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

Texas Tech University, Lubbock TX

Investigators

Abstract

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.