As we have discussed in Chapter I of this thesis, the nematic director is apolar. IIence the usual dielectric coupling with an external electric field depends quadratically on the latter. However, as has been discussed earlier a deformed director field with a splay and/or bend distortion can lead to a flexoelectric polarisation of the medium. The response of liquid crystals to an electric field...

One of the key technologies to evolve in the displays market in recent years is liquid crystal over silicon (LCOS) microdisplays. Traditional LCOS devices and applications such as rear projection televisions, have been based on intensity modulation electro-optical effects, however, recent developments have shown that multi-level phase modulation from these devices is extremely sought after for ...

Crumpled flexoelectret film demonstrates enhanced flexoelectricity at the macroscale compared to that of a typical pure dielectric film.

We use the discrete phenomenological model to study theoretically the phase diagrams in antiferroelectric liquid crystals (AFLCs) as a function of optical purity and temperature. High sensitivity of the phase sequence in the AFLCs to optical purity is attributed to the piezoelectric coupling which is reduced if optical purity is reduced. We limit our study to three topologically equal smetic (S...

We present a mixed finite element formulation for flexoelectric nanostructures that is coupled with topology optimization to maximize their intrinsic material performance with regards to their energy conversion potential. Using Barium Titanate (BTO) as the model flexoelectric material, we demonstrate the significant enhancement in energy conversion that can be obtained using topology optimizati...

The flexoelectric effect is a coupling of polarization and strain gradient, which exists in a wide variety of materials and may lead to strong size-dependent properties at the nanoscale. Based on an extension to the classical beam model, this paper investigates the electromechanical coupling response of piezoelectric nanobeams with different electrical boundary conditions including the effect o...

Liquid crystal flexoelectric actuation uses an imposed electric field to create membrane bending, and it is used by the outer hair cells (OHCs) located in the inner ear, whose role is to amplify sound through generation of mechanical power. Oscillations in the OHC membranes create periodic viscoelastic flows in the contacting fluid media. A key objective of this work on flexoelectric actuation ...

The pyroelectric technique, called the laser-intensity-modulation method, was used for investigations of the spatial distribution of the pyroelectric coefficient that gives information about the director profile in ferroelectric liquid crystal ~FLC! cells. The pyroelectric current from a cell, illuminated by the intensity-modulated laser beam, was measured as a function of the modulation freque...

2014 Within the general framework of Landau-de Gennes theory for nematic liquid crystals it is shown that the difference of flexoelectric coefficients e* = e1 e3 ~ S2, where S is the nematic order parameter. This result agrees with the molecular theory but is in contradiction with recent measurements of the constant e* which yield e* ~ S. The contradiction can be resolved by the inclusion of co...