Abstract: Piezoelectric and pyroelectric elements made from polarized plastics substances such as polyvinylidene fluoride are of considerable interest in a number of fields. Unfortunately, they also suffer from a number of not insignificant drawbacks. Specifically, the maximum thickness of fully-polarized plastics film obtainable is often not sufficient to give the desired sensitivity.

Abstract: A pressure sensitive switch including a poly (vinylidene fluoride) (PVF.sub.2) sheet arranged to be compressed and laterally outwardly distended under a load carrying on each major surface thereof contact means for receiving a signal generated by the sheet when compressed and distended two thick blocks of solid elastomeric material between which is sandwiched the sheet, and means for compressing and laterally outwardly distending both blocks by relative motion toward each other thereby in the absence of tension forces compressing and laterally outwardly distending the sheet sandwiched therebetween to generate the signal.