Characterization on the fatigue performance of a piezoelectric microvalve with a microfabricated silicon valve seat

We have developed a piezoelectric microvalve with a silicon seat for the propulsion system of a micro-satellite. The silicon seat is fabricated with narrow sealing rings to reduce internal leaks. The fatigue performance of the silicon seat is characterized. The lifetime of the silicon seat without coating is approximately 25 000 times, which cannot meet the requirement for astronautic applications. To improve its fatigue performance, the silicon seat is deposited with Cu and parylene, respectively. The two seats both meet the sealing requirement after 10⁵ cycle operation. Several rings of the seats deposited with Cu fractured after the fatigue tests, whereas none of the rings of the seats deposited with parylene fractured due to the obvious reduction of the impact stress.