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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. 

The development of fibrous actuators with diverse actuation modes is expected to accelerate progress in active textiles, robotics, wearable electronics, and haptics. Despite the advances in responsive polymer-based actuating fibers, the available actuation modes are limited by the exclusive reliance of current technologies on thermotropic contraction along the fiber axis. To address this gap, the present study describes a reversible and spontaneous thermotropic elongation (~30%) in liquid crystal elastomer fibers produced via ultraviolet-assisted melt spinning. This elongation arises from the orthogonal alignment of smectogenic mesogens relative to the fiber axis, which contrasts the parallel alignment typically observed in nematic liquid crystal elastomer fibers and is achieved through mesophase control during extrusion. The fibers exhibiting thermotropic elongation enable active textiles increase pore size in response to temperature increase. The integration of contracting and elongating fibers within a single textile enables spatially distinct actuation, paving the way for innovations in smart clothing and fiber/textile actuators.