Untethered magnetically actuated soft microrobots are promising for biomedical and industrial tasks, yet their practical deployment remains limited by poor adaptability to heterogeneous environments and insufficient motion controllability. This paper presents a soft magnetic microrobot, termed the Bio-mimetic Mudskipper Bot (BM-bot), inspired by the morphology and crawling mechanism of amphibious mudskippers. The BM-bot consists of a compliant body and a pair of soft-magnetic half-wheel feet, enabling crawling locomotion driven solely by magnetic torque–induced foot rotation without onboard actuation. A vision-based pose estimation framework integrating temporal differencing and adaptive histogram equalization is developed for real-time localization, achieving a mean position error of approximately 0.3 mm across multiple experimental conditions. For motion control, a Stepwise Dynamic Compensation (SDC) strategy is introduced, which decouples local motion execution from global path planning and performs discrete heading corrections based on real-time visual feedback. This control scheme allows the BM-bot to maintain a median trajectory deviation of 0.33 mm during long-duration path-following tasks in dynamic environ-ments. Experimental results demonstrate that the proposed robot and control framework enable stable and repeatable locomotion across diverse terrains, including granular media, soil, shallow water, constrained maze environments, and ex vivo soft and dynamic biological tissues. The presented system provides a practical solution for achieving robust, high-precision locomotion in magnetically actuated soft microrobots under unstructured, compliant, and dynamically changing conditions.

Untethered capsules are capable of entering the gastrointestinal (GI) tract and collecting fluid samples containing microbial communities from specific locations, facilitating the study of chronic diseases. However, existing sampling capsules are designed for single-site sampling, making it challenging to gather samples from multiple targets. This paper reports a magnetic-driven capsule for multiple sampling within the GI tract and an on-demand magnetic-triggered fluid sampling strategy. The capsule consists of a body, a magnetic-triggered negative pressure unit, and a reservoir unit. Composed of an elastic membrane and Magnet I, the negative pressure unit controls pressure change inside the capsule cavity on demand to pump the sample by switching the magnetic field, while the embedded Magnet I also enables real-time magnetic localization for regional targeting and position tracking. The reservoir unit integrates three sampling papers for fluid absorption, two waterproof layers that maintain contamination levels below 25% to ensure reliable multi-site sampling, and a rotating arm embedded with Magnet II for posture adjustment of the sampling paper. The pumping and storage performance of the capsule was systematically evaluated and optimized. Meanwhile, the capsule, actuated by an external magnetic field, was evaluated for its active locomotion performance. Finally, the feasibility of using the capsule to perform active navigation and multi-target sampling in a porcine intestine was validated viaex vivoexperiments.

Magnetic microswarms have attracted significant attention in medical robotics, owing to their potential for performing complex tasks in challenging environments. However, developing microswarms that can operate effectively in both liquid and air environments remains a substantial challenge. This study presents the design and characterization of hydrogel-based microswarms composed of magnetic hydrogel particles prepared from agarose hydrogel and NdFeB magnetic microparticles. These microswarms form stable monolayer structures actuated by rotating magnetic fields at high frequencies (10 Hz) in liquid environments, enabling synchronization with the external magnet and achieving translational motion. Actuated by an oscillating magnetic field, the swarms transition from a monolayer configuration to a three-dimensional (3D) structure in the air environment. Experimental results demonstrate that the 3D swarms are capable of navigating complex terrains and interacting with tissue surfaces in air environments. Finally, we demonstrate the potential of these 3D swarms for targeted delivery and adaptive filling of gastric perforations using an ex vivo gastric tissue model, showcasing their potential for biomedical applications.

Biological machines that use biological cells and soft materials in combination to obtain a sense of the environment driven by bioenergy and generate driving force are called biohybrid actuators. With the development of tissue engineering and organoid technology, researchers have applied biohybrid actuators technology to the research of precision medicine and targeted drug delivery, but the research on feedback and evaluation of biohybrid actuation performance is limited to visual and simulation calculations. Therefore, we hope to develop an intelligent crawling skeleton for sensing function, which can be used to evaluate the actuation ability of muscle actuators, and eventually realize the high-precision control of biohybrid actuators. In this work, an intelligent crawling skeleton based on three-dimensional liquid metal is proposed to detect and feedback the crawling of C2C12 muscle actuators. Three-dimensional muscle tissue was composed of mixing hydrogels and cells, and the functionalization of muscle rings was promoted using static mechanical forces and external electric field stimulation. The composite crawling skeleton is fabricated by inverting mold and soft lithography technology. The skeleton can adapt to large deformations above 90 degrees and is more sensitive to deformations by adjusting materials with different elastic modulus. Inspired by the tendon-bone structure, the intelligent crawling skeleton can obtain the deformation degree of the biohybrid actuator in the crawling process according to the characteristics of the deformation from the muscle tissue, and put forward a good idea for the feedback and closed-loop control of the biohybrid actuators.

This study describes a microfluidics experiment with ready classroom applications, designed to enhance students' understanding of fluid dynamics, controlled mixing, and bubble formation. The materials employed are safe and readily accessible, such as vinegar and baking soda, combined with PDMS microfluidic chips and a high-resolution microscope, to provide real-time observation of gas-liquid interactions. A syringe pump delivers the reactants into a micro-channel through which the fluid flow behavior and bubble formation can be visualized and quantified.(/p)The focus of the experiment is on elucidating the effects of different soda concentrations on bubble generation in a controlled laminar flow. The results show a nonlinear trend between soda concentration and bubble features: lower concentrations produce fewer but larger bubbles, moderate concentrations produce small bubbles more frequently. At 0.2 M, the average bubble area was approximately 389 μm2, and at 0.4 M, there were smaller bubbles but more frequent occurrences. As concentrations increased above 0.6 M, bubbles became more uniform in size and more circular.Flow rates were varied from 3 to 15 μL/min to assess bubble behavior. Most bubbles functioned as wall bubbles in the micro-channel and were not perfectly spherical because of the influence of the local flow field and concentration gradients. The size distribution and circularity of the bubbles were measured using image analysis tools developed in Python.This affordable and visually appealing platform provides an alternative hands-on experience for students to learn the fundamental principles of microfluidics, thereby connecting classroom concepts with real-world observations. The lab activity promotes data analysis, hypothesis testing, and deepening understanding of concepts—skills essential for both academic and applied research.

This work presents a flexible and effective micromixer based on optoelectronic tweezers (OET), which leverages both asymmetric induced-charge electro-osmosis (ICEO) and dielectrophoresis (DEP) phenomena on microscale anisotropic NdFeB particles. The asymmetric ICEO phenomenon is generated by symmetry breaking in the induced charge distributions of geometrically anisotropic NdFeB particles under AC electric field polarization. The DEP forces exerted on NdFeB particles are induced by the light-generated non-uniform electric field. Under the combined action of hydrodynamic forces from asymmetric ICEO vortices and positive DEP forces, NdFeB particles can be attracted into light-induced "virtual" electrodes and precisely track along light-defined trajectories. Experimental results demonstrate that the maximum motion speed of the NdFeB particles exceeds 300 μm/s, with the motion speed exhibiting a positive correlation with the applied voltage. Dynamically controlled virtual electrodes enable accurate capture and relocation of microparticles to arbitrary target positions. The stirring and mixing capability of the NdFeB particles is demonstrated by driving yeast cell motion.

Tactile information is the research hotspot of wearable flexible sensors due to its importance and complexity. With the innovation of wearable technology and robotics in healthcare, researchers are increasingly integrating wearable flexible sensors on the front end of robots to reproduce the hand tactile manipulation of human tissues. Therefore, it is hoped to develop a thin-film sensor that can be deployed in a small area to assist robots in surgery and data collection of human tissues. Here we use a one-step injection method to fabricate a novel composite sensor based on liquid metal. By laminating multiple PDMS microfluidic layers, the two parameters of pressure and deformation are measured simultaneously in a decoupled manner. The sensor is small and thin, making it easy to integrate into fingers/robot fingers for assistance. The finger/robot finger exerts pressure on the sensor and the sensor deforms with the material to identify the hardness of the material being touched. Separate performance tests of the two sensors show that the strain and pressure functions are decoupled from each other, and their ratios can identify and classify the hardness of different touched materials (glass, PDMS and silicone). This novel composite sensor we proposed can assist robots in manipulating human tissues during medical surgeries. At the same time, its function in tactile information feedback also has broad applications in medical treatment, rehabilitation and services.

This article reports an automated optically-induced dielectrophoresis (ODEP) system for characterizing the specific membrane capacitance (SMC) of individual cells. The simulation of cell motion is conducted to analyze the electrokinetic forces acting on the cell. A self-developed visual tracking algorithm for multicells is used to realize an automated process for determining the frequency-sweeping range, crossover frequencies, and cell radii. The SMC values of malignant bladder cancer cells (T24 and RT4) and normal urothelial cells (SV-HUC-1) were quantified using the automated system, demonstrating that the system has a measurement speed of ~1 cell/s, an accuracy of 1 kHz for the crossover frequency determination, and an accuracy of 0.2 μm for the cell radius measurement.

To improve the mobility of locomotive devices on loose, sandy terrain, protrusions or convex patterns called lugs (i.e., grousers) are attached to the surface of a locomotive modulus. Following our previous study, in which the effects of angular speed, lug sinkage length, and soil cumulative deformation on lug-soil interaction forces during the fixed-axis rotational motion were experimentally confirmed, this study proposed an approximation equation to formulize the relationship among the normal force, lug sinkage length, and lug rotational angle. Moreover, the measured tangential force is compared with values calculated from a conventional tangential force model for discussing its accuracy of predicting the tangential force. Conclusions from this study present the fundamental principles for understanding the lug-soil interaction mechanics for a lug that is performing arbitrary planar motion on sandy terrain.