GOALI: Development of Metallic MEMS Materials for Extreme Environments

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Non-technical Summary: Over the past several decades micro-devices and microelectromechanical systems (MEMS) have found uses as ink jet printers, accelerometers, gyroscopes, pressure sensors, and digital light projectors and have become a multi-billion dollar industry. This study is motivated by the fact that a broader spectrum of MEMS materials would offer a wider range of functionality and fuel a greatly expanded assortment of MEMS applications. Elevated temperature MEMS devices are of particular interest in: aviation, automotive, power generation, sub-sea drilling, and chemical processing industries in which MEMS sensing and guidance in harsh environments would provide enhanced feedback and control. Metal MEMS alloys that offer: high density, electrical and thermal conductivity, strength, ductility and toughness; low cost; and fabrication routes for complex geometries would be especially attractive for these applications. But, highly engineered metallic alloys that can be sculpted with submicron resolution are currently not in the suite of available MEMS materials. For this reason, an interdisciplinary team from Johns Hopkins University (JHU) and General Electric Global Research (GEGR) has been formed to undertaking a collaborative program to develop Metal MEMS alloys for use as high temperature MEMS sensors and micro-switches. Extended internships at GEGR will provide students with an invaluable perspective on systems level materials integration. Participation in the SABES outreach program (an NSF-sponsored partnership between JHU and Baltimore City Public Schools) also provides the PI and his students with the chance to pay it forward by giving Baltimore elementary school students a unique perspective on STEM activities.Technical Summary:An interdisciplinary team from Johns Hopkins University (JHU) and General Electric Global Research (GEGR)is undertaking a collaborative program to develop metal MEMS alloys for high temperature MEMS sensors and micro-switches. The motivation for this collaboration lies in the desire to expand the MEMS material set beyond silicon to metallic alloys that can be deposited and shaped on the micro-scale and offer an attractive balance of properties: electrical and thermal conductivity, high density, low thermal expansion, strength, ductility, and toughness. The intellectual challenges to be addressed include the establishment of a science-based protocol for developing metal MEMS alloys that possess requisite physical and mechanical properties and can be used in extreme environments, e.g. temperatures of 300-500ºC for operational lifetimes exceeding one year. Candidate single- and multi-phase alloys have been identified and are being used to improve scientific understanding in five areas: (i) techniques for processing and shaping metallic alloys at the micro-scale, (ii) alloy design for dimensional stability, (iii) unique microstructure-mechanical property pathways and relations in alloys deposited far-from-equilibrium, (iv) thermal and mechanical drivers for microstructural evolution, and (v) integration of metal MEMS alloys into commercial applications. Fundamental processing-structure-properties studies at JHU have been designed to provide a foundation for concurrent GEGR efforts on the development of next-generation MEMS switches and sensors. Extended internships at GEGR are planned and will provide the visiting graduate student with an invaluable perspective on systems level materials integration. Moreover, participation in the SABES program (an established NSF-sponsored partnership between JHU and Baltimore City Public Schools) provides the PI and his students the chance to give Baltimore elementary school students a unique perspective on STEM research.