Piezocapacitive effect of a sandwich structure in a microfabricated cantilever

This paper gives insight into the origin of the piezocapacitive effect of a sandwich structure (metal-dielectric-heavily doped silicon) in a microfabricated cantilever. It implies that the mechanical stress changes both the sizes of the capacitor and the dielectric constant of the dielectric. A beam bending method was used to study the effect of the mechanical stress on the dielectric constant of Si₃N₄. The piezocapacitive effect can be used as a basic sensing technology in the MEMS devices. As an application, a novel flow rate sensor with a piezocapacitive sensing element is reported.