Dynamic Response in Nanoelectrowetting on a Dielectric

Abstract

Droplet spreading at an applied voltage underlies the function of tunable optical devices including adjustable lenses and matrix display elements. Faster response and the enhanced resolution motivate research toward miniaturization of these devices to nanoscale dimensions. The response of an aqueous nanodroplet to an applied field can differ significantly from macroscopic predictions. Understanding these differences requires characterization at the molecular level. We describe the equilibrium and nonequilibrium molecular dynamics simulations of nanosized aqueous droplets on a hydrophobic surface with the embedded concentric electrodes. Constant electrode potential is enforced by a rigorous account of the metal polarization. We demonstrate that the reduction of the equilibrium contact angle is commensurate to, and adjusts reversibly with, the voltage change. For a droplet with O(10) nm diameter, a typical response time to the imposition of the field is of O(10(2)) ps. Drop relaxation is about twice as fast when the field is switched off. The friction coefficient obtained from the rate of the drop relaxation on the nonuniform surface, decreases when the droplet approaches equilibrium from either direction, that is, by spreading or receding. The strong dependence of the friction on the surface hydrophilicity points to the dominance of the liquid-surface friction at the drop's perimeter as described in the molecular kinetic theory. This approach enables correct predictions of trends in dynamic responses associated with varied voltage or substrate material.

One-step electric-field driven methane and formaldehyde synthesis from liquid methanol

“…, water dissociation). 29,30 Since a very similar computational setup 29 has been exploited in order to accurately predict the experimental dissociation threshold of the water molecule, 31 thus confirming some preliminary 30 and extremely recent 51 results, there is no reason to think that the same reliability is not preserved for the present chemical reaction. Hence, all the evidence suggests the concrete experimental feasibility of reproducing the proposed reaction by exploiting, as an example, the high field capability of field emitter tips.…”

P(VDF-TrFE)/PMMA Blended Films with Enhanced Electrowetting Responses and Superior Energy Storage Performance

“…Linear PMMA polymer was introduced into P(VDF-TrFE) matrix in order to minimize the ferroelectric effect of P(VDF-TrFE) and thus increase the reversibility. In addition, dynamic hysteresis is also associated with the friction force between water droplets and the insulator surface [31,32]. To minimize this interaction, Teflon was selected to cover the dielectric layer.…”

Significantly enhanced dielectric and hydrophobic properties of SiO2@MgO/PMMA composite films

“…Electrowetting-on-dielectric is a small-scale liquid handling technology that has been signicantly used for numerous applications, including electronic displays, optical devices, lab on a chip, liquid transport in microuidic devices, and surface science. [1][2][3][4] In recent years, the electrowetting display has been widely investigated and plays an important role in the eld of display devices, combining the special reective display characteristics of conventional printed paper with the changeable electronic information. [2][3][4][5] Fig.…”

“…Dielectric layer is one of the vital sections in electrowetting display device, the materials selection and preparation of dielectric layer can directly inuence the performance and application of the device. According to the eqn (1), the lm should provide some special properties for the electrowetting display devices except for insulation. First, the surface should be hydrophobic to ensure a huge variation in contact angle under electrical eld.…”