Browsing by Subject "Wireless passive sensor"

Now showing 1 - 6 of 6

Open Access
An electromagnetic sensing system incorporating multiple probes and single antenna for wireless structural health monitoring
(IEEE, 2017) Özbey, Burak; Altıntaş, Ayhan; Demir, Hilmi Volkan; Ertürk, Vakur B.; Kurç, Ö.
In this study, a wireless and passive displacement/strain sensing system is proposed for structural health monitoring (SHM). The wireless and passive interrogation of the sensing unit [a variant of a nested split-ring resonator (NSRR)] is achieved through the near-field interaction and electromagnetic coupling between the single antenna in the system and the multiple sensors called the NSRR probes. It is demonstrated that the system can acquire data from more than one NSRR probe simultaneously in a real-life scenario, where the probes are confined within concrete inside a beam, while the antenna monitors them from outside.
Open Access
An equivalent circuit model for nested split-ring resonators
(Institute of Electrical and Electronics Engineers Inc., 2017) Ozbey, B.; Altintas, A.; Demir, Hilmi Volkan; Ertürk, V. B.
In this paper, an equivalent circuit model for nested split-ring resonators (NSRRs) is proposed. NSRRs are an emerging class of split ring resonators, preferred in a range of areas from sensing in biomedical or civil engineering applications to antenna design, due to their more compact size and enhanced sensitivity/resolution characteristics over the conventional SRRs. In the proposed model, the NSRR structure is treated as a combination of basic elements, i.e., strips and gaps, and the electromagnetic characteristics of the whole geometry are expressed in terms of capacitances and inductances of each of these elements. The outputs of the model are compared with those obtained via full-wave simulations using the package programs as well as measurements. The variation of NSRR resonance frequency (fres) with all important design parameters is also compared with full-wave simulations. In all comparisons, the results demonstrate agreement, showing that the proposed model can correctly explain the electromagnetics of the NSRR structure and that it provides an intuitive way for a better and easier analysis and a preliminary design of normally complex structures.
Open Access
Multi-point single-antenna sensing enabled by wireless nested split-ring resonator sensors
(Institute of Electrical and Electronics Engineers Inc., 2016) Ozbey, B.; Ertürk, V. B.; Kurc, O.; Altintas, A.; Demir, Hilmi Volkan
In this paper, simultaneous multi-point wireless sensing is proposed and demonstrated via multiple sensors in nested split-ring resonator (NSRR) geometry coupled to a single illuminator antenna. In this passive multi-point sensing system, each probe in the sensor array is assigned a non-overlapping spectral interval for frequency shift in response to local mechanical loading around a unique operating resonance frequency in the band of the antenna. Here, it is shown that the antenna is capable of capturing the responses from all probes in a single frequency sweep. Furthermore, the inter-coupling between the array elements and the effect of antenna illumination on the coupling are experimentally investigated in a systematic way. In addition, as a proof-of-concept real-life application in structural health monitoring, two NSRR sensors are located inside a concrete beam to monitor the strain forming on reinforcing bars, and this dual-probe system is demonstrated to record strain simultaneously via both of the embedded probes.
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
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.
Open Access
Wireless sensing in complex electromagnetic media: construction materials and structural monitoring
(Institute of Electrical and Electronics Engineers Inc., 2015) Özbey, B.; Demir, Hilmi Volkan; Kurc, O.; Ertürk, V. B.; Altıntaş, A.
In this paper, wireless sensing in the presence of complex electromagnetic media created by combinations of reinforcing bars and concrete is investigated. The wireless displacement sensing system, primarily designed for use in structural health monitoring (SHM), is composed of a comb-like nested split-ring resonator (NSRR) probe and a transceiver antenna. Although each complex medium scenario is predicted to have a detrimental effect on sensing in principle, it is demonstrated that the proposed sensor geometry is able to operate fairly well in all scenarios except one. In these scenarios that mimic real-life SHM, it is shown that this sensor exhibits a high displacement resolution of 1 μm, a good sensitivity of 7 MHz/mm in average, and a high dynamic range extending over 20 mm. For the most disruptive scenario of placing concrete immediately behind NSRR, a solution based on employing a separator behind the probe is proposed to overcome the handicaps introduced by the medium. In order to obtain a one-to-one mapping from the measured frequency shift to the displacement, a numerical fit is proposed and used. The effects of several complex medium scenarios on this fit are discussed. These results indicate that the proposed sensing scheme works well in real-life SHM applications. © 2001-2012 IEEE.