Microfabricated thin-film physical sensors for hostile environment

Advanced microfabricated thin film sensors are being developed to provide accurate temperature, heat flux and strain measurements for use in hostile propulsion environments. These sensors are sputter deposited and microfabricated directly onto the test articles with no additional bonding agent. The thickness of the sensors is only a few micrometers, which creates minimal disturbance of the gas flow over the test surface. Thus thin film sensors have the advantage over conventional wire-based sensors by providing minimally intrusive measurement and having a faster response. These microfabricated thin film sensors are being developed for characterization of advanced materials and structures in hostile, high-temperature environments, and for validation of design codes. This paper presents the advances of microfabricated physical sensor technologies developed at NASA Lewis Research Center: thermocouples, heat-flux gages and resistance strain gages. The fabrication techniques of these thin film sensors are described. Sensor demonstrations on a variety of engine materials in several hostile, high-temperature test environments are presented. The advantages and limitations of thin film sensor technology are also discussed