Development of molecular design and fabrication technology for a new bio-compatible piezo-electric Perovskite crystal micro-actuator of Bio-MEMS medical device

在本研究中，采用先进的技术开发，设计和制造了一种新型生物相容性压电材料，用于Bio-MEMS医疗设备的生物微致动器。主要有两个研究对象；(1)利用ab-initio分子力学分析设计了一种新的三元素钙钛矿晶体结构。(2)利用螺旋波等离子溅射装置制备了生物相容性压电材料薄膜。摘要如下所示。三元生物相容性压电材料从头算分子设计研究进展。一种新型钙钛矿晶体型弹性压电材料具有良好的动态响应性能和发电性能。该材料的设计如下：(1)采用HSAB规则筛选生物相容性元件，HSAB规则是评价材料与重要DNA之一鸟嘌呤和构成蛋白质的氨基酸相互作用特性的技术。(2)利用基于容差因子法的相互作用评价技术，对钙钛矿型晶体结构的三个候选原子进行了几何搜索和选择。(3)基于密度函数分析的Ab-initio分子结构分析证实了候选晶体材料MgSiO_3的稳定性，并对其压电性能进行了评价。利用密度函数分析和电子密度分布法对立方结构和四方结构钙钛矿晶体的势能进行了评价，并进一步探讨了从立方结构到四方结构自发极化的可能性。证实了候选材料MgSiO_3在四方自发极化状态下是最稳定的，并得出MgSiO_3表现出高性能的压电特性。利用螺旋波溅射装置制备生物相容性压电材料MgSiO_3的工艺研究。本研究经费购买了螺旋波等离子体溅射（HWPS）装置，用于制备MgSiO_3钙钛矿晶体型压电材料薄膜。溅射条件的许多因素可以考虑。为了克服制造工艺寻找最佳条件的困难，提出了一种基于经验的启发式方法和基于统计分析的实验设计方法相结合的混合方案。首先，本设计的HWPS装置具有良好的真空和温度性能，没有污染物的混合，因此我们采用10^<-4>Pa的压力，射频电源和高温溅射制备了具有目标晶体结构的薄膜“沉积”。选取(1)Ar:O_2（通量比）、(2)Si的面积分数、(3)衬底温度和(4)溅射室压力4个条件进行实验设计，寻找最佳制备条件。我们采用了三个目标函数，即通过ESCA测量制备薄膜材料的体积分数，通过XRD分析评估钙钛矿晶体结构，以及通过悬臂式测试装置评估压电性能d_<31>。通过27次试验，采用正交试验法，确定了最佳工艺条件。研究了制备MgSiO_3压电薄膜的最佳条件。表示如下：(1)Ar:O_2=3:1 (0.6sccm:0.2sccm), (2) Si的面积分数=0.75,(3)衬底温度=700℃，(4)压力=8.0 × 10^<-2>Pa。少

In this research, a advanced technology development was performed to design and fabricate a new bio-compatible piezo-electric material for a bio-microactuator of Bio-MEMS medical device. There were two main research subjects ; (1)A new three elements Perovskite crystal structure was designed by using ab-initio molecular mechanics analysis. (2)A thin film of bio-cornpatible piezo-electric material was fabricated by using Helicon wave plasma sputtering apparatus. A summery is shown as below.1.Develonment of ab-initio molecular design of three elements bio-comnatible piezo-electric material.A new Perovskite crystal type elastic piezo-electric material shows a high performance of dynamic response and power generation. This material was designed as follow : (1)Selection of bio-compatible 'element was carried out by using HSAB rule, which is the Technique of evaluating interaction properties with Guanine, which is one of important DNA, and Amino acid, which constitutes protein. (2)A geometri … More cal search and selection of three candidate atoms of Perovskite type crystal structure was carried out by using the interaction evaluation technique based on the tolerance factor method. (3)Ab-initio molecular structure analysis based on the density function analysis was used to confirm the stability and evaluate piezo-electric properties of a candidate crystal material MgSiO_3. The density function analysis and the electron density distribution method evaluate potential energies of a cubic crystal structure and a tetragonal Perovskite one, and further a possibility of spontaneous polarization state from cube structure to tetragonal one is investigated. It is confirmed that the candidate material MgSiO_3 becomes the most stable in the state of tetragonal spontaneous polarization, and it is concluded that MgSiO_3 shows a high-performance of piezoelectric characteristics.2.Fabrication technology development of a bio-compatible piezo-electric material MgSiO_3 by using Helicon wave sputtering apparatus.Helicon wave plasma sputtering (HWPS) apparatus was purchased by this research grant and used to fabricate thin film of MgSiO_3 Perovskite crystal type piezo-electric material. Many factors of sputtering conditions can be considered. To overcome this difficulty to find an optimum condition for a fabrication technology, a hybrid scheme was introduced, which is combined with the heuristic method based on the experience and the experimental design method based on a statistical analysis. At first, this designed HWPS apparatus shows a high performance of vacuum and temperature without a contaminant mixing, therefore we adopted 10^<-4>Pa pressure, RF electric power and a high temperature sputtering to fabricate a thin film with a aimed crystal structure "as deposited."Four conditions, such as, (1)Ar:O_2 (flux ratio), (2)area fraction of Si, (3)substrate temperature and (4)pressure in the chamber of sputtering, were selected to carry out the experimental design method to find an optimum fabrication condition. We have employed three objective functions, such as the volume fraction of fabricated thin film material measured by ESCA, the Perovskite crystal structural evaluation measured by XRD analyses, and the piezo-electric property, d_<31>, evaluated by a cantilever type testing apparatus. A optimum fabrication condition was found by using interaction diagram, "the orthogonal diagram," through twenty seven trials. The best condition to fabricate a thin piezoelectric film of MgSiO_3. is indicated as follo9w ; (1)Ar:O_2=3:1 (0.6sccm:0.2sccm), (2)area fraction of Si=0.75, (3)Substrate temperature=700℃ and (4)Pressure=8.0x10^<-2>Pa. Less