Development of Bio-Compatible Piezo-Electric Ultra Thin Film Fabrication Technologies for Implantable Nano-Actuator

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In this research, we have developed (1) a crystallographic process design algorithm based on the ab-initio molecular mechanics and the homogenization finite element analyses, (2) a sputtering process technique to generate a newly designed biocompatible piezoelectric material MgSiO_3 for the nano-actuator, and (3) the piezoelectric characterization techniques to qualify the promised functions for a nano-actuator, as described below;1. Development of ab-initio・triple-scale simulation based bio-compatible piezo-electric material design system: A new biocompatible Perovskite crystal type elastic piezo-electric material was invented by employing a newly developed triple-scale analyses based design system. We found a candidate bio-compatible piezo-electric crystal material MgSiO_3. Further, the process crystallographic analysis algorithm was developed to find an optimum crystal structure of substrates for MgSiO_3 tetragonal structure, such as Ir and Cu.2. Material process technology developm … More ent of a bio-compatible piezo-electric ultra-thin MgSiO_3 film by using Helicon wave sputtering apparatus.An optimum condition of HWPS fabrication process to generate MgSiO_3 tetragonal perovskite structure was sought by using the experimental design method, the surface response method and the interpolation method. Finally, we found 1) the substrate temperature 613℃, 2) the target ratio 40.2% and the post annealing temperature 663℃.3. Piezo-electric properties evaluations of a newly fabricated ultra-thin MgSiO_3 film. :We evaluated piezo-electric properties of MgSiO_3 films by employing (1) the chemical compositions by the XPS, (2) the crystal structure by XRD・EBSD, (3) Surface morphology properties by SEM・AFM and (4) a piezo-electric constant d_<33> by using the AFM piezoelectric tester and a "double-beam" nano-vibration tester. It shows the piezoelectric constant d_<33>=2.70pm/V in the case of the high temperature sputtering, and further d_<33>=29.8pm/V in case of the combined process of low temperature sputtering at 613℃ and high temperature annealing at 663℃. Less