Shear flow behavior of tumbling liquid crystals and development of micro mechanical sensors

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In order to investigate whether a tumbling-type liquid crystal, which continues to rotate in simple shear flow, may be "a liquid-like piezoelectric material", we have measured the polarization induced by the sheared liquid crystal. A certain level of success of this research leads to the development of micro- mechanical sensors with flexible shape.We prepared concentric two cylinders which consist of the outer cylinder with the inner diameter of 6 mm and the inner cylinder with the outer diameter of 5 mm, injected a liquid crystal between the two cylinders, and imposed a shear force on the liquid crystal by rotating the inner cylinder. We used 4-cyano-4'-octylbiphenyl as a tumbling-type liquid crystal. When the rotation speed of the inner cylinder was 0.2 rpm, the induced voltage showed a pulsatile shape with +-70 mV in magnitude. Thus, a tumbling-type liquid crystal is suitable to a piezoelectric material.