Printing low-voltage dielectric elastomer actuators
We demonstrate the fabrication of fully printed thin dielectric elastomer actuators (DEAs), reducing the operation voltage below 300V while keeping good actuation strain. DEAs are soft actuators capable of strains greater than 100% and response times below 1ms, but they require driving voltage in the kV range, limiting the possible applications. One way to reduce the driving voltage of DEAs is to decrease the dielectric membrane thickness, which is typically in the 20–100 µm range, as reliable fabrication becomes challenging below this thickness. We report here the use of pad-printing to produce µm thick silicone membranes, on which we pad-print µm thick compliant electrodes to create DEAs. We achieve a lateral actuation strain of 7.5% at only 245V on a 3 µm thick pad-printed membrane. This corresponds to a ratio of 125%/kV2, by far the highest reported value for DEAs. To quantify the increasing stiffening impact of the electrodes on DEA performance as the membrane thickness decreases, we compare two circular actuators, one with 3 µm- and one with 30 µm-thick membranes. Our experimental measurements show that the strain uniformity of the 3 µm-DEA is indeed affected by the mechanical impact of the electrodes. We developed a simple DEA model that includes realistic electrodes of finite stiffness, rather than assuming zero stiffness electrodes as is commonly done. The simulation results confirm that the stiffening impact of the electrodes is an important parameter that should not be neglected in the design of thin-DEAs. This work presents a practical approach towards low-voltage DEAs, a critical step for the development of real world applications.