Magnetic microrobots can be miniaturized to a nanometric scale owing to their wireless actuation, thereby rendering them ideal for numerous biomedical applications. As a result, nowadays, there exist several mechano‐electromagnetic systems for their actuation. However, magnetic actuation is not sufficient for implementation in biomedical applications, and further functionalities such as imaging and heating are required. This study proposes a multimodal electromagnetic system comprised of three pairs of Helmholtz coils, a pair of Maxwell coils, and a high‐frequency solenoid to realize multimodal locomotion and heating control of magnetic microrobots. The system produces different configurations of magnetic fields that can generate magnetic forces and torques for the multimodal locomotion of magnetic microrobots, as well as generate magnetic traps that can control the locomotion of magnetic swarms. Furthermore, these magnetic fields are employed to control the magnetization of magnetic nanoparticles, affecting their magnetic relaxation mechanisms and diminishing their thermal properties. Thus, the system enables the control of the temperature increase of soft‐magnetic materials and selective heating of magnetic microrobots at different positions, while suppressing the heating properties of magnetic nanoparticles located at undesired areas.

Magnetic microrobots are propelled by magnetic fields or magnetic field gradients generated by electromagnetic systems. Generally, 3D Helmholtz coils systems are used for microrobot propulsion, because of their low power consumption, ease of manufacture, and ease of control, for which, only three power supplies are required. Systems of this kind can only generate uniform magnetic fields, which limits their range of applications. However, generating both uniform magnetic fields and gradients typically requires more coils and power supplies, resulting in large expensive energy-intensive systems with complicated control algorithms. Although the aforementioned systems can control magnetic robots with up to 6 degrees of freedom (DOFs), most existing applications at the micro/nanoscale only require 2 rotational DOFs and 1 translational DOF. Here, we propose a new control system capable of producing 3D uniform magnetic fields with 3 DOFs and 3D gradients with 1 DOF. With this system, one pair of coils in a traditional 3D Helmholtz coil system is modified, to enable independent control of the individual coils directing a selected axis, while the configuration of the remaining two pairs of coils is unchanged. This results in a control system with low power consumption, and a simple control algorithm that can be easily applied to existing 3D Helmholtz systems, as it only requires the addition of a power supply. In combination with the developed system, we also propose a new control algorithm applicable to both permanently and temporarily magnetized microrobots, and verify this experimentally.

Three-dimensional (3D) printer-based self-healing capsules, embedded in cement composites, were proposed to heal cracks, as they allow for various structural designs of capsules, repeatable fabrication, and strength analysis. Out of many 3D printing methods, such as fusion deposition modeling (FDM), powder layer fusion, and PolyJet printing, FDM was used to design, analyze, and produce new self-healing capsules, which are widely used due to their high-speed, low-cost, and precise manufacturing. However, the PLA extruded in the FDM had low adhesion energy between stacked layers, which caused a degradation of the performance of the self-healing capsule, because it had different strengths depending on the angle between the stacked layers and the applied load within the concrete structure. Therefore, in this paper, specimens were produced, in accordance with ASTM specifications, using the FDM PLA method, and mechanical properties were obtained through tensile, shear, and compression tests. Additionally, the isotropic fracture characteristics of the four types of capsules were analyzed through finite element method analysis. Subsequently, the 3D-printed capsules were produced, and the fracture strength was analyzed in the x, y and z directions of the applied load through a compression test. As a result, the newly proposed capsule design was verified to have an isotropic fracture strength value of 1400% in all directions compared to conventional spherical thin film capsules

As contaminated water increases due to environmental pollution, the need for excellent water treatment is increased, and several studies have reported the polyvinylidene fluoride (PVDF)-based water treatment membranes. However, the PVDF membrane has several problems such as low filtration performance, fouling resistance, and difficulty in precisely controlling the morphology of the pores and hydrophilicity. Therefore, we newly produced a water treatment PVDF membrane containing graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) to improve the filtration performance. Surface properties of the fabricated membrane such as morphology, and size of pores, hydrophilicity, and water flux of the membrane were investigated. Additionally, the performance of these membrane filters was evaluated for free residual chlorine, turbidity, chromaticity, magnesium, sulfate, and particulates class 1 according to drinking water management act criteria, respectively. A performance improvement of at least 108.37% was observed compared to the Pure PVDF filter module and anti-fouling effects due to the functional groups of GO and MWCNTs. These results reveal that proposed membrane can accelerate the development of various water filtration applications.

Recently, several fluidlike, shape‐adaptable magnetic microrobots have been developed to overcome the drawbacks posed by the rigid structure of traditional magnetic microrobots. However, most of their control systems rely on permanent magnet‐based systems, which are unfeasible for large‐scale environments, such as in vivo applications. Herein, an electromagnetic system comprising orthogonal pairs of coils is used to generate global magnetic fields, that is, magnetic fields that are applied equally to large volumes, for the multimodal locomotion of ferrofluidic robots composed of magnetic micro‐/nanoparticles. Three main magnetic field configurations, with their respective locomotion mechanisms, are explored: uniform rotating fields for droplet fission–fusion motions and locomotion; magnetic trapping point‐based locomotion for single‐ and collective‐droplet manipulation; and field‐free region‐based dragging locomotion and selective droplet control. The effectiveness of the proposed multimodal locomotion mechanisms and potential applications are experimentally demonstrated in minichannels through selective mixing, targeted delivery, and optimized magnetic heating applications. These locomotion mechanisms using global fields enable the use of fluidlike magnetic microrobots in large‐volume applications.