Cholesteric Metronomes with Flexoelectrically Programmable Amplitude

Replicating natural phenomena using soft material actuators is a major challenge for material scientists. For example, a metronome is a device that produces an audible beat at a selected interval. In anisotropic soft materials, a flexoelectrically-driven cholesteric liquid crystal (CLC) can display a metronome-like swinging effect when an applied electric field is normal to the helices of a CLC that are aligned normal to the substrates. The amplitude and direction of swing of a flexoelectrically-driven CLC is electrically programmable. Combining a bimesogen and a CLC with an optimized helical pitch, the mixture enables a large flexoelastic ratio (e/K = 2.758 CN-1 m(-1)) and swinging amplitude of 53 degrees. Furthermore, assisted by polymer stabilization the composite mixture offers many benefits of electro-optical characteristics including fast response time (425 mu s) and high optical contrast (500:1) between the field-on and field-off states as well as wavelength-independent transmittance. The advances in the flexoelectro-optical behavior of cholesteric metronomes open new avenues for applications in information displays, sensors and photonic devices.