Cutting a Drop of Water Pinned by Wire Loops Using a Superhydrophobic Surface and Knife

Abstract

A water drop on a superhydrophobic surface that is pinned by wire loops can be reproducibly cut without formation of satellite droplets. Drops placed on low-density polyethylene surfaces and Teflon-coated glass slides were cut with superhydrophobic knives of low-density polyethylene and treated copper or zinc sheets, respectively. Distortion of drop shape by the superhydrophobic knife enables a clean break. The driving force for droplet formation arises from the lower surface free energy for two separate drops, and it is modeled as a 2-D system. An estimate of the free energy change serves to guide when droplets will form based on the variation of drop volume, loop spacing and knife depth. Combining the cutting process with an electrofocusing driving force could enable a reproducible biomolecular separation without troubling satellite drop formation.

The Eukaryotic CO2-Concentrating Organelle Is Liquid-like and Exhibits Dynamic Reorganization

“…Towards the end of fission, a “bridge” of matrix material connecting the two lobes of a dividing pyrenoid is briefly visible (Figure 3). After the bridge ruptures, daughter pyrenoids quickly revert to spherical shapes, similar to the behavior of liquid droplets (Stone, 1994; Yanashima et al , 2012). Furthermore, during apparent de novo pyrenoid formation, we typically observed that smaller puncta shrank while larger ones grew until the cell contained a single pyrenoid (Figure 2B,D,G–I ) – much like Ostwald ripening in systems containing multiple liquid droplets (Hyman et al , 2014), indicating that components likely exchange between the puncta.…”

Water impacting on superhydrophobic macrotextures

“…New behaviours were also evidenced at room temperature on superhydrophobic materials decorated with macrotextures. Grooves of submillimetric width and depth etched at the surface can guide liquid moving at the surface 18 , and water projected against the edge of a blade can be split 19 or cut when the blade is used as a knife 20 .…”

Micro‐nanostructured silicone‐carbon composite coatings with superhydrophobicity and photoluminescence prepared by oxidative chemical vapor deposition

“…As known, generating a tiny drop is easy through micro‐syringe, however, it is difficult to cling to the superhydrophobic surface independently due to the strong capillary action between the drop and the tip of the syringe [Figure (c)]. Superhydrophobic knife can solve the problem, and here we also prepared a superhydrophobic knife by coating on both sides of a thin blade, as shown in Figure (a). By using this superhydrophobic knife, water droplets of 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 µL can successfully stay on the superhydrophobic surface from the tip of a syringe, as shown in Figure (b).…”