Surface tension-driven autonomous tweezers using PDMS sheets

We proposed and demonstrated autonomous tweezers driven by surface tension without any actuators. The tweezers are composed of only a pair of surface modified polydimethylsiloxane (PDMS) cantilevers. Since the front and back surfaces of the cantilevers have different wettability, they can be bent due to the difference of surface tension and hydrostatic pressure exerted on each surface when they come in contact with the surface of a liquid. Using this phenomenon, we succeed in not only grasping but also releasing a floating object under proper conditions. The autonomous tweezers will be useful for damageless manipulation of biological samples without any actuators and external energy source.