Figure 1 shows one of the designs used in the one-dimensional sensors. The sensors use Moiré Fringe transduction to amplify the movement on the floating element (figure 1B). The movement can be as small as tens of nanometres. LEDs and photodiodes detect the movement. The output from the photodiodes is used to directly measure the instantaneous wall-shear stress.
Laser Doppler Velocimetry (LDV) is seen as a "gold standard" measurement of fluid velocity, and can be used to indirectly measure wall-share stress. Our solution shows excellent agreement with LDV (figure 2).
