A Study on Bio-Compatible Piezoelectric Materials by First Principles Calculation

Abstract

Bio-compatible piezoelectric materials are becoming increasingly important for actuators and sensors in medical devices, that is Bio-MEMS such as health monitoring systems and drag delivery systems. In this study, we challenged to search new piezoelectric materials with bio-compatibility by first principles calculation. Firstly, constituent atoms of bio-compatible piezoelectric materials have been specified by HSAB method from the viewpoint of interaction energy with in vivo molecules. Secondly, in order to create a perovskite-type crystal structure with good piezoelectric response, the combination of bio-compatible atoms was selected to satisfy geometric stable condition defined by tolerance factor. As a result, we discovered 7 kinds of new piezoelectric materials. One of them, MgSiO3 is known to be a mineral with perovskite-type crystal structure, but it has never been applied to piezoelectric materials. Therefore, we focused on MgSiO3 as a candidate for biocompatible piezoelectric materials, and then the stable cubic and asymmetric tetragonal structures of MgSiO3 were analyzed by first principles DFT. Finally, structural phase transition of MgSiO3 has been investigated on the assumption of linear structural change from cubic structure to tetragonal one. DFT calculation indicated that MgSiO3 can change spontaneously to tetragonal structure with electric polarization, and that MgSiO3 can present a good piezoelectricity.