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This paper presents a method for 3D printing self-folding robots from flat conductive PLA sheets, using routed elastic bands for actuation and integrated functional modules like capacitive touch sensors and Hall effect sensors. A closed-form folding model is derived to predict equilibrium fold angles based on hinge stiffness and elastic band moment, validated experimentally to create a design map. The approach enables the creation of modular robots, deployable grippers, and tendon-driven fingers with integrated actuation and sensing, all from a single 3D printing process.
Forget complex assembly: this 3D printing technique lets you pop out functional, self-folding robots with integrated sensors and actuators directly from a flat sheet.
We introduce an elastic-driven self-folding approach that fabricates robots directly from flat 3D-printed conductive PLA nets. Elastic bands routed through printed hooks store energy that folds the sheet into programmed 3D geometries, while the flat state allows accurate placement of electronics and magnets before deployment. The same substrate doubles as electrodes for capacitive touch and supports a reusable platform I/O palette with Hall sensors and eccentric rotating mass (ERM) motors for docking detection and vibration actuation. We also derive a closed-form folding model that balances hinge stiffness with elastic band moment to predict equilibrium fold angles; experiments validate the model and yield a design map linking hinge thickness, band size, and hook spacing to target angles. Using this workflow we realize multiple polyhedral modules and demonstrate three applications: a cube that highlights the potential of self-folding for scalable modular robot collectives, a deployable gripper, and a tendon-driven finger. The method is low cost, stimulus-free, and integrates actuation and sensing.
