22. A Beetle-Inspired Switch
Paul H. Steen, Chemical and Biomolecular Engineering, and research colleagues designed a new switch that is simple, small, fast, and capable of working by itself or combined in larger arrays for applications, such as powerful adhesive bonding. Steen’s design was inspired by Cornell entomologist Thomas Eisner’s lecture on palm beetles. Like the beetle, which clings to a palm leaf at adhesive strengths equal to a hundred times its own body weight, the switch in its most basic form uses surface tension created by water droplets in contact with a surface, like the way two pieces of wet paper cling together. When attacked, the palm beetle attaches itself to a leaf, adhering to it with 120,000 droplets of secreted oil, each making a bridge-like contact between the beetle’s feet and the leaf. Each droplet is a few microns wide. Whereas the beetle controls the oil contact mechanically, Steen’s switch uses water and electricity. With millimeter-sized water droplets and micron-sized pores, five volts can turn the switch on in one second. Although its uses are not yet understood, this novel switch has enormous potential. The greatest technological advances have depended on switches. This switch bridges the gap between scales as large as the hand and nanoscale.