Residual-stress-balanced piezoelectric film based direction sensitive flow shear-stress sensor for quadcopter navigation

This paper presents an innovative piezoelectric thin-film based flow shear stress sensor fabricated by micromachining and stereolithography (Fig. 1). The sensor has three novelties: (1) Use hydrothermal method to simultaneously grow lead zirconate titanate (PZT) films on both sides of micromachined titanium cantilever beams. This results in an approximately zero stress gradient in the thickness direction of the sensing beam due to residue stress balance. (2) Directly fabricate 3-dimensional high aspect ratio structure array on the micromachined planar structure by sterorelithograhy. This allows the measurands effectively to couple with the sensing beams. (3) Using the unique 3D photopolymer structure array for sensing coupling, the detected flow direction and the shear stress caused by measured flow can be identified and evaluated. The detailed fabrication process and preliminary characterization results are described.