3D printed microstructures handling by ultra-conformable freestanding polymeric membranes

With the introduction of 2-photon lithography, it has become possible to fabricate detailed 3D structures with sub-micrometer precision. To widen the prospect of potential applications, we have overcome an important limitation of the current 2PP technology: the lack of post-fabrication handling possibilities. Our method exploits thin, ultra-conformable parylene films as freestanding supports for microstructures. These separate the microstructures from the flat support used for 2PP and allow, by a simple and elegant method, to wrap arrays of structures around geometrically complex shapes, a previously very difficult challenge. The method follows from previous work by our group on conformable freestanding capacitors based on polyvinyl formal films instead of parylene. [1] The preparation of the substrate films for this work, involves chemical vapor deposition of the parylene dimer resulting in a polymerized coating on top of a glass or silicon support (Fig. 1). After fabrication of 3D structures, the coating delaminates from the glass coating by slow immerging in water under an angle and light pulling. From there, we could transfer the floating film to a new support such as a thin needle. Since the films are so thin (<400 µm), they strongly attach to the new support due to vanderwaals-forces. In this project, we have exploited the possibilities and limitations of the new microstructure handling technique, shown its ultra-conformability, fabricated in-air floating membranes with structures on top and, as a follow up of previous work from our group [2], developed a structure pattern that can retain air on a curved surface.