Controllable dry adhesion based on two-photon polymerization and replication molding for space debris removal

Space debris is a growing problem for the long-term usage of the low earth orbit. Currently no debris capture and removal method is successfully deployed in space. Anisotropic dry adhesive microstructures have a great potential to be an effectual approach for space debris capture. So far, no anisotropic dry adhesive structures have been produced with two-photon polymerization, which can then be replicated using a casting process. We 3D printed master molds with the use of two-photon polymerization and molded anisotropic dry adhesive structures with space rated polydimethylsiloxane. This paper describes the fabrication process and adhesion measurements on glass and acrylic glass surfaces. Our 3D dry adhesive microstructures showed an anisotropic adhesion factor of 7.52:1 and a maximum adhesion strength on glass and acrylic glass to be 1105.29 +/- 40.93 and 1002.72 +/- 8.24 mN/cm(2). In conclusion, two-photon polymerization and the established molding process can be used to develop new types of mass producible anisotropic dry adhesives for the use in space and other applications where a high anisotropy of the holding force is needed. This promising approach can lead to faster design studies for dry adhesive structures.