The technique for measuring the wall shear stress accurately is developed with two types of micro-scale sensor fabricated with MEMS technique. One of the sensors is a thermal type sensor which is based on the quantity of heat diffusion from thin hot film (hereafter called "HF sensor"). The other is a floating type sensor which is based on the electric capacity variety by displacement of the floating element (hereafter called "FE sensor"). To calibrate these sensors, two types of calibration instruments are manufactured. One is an instrument which generates the flow by rotating the cylinder above the flat plate (hereafter called "Cylinder instrument"). Another is an instrument which generates the wall shear stress by Stokes Layer using plane acoustic wave is used (hereafter called "Stokes Layer instrument"). The result of HF sensor calibration shows that the sensor output increases with wall shear stress. Moreover, the square of the sensor output voltage is proportional to 1/3 power of wall shear stress on the hot film, which is consistent with the heat transfer theory. The preliminary experiment results of FE sensor indicates that sensor output voltage seems to increase with the wall shear stress.
