Transfer Printing of Self-Folding Polymer-Metal Bilayer Particles

A simple and robust alternative for fabricating stimuli-responsive 2D self-folding films was introduced. The approach combines metal-sputtering, layer-by-layer assembly of polyelectrolytes, and transfer-printing of the bilayer film onto a substrate coated with a sacrificial layer. With this technique, self-folding bilayer films can be fabricated without using harsh chemical etchants, complicated chemical synthesis, or complex lithographic techniques. Upon release, the microsized 2D film is shown to reconfigure into a 3D structure caused by a mismatch in the properties of the individual layers. The actuation of the bilayer film can be triggered by partial swelling due to absorption of water or by partial expansion of one of the layers due to an increase in temperature.