Magnetic manipulation is very promising for the motion control of micro- and nano-objects, which has wide applications in the mixing, trapping, colloidal assembly and object transport, and the recent progress in these areas is reviewed in this work.

Untethered capsules hold clinical potential for the diagnosis and treatment of gastrointestinal diseases. Although considerable progress has been achieved recently in this field, the constraints imposed by the narrow spatial structure of the capsule and complex gastrointestinal tract environment cause many open-ended problems, such as poor active motion and limited medical functions. In this work, we describe the development of small-scale magnetically driven capsules with a distinct magnetic soft valve made of dual-layer ferromagnetic soft composite films. A core technological advancement achieved is the flexible opening and closing of the magnetic soft valve by using the competitive interactions between magnetic gradient force and magnetic torque, laying the foundation for the functional integration of both drug release and sampling. Meanwhile, we propose a magnetic actuation strategy based on multi-frequency response control and demonstrate that it can achieve effective decoupled regulation of the capsule’s global motion and local responses. Finally, through a comprehensive approach encompassing ideal models, animal ex vivo models, and in vivo assessment, we demonstrate the versatility of the developed magnetic capsules and their multiple potential applications in the biomedical field, such as targeted drug delivery and sampling, selective dual-drug release, and light/thermal-assisted therapy.

A simple active microfluidic mixing system based on magnetic actuation strategy of fluids in the microchannel under a hybrid gradient magnetic field was proposed. The hybrid magnetic field, combined of a static gradient magnetic field and an external AC uniform magnetic field, is specially designed to generate periodic magnetic body forces acting on the mixed fluids. Two-dimensional numerical simulation has been performed to investigate the mixing behavior caused by the interactions of magnetic field, fluid flow and convection-diffusion. Numerical results show that the proposed mixer system achieved up to 97% mixing of the two fluids with a small current flowing in micromagnets.

At present, the cylindrical coil is used to generate the electromagnetic force in electromagnetic tube expansion process. The obtained radial electromagnetic force in the end of the tube is less than the one in the middle of the tube for the end effects. Hence, the tube deformation is inhomogeneous in the axial direction. This paper presents a method named electromagnetic tube expansion with a concave coil to obtain more homogeneous deformation. By using COMSOL software, it gives the simulations for the effect of the geometry parameters of the concave coil on the distribution of the radial electromagnetic force and deformation behavior for the given AA6063-T6 tube. Simulations show that the concave coil with suitable parameters can obtain the homogeneous deformation. Furthermore, the homogeneous deformation range obtained by the concave coil is 36 mm which is better than the obtained range by the cylindrical coil.

The 65 T pulsed magnetic field with 10 ms flat-top has been achieved at the Wuhan National High Magnetic Field Center (WHMFC). This is an upgrade based on the 41 T with 6 ms flat-top system. Both the magnet and the coupling transformer were newly designed and fabricated. The magnet circuit and the auxiliary circuit were driven by ten and two 1 MJ capacitor bank modules, respectively. At the voltage of 19.1 kV for the magnet circuit and 8.5 kV for the auxiliary circuit, peak field of 64 T with 10 ms flat-top and 0.3% flatness was obtained. The primary specific heat measurement of sample CeRhln5 was successfully performed.