Multistable Structures for Fluid Manipulation

Surface patterning is an effective means to control liquid-solid interactions, particularly for managing droplet motion and interfacial flows. Conventional structures employed in liquid flow operations are often constrained by fixed shapes, limiting their adaptability in fluid obstruction and flow rate control scenarios. In this talk, I will present our recent studies on utilizing a multistable ribbon structure fabricated from magnetic polydimethylsiloxane (PDMS) to manage water flow using rapid, remote magnetic fields. Each ribbon can transition between three stable states: a central peak (buckled arch shape), a left peak, and a right peak state. We investigate the ease of magnetic control over ribbon states under various magnetization conditions. The three states of the ribbon array afford varying degrees of control over water flow, with the right peak state providing the largest critical angle for water flow. Additionally, each individual ribbon's state within the array is independently tunable using a small external magnet, enhancing flexibility in controlling the critical angle of water droplet flow. Furthermore, in practical applications, we employ two groups of ribbon arrays to construct channel structures for controlling droplet flow and facilitating mixing. The manipulation of water droplets using these advanced multistable structures shows promise in applications such as chemical reactions, nanomanufacturing, and drug delivery, thus offering multistable, magnetically controlled structures as a versatile tool.