During piezo d33 measurement, there is a static force and a dynamic force applied on the sample. The dynamic force is controlled by the meter, the static force is controlled by the user (how hard to move the top probe down to squeeze your sample). In most commercial d33 meters, the static force is controlled by the operator’s “finger” feeling. For soft and fragile polymers (PVDF, PVDF-TrFE, or polylactide, etc), electret, foam, or crystal, the static force can significantly the measured d33 value (see the PVDF d33 under different static force), therefore, many users complained the reproducibility of d33 of polymer piezo materials measured with standard d33 meters.
PolyK developed a force sensor that can be integrated to existing commercial (ZJ-3/4/6X, YE2730A, or PolyK) d33 meter with simple adapters. This allows the user to accurately monitor the static force with a digital display, therefore, significantly improve the accuracy and reproducibility of d33 measurement.