Fabrication of zipping electrostatic actuators incorporating inkjet-printed layers

Zipping electrostatic actuators operate by bending flexible electrodes using electrostatic forces. This principle allows the use of a wide range of dielectric and conductive materials. Additive Manufacturing (AM) techniques can be used to fabricate these actuators. The selective direct deposition of multiple materials improves the actuator design flexibility, as customized prototypes can be fabricated without masks and moulds. Here we present the first integration of AM techniques in the fabrication process of Hydraulically Amplified Taxels (HAXELs), a class of electrostatic actuators combining zipping electrodes deformation with the inflation of a stretchable material using fluidic coupling. We use an inkjet printer (jetlab (R) 4 by MicroFab) to deposit Polydimethylsiloxane (PDMS) as the stretchable material and Ethyl Cellulose as a sacrificial material for fluidic features patterning. We integrate gold-sputtered, laser-cut Mylar foils for the flexible part of the actuator by encapsulating them between the inkjet-printed layers. After dissolving the sacrificial material, a dielectric fluid can be injected in the fabricated actuators. Qualitative evaluation of a fabricated device is reported, showing electrode zipping. The presented fabrication process allows future fabrication of highly integrated actuators having arbitrary shapes.