A MEMS-Based Fast-Response Miniature Five-Hole Probe With Optical Pressure Transducers

This paper presents the first realization of a fiberoptic lever-based, miniature five-hole probe (511P) for aerodynamic flow angle sensing applications. Five MEMS optical transducers are embedded in a hemispheric probe tip to mitigate the pneumatic lag problem of conventional 511P technology. A silicon die with five optical pressure transducers of 400 μm radius is microfabricated from a silicon-on-insulator (SOI) wafer and bonded to a hemispheric tip of 5 mm diameter. The optimal transducer and probe tip designs are determined using lumped element modeling. Laser micromachining is utilized to drill micro holes of about 50 μm radius on the hemispheric tip. The optical transduction allows for remotely located electronics. This facilitates probe miniaturization and offers potential for high-temperature capability. The resulting 511P has a fast response with a modeled settling time of 0.24 ms and a measured high-frequency range of about 3.5 kHz. [2020-0182].