Study and modeling of an electrostrictive polyurethane diaphragm loaded with conductive carbon black

Electroactive polymers (EAPs) have been shown to have great potentials as actuators in micro-systems due to their light weight, low cost and large electrical field-induced strains. In this article, a diaphragm type actuator comprising an electrostrictive carbon black (CB) loaded polyurethane (Pu) membrane is described. First, equations are derived for such a system, taking into account its resonant nature. Then, equations for a diaphragm actuator in plate-like and membrane like behavior are written. A resonance frequencies study has been done in order to confirm the membrane-like behavior of the proposed system. Thus, a large deflection model was applied and showed good fitting between experimental and calculated data. To completely model the system, electrodes clamping effect term and a quality factor term are added. The effect of CB loading on the deflection is thoroughly discussed. It was found that a CB concentration of 1.25 wt% gave a deflection at the center of a 50 μm-thick diaphragm of 12 μm under a 9 V/μm electric field at 700 Hz whereas a 50 μm pure Pu membrane gave a deflection of 3 μm at the same electric field. An increase of 4-fold is therefore achieved, allowing significant enhancement in using such devices in MEMS systems.