Facile Handling of 3D Two-Photon Polymerized Microstructures by Ultra-Conformable Freestanding Polymeric Membranes

Micro-nano-fabrication on objects with complex surfaces is essential for the development of technologies in the growing fields of flexible electronics and photonics. Various strategies are devised to extend the fabrication from conventional planar substrates to curved ones, however, significant challenges still exist, especially in the framework of 3D printing and additive manufacturing. In this study, a novel technique is presented to realize 3D micro-structures on arbitrary complex surfaces providing an extreme level of conformability. This method relies on the fabrication of micro-structures via two-photon polymerization on polymeric nano-membranes that can be efficiently transferred to a specific target. Ultra-thin polymeric films are exploited as the support to suspend and transfer the printed micro-structures on the predefined surface. The nanofilm can finally be easily removed, apart from the region underneath the printed elements where it serves as a few tens of nanometers adhesive. The repeatability and feasibility of the proposed process are investigated and shown to provide large flexibility of choice on the printed structures, materials used, transfer procedures, and targeted substrate geometries. By integration with standard fabrication processes, the described technique offers a great potential for the development of next-generation multidimensional/multi-material micro-nano-technologies.