Mechano-electric effect

Flexoelectricity is a basic mechano-electric effect that enables the nanometre-thick membranes of living matter to function like soft machines, thus converting the electrical stimuli of the hving world into mechanical ones, and vice versa. It also allows, by using model nanomembranes, the construction of mechanosensors and actuators for nanoionics applications. 

The direct piezoelectric (or mechano-electrical) effect is due to the shear polarization arising from the distortion of the helix as illustrated in Figure 8.15. 

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. 

Chemiluminescence has been used to determine the extent of mechano-chemistry [117-121]. A change of luminescence has been shown to follow second order kinetics at — 78°C and first order at 70°C. Polymer type has practically no effect on intensity or wavelength of luminescence [121]. Findings show that luminescence is due to a gas discharge on the electrically charged polymer surface [120]. The changes are generated by the mechanical forces. Thus radical formation and recombination processes play only a minor role [121]. 

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