IPMC-PVDF structure and sensing circuit

Elastic Epoxy (Polysciences Inc., Warrington, PA). When the IPMC-PVDF structure is bent due to the actuation of I PMC or some external force, charges are generated on the PVDF film, which are then measured with a differential charge amplifier as shown in Fig. 8.2. 

The charge Q generated on the PVDF film is proportional to the bending displacement Z of the beam, Q = GZ, where G is a constant dependent on the transverse piezoelectric coefficient dsi, and the dimensions and Young s moduli of individual layers of the composite beam [Shen et al. (2004)]. The transfer function from Z s) to the measured voltage V/(s) can then be written as 

Experiments were conducted to calibrate the PVDF sensor. To avoid the influence from the actuation voltage, we simply tapped the composite beam tip and measured simultaneously the charge amplifier output and the tip displacement. The displacement was measured with a laser distance sensor (OADM 20I6441/S14F, Baumer Electric, Southington, CT). Fig. 8.3(a) shows the measured charge response under the damped beam oscillation at 42 Hz, while Fig. 8.3(b) depicts the measured charge vs. the actual displacement, from which we can conclude that the beam tip displacement can be well captured by the PVDF sensor. 

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