Design and fabrication of a soft micro-actuator based on distributed magnetic composite

Benefit from the development of micro/nano manufacturing and flexible electronics technology, soft micro-actuators which could be potentially applied in drug delivering and environment monitoring have developed rapidly in recent years. Due to the simplicity of fabrication process and flexibility of control strategies, magnetic-controlled soft actuators based on magnetic-responsive composites have attracted intensive interests. In literature, lots of works focus on the structure and manufacturing process of the micro-actuators in order to enhance their driving performance. However, as fully soft micro-actuators, the driving efficiency of the soft parts is comparatively low, and the stability is poor in a liquid environment. In this work, a micro-actuator combined with rigid and flexible parts was presented to improve the driving force as well as the stability. We proposed a method of using substrates with higher stiffness to manufacture the nonuniform stiffness composites. The magnetic unit is made of magnetic particles mixed with rigid substrate, and then embedded in or connected with the flexible body. Following this strategy, the rigid sections take responsible for quick magnetic response while the soft area have desired deformation performance. Firstly, the magnetic response of magnetic composite made of epoxy resin was analyzed. Then, hysteresis loop test was deployed to investigate the effect of magnetic particle concentration on magnetic properties. Furthermore, the deformation of the composite actuator is analyzed by simulation with respect to the different positions and quantity of the rigid parts. Finally, the fabricated soft micro-actuator is controlled by external magnetic field to demonstrate the potential applications. It was believed that the combination of rigid and flexible components in micro electro mechanical system is beneficial to improve the driving ability and broaden the application range of micro actuators.