An actuator is a device that converts chemical into kinetic energy. It has been used in industry, medicine, and various other fields. In this study, we focused on the use of conductive fibers as actuator elements. By using fiber-shaped materials as actuators, we can expect three-dimensional driving compared with conventional two-dimensional fiber materials and suggest the novel utilization of conductive fibers. Therefore, we evaluated the driving behavior by applying electric potential using various conductive fibers. The conductive fibers which used in this study have already been commercialized and used in various fields. We evaluated the driving behavior when an electric potential was applied to the conductive fibers with different electric resistivity. The driving behavior of a floating fiber with a length of 1 mm was evaluated when alternating current was applied at both fiber ends. As a result, it was confirmed that the fibers with high conductivities were driven. In particular, stainless-steel fibers exhibited the best driving behavior. In addition, the characteristics of driving behavior improvement was correlated with frequency up to 5 Hz. Even after 24 h of continuous operation, 60% of the driving behavior stability was maintained. These driving patterns are considered to be based on the thermal expansion and contraction based on the Joule heating generated by the applied electric potential.

Transfer process such as nanoimprinting is effective for fabricating micro/nano structures over a large area. Releasability of nanoimprint molds is improved by the inclination of its side walls. In this study, we focused on the shape of the resist sidewall, which is the template of the mold, and tried to control the inclination of the sidewall by modifying the scanning method of the electron beam in electron beam lithography. By using the proposed method, inclination angles of 86.1~95.8° were successfully fabricated. It was also shown that this result was due to electron scattering and inhomogeneity of the dose amount.

To evaluate the mechanical output of small fish driven mechanisms, floating rotors have been designed and fabricated. So far, most of the micro mechanisms are driven by the collisions of microorganisms stimulated by phototaxis, this research focused on collisions of the predatory behavior of small fish for the larger power generation, compared with those of plankton driven. Two types of rotary actuator floats have been proposed according to the floating or sinking nature of the food. The asymmetry of the feeding to the fish is incorporated so that it rotates the float only in specific direction. Floats are fabricated by a 3D printer with a UV-cure resin, and Styrofoam has been added to increase the buoyancy. Experiments are tried using 16 adult fish, resulting in a intermittent rotation during feeding. A maximum rotation speed of 1.08 rpm for the rotor designed for sinking food and 3.06 rpm for floating food with an instantaneous torque of 0.127 mN·m. A mechanical power of 0.127 mW, which is approximately 10³ times lager compared to the plankton-driven mechanism, has been obtained.