Countersnapping

Observations of snapping-based prey capture strategies of the Venus flytrap and mantis shrimp have inspired research to design materials with exotic and programmable functions. At AMOLF, researchers expanded this repertoire by demonstrating countersnapping, where a combination of geometrically nonlinear building blocks cooperate to suddenly shrink when put under increased tension. It is refreshingly counterintuitive, as shrinking often tends to be.

In current forms of snapping, shapes usually deform in the same direction as the incremental load. Think of a light switch: you push it incrementally harder until the switch suddenly snaps in the direction of the force. While this link between the direction of forces and deformations seems natural, there is no physical law that requires it. AMOLF researchers created an elegant mechanical structure that responds in the opposite way. In contrast to regular snapping, countersnapping manifests itself in a sudden shortening transition under increasing tension. Some of the interesting theoretical underpinnings includes the Braess Paradox and the principle of moving from series to parallels as nicely explained in this Veritasium video. Cooperation: countersnapping (shrinking) is a collective thing.