We demonstrate a novel, inexpensive and simple strategy to self-fold three-dimensional (3D) structures from pre-strained polymer sheets using local light absorption through black ink printed via ink-jet printing. Converting two-dimensional (2D) patterns into three-dimensional (3D) structures is attractive for robotic actuation, packaging and reconfigurable devices. Self-folding takes advantage of 2D patterning techniques (e.g., lithography, inkjet printing) and converts predefined 2D templates into 3D structures. The appeal of our work is its simplicity without using heterogeneous materials and multi-step fabrication. The local thermal gradient due to the effective heat absorption of printed inked hinge determines the localized shrinkage gradient of the polymer so induces out-of-plane folding. A geometric model incorporated with the macroscopic, thermally-driven shrinkage of pre-strained polymer sheet provides a simple approach to capture the folding kinetics (change of folding angle with time) without requiring complex modeling using thermo-mechanical properties of polymer.  This work can be useful for localized heat management and for achieving 3D structures with desired folding angles in a certain time on pre-strained polymer sheets.

Simple geometric model to predict self-folding of polymer sheets

248th National Meeting (2014)

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