Additive manufacturing of flexible 3D surface electrodes for electrostatic adhesion control and smart robotic gripping

TLDR

Mechanically flexible surface structures with embedded conductive electrodes are attractive for contact‑based devices, but their adhesion and sensing performance is limited by fabrication‑restricted geometries. The authors additively manufacture elastomeric structure arrays with diverse angles, shapes, and sizes and integrate conductive nanowire electrodes. They designed soft, anisotropic structures that mimic gecko adhesion and integrated nanowires to manipulate localized electric fields, enabling digital tuning of electrostatic attraction. The resulting flexible 3D surface electrodes are mechanically compliant, electrically conductive, can sense touch and contact force, and enable a soft gripper that grasps diverse objects with 72% greater electroadhesive force when voltage is applied.

Abstract

Abstract Mechanically flexible surface structures with embedded conductive electrodes are attractive in contact-based devices, such as those used in reversible dry/adhesion and tactile sensing. Geometrical shapes of the surface structures strongly determine the contact behavior and therefore the resulting adhesion and sensing functionalities; however, available features are often restricted by fabrication techniques. Here, we additively manufacture elastomeric structure arrays with diverse angles, shapes, and sizes; this is followed by integration of conductive nanowire electrodes. The fabricated flexible three-dimensional (3D) surface electrodes are mechanically compliant and electrically conductive, providing multifunctional ability to sense touch and to switch adhesion via a combined effect of shear- and electro adhesives. We designed soft, anisotropic flexible structures to mimic the gecko’s reversible adhesion, which is governed by van der Waals forces; we integrated nanowires to further manipulate the localized electric field among the adjacent flexible 3D surface electrodes to provide additional means to digitally tune the electrostatic attraction at the contact interface. In addition, the composite surface can sense the contact force via capacitive sensing. Using our flexible 3D surface electrodes, we demonstrate a complete soft gripper that can grasp diverse convex objects, including metal, ceramic, and plastic products, as well as fresh fruits, and that exhibits 72% greater electroadhesive gripping force when voltage is applied.