Direct-write 3D printed self-supporting flexible microstructure devices**Resrach supported by the National Science Foundation of China (No. 52005239), Guangdong Basic and Applied Basic Research Foundation (No. 2019A1515110637, No.2020A1515010165), Guangdong Province Youth Innovation Talent Project (No. 2019KQNCX076), Science and Technology Planning Project of Zhanjiang (No. 2020A01044, NO. 2020B01363, No. 20l8A02009).

Conventional 3D printing methods often require supporting structures to maintain the structure of the suspended parts in the manufacture of metamaterials, micronano arrays, micro-channels. The remaining uncured resin in the microstructure and the removal of the sacrificial layer material by post-processing are a key challenge for structural molding. Therefore, we propose a free-form-based direct writing 3D printing technology for manufacturing flexible microstructures without self-supporting materials. We proved that the 3D printed microstructure can withstand the bending moment it generates to prevent the collapse of the flexible microstructure. This method provides a new way for the manufacture of flexible microstructure devices such as soft robots, flexible sensing, biological tissues, micro-nano fluidics, and metamaterials.