Measurement of the Sum (e₁ + e₃) of the Flexoelectric Coefficients e₁ and e₃ of Nematic Liquid Crystals using a Hybrid Aligned Nematic (HAN) cell

Abstract

A hybrid aligned nematic cell (HAN) is often used to measure the sum (e ₁ + e ₃) of the flexoelectric coefficients e ₁ and e ₃. However, a HAN cell has the difficulty of an internal offset voltage (internal bias) caused by the homeotropic alignment. We present a method to determine the internal bias and then take it into account in the flexoelectric measurement.

Keywords:

• flexoelectric coefficient
• flexoelectricity
• HAN
• hybrid aligned nematic
• offset voltage
• sum

Acknowledgments

The authors would like to thank EPSRC for funding the project and Merck Chemicals Ltd. for supplying materials and devices and Lesley Parry-Jones for useful discussions.