Advanced Electro-active Dry Adhesive Actuated by an Artificial Muscle Constructed from an Ionic Polymer Metal Composite Reinforced with Nitrogen-doped Carbon Nanocages

Abstract

An advanced electro-active dry adhesive, which was composed of a mushroom-shaped fibrillar dry adhesive array actuated by an Ionic Polymer Metal Composite (IPMC) artificial muscle reinforced with nitrogen-doped carbon nanocages (NCNCs), was developed to imitate the actuation of a gecko's toe. The properties of the NCNC-reinforced Nafion membrane, the electro-mechanical properties of the NCNC-reinforced IPMC, and the related electro-active adhesion ability were investigated. The NCNCs were uniformly dispersed in the 0.1 wt% NCNC/Nafion membrane, and there was a seamless connection with no clear interface between the dry adhesive and the IPMC. Our 0.1 wt% NCNC/Nafion-IPMC actuator shows a displacement and force that are 1.6 – 2 times higher than those of the recast Nafion-IPMC. This is due to the increased water uptake (25.39%) and tensile strength (24.5 MPa) of the specific 3D hollow NCNC-reinforced Nafion membrane, as well as interactions between the NCNCs and the sulfonated groups of the Nafion. The NCNC/Nafion-IPMC was used to effectively actuate the mushroom-shaped dry adhesive. The normal adhesion forces were 7.85 mN, 12.1 mN, and 51.7 mN at sinusoidal voltages of 1.5 V, 2.5 V, and 3.5 V, respectively, at 0.1 Hz. Under the bionic leg trail, the normal and shear forces were approximately 713.5 mN (159 mN·cm−2) and 1256.6 mN (279 mN·cm−2), respectively, which satisfy the required adhesion. This new electro-active dry adhesive can be applied for active, distributed actuation and flexible grip in robots.