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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. 

We present a successful discrimination of heparin, FGF-1, and heparin–FGF-1 complexes at a single-molecule level through solid-state nanopores. 

Planar magnetic microswimmers are well-suited for in vivo biomedical applications due to their cost-effective mass production through standard photolithography techniques. The precise control of their motion in diverse environments is a critical aspect of their application. This study demonstrates the control of these swimmers individually and as a swarm, exploring navigation through channels and showcasing their functional capabilities for future biomedical settings. We also introduce the capability of microswimmers for surface motion, complementing their traditional fluid-based propulsion and extending their functionality. Our research reveals that microswimmers with varying magnetization directions exhibit unique trajectory patterns, enabling complex swarm tasks. This study further delves into the behavior of these microswimmers in intricate environments, assessing their adaptability and potential for advanced applications. The findings suggest that these microswimmers could be pivotal in areas such as targeted drug delivery and precision medical procedures, marking significant progress in the biomedical and micro-robotic fields and offering new insights into their control and behavior in diverse environments. 

Transferrin, a central player in iron transport, has been recognized not only for its role in binding iron but also for its interaction with other metals, including titanium. This study employs solid-state nanopores to investigate the binding of titanium ions [Ti(IV)] to transferrin in a single-molecule and label-free manner. We demonstrate the novel application of solid-state nanopores for single-molecule discrimination between apo-transferrin (metal-free) and Ti(IV)-transferrin. Despite their similar sizes, Ti(IV)-transferrin exhibits a reduced current drop, attributed to differences in translocation times and filter characteristics. Single-molecule analysis reveals Ti(IV)-transferrin’s enhanced stability and faster translocations due to its distinct conformational flexibility compared to apo-transferrin. Furthermore, our study showcases solid-state nanopores as real-time monitors of biochemical reactions, tracking the gradual conversion of apo-transferrin to Ti(IV)-transferrin upon the addition of titanium citrate. This work offers insights into Ti(IV) binding to transferrin, promising applications for single-molecule analysis and expanding our comprehension of metal–protein interactions at the molecular level. 

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. 

ABSTRACT Detection of ultra‐short peptides is one of the critical steps toward deeper understanding of proteins and the sequencing of amino acids using solid‐state nanopores. The ability of solid‐state nanopores to detect these ultra‐short peptides can help us reveal their hydrodynamic state under different conditions like the concentrations and the external voltage, which may further guide the future development in this field for deeper investigation and possible improvement. In this study, we fabricate Si_xN_ynanopores by CDB with various pore sizes and use them to detect ultra‐short peptides comprised of five different amino acids. The peptide translocation events are extracted under various external voltages. Optimal experimental conditions such as the concentration of electrolytes and analytes, and the range of external voltage are investigated and compared. The statistical results based on volume exclusion analysis indicate that a significant portion of peptides exist in aggregation form. Due to the limitations of Si_xN_ynanopores such as the thickness and the noise, most of the single peptide signals are masked under the baseline noise. In addition, the results show that peptide–pore interactions are dependent upon the diameter of the nanopore. Higher voltage may also influence the degree of peptide aggregations. This study serves to further comprehend the physical and chemical properties of peptides, find possible ways to improve the performance of solid‐state nanopores in the area of protein and peptide detections, and indicate the potential improvements in solid‐state nanopore‐based peptide sequencing.