Nano-scale thermal anemometry probe

A nano-scale thermal anemometry probe is being developed with high spatial and temporal resolution to measure small-scale turbulence in high Reynolds number flows. Manufactured using a combination of semiconductor and micro-electromechanical manufacturing processes, current models of the probe consist of a platinum sensing wire of length of 60$\times $1$\times $0.1 $\mu $m suspended between two contact pads. Future versions of the probe will have their sensing length reduced, through the use of focused ion beam milling, to 20$\times $0.1$\times $0.1 $\mu $m. Preliminary comparison has been made in a low turbulence free-stream between a conventional hot-wire probe and a nano-scale probe before reshaping of the supporting silicon substrate. Despite $\sim $100 $\mu $m of silicon protruding alongside of the free-standing wire, results showed that the two probes had similar static response with qualitatively higher frequency response observed for the nano-scale probe.