Design and Fabrication of Micro-Pillar Based Piezoresistive Flow Sensors

This study is focused on developing a new type of micro-scale gas flow sensors to be used in critical environments such as combustion engines with high pressure high temperature gas flow and integrated micro electro mechanical applications such as lab-on-chip devices. Proposed flow sensor is based on piezoresistivity of Silicon micro column cantilever. Change in resistivity tensor due to gas flow induced stress in the piezoresistive layer results in generating of an output voltage proportional to the gas flow rate in the channel. Current results show that the anisotropic properties of the Silicon can be successfully used in the gas flow sensor to differentiate flow components in different directions. Furthermore the model demonstrates its applicability in measuring local flow fields in high resolution due to its micro-scale dimensions. Fabrication of the Flow sensor is carried out at the Center for Functional nanomaterials at Brookhaven National Laboratory and Friedrich Schiller University in Germany. With fundamental understanding obtained by the parameter analysis and the experimental process developed for the device fabrication this study provides a useful and timely guidance in designing and fabricating flow sensors with ability to differentiate between local flow directional components at high spatial resolution