Shaping Nematic Liquid Crystal Flow States with In-Plane Electric Fields

We demonstrate electrical control of flow states in a nematic liquid crystal driven through microfluidic channels. Patterned electrodes generate in-plane fields using a 1 Hz bipolar square-wave drive with peak amplitudes of 3.5 to 9 V. At flow velocities of 50 to 80 μms-1, these fields reversibly reshape flowing dowser domains, split them into smaller domains, and nucleate new dowser or chiral domains. Field orientation and flow conditions select between domain pairs, individual domains and chiral streams, with nucleation intervals of 0.5 to 2 s under steady flow. Combining the field with pulsating flow produces larger individual domains. These results establish patterned electrodes as localized electrical triggers for controlling nematic flow states, with prospects for integration in optofluidic and lab-on-a-chip devices.