Periodic arrays of liquid crystalline torons in microchannels

Abstract

We have fabricated very well ordered periodic arrays of torons using cholesteric liquid crystal phase (CLC) in microchannels. The liquid crystal (LC) director exhibited different orientations with variations in the microchannel width. In particular, LC molecules were homeotropically aligned to the bottom substrate of the microchannel when the microchannel width was less than the helical pitch of the CLC, while wound CLC structures ("fingers") grew from the sidewall of the microchannels that were wider than the helical pitch. The thermal quenching process generated torons that were locally isolated from the microchannel surfaces due to the thermal gradient from top/bottom to the centre position of the microchannel. The individually grown torons were periodically arranged in a row with a uniform size-distribution and long-term stability under ambient conditions.