To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Movie S4. Propulsion of a two-stroke directional swimmer. The programmed path is straight followed by a left turn. The distance traveled is approximately 0.5l after the first stroke, and a turn of 23.85° after the second stroke. Harnessing bistability for directional propulsion of soft, untethered robots Tian Chen, Osama R. Bilal, Kristina Shea, and Chiara Daraio PNAS. 2018. 115:5698-5702 DOI: 10.1073/pnas.1800386115 Download Original Video Browse All Videos »