A unique feature of nematic liquid crystals is orientational order of molecules that can becontrolled by electromagnetic fields, surface modifications and pressure gradients. Here wedemonstrate a new effect in which the orientation of nematic liquid crystal molecules is alteredby thermal expansion. Thermal expansion (or contraction) causes the nematic liquid crystal toflow; the flow imposes a realigning torque on the nematic liquid crystal molecules and the opticaxis. The optical and mechanical responses activated by a simple temperature change can beused in sensing, photonics, microfluidic, optofluidic and lab-on-a-chip applications as theydo not require externally imposed gradients of temperature, pressure, surface realignment,nor electromagnetic fields. The effect has important ramifications for the current search ofthe biaxial nematic phase as the optical features of thermally induced structural changesin the uniaxial nematic liquid crystal mimic the features expected of the biaxial nematicliquid crystal.
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