Ultra-high-speed cantilever tactile probe for high-aspect-ratio micro metrology

A silicon cantilever-based piezoresistive tactile probe coated with an aluminum oxide (Al
₂
O
₃
) thin film in an atomic layer deposition (ALD) process is designed and fabricated to detect surface irregularities of high-aspect-ratio micro structures at ultra-high speed. Very good sensing reproducibility has been demonstrated from surface profile characterization of a micro sac direct injection (DI) Diesel nozzle spray hole at identical position but at different speeds. From the repeatable friction and wear measurements, the developed cantilever tactile sensor has been successfully used in 100 fast measurements on a 5-mm-long standard artifact surface with a speed of 15 mm/s and forces of 60-100 μN, where its results are in very good agreement with those of a calibrated stylus profilometer. Miniaturized form and roughness measuring systems based on this ultra-speed tactile sensor integrated into machine tools will help to pave the way for smart manufacturing as requested, e.g., in the frame of the German government initiative Industry 4.0.