonstrate that our method supports accurate and dynamic reconstruction of desired acoustic field with distinct morphologies, with an average reconstruction error of 0.085 and average POH computing time of 47 milliseconds on GPU. Indeed, this work shows the future potential of AH in the field of noninvasive medical therapy, exogenous material delivery, and miniaturized industrial assembly.Note to Practitioners—This paper addresses the challenge of noncontact micro-nano robotic manipulation by PAT-based AH, an intriguing technique in bioengineering, micro-assembly, and material characterization. However, existing approaches have limited precision and real-time performance. To overcome these limitations, this paper proposes a physics-based deep learning method with a novel training framework. Our method achieves excellent accuracy and real-time performance, enabling efficient reconstruction of various complicated acoustic field morphologies for precise and dynamic acoustic manipulation. Experimental results demonstrate its high manipulation flexibility due to the independent modulation of each channel of PAT and real-time precise control due to the ultrafast calculation of the proposed deep learning method, though the method has not yet been deployed into an acoustic manipulation system and tested in practice. Future research will focus on designing physical experiments for further evaluation. Overall, the proposed method provides a novel and promising basis for desired acoustic field generation.

Noncontact particle manipulation (NPM) shows great application potential than its conventional counterpart particularly in terms of non-invasiveness, and thus has significantly extended robotic manipulation capacity into bio- medical engineering, material science, etc. As NPM by means of electric, magnetic, and optical field has successfully demonstrated powerful strength in both academia and industry, NPM boosted by acoustic field, however, still faces staggering challenges. It is indeed in the very recent years that controllable dynamic airborne or waterborne acoustic field modulation technology emerged in academia. In this paper, we report our latest research regarding dexterous and dynamic noncontact micro-particle manipulation on water surface effected by acoustic field in terms of automated trapping, closed-loop positioning, and real-time motion planning, which can be applied to scenarios such as parallel 3D printing, cell assembly, etc. The main contribution of this work is we demonstrated the feasibility of objective-oriented and fully automated acoustic manipulation of micro-particle in precision scale based on robotic approach in 2D plane. Experiment results showed that the repetitive positioning accuracy can reach as high as 16 μm, which is essentially the pixel scale factor.