Bioinspired design of functional optical structures

本论文将探索以植物细胞组织为三维形态发生模板，在微米和亚微米尺度上制作光学功能材料的微结构图案。本文研究了以稀土掺杂碱土铝酸盐为基的X射线存储荧光粉（XRSP）陶瓷的高取向波导柱的随机和周期性阵列的制备。高分辨率X射线成像系统在医疗诊断系统以及包括质量控制、材料科学或安全检查的各种其他领域中具有越来越重要的意义。采用并列复眼的原理，其中各个微透镜面和波导元件彼此光学隔离，生物模板XRSP阵列为优化X射线存储成像系统的空间分辨率提供了很大的潜力。从裸子植物中选择具有三维孔道形态的生物模板，使其具有均匀的管胞解剖结构。扩散流反应器将用于控制模板膜中的材料传输和局部离子浓度。要解决的主要科学问题集中在控制微结构形成的生物模板的作用。虽然单个细胞形态提供了用于控制孔腔（大单晶域）或细胞壁（纳米晶体）中的成核和晶体生长的独特隔室，但组织解剖学应该确定柱阵列中的几何排列。虽然实验工作集中在SrAl2O4：Eu被加工成XRSP阵列，但通过使用三维形态发生生物模板的微结构图案化的原理可能对其他陶瓷材料系统和应用（例如大面积压电传感器和致动器阵列）越来越感兴趣。

The application of cellular plant tissue as three-dimensional morphogenetic template for microstructure patterning of optical functional materials in the μm and sub-μm length scale will be explored. Processing of random as well as periodical arrays of highly oriented wave guide pillars of X-ray storage phosphor (XRSP) cera-mics based on rare earth doped earth alkaline aluminate will be investigated. High resolution X-ray imaging systems are of increasing importance in medical diagnosis systems as well as various other fields including quality control, materials science or security inspection. Adopting the principle of apposition compound eyes, where the individual microlens facets and wave guiding elements are optically isolated from one another, the biotemplated XRSP arrays offer a high potential for optimising spatial resolution of X-ray storage imaging systems. Biotemplates of suitable three dimen-sional pore channel morphology will be selected from Gymnospermae which offer a uniform tracheidal cell anatomy. A diffusional flow reactor will be used to control ma-terial transport and local ion concentration in the template membrane. Major scientific questions to be addressed centre on the role of the biotemplate for governing the microstructure formation. While the individual cell morphology provides a unique compartment for controlling nucleation and crystal growth in the pore lumae (large single crystalline domains) or in the cell wall (nano crystalline), the tissue anatomy is supposed to determine the geometrical arrangement in the pillar arrays. Though experimental work concentrates on SrAl2O4:Eu to be processed into XRSP arrays the principles of microstructure patterning by use of three dimensional morphogenetic biotemplates might be of increasing interest for other ceramic material systems and applications such as for example large area piezoelectric sensor and actuator arrays.