Numerical prediction of the driving performance of liquid crystal actuators

Abstract

To study the performance of liquid crystal actuators, we prepared a sandwich cell with a movable upper plate and drove this upper plate in its plane. To predict the driving performance of such an actuator, we proposed a simple one-dimensional model that combines the motion of the upper plate of the liquid crystal cell with the flow of the liquid crystal, and then, we compared the predicted motion of the plate with reported experimental results. The proposed model qualitatively predicted the motion of the upper plate. Using this model, we studied the rotation of the liquid crystal molecules and the velocity profiles between the two plates. When the applied voltage has a frequency of 1 Hz, the molecules between the two plates return completely to their initial angle when the electric field is released; at 10 Hz, the molecules do not return to their initial angle but instead return to approximately 40°; at 100 Hz, they oscillate around 90° with a small amplitude. At 10 Hz, the induced velocity profile is S-shaped, while at 20 Hz, the profile is double-S-shaped; this unusual behavior stems from the so-called kickback effect.