Regensburg 2016 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 58: Wetting, Nano- and Microfluidics II (joint session CPP/DY, organized by CPP)

CPP 58.5: Talk

Thursday, March 10, 2016, 16:00–16:15, H42

Connecting and disconnecting nematic disclination lines in microfluidic channels — •Hakam Agha and Christian Bahr — Max Planck Institute for Dynamics and Self-Organization (MPIDS), Am Fassberg 17, 37077 Göttingen, Germany

The controlled creation of a disclination line in nematic liquid crystal (NLC) spanning along the microfluidic channel as a result of imposed anchoring conditions on the four confining channel walls has proven to be a novel and successful approach to guided transport of microfluidic cargo, with the disclination line serving as a soft rail [1]. In this study, we report on a method to connect and disconnect disclination lines using the interplay between anchoring, flow, and electric field. We design the anchoring conditions in a way that the formation of the disclination is suppressed in one or several short sections of the channel. The application of an external electric field across the channel and perpendicular to the NLC flow can overcome the imposed anchoring conditions and allows the disclination line to span across the forbidden regions, establishing a continuous disclination along the complete channel. Thus, the manipulation of the anchoring conditions combined with the effect of the electric field allows us to interrupt and to reestablish the transport of colloidal particles through the microchannel.

[1] A. Sengupta, C. Bahr, S. Herminghaus, Soft Matter, 2013, 9, 7251.