A STUDY ON PIEZOELECTRIC NANOCRYSTALS FOR DETECTION OF ULTRA-SMALL APPLIED MECHANICAL PRESSURES

Detection of ultra-small mechanical pressures in an atmospheric environment is of a high technological interest in various applications such as medical diagnosis, gas leakage detection and artificial intelligence. The piezoelectric effect enables detection of a mechanical pressure by a change of the materials dielectric polarization. This research reports on detection of ultra-small mechanical pressures in an atmospheric environment, using low dielectric permittivity piezoelectric nanocrystals embedded inside alumina pores on flexible metal substrates.

The talk will focus on Sodium Nitrite (SN) nanocrystals grown by precipitation from a liquid solution inside nano-pores made of amorphous alumina. The SN crystals were grown with controlled preferred crystallographic orientations along the longitudinal axis of the pores. The SN crystals exhibited a high sensitivity to ultra-low mechanical pressures (lower than 1 Pa). Their sensitivity to applied mechanical pressure depends on their crystallographic orientation. An asymmetric piezoelectric response to compressive vs. tensile applied pressures were found and explained based on the SN molecular structure and dielectric polarizability. The talk includes a detailed description of the preparation methods of the samples, their microstructure and piezoelectric characteristics and a discussion on the advantages of utilizing nanocrystals inside a porous alumina in improving the ability to detect ultra-small applied mechanical pressures.