Robotic non-contact three-dimensional (3-D) micromanipulation of micro-objects is critical for micro-assembly applications, but achieving high precision and reliable release in the microscale remains challenging. Traditional contact and non-contact techniques face limitations in automated 3-D operation. We present a fully automated micromanipulation system using an acoustic bubble end-effector for non-contact 3-D handling of microbeads. The system integrates real-time vision feedback with Z-axis autofocus and adaptive proportional-integral-derivative control for precise trapping, transport, and release. Leveraging localized bubble-driven microstreaming and acoustic radiation forces, our end-effector forms a stable trap within 100 ms and transports microbeads at speeds up to 1 mm/s. Experiments demonstrate exceptional 3-D dexterity, with trapping success rates consistently greater than 80% for microbeads of 60-120 μm diameter, and release placement accuracy is confirmed to be within ±2.5 μm when operating below a 150 μm height. The system achieves broad size adaptability and operates in free-space 3-D environments, overcoming workspace constraints of microfluidic setups. By eliminating mechanical contact, this approach reduces contamination and damage while delivering precise 3-D control often lacking in other non-contact methods. Our system bridges acoustofluidics and robotic automation, offering a versatile solution for automated micro-assembly and biomedical applications.

Traditional single-cell mechanical characterization techniques (e.g., atomic force microscopy) often face limitations in throughput, require invasive labeling, or fail to replicate physiological microenvironments, impeding their clinical utility for rapid cancer cell analysis. To address these limitations for automated characterization of cellular mechanical properties, this study proposes a novel method using microchannels with narrow geometric structures to measure cellular mechanical characteristics. A dynamic mechanical characterization technique with serially connected microchannels simulates malignant tumor cell deformation and migration in vivo, enabling precise identification of three malignant tumor cell lines and three normal cell lines through consecutive compressions. High-speed imaging combined with computer vision and image processing techniques facilitates rapid and accurate automated analysis for tumor cells. Furthermore, this study reveals that the mechanical properties of the cell nucleus determine the overall cellular mechanics, with the differences between tumor and normal cells attributed to variations in nucleus mechanics. This approach shows promise for early cancer diagnosis.

Micro-nano robots must break the symmetry of the flow field to generate net displacement in the low Reynolds number environment. The spherical micro-robots utilize the frictional forces generated through interaction with the surface. We designed a magnetic microroller robot powered by the rotating AC magnetic field. Here, we employed dual measurements of laser ranging and computer vision to demonstrate that a single 100 μm microroller maintains a lubrication film of 1 to 15 μm with the surface during normal motion. We found that the translational velocity of the microroller is correlated with the lubrication film thickness. Based on the robot's gravity, we controlled an additional downward gradient magnetic field to effectively increase the load of robot and reduce the lubrication film thickness, thereby controllably increasing the translational velocity of the robot. For example, the gradient magnetic field generated by superimposing a 30mA direct current input can reduce the lubrication film thickness from 8 μm to 4 μm in a 10 Hz rotating magnetic field, and increase the translational velocity from 230 μm/s to 460 μm/s. The enhancement of the robot's motion performance enables it to better control its movement in fluids. Finally, we validated the strategy for controllable acceleration of micro-scale particles rolling on surfaces, applied to control fluid motion in multiple arteries within blood vessels. These results offer deeper insights into the physical motion mechanism of surface robots and hold significant implications for future applications in biomedical engineering.

Micromanipulation techniques that can achieve controlled fine operations at the micro scale play an important role in biomedical fields including embryo engineering, gene engineering, drug screening, and cell analysis. However, micromanipulation of biological micro-objects, such as cells and micro tissues, suffers from mechanical damage and low efficiency. Several techniques have been introduced to manipulate cells more easily, but most of them are restricted by expensive devices, limited work area, and potential damage to cellular structure. Here we develop a hydrodynamic manipulation method to rotate and transport mouse oocytes, which utilizes acoustic waves and micropipette to generate acoustic radiation force and excite microstreaming. This method can accomplish rotational and translational operations precisely and controllably. We tested the process of trapping, rotation, and transportation of the mouse oocytes, and measured rotational and translational speed with a range of applied voltage. The method was able to shorten the cost time of delivery and posture adjustment before oocyte injection. Our study provides an easy-to-use technique for oocyte manipulation without contact, and it has the potential to be universally applied in many cellular studies.

In the last decade, researchers have been trying to develop many microrobots that mimic the extraordinary abilities of bionts in complex environments. How to fabricate the biomimetic microrobot with satisfying deformability and complex shapes to realize desired precise motion is the key issue. In this paper, we proposed an efficient programable fabrication method of the magnetic soft micro-robot through an on-chip photopolymerization system. The superparamagnetic nanoparticles were compiled according to the magnetic anisotropy and assembled in the micro-robot. Then these nanoparticles were immobilized by photopolymerization of the hydrogel polymer. With this fabrication method, a joint rotation mechanism was first fabricated to characterize the deformation performance under the magnetic field control. Besides, the snake-like micro-robot were also fabricated, and the desired motions were achieved. The experimental results show that the proposed programable on-chip fabrication of magnetic soft micro-robot has the potential to facilitate the development of magnetic microrobots and their applications in the biomedical field.

Microfluidic devices for cell immobilization have significantly advanced the biological analysis at the single-cell level. However, the previous research on immobilization of multiple single cells, especially with deterministic quantities, is insufficient. In this paper, we proposed a novel microfluidic device based on the passive hydrodynamics and the uniform geometric design principle, which can array different numbers of cells in every capture cavity. The capture cavities could be stretched to accommodate more cells, and the trapping force was adjusted by modifying the related geometric parameters of the inside channel. The whole procedure was monitored and further automatized by integrating computer vision technology under a microscope. On the proposed integrated on-chip platform, we realized full-automated arraying of a single cell, two cells, and three cells on a single chip, achieving success rates up to 95%, 75%, and 72%, respectively. As a primary experimental demonstration, the cell viability test of arraying multiple cells with different quantities showed excellent biocompatibility and no significant association between trapping quantity and cell survivability. We envision that the proposed quantity-controllable, high-efficiency microfluidic devices for multiple cell arraying could be a powerful platform for an in-depth study of cell heterogeneity and cell communication between multiple cells.Note to Practitioners—This article is motivated by the biomedical applications of multi-cell arraying. The designed microfluidic devices employ passive hydrodynamics, and the capture cavities are stretched to accommodate different numbers of cells. The whole arraying procedures are automatized using computer vision technology. Simulations and experiments demonstrate the high efficiency, controllability of the cell quantity, and excellent biocompatibility.