Effect of Fumed Silica Nanoparticles on the Performance of Magnetically Active Inks and DIW Printing

Magnetically active soft materials (MASMs) demonstrate considerable potential for applications in sensors, biomedicines, and bionic and soft robotics. However, owing to the low viscosity of unmodified MASMs with weak molding stacking ability, these materials cannot be printed directly, making the fabrication of MASMs with complex structures. A modified MASM printing ink and its preparation method are proposed for the problem of material and printing process of MASM 3D, and the effects of fumed silica nanoparticles as the modifier on the rheological and mechanical properties of MASM ink were experimentally analyzed. A direct ink writing (DIW) three-dimensional (3D) printing process using MASM printing inks was also proposed. To obtain a highly accurate and stable printing process, the influence of process parameters such as printing speed, nozzle diameter, printing air pressure, and ink viscosity on the ink line width was analyzed. The experimental results show that the MASM objects with different characteristics and structures can be printed stably and with high accuracy, reflecting the feasibility of the proposed MASM ink and DIW 3D printing process. To further validate the characteristics of the DIW 3D-printed MASM objects, a MASM gripper was fabricated using the prepared MASM ink with DIW 3D printing. The magnetization-programmed MASM gripper exhibited excellent magnetic response and excellent gripping and shape-adaptation capabilities. The gripping force was ∼294 mN. Under the driving magnetic field of 270 mT, the gripping force can be more than 1765% of the weight of the gripper (1.7 g). The results of this study show that the proposed MASM printing ink with the DIW 3D printing process can be used for various applications with high performance.