The elasto-pipette: grabbing water with thin elastic sheets

Py \emph{et. al.} [1] have recently shown that the coupling between surface tension and elasticity of thin sheets can be used to induce self-assembly of flat elastic objects into three dimensional structures: \emph{capillary origami} at play. We here present the results of a combined experimental and theoretical investigation of a related system in which a thin elastic petal-shaped plate is withdrawn from the flat interface of a liquid bath. As the plate is drawn upwards, it deforms due to interfacial and hydrostatic forces, up to a point where it completely detaches from the interface. If the bending stiffness of the plate is sufficiently low, upon detachment a regime can be attained where the petal-shaped plate can fully enclose and therefore \emph{grab} a drop from the liquid bath. We propose this mechanism as a robust means by which to manipulate and transport small fluid droplets. \noindent [1] C. Py, P. Reverly, L. Doppler, J. Bico, B. Roman and C. Baroud, \emph{Phys. Rev. Lett.} \textbf{98}, 156103 (2007).