Failure Assessment In Aerospace Systems Via Integrated Multi-functional Sensors

Integrated sensors fabricated on flexible substrates show lots of promise due to their ability to conform on non-planar surfaces. Potential applications could be smart-skin and wearable electronics which can be used on prosthetic devices or in harsh environments to provide with the sense of feel of the ambient. Design, fabrication and characterization of MEMS piezoresistive pressure sensors and capacitive accelerometers were done on Si and flexible polymer substrates using surface micromachining to be used on aerospace applications. Devices were successfully tested on planar surfaces.For the pressure sensor fabrication, Si3N4 was used as a membrane material due to its linearity and high elasticity while polysilicon was used as a piezoresistive material because of its high gauge factor as well as linear response. Response measurements of fabricated devices resulted in slightly lower values compared to the ones obtained from simulations.Accelerometer fabrication was done with UV-LIGA (Ultra-violet Lithographie, Galvanoformung, Abformung). Ni was used as a proof mass because of its relatively high density and corrosion resistance. Response measurements of fabricated accelerometers resulted in higher values compared to simulated ones. Although there was difference between simulated and fabricated responses, device measurements on Si and flexible substrates showed comparable values.