Soft magnetic composites for highly deformable actuators by four-dimensional electrohydrodynamic printing

Soft magnetic composites have been orderly deposited using an advanced four-dimensional electrohydrodynamic printing process to build deformable actuators that have favorable attributes in fast response, untethered control, and harmless human-machine interactions under low-strength magnetic fields. To effectively deliver the mag-netic composites ink with a high viscosity, a rotating needle is utilized to induce the microscale Weissenberg effect (MWE) and help ejecting the polymer solution. The magnetic polarities of microparticles in the resulting structure can be controlled via a permanent magnet structure which is designed and added into the printing system. The main process parameters have been investigated for obtaining optimal options of the motor rota-tional speed (2000 rpm), electrostatic field strength (2.0 kV), and the ratio (0.732) of the needle diameter to nozzle diameter. Prototype actuators with different magnetization orientations and profiles have been designed and tested, including magnetically powered electrical switches and bionic soft robots to emulate the operations of inchworms and dragonflies. As such, this printing process offers a facile and effective path to fabricate soft magnetic composites toward potential applications.

Automated summary

The study utilized an advanced printing process to deposit soft magnetic composites in an orderly manner, creating deformable actuators with fast response, untethered control, and harmless human-machine interactions under low-strength magnetic fields. By controlling the magnetic polarities of microparticles and utilizing the microscale Weissenberg effect (MWE) through a rotating needle, the research effectively delivered the high viscosity magnetic composites ink.