Active deformation of dielectric elastomer for detection of biofouling

Biofouling accumulation on synthetic underwater surfaces presents serious economic problem for the marine industry. When a substrate-bonded dielectric elastomer (DE) is subjected to high voltage, deformations in form of creases can be formed at the surface of the DE. This deformation, has been already demonstrated for the prevention and detachment of biofouling from the surface of DEs. In this work, we add sensing capability to the anti-biofouling effect of active DE surfaces. A device consisting of a metallic plate, a Kapton sheet, and a thin silicone membrane is immersed in conductive solution, which acts as one electrode, with the metal plate being the second electrode. Two different conductive solutions were used 3.5 wt% NaCl and 20 wt% NaCl. The surface deformation of the silicone as a function of applied voltage is monitored under microscope in order to verify electrical measurements. Breakdown measurements of the dielectric material in different conductive solutions are also performed. Because the membrane is made from incompressible elastomer and bonded to a rigid substrate, voltages below the creasing threshold create no deformation in the membrane, and therefore no change in capacitance. Above the voltage threshold, creasing instabilities appear at the surface of the silicone, thus increasing the capacitance of the device. Therefore, the capacitance of the sensor is measured as a function of applied voltage, and the voltage at which the capacitance increases is the threshold voltage at which creases occur. Creases are identified when using both 3.5 wt% NaCl and 20 wt% NaCl as top electrode. Theoretical values of creasing voltage deviate from the experimental measurements. Type of conductive solution is shown to have no significant influence on a breakdown voltage.