Discontinuous Meniscus Location in Tapered Capillaries Driven by Pressure Difference and Dielectrophoretic Forces

TL;DR

This paper investigates how pressure and dielectrophoretic forces influence the position of the meniscus in tapered capillaries, revealing discontinuous jumps and phase diagrams that depend on system parameters.

Contribution

It introduces a comprehensive analysis of meniscus behavior under combined pressure and dielectrophoretic forces, including phase diagrams and effects in wedge capillaries and electrowetting.

Findings

Meniscus position can change discontinuously with pressure or voltage.

Phase diagrams map meniscus states based on system parameters.

Discontinuous liquid-gas interface locations occur in closed volumes.

Abstract

We calculate the meniscus location in tapered capillaries under the influence of pressure difference and dielectrophoretic forces with and without gravity. We find that the meniscus location can be a discontinuous function of the pressure difference or the applied voltage and that the meniscus can ``jump'' to one end or another of the capillary. Phase diagrams are given as a function of the pressure and voltage, depending on the geometrical parameters of the system. We further consider a revision of the dielectric rise under dielectrophoretic force in wedge capillaries and in the case of electrowetting, where the dielectrophoretic force is a small perturbation. Finally, we also find discontinuous liquid--gas interface location in the case of liquid penetration into closed volumes.