PVDF-based micro-force sensor

The micro-force sensor, attached at the end of the IPMC-PVDF beam, has a similar structure as the IPMC-PVDF composite beam shown in Fig. 8.16, except that the IPMC layer is replaced by a (relatively) rigid passive film. In the prototype, we used 200 pm thick polyester film as the middle layer. The same charge amplifier circuit as in Fig. 8.17, with possibly different gains, is used for the force sensor. Analogous to the case of measuring the bending displacement, one can derive the sensitivity of the force sensor in terms of the electromechanical properties and dimensions of the layers [Chen et al. (2008)]. 

Experiments were conducted to characterize the micro-force sensor. The IPMC-PVDF sensory actuator with integrated bending and force measurement was enclosed in a conductive shielding box, with its end-effector, a needle, protruding out of a slit on the box. To emulate the force level typically encountered in bio and micro applications, soap bubbles were pierced with the end-effector. The experimental setup is shown in Fig. 8.21(a). Fig. 8.21(b) shows the force sensor output when a bubble was moved man- 

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Experiments were conducted to measure the stiffness of an IPMC beam and two IPMC-PVDF composite beams with different insulating layer thickness (30 pm vs. 100 pm). The two composite beams were named IPMC/PVDFl and IPMC/PVDF2, respectively. As illustrated in Fig. 8.5(a), the cantilevered beam under measurement was pushed quasi-statically at the tip by a linear actuator. Between the linear actuator and the tip was a PVDF-based micro force sensor measuring the interaction force. The tip displacement was measured with a laser distance sensor. Fig. 8.5(b) shows the measured tip displacement together with the corresponding force for each beam, with the spring constants determined to... 

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