Near-Field Electrospray Microprinting of Polymer-Derived Ceramics

Ceramic microelectromechanical systems (MEMS) sensors are potentially game-changing devices in many applications in high-temperature and corrosive environments, where the use of conventional MEMS materials such as silicon is prohibited. However, the microfabrication of ceramic MEMS devices remains a major technical challenge. Here, we report a method to directly print micro ceramic patterns using near-field electrospray (ES) of polymer-derived ceramics (PDCs). We demonstrated that the viscous ceramic precursor liquids can be printed reliably without any clogging problem. The spray self-expansion due to Coulombic repulsion force among charged droplets can be suppressed by decreasing the droplet residence time in space. A spray expansion model is used to predict the line width, and the results are in decent agreement with the experiments. We demonstrated a 1-D printed polymer feature as narrow as 35 mu m and a micro pentagram pattern. Moreover, after the pyrolysis of PDC at 1100 degrees C in nitrogen, amorphous alloys of silicon, carbon, and nitrogen (SiCN) are obtained. The samples show good integrity and adhesion to the substrate. The near-field ES PDC printing can become a useful addition to the toolbox of high-temperature MEMS.