Epitaxial AIN/AIN bimorph piezocantilevers for geothermal monitoring

Abstract

The problem of early and reliable prediction of earthquakes, which can lead to catastrophic consequences, is far from being solved, so it remains extremely topical. The next step towards its solution, as it is supposed, could be the creation of a network of sensors located in the hot deep layers of geothermal systems and capable of continuous monitoring of geophysical parameters characterizing the activity of magma. In this paper we propose the use of matrices of thermally stable bimorph piezocantilevers formed on the basis of epitaxial AlN/AlN structures and allowing the possibility of excitation of acoustic waves of various types as a universal platform for the subsequent creation of various sensors capable of operating in high-temperature and chemically aggressive environments. Since in static modes the main manifestation of the inverse piezo effect is the appearance of bending deformations, for preliminary estimation of the geometrical parameters of such cantilevers, a mathematical model of the change in the deflection value was constructed, and a computational algorithm (MATLAB environment) was developed to make it possible to obtain the optimal ratios between the thicknesses of active AlN layers from the point of view of minimizing the control stresses.