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Abstract Planar magnetic microswimmers offer substantial potential for in vivo biomedical applications, owing to their efficient mass production via photolithography. In this study, we demonstrate the effective control of these microswimmers using an open-loop approach in environments with minimal external disturbances. We investigate their surface motion characteristics through both theoretical modeling and experimental testing under varying magnetic field strengths and rotation frequencies, identifying regions of stable and unstable motion. Additionally, we analyze how field frequency and strength influence surface motion speed and identify the frequencies that promote stability. Open-loop control of surface motion in fluid environments and swimming in channels is also demonstrated, highlighting the operational flexibility of these microswimmers. We further demonstrate swarm motion for both swimming and surface operations, exhibiting larger-scale coordination. Our findings emphasize their potential for future applications in biomedical engineering and microrobotics, marking a step forward in the development of microscale robotic systems. 

Microrobots powered by an external magnetic field could be used for sophisticated medical applications such as cell treatment, micromanipulation, and noninvasive surgery inside the body. Untethered microrobot applications can benefit from haptic technology and telecommunication, enabling telemedical micro-manipulation. Users can manipulate the microrobots with haptic feedback by interacting with the robot operating system remotely in such applications. Artificially created haptic forces based on wirelessly transmitted data and model-based guidance can aid human operators with haptic sensations while manipulating microrobots. The system presented here includes a haptic device and a magnetic tweezer system linked together using a network-based teleoperation method with motion models in fluids. The magnetic microrobots can be controlled remotely, and the haptic interactions with the remote environment can be felt in real time. A time-domain passivity controller is applied to overcome network delay and ensure stability of communication. This study develops and tests a motion model for microrobots and evaluates two image-based 3D tracking algorithms to improve tracking accuracy in various Newtonian fluids. Additionally, it demonstrates that microrobots can group together to transport multiple larger objects, move through microfluidic channels for detailed tasks, and use a novel method for disassembly, greatly expanding their range of use in microscale operations. Remote medical treatment in multiple locations, remote delivery of medication without the need for physical penetration of the skin, and remotely controlled cell manipulations are some of the possible uses of the proposed technology. 

Planar magnetic microswimmers bear great potential for in vivo biomedical applications as they can be mass‐produced at minimal costs using standard photolithography techniques. Therefore, it is central to understand how to control their motion. This study examines the propulsion of planar V‐shaped microswimmers in an aqueous solution powered by a conically rotating magnetic field and compares the experimental results with theory. Propulsion is investigated upon altering the cone angle of the driving field. It is shown that a V‐shaped microswimmer magnetized along its symmetry axis exhibits unidirectional in‐sync propulsion with a constant (frequency‐independent) velocity in a limited band of actuation frequencies. It is also demonstrated that the motion of individual and multiple in‐plane magnetized planar microswimmers in a conically rotating field can be efficiently controlled. 

This study investigates the motion characteristics of soft alginate microrobots in complex fluidic environments utilizing wireless magnetic fields for actuation. The aim is to explore the diverse motion modes that arise due to shear forces in viscoelastic fluids by employing snowman-shaped microrobots. Polyacrylamide (PAA), a water-soluble polymer, is used to create a dynamic environment with non-Newtonian fluid properties. Microrobots are fabricated via an extrusion-based microcentrifugal droplet method, successfully demonstrating the feasibility of both wiggling and tumbling motions. Specifically, the wiggling motion primarily results from the interplay between the viscoelastic fluid environment and the microrobots’ non-uniform magnetization. Furthermore, it is discovered that the viscoelasticity properties of the fluid influence the motion behavior of the microrobots, leading to non-uniform behavior in complex environments for microrobot swarms. Through velocity analysis, valuable insights into the relationship between applied magnetic fields and motion characteristics are obtained, facilitating a more realistic understanding of surface locomotion for targeted drug delivery purposes while accounting for swarm dynamics and non-uniform behavior. 

This paper demonstrates a manipulation of snowman-shaped soft microrobots under a uniform rotating magnetic field. Each microsnowman robot consists of two biocompatible alginate microspheres with embedded magnetic nanoparticles. The soft microsnowmen were fabricated using a microfluidic device by following a centrifuge-based microfluidic droplet method. Under a uniform rotating magnetic field, the microsnowmen were rolled on the substrate surface, and the velocity response for increasing magnetic field frequencies was analyzed. Then, a microsnowman was rolled to follow different paths, which demonstrated directional controllability of the microrobot. Moreover, swarms of microsnowmen and single alginate microrobots were manipulated under the rotating magnetic field, and their velocity responses were analyzed for comparison.