Keywords

capillary forces, droplet-based bearings, stiffness

Abstract

While Capillary forces are negligible relative to gravity at the macroscale, they provide adequate force to effectively manipulate millimeter to micro meter objects. The fluidic actuation can be accomplished using droplets that also act as bearings. While rotary droplet bearings have been previously demonstrated, this paper considers the performance potential of discrete droplets acting as linear bearings. Specifically, it addresses the positioning accuracy of a droplet-based bearing consisting of a droplet between a moving plate and a stationary substrate with constrained wetting region under a normal load using both closed form analytical solutions and numerical simulations. The vertical force and stiffness characteristics are analyzed in relation to the wetting boundaries of the supporting surface. Case studies of different wetting boundaries are presented and summarized. Design strategies are presented for maximizing load carrying capability and stiffness.

Original Publication Citation

Qi Ni, Nathan B Crane, “Controlling Normal Stiffness in Droplet-Based Linear Bearings,” Micromachines, special issue on Microscale Surface Tension and Its Applications, https://doi.org/10.3390/mi9100525, 9(10), p 525, 2018.