Locally Bendable Stimuli-Responsive Hydrogel Actuator with Axially Patterned Functional Materials

This paper describes a locally bendable stimuli-responsive hydrogel actuator with axially patterned functional materials fabricated by a valve-controlled microfluidic device. By application of an external stimuli to the complete actuator, it can be locally bended owing to the axial pattern of the responsive and non-responsive material. These materials are axially patterned on a microfiber through the Y-shaped channel coupled with the open/close motion of the valves in the microfluidic device. The microfluidic device can regulate the on/off of the flow by thin membrane pneumatic valves controlled by a computer. The patterning frequency of the two materials in the microfiber could be adjusted by modifying the switching intervals of the solutions. Also, we successfully demonstrated the curvature-change through heating and cooling. We believe that this locally bendable stimuli-responsive hydrogel could contribute to microfiber-shaped soft actuators, biomedical sensors, and self-assembly of complex 3D microstructures.