Direct Fabrication of Metallic Microgear via Electrohydrodynamic Inkjet 3D Printing

Microgear is used to transmit power and motion. It is one of the key elements in various microdevices which have been successfully implanted with a wide range of application areas such as microfluidic, medical equipment, and biotechnology. A variety of techniques have been developed to realize both light-weight and high-strength microgear manufacturing. However, those techniques often contain hazard substances with many complex procedures. Extreme conditions such as ultrahigh temperature and pressure are also often required. Herein, a direct fabrication of a metallic microgear using electrohydrodynamic inkjet 3D printing with silver nanoparticles (Ag-NPs) is demonstrated. Both printing resolution and microgear surface morphology are enhanced by controlling printing parameters such as dot diameter and pitch. The microgear with excellent surface finish can be obtained. Its teeth face has an average surface roughness (R_a) of 200 nm after optimization of the printing condition. After the printing process, a post-thermal curing process with different curing temperatures is conducted to improve its mechanical properties. Finally, the printed microgear has a hardness of 210 MPa and yield stress over 200 MPa due to Ag-NP aggregation during thermal curing.