Using Feedback Mechanism to Control Phase Transition of Vanadium Dioxide to Exploit its Full Operating Range

二氧化钒（VO 2）是一种智能多功能材料，其在其金属相和绝缘体相之间具有特征性转变，其在电学、光学和机械性能方面具有突然和实质性的变化（几个数量级）。这在包括传感器、致动器和高速开关在内的各种应用中引起了相当大的关注。然而，VO 2的金属-绝缘体相变的数字ON/OFF不稳定性具有尖锐和狭窄的温度窗口，限制了其在需要具有连续可调特性的模拟操作模式的应用中的进一步发展。该项目将尝试利用反馈机制，以实现VO 2的全工作范围，从而显著增强其广泛的适用性，就像几十年前的运算放大器一样。 研究将利用VO 2在过渡阶段固有的复杂动态行为，利用反馈控制理论的进步实现重构能力。潜在的影响是巨大的，因为这项研究的结果将为多个领域的模拟应用提供更强大、更有能力的设备。例如，具有可重构相变光学特性的VO 2将促进太赫兹光学器件的发展，其应用于医疗诊断和生物学、宽带通信、安全、国防和无损检测的成像和光谱学。研究结果将纳入本科和研究生教育，并将通过教育和外展活动向公众传播。该项目将研究通过引入控制理论中的基本反馈机制来赋予VO 2可重构相变的可行性，以实现其全操作范围。该项目将开发关于不确定性和滞后系统的建模和控制的新知识，以同时实现精确的连续VO 2相变和高调制深度。新的知识将构成一个基本的贡献，将有利于其他几个应用程序的动态非线性控制，如滞后下的不确定性是必需的。这两个可重构的VO 2硬件在环和实验测试床将建立，以验证的方法，利用现有的设施和资源，在得克萨斯理工大学？纳米技术中心。这项研究也很好地融合了理论、实验和计算工作。该项目有新颖的外展活动，如为K-12学生和代表性不足的群体注入研究元素到新颖的动手实验中。

Vanadium dioxide (VO2) is a smart multifunctional material which has characteristic transition between its metal and insulator phases, which have abrupt and substantial changes (several orders of magnitude) in electrical, optical, and mechanical properties. This has led to considerable attention in a variety of applications including sensors, actuators, and high-speed switches. However, the digital ON/OFF abruptness of the metal-insulator phase transition of VO2 with a sharp and narrow temperature window limits its further development for applications that demand analog operation mode with continuously tunable properties. This project will try to exploit the mechanisms of feedback to enable the use of full operational range of VO2 and thereby significantly enhancing their wide-spread applicability like it did for operational amplifiers several decades ago. The research will leverage inherent complex dynamic behavior of VO2 in transition phase to achieve reconfiguration capability using advances in feedback control theory. The potential impact is significant as the outcomes of this research will enable more powerful and capable devices for analog applications in several fields. For example, VO2 with reconfigurable phase transition optical property will facilitate advances in terahertz optical devices with applications in imaging and spectroscopy for medical diagnostics and biology, broadband communications, security, defense, and nondestructive testing. The research results will be incorporated into both undergraduate and graduate education and will be disseminated to public through educational and outreach activities.The project will investigate the feasibility of empowering VO2 with reconfigurable phase transition via introducing the fundamental feedback mechanisms in control theory to achieve its full operational range. The project will develop new knowledge on modeling and control of systems with uncertainties and hysteresis to achieve both precise continuous VO2 phase transition and high modulation depth simultaneously. The new knowledge will constitute a fundamental contribution that will benefit several other applications where control of dynamic nonlinearities such as hysteresis under uncertainties is required. Both reconfigurable VO2 hardware-in-the-loop and experimental test beds will be built to validate the methodologies by leveraging the available facilities and resources at Texas Tech University?s Nano Tech Center. The research also has a nice blend of theoretical, experimental, and computational work. The project has novel outreach activities such as infusion of research elements into novel hands-on experiments for K-12 students and underrepresented groups.