Electrowetting on conductors: anatomy of the phenomenon

Abstract

We have recently reported that reversible electrowetting can be observed on the basal plane of graphite, without the presence of a dielectric layer, in both liquid/air and liquid/liquid configurations. The influence of carbon structure on the wetting phenomenon is investigated in more detail here. Specifically, it is shown that the adsorption of adventitious impurities on the graphite surface markedly suppresses the electrowetting response. Similarly, the use of pyrolysed carbon films, although exhibiting a roughness below the threshold previously identified as the barrier to wetting on basal plane graphite, does not give a noticeable electrowetting response, which leads us to conclude that specific interactions at the water–graphite interface as well as graphite crystallinity are responsible for the reversible response seen in the latter case. Preliminary experiments on mechanically exfoliated and chemical vapour deposition grown graphene are also reported.

Active Control over the Wettability from Superhydrophobic to Superhydrophilic by Electrochemically Altering the Oxidation State in a Low Voltage Range

“…Recently, low voltage has been used to facilitate electrowetting without any electrochemical reactions following the accumulation of charges at the interfaces. The basic requirement for low‐voltage electrowetting involves using a material with low intrinsic electroactivity such as steel, gold, and graphite . The potential required for such electrowetting process is on par with that of the electrochemical process.…”

Removable Composite Electrode Made of Silver Nanoparticles on Pyrolyzed Photoresist Film for the Electroreduction of 4-Nitrophenol

“…4 μm thick before the pyrolysis in a 5% H 2 /Ar gas flow (30 L•h −1 ). The heating protocol is derived from the one used by K. Ounnunkad et al 45 (Supporting Information, SI 2).…”

Polarity dependent electrowetting for directional transport of water through patterned superhydrophobic laser induced graphene fibers

“…[4] However, recently few studies have described the dielectric-free approach to electrowetting on the basal plane of conductive graphite surface where specific interactions at the water-graphite interface and graphite crystallinity are said to be responsible for electrowetting on conductive graphite and the phenomena is also referred to as electrically driven flow. [29][30][31] But surprisingly, until now, single-step synthesis of micropatterned LIG has not been investigated and no reports are available showing their electrowetting and corresponding wetting properties. Liquid repellency and electrowetting characteristics of hierarchical structured LIG fibers are still unexplored.…”