Environmental actuation of helical microfibers formed by asymmetric wetting

Biological systems often self-assemble microscale helical structures that enable various sensing and actuation functions. Here, we use asymmetric wetting of a Landau-Levitch film on thin polymer fibers to create helical microfibers. These fibers may spontaneously coil during fabrication and can actively respond to environmental stimuli. We characterize the coil radius and pitch and explain the phenomenon using a simple model.