Fig 4. Interaction between worms and a simple hinge-pin mechanism fabricated within a millimeter-scale area.

(a) Sequential frames show the lower worm contacting the hinge and extending its body, causing the hinge to rotate around the encapsulated pin. (b) Angle of the hinge with respect to vertical position plotted against time. Over six seconds the hinge rotates from 6° to 27°. (c) Schematics of worm motion as observed in the experiment, which is also shown in S2 Video. When the worm contacts two points spanning from the frame to the hinge, it extends its body, exerting force on the hinge and causing it to rotate. The motion cycle is repeated, rotating the hinge clockwise a small amount with each cycle.