SEMINAR: WIRELESS METAMATERIAL-INSPIRED ROTATION SENSORS
Ali Maleki Gargari
M.S. in Electrical and Electronics Engineering
Prof. Dr. Vakur B. Ertürk & Prof. Dr. H. Volkan Demir
The seminar will be on Friday, June 16, 2017 at 10:00 @ EE-314
Recently, steel construction structures have been attracting more attention due to the speed and ease of their construction. However, to detect the damage in these structures, a long-term, and cost effective health monitoring solution should be provided. A rotation based bending movement which is typically occurred in the load carrying elements of these structures (such as beams) is an example of the aforementioned potential damage. In this thesis, for measuring very small bending based rotations (10-5 to 10-4) in materials such as steel, a novel wireless rotation sensing system with a high level of sensitivity and resolution is presented. This system consists of two elements; an interrogating antenna, and an inter-digital double layer sensor. It operates based on the principle of near-field coupling between the antenna and sensor. Briefly, by rotating one layer with respect to the other, the electromagnetic coupling between the layers become stronger/weaker, and the resonance frequency is consequently shifted down/up. This frequency change can be recorded from the shift of the resonance dips in the S11 response of the antenna.
Various experiments have been performed in order to characterize the sensing system. A high rotation resolution of 20 µ-radians, a good sensitivity of 28 MHz/degree, and a high dynamic range extending over 40° are outcomes of this characterization. Furthermore, the validity of measurement results has been verified by using full-wave electromagnetics simulator as well as applying digital image correlation (DIC) method for 2D measurements.
Keywords: Wireless passive sensor, rotation sensor, metamaterial-inspired sensor, frequency measurement, resonant frequency, sensitivity, microstrip resonators.