Validation of the trapped charge model of electrowetting contact angle saturation on lipid bilayers

Abstract

The problem of modeling contact angle saturation in electrowetting has resisted a number of concentrated efforts by leading researchers. Several models have been proposed, from charge trapping, to droplet ejection, to thermodynamic instability, but no consensus has been reached as to which model better describes the effect. In this paper, we validate the charge trapping based model of contact angle saturation in electrowetting on lipid bilayers, through careful analysis of charge movement between the liquid charge states and trapped charge states at the solid dielectric interface. We also describe a powerful new methodology for studying electrowetting systems by modeling them with an equivalent circuit and simulating the circuit using the SPICE circuit simulator.