数字超材料及其对太赫兹波的调控

Cancer is a medical problem that is urgently needed to be solved. In the past 30 years, the effect of surgical treatment for many types of cancer has not been improved significantly, because the boundary of tumor tissues cannot be accurately determined during surgery. Another problem lies in that the patients’ surgery time is greatly extended by the method currently being used, i.e. HE staining method, as it needs patients on the operation table waiting 40 mins to get the test results. Therefore, the development of a rapid medical imaging diagnostic technology is very necessary. Terahertz wave have low photon energy and capability of distinguishing between tumor tissue and normal tissue. In this application, we plan to carry out the theoretical and experimental research on the new principles of manipulating electromagnetic wave utilizing digital metamaterial, solve the key scientific problems including the design of the unit cell of highly efficient and tunable digital metamaterials and top-down or "reverse mode" design and optimization of digital metamaterials. We will also employ the liquid crystal material with a large birefringence effect which was independently developed by Nanjing University for the electronic control components, and finally achieve the efficient and fast modulation of terahertz wave. Based on the above technology, we plan to build a rapid terahertz imaging demonstration system, realize the high speed and high resolution imaging of the samples, verify the design and control mechanism of digital metamaterials, and explore its application in medical imaging.

癌症是目前人类亟待攻克的医学难题,在过去的30年中，很多类型癌症的手术治疗效果没有明显改善，这是因为在手术中不能很准确地确定肿瘤组织的边界，还有目前采用的办法是HE染色法，这个过程需要40分钟，这期间病人只能在手术台上等候检测的结果，大大延长病人手术的时间，因此发展一种快速成像诊断技术是十分必要的。太赫兹波具有光子能量低，可区分肿瘤组织和正常组织等特点。在本申请中，我们拟开展数字超材料电磁波调控新原理的理论和实验研究，通过解决高效可调节数字超材料单元结构的设计和自上而下“逆向方式”的数字超材料整体的综合设计和优化的关键科学问题，利用南京大学自主开发的具有大双折射效应的液晶材料为电控元件，实现对THz波的高效和快速调制。再搭建一个基于上述技术的快速太赫兹成像演示系统，实现对样品的高速、高分辨成像，验证数字超材料的设计和调控机理，探索其在医学成像中的应用。

太赫兹波是电磁频谱中唯一尚待开发的频段，拥有丰富指纹谱特征、穿透性好、非电离辐射的太赫兹波在生物医学成像、安全、无损探测、通信等领域展现了巨大的应用价值。太赫兹数字编码和可编程超材料具有灵活精准的空间调制能力，是太赫兹技术发展的主要方向。本项目中，团队开展了数字超材料电磁波调控新原理的理论和实验研究，解决了高效可调数字超材料单元结构设计和“逆向方式”整体综合设计等关键科学问题。基于液晶、相变材料等可调谐材料，自主设计开发了太赫兹数字编码和可编程超材料器件。在此基础上，搭建了太赫兹单像元成像系统，通过引入自校准算法克服了单元不一致性的不利影响，实现了对样品的高保真度成像。利用相变材料的热敏特性，研制了同时具有检测和调制功能的太赫兹智能超表面，并实现了自适应波束调控的原理性实验演示。上述研究成果对于推动太赫兹和超材料技术在生物医学成像、无线通信、雷达等领域的应用具有重要意义。