For a number of years, the possibilities of using polymer or co‐polymer materials exhibiting piezoelectric properties have attracted the attention of those engaged in non‐destructive testing.
P. Marin-FranchI.G. PettigrewM.F. ParkerK.J. KirkS. Cochran
F. HarnischΝ. KroemerW. Manthey
Hiroshi TakeuchiShigeru JyomuraChitose Nakaya