2003
Polyvinylidene Fluoride (PVDF) film is the
most sensitive among piezoelectric polymers,
although it is less sensitive than PZT piezoelectric
element used as ordinal AE transducer. PVDF
film can be easily attached to curved and
irregularly shaped materials, since it is
thin (28 to 200µm in thickness) and
quite flexible. The frequency response of
PVDF film is flat, since it has a lower Q-value
(sharpness of resonance), comparing with
PZT piezoelectric element having a resonant
frequency. The film has low acoustic impedance
and matches with that of wood.
In this study, feasibility of PVDF film as
AE sensor was investigated by comparing the
attenuation of artificial AE wave generated
by breaking of a pencil lead among several
wood specimens and wood-based materials.
It was clarified that PVDF film can be used
as AE sensor for the non-destructive inspection
of wood and wooden materials.
Table. 1. Comparison of some piezoelectric materials  |
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 Fig. 1. PVDF film and PZT piezoelectric transducer |
 Fig. 2. Example of the wave form of artificial AE detected by PVDF film |
 Fig. 3. Relation of AE amplitudes to distance using artificial AE source |
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