Capacitor Integrated Magnetic Actuator

In robotics, especially in soft robotics with electronic devices such as motors, light emitting diodes (LEDs) and sensors, a stable power supply is one of the major concerns to operate their components properly. For the remote control and simple body structure without tethering to outer signal/power line, integration of the power source such as battery or capacitor is an unavoidable option. Although there are several types of substitutes such as thermal-, optical-, and hygro-energy based systems, it is obvious that electric energy is still used as major power source.<br/>Most of electronic systems rely on batteries for their power supply and many of electronic energy harvesting systems require batteries for stable energy storage and supply. Accordingly, researches on materials and manufacturing methods related to power sources have been actively conducted, and they led remarkable improvement of the energy efficiency and electrochemical properties related to safety and stability. Conventional-shaped power sources, however, is limitation in design of electronic devices because they have to secure specific space and geometry for the deployment of power sources. For the reason, developing advanced power sources with various form factor has been encouraged for scalability, design diversity, shape compatibility, and so on.<br/>There were several approaches to promise form factor-free power sources in printable power sources or smart materials combined power sources. Although they showed high flexibility and responsibility to external stimuli compared to previous rigid counterparts, it was still a challenge to integrate them into complex surface or 3D structure, and an additional actuator was required to be fabricated and attached for actuation. To address this limitation, we fabricated a capacitor-integrated magnetic actuator having monolithic structure by combining flexible capacitor as a power source and soft magnetic actuator as driving parts. We used neodymium-based magnetic particle to compose an active material of capacitor to assign magnetically responsibility. Mask-based printing technique makes it possible to fabricate several capacitors having seamless pattern on a single substrate at once. The pattern of the capacitors is created from linear shape to origami pattern for 3D structure, and it is designed for series connection, parallel connection, or hybrid connection between each capacitor. Furthermore, not only by pre-patterning of capacitor, but also by magnetic actuation on the designed electronic circuit, we can control the state of connection of the capacitors to certain circuit as a switch, for example, on and off control and changing connection state from series to parallel.<br/>Finally, we built a firefly-shaped robot to demonstrate a LED lighting control using magnetic actuation. We installed a LED for lighting in the tail of the 3D printed firefly-shaped body and, on the shoulder, origami patterned capacitor-integrated magnetic actuator which was designed as a pair of wings. Wings were connected parallelly and each of them composed of serially connected 3 capacitors. According to on and off of the external magnetic field, origami patterned wings were folded and stretched. When the wing was folded by applied magnetic field, the tab from the electrode of the capacitor connected to the electric circuit, and then a LED is turned on. Conversely, the LED is turned off when the wing is stretched.<br/>Here, we suggest a new approach to fabricate power suppliable actuator having monolithic structure. We demonstrated several capacitor-integrated magnetic actuators by leveraging power source with magnetic functionality. Our fabrication methods provide the way to design power source having different energy level related to series/parallel connection as well as shape-morphing properties.