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A cell rotation method by using optoelectronic tweezers (OET) is reported. The binary image of a typical OET device, whose light and dark sides act as two sets of parallel plates with different ac voltages, was used to create a rotating electric field. Its feasibility for application to electrorotation of cells was demonstrated by rotating Ramos and yeast cells in their pitch axes. The electrorotation by using OET devices is dependent on the medium and cells' electrical properties, the cells' positions, and the OET device's geometrical dimension, as well as the frequency of the electric field.

Transient currents induced by the polarity reversal of an applied dc voltage in nematic liquid crystal hybridized with montmorillonite clay have been studied. Comparative values of the ion-charge concentrations deduced from the experimental data suggest that the clay hybridized into liquid crystal has a great impact on the ion-charge concentration, which can be dramatically reduced to as low as to for a nematic cell containing merely 0.5 wt% clay. Such hybridization suppresses the formation of electric bilayers and the charge-screening effect. Due to the clay and liquid-crystal molecules being aligned to the direction of the field, a higher mobility is observed in hybridized cells. This study demonstrates that montmorillonite clay hybridized into liquid crystal yields many advantages to improve the electro-optical properties of the display device.

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The optical transmittance and the electrical capacitance as a function of the externally applied dc voltage are obtained for a twisted nematic cell composed of inorganic clay; i.e., sodium montmorillonite, as an additive to the organic liquid crystal E7. Higher loaded nematic, with smectite clay content of over 3 wt%, exhibits wider voltage–transmittance and voltage–capacitance hystereses, indicating that such cells suffer from more serious ion-charge effects and the orientation barrier of the liquid crystal. Experimental evidence suggests that the addition of merely 0.5–1% by weight of clay substantially rectifies the electro-optical characteristics of the pristine nematic, leading to an apparent lowering of the dc threshold voltage.