$\hbox {MnO}_{2}$ Nanowire Embedded Hydrogen Peroxide Monopropellant MEMS Thruster

Feasibility of chemically synthesized MnO₂ nanowire catalyst embedded silicon microelectromechanical systems (MEMS) H₂O₂ monopropellant microthruster has been demonstrated. Due to exothermic reaction process, sustenance of thrust generation does not require any heating of propellant thus minimizing electrical power requirement. The thruster device integrates inlet nozzle, microchannel, MnO₂ nanowire embedded reaction chamber, in-plane exit nozzle and a microheater in the silicon layer. Nozzle configuration and catalyst bed was designed using simple analytical equations to achieve complete decomposition of H₂ O₂ and maximum thrust force by controlling the propellant flow. Simulation of hydrogen peroxide decomposition process was carried out to evaluate the thermo-chemical characteristics. The MnO₂ nanowire has been obtained using a low-cost synthesis process and characterized using field emission scanning electron microscopy, Energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction studies. Thruster fabrication using micromachining process and its testing have been briefly described. The device is capable to produce 1 mN thrust and specific impulse of 180 s using 50 wt.% concentrated H₂O₂ of flow rate 1.25 mg/s with total ignition energy of 44 J required for preheating the catalyst bed. Detailed thrust measurement was carried out with propellant mass flow rate for different throat area of exit nozzle, and the results were interpreted with theoretical model.