Experimental results of a controllable electrostatic/gecko-like adhesive on space materials

Abstract

Many space applications, such as docking, satellite capture, or robotic inspection, could benefit from the use of a controllable (i.e. on-off) adhesive capable of functioning on a wide range of surfaces. This paper focuses on the experimental results of such an adhesive, which combines the benefits of both electrostatic and directional dry adhesives (i.e. gecko-like adhesives). The electrostatic element consists of a conductive electrode pattern embedded inside a soft silicone polymer dielectric. Between the electrodes and the substrate lies a dry adhesive element comprised of directional fibrillar structures. The combination of these two technologies creates a positive feedback cycle in which, depending on surface roughness and material, adhesive levels can be greater than the sum of the two individual technologies. The electrostatic adhesive serves to initially engage the micro-wedges with the surface substrate. As they engage, the micro-wedges bring the electrostatic element closer to the surface, which further increases its adhesion. This consequently allows more of the dry adhesive micro-wedges to engage, particularly on rough surfaces. This paper presents the results of experimental testing of these adhesives over a range of different space-grade materials. These include different paints, composites, and blankets. Results show that the hybrid adhesive performs up to 7.1× greater than electrostatic adhesives alone.