Linear electromechanical effect

Eber, N., Bata, L., Scherowsky, G., and Schliwa, A., Linear electromechanical effect in a polymeric ferroelectric liquid crystal, Ferroelectrics, 122, 139-147 (1991). Kozlovsky, M. V., Darius, M., and Haa.se, W., Frustrated pha.se behaviour of a chiral side chain polymer, European Polymer Journal, (in press). 

Let us note here that a kind of linear electromechanical effect (electric field-induced director rotation) observed in cholesterics, does not fall into the category of piezoelectricity, since it does not involve a collective displacement of the center of mass. 

The strength of the linear electromechanical effect of a FLC was defined as the maximum obtainable displacement induced by a unit electric field. For polymer 65 the... 

The piezoelectric effect, discovered in 1880 by French physicists Jacques and Pierre Curie, is defined as the linear electromechanical interaction between the mechanical and electrical state (in a crystalline material with no inversion symmetry), such that... 

Piezoelectricity. The Piezoelectric Ejfect. Because all acoustic gravimetric sensors are based on the phenomenon of piezoelectricity, it seems appropriate to discuss briefly the effect itself. Piezoelectricity was first observed by the Curie brothers (Jaques and Pierre) in 1880 [258]. It is a reversible phenomenon, consisting of linear electromechanical interactions between mechanical and electrical properties in certain crystals (Fig. 52). The effect is generated, as already men-... 

The operation of proximity sensors can be based on a wide range of principles, including capacitance, induction, Hall and magnetic effects variable reluctance, linear variable differential transformer (LVDT), variable resistor mechanical and electromechanical limit switches optical, photoelectric, or fiber-optic sensors laser-based distance, dimension, or thickness sensors air gap sensors ultrasonic and displacement transducers. Their detection ranges vary from micrometers to meters, and their applications include the measurement of position, displacement, proximity, or operational limits in controlling moving components of valves and dampers. Either linear or angular position can be measured ... 

Unfortunately, even today, inverse (or converse) piezoelectricity is still sometimes called electrostriction because the name electrostriction suggests the electromechanical direction (electrical stimulus leads to mechanical response), while piezoelectricity seems to refer only to the opposite mechano-electrical direction. In order to avoid the misleading use of the term, it should be kept in mind that our modem terminology is based on phenomenological thermodynamical relations so that the linear effects of direct and inverse piezoelectricity must be identical due to the mathematically required reciprocity. 

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