A Generalized Electrowetting Equation: Its Derivation and Consequences

TL;DR

This paper derives a comprehensive electrowetting equation from first principles, revealing that the classical Lippmann Equation is a special case, and highlights the importance of capacitance gradients near the triple line in determining contact angles.

Contribution

It introduces a generalized electrowetting equation based on thermodynamics, extending the classical Lippmann Equation to account for capacitance gradients near the triple line.

Findings

The classical Lippmann Equation is a special case of the generalized equation.

The apparent contact angle depends on the capacitance gradient near the triple line.

The area adjacent to the triple line influences the equilibrium contact angle.

Abstract

The thermodynamics of electrowetting is treated. A general equation of electrowetting is derived from the first principles. It is demonstrated that the well-known Lippmann Equation describes a particular case of electrowetting when the radial derivative of the capacitance of the double layer is constant. The apparent contact angle of electrowetting depends on the gradient of capacity of a double layer in the vicinity of the triple line. The role of the area adjacent to the triple line in constituting the equilibrium apparent contact angle of electrowetting is emphasized.