Slender Tactile Sensor for High-Aspect-Ratio Micro Metrology

A tactile probe sensor was addressed which was designed for quality assurance of high-aspect ratio micro parts, e.g. engineered apertures of fuel nozzles. It was constructed as an extremely slender silicon cantilever of 1-5 mm in length, 30-200 mum in width and 25-50 mum in height comprising a pyramid-shape probing tip and a piezoresistive strain gauge for signal read out. The tactile sensor can be operated at scanning speeds several orders of magnitude higher than conventional atomic force microscopes offering mm scanning range at mum lateral resolution. The 5-mm-long cantilever can be deflected vertically by 200 mum exhibiting a non-linearity of 0.3 %FS and nanometer resolution at high sampling rates in the kHz range. Cross sensitivity vs. temperature and ambient light referred to deflection is below 10 nm at typical measurement conditions of temperature and light intensity variations of 1 K and 0.1 mW/cm², respectively.