Movie S3.

An undulating swimmer, which produces a swimming gait that is similar to a spermatozoid. The traveling wave induced by the swimmer has a nonuniform amplitude that gradually increases from the head (fixed end) to the tail (free end). The desired undulating motion is first demonstrated with simulations. Subsequently, the swimmer could achieve a similar motion when it was tethered. The swimming capabilities of the device were also demonstrated when it swam on a water surface when it became untethered.