Investigating the Potentials of A MEMS-based Sensory Platform Health Monitoring of Critical Systems

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The utilization of piezoresistivity (PR) in silicon has attracted many researchers to develop different types of sensing mechanisms for measuring physical phenomena such as deformation, stress, force and/or acceleration. Specifically, Micro and Nano Electro-mechanical Systems (MEMS/NEMS) PR has been utilized to develop external force and internal stress and strain sensors for applications in mining, oil and gas, aerospace, civil, electronic packaging, bio-mechanics, water flow and composite materials. Stress monitoring and analysis is considered a unique branch of engineering, which determines and improves the mechanical strength of structures and machines. With experimental stress analysis it is possible to know the stress distribution in a machine component in actual operation without knowing the applied forces acting on the part under these conditions, which is major improvement over analytical and numerical methods; and is essential for Structural Health Monitoring (SHM) involving potential damage detection and the following phases of condition-based maintenance and failure prevention of critical aging structures. Monitoring stresses and strains levels and internal forces are considered key performance parameters for the analysis of fatigue strength. Most available strain and force sensory are single direction and usually is combined with other sensors to allow for 2D (in-plane) measurements; resulting in a bigger footprint with low gauge factor. Achieving a three-dimensional (3D) strain or force sensing with typical sensory techniques requires even larger foot print with significant challenges in instrumentation. This proposal builds on our current breakthrough in achieving a 10-Element PR rosette capable of sensing the full stress picture in 3D. This MEMS based concept is based on manipulating the doping concentration over n-Si (1 1 1) plan to achieve a list of linear independent equation capable of detecting the in-plane and out of plane normal and shear stresses applied on the sensor chip; with the potential to be equipped with temperature compensation to operate accurately in tough environmental conditions. This proposal improves the fabrication of the 3D stress rosette to achieve higher sensitivity in out of plan normal stress and to enhance the signal to noise ratio achieved in other directions of the stresses. This will allow for the rosette to be used further as the backbone substrate to improve another technology of our team, a 3D load sensor platform, which has the potential to be used in various tactile and consumer electronics applications. The use of high gauge factor MEMS--based PR in building our 3D stress and load sensory platforms allow it to be optimum approach to increase its sensitivity level while using less energy to operate; which is a need in many remote sensing wireless systems and consumer electronics applications, such as smart touch screen and phones.