ShrinkCells: Localized and Sequential Shape-Changing Actuation of 3D-Printed Objects via Selective Heating

The unique behaviors of thermoplastic polymers enable shape-changing interfaces made of 3D printed objects that do not require complex electronics integration. While existing techniques rely on external trigger, such as heat, applied globally on a 3D printed object initiating all at once the shape-changing response (e.g., hot water, heat gun, oven), independent control of multiple parts of the object becomes nearly impossible. We introduce ShrinkCells, a set of shape-changing actuators that enables localized heat to shrink or bend, through combining the properties of two materials — conductive PLA is used to generate localized heat which selectively triggers the shrinking of a Shape Memory Polymer. The unique benefit of ShrinkCells is their capability of triggering simultaneous or sequential shape transformations for different geometries using a single power supply. This results in 3D printed rigid structures that actuate in sequence, avoiding self-collisions when unfolding. We contribute to the body of literature on 4D fabrication by a systematic investigation of selective heating with two different materials, the design and evaluation of the ShrinkCells shape-changing primitives, and applications demonstrating the usage of these actuators.