Direct fabrication of polymer-metal microstructures for micro coils

A two-photon stereolithgraphy process is an effective method to fabricate 3D polymer microstructures. However, additional functionality, such as electrical conductivity, must be realized to allow them to be used in functional micro-devices. Electrical conductivity is a fundamental requirement for transferring signals and powering microsystems. We report a method for the direct fabrication of complex 3D polymer-metal microstructures. Patterning a hybrid material (a polymer and a metal coatable polymer) in chosen regions is achieved by a two-photon stereolithography process using a dual-stage scanning system. Selective metallization of the metal coatable polymer structure is performed through silver deposition by electroless plating. This process can produce arbitrary 3D polymer-metal hybrid microstructures with high resolution. In this paper, a 3D micro coil structure with an arbitrary shape is demonstrated. The fabricated 3D micro coil is operated at 25.4 GHz, which is useful for compact wireless communication devices, wireless power transmission, and small antennas.