Contact Mechanics, the discipline that studies how objects interact when in contact, is of primary importance in several fields of science. Determining the forces transmitted when two objects are in contact enables the design of machine elements, robotic arms, tires, touchscreens, seals, washers, shoes, and brakes. SURFACE focuses on “soft contacts”, i.e. on contact scenarios involving materials such as rubbers, silicones, and hydrogels. This class of materials is attracting attention in the scientific community due to their crucial role in the development of cutting-edge technologies, including robotics, space tools, climbing robots, grasping systems, and manipulators. Traditionally, object manipulation has relied on energy-intensive systems like electromagnets, suction cups, and adhesives. However, manipulators that use electromagnets work only with ferromagnetic materials, suction cups fail in a vacuum, and adhesives leave residues on interfaces and are not reversible. High-level interactions between humans and robots, on the other hand, require compliant intrinsically safe materials and the capability for rapid regulation of interfacial forces, particularly adhesion. Bioinspiration has led researchers to design patterned interfaces at the micrometric scale that exploit fundamental interactions between materials, such as van der Waals forces, which occur at the nanometer scale. By imitating nature solutions as in geckos and lizards, researchers have achieved high levels of stickiness. However, the challenge remains to efficiently detach the mating interfaces, which is crucial for manipulation tasks. An alternative mechanism for adhesion enhancement exploits the viscoelastic nature of soft materials, using high-frequency, low-amplitude vibrations to excite the soft substrate. SURFACE aims to advance the state of the art in adhesion regulation by leveraging both the surface’s micrometric geometry and the viscoelastic properties of materials. The objective is to develop a metasurface whose adhesive behavior can be actively regulated in real time. By exploiting van der Waals interactions, SURFACE's working principle is not limited to ferromagnetic materials, functions in vacuum or outer space, leaves no chemical residues on contacting objects, and, by adopting soft polymers, is inherently safe for human-robot interaction. The objectives of SURFACE are to deepen our understanding of the rate-dependent adhesion properties of soft viscoelastic materials, focusing on how geometrical parameters, material properties, and loading protocols influence stickiness. To achieve this, SURFACE plans to: (i) develop efficient contact algorithms to simulate adhesive interactions with high spatial and temporal resolution, (ii) exploit the coupling effects between adhesion and viscoelasticity to understand how these mechanisms influence macroscopic adhesion properties, (iii) leverage machine learning to predict and optimize adhesion performance, (iv) validate numerical and theoretical findings through experimental tests. SURFACE's results are relevant to the fields of soft robotics, space exploration, and disaster relief, enabling the creation of lightweight, reusable, and reversible adhesive systems. By addressing both scientific and technological challenges, the project aspires to bridge the gap between theory and application, advancing the state of the art in adhesive technology.
