Engineering Mountain Folds in Cell Origami

We report a method to create mountain folds, protruding ridges, in cell origami, a polymer structure folding technique driven by cell traction force (CTF). Formerly, cell origami was based on valley folds, indented creases, only [2]. We created mountain folds adjacent with valley folds. We present designs for self-folding structures as well as for physically stimulated structures. The adhered cells hold the microstructure in position after self-folding or stimulus, when without cells the structure unfolds again. Our method increases structure complexity achievable by cell origami and possibly by other micro-origami techniques that utilize an one-directional folding force.