Browsing by Subject "Metamaterial-inspired sensor"

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Open Access
Wireless meta-structured RF probes for vibration sensing
(2023-07) Kılıç, Tuğba
Vibration signals are widely used for different monitoring purposes in numerous areas of applications. Sensing vibration and examining its properties play a critically important role essential to damage monitoring especially in the fields of construction and machinery. Detection of possible damages to these structures/machines requires cost-effective and easy-to-use solutions both to protect human health and/or reduce the cost of potential damage to the structures/machines. In this thesis, to offer an efficient and reliable solution for monitoring the health and integrity of various structures and machinery, we proposed and developed a new class of meta-structure based vibration probes that offer high-resolution and real-time wireless monitoring capabilities in vibration sensing. Operating in the radio frequency (RF) domain, this sensor concept relies on the near-field coupling of two nested split ring resonators (NSRRs), each of which is free to move toward each other. In response to the mechanical vibration occurring on a surface to which one of the NSRRs is attached, the amplitude of the electromagnetic wave read out only in vertical direction with respect to the NSRR probe from the coupled-NSRR pair by a transceiver antenna monotonously changes, making the sensing system capable of detecting mechanical vibrations over a wide RF range. The most important advantage of the proposed sensing architecture is that the resonant frequency read-out is very strongly dependent on the spacing between the coupled-NSRR probes, which makes wireless vibration detection at low amplitudes possible. The experimental findings show that this system can wirelessly measure vibration amplitudes as low as 50 µm. Equally important, this opportunely enables a high level of vibration resolution of (differentiation of two close vibration amplitudes separated by) 38.4 µm with an average error rate of only 1.2%. The sensing system exhibits a sensitivity level of 866 kHz/mm. The wireless and passive nature of the proposed system, together with the cost-effectiveness of our NSRR probes, make it highly promising for real-life applications including remote structural health monitoring, deformation detection, and vibration wave monitoring.
Open Access
A wireless metamaterial-inspired passive rotation sensor with submilliradian resolution
(Institute of Electrical and Electronics Engineers, 2018) Gargari, Ali Maleki; Özbey, Burak; Demir, Hilmi Volkan; Altıntaş, Ayhan; Albostan, U.; Kurc, O.; Ertürk, Vakur B.
A novel passive wireless rotation sensing system with high levels of sensitivity and resolution is proposed and demonstrated for measuring elastic-region bending in materials such as steel. This system is composed of a transceiver antenna and a double-plate sensor in the form of an inter-digital configuration, which does not incorporate any active component. The sensor exhibits a large rotation resolution of 20μ -rad, an excellent sensitivity of 28 MHz/° in average, and a large linear dynamic range of approximately 40°. In operation, as a result of the relative rotation between the plates of the sensor, the operating resonance frequency of the system is shifted. This is read out and tracked in the S11 response of the transceiver antenna from which the rotation angle is determined. The prototype is designed for microwave regime and it is suitable for measuring very small angles (10-4 10-5 rad). Critical figures-of-merit of the sensor including sensitivity, dynamic range, and resolution are assessed via systematic measurements, and the validity of resolution experiment is verified by employing digital image correlation method for 2-D measurements.
Open Access
Wireless metamaterial-inspired rotation sensors
(2017-06) Gargari, Ali Maleki
Recently steel construction structures have been attracting increasingly more attention due to the speed and ease of their construction. However, to detect potential damages in these structures, long-term and cost-effective health monitoring solutions are required. A rotation-based bending movement, which typically occurs in the load carrying elements of these structures (such as beams), is an example of the aforementioned potential damage. In this thesis, for measuring small bending rotations (10−4 ~ 10−5 radians) in the structures made of materials such as steel, a novel wireless rotation sensing system with a high level of sensitivity and resolution is proposed and demonstrated. This system consists of two elements: an interrogating antenna and an inter-digital double-layer sensor. The proposed sensing system operates based on the principle of near-field coupling between the antenna and the sensor. Briefly, by rotating one layer with respect to the other, the electromagnetic coupling between the layers changes and the resonance frequency is consequently shifted. This frequency shift can be recorded by tracking the resonance dips in the S11 response of the antenna. In the thesis work, various experiments were systematically performed to characterize the sensing system. A high rotation resolution of 20 µ-radians, an excellent sensitivity level of 28 MHz/degree, and a large dynamic range extending over 40◦ were measured. Furthermore, the validity of measurement results was verified by using full-wave electromagnetics simulator and applying digital image correlation (DIC) method for 2D measurements.