Microscale Shock Tube

This paper reports on the design, microfabrication, characterization, and testing of the first instrumented micrometer-scale shock tube. This device was fabricated by a series of etching, deposition, and patterning processes of the different structural layers on a silicon substrate to first create an array of direct-sensing piezoelectric pressure sensors followed by the bonding of another substrate to create a microchannel. The resulting assembly is a rectangular channel with a hydraulic diameter of 34 μm and a length of 2000 μm, instrumented with five wall pressure sensors along its length. This device is used to characterize, for the first time, the propagation of shock waves at microscales, where transport effects such as wall friction and heat transfer are important. The results show shock-wave attenuation along the length of the microchannel in accordance with simple analytical models for these flows.