Browsing by Subject "Displacement sensor"

Now showing 1 - 4 of 4

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
Integrated optical displacement sensors for scanning force microscopies
(2003) Kocabaş, Coşkun
In this thesis, we have studied the use of integrated optical waveguide devices acting as integrated displacement sensors on cantilevers for scanning probe microscopes. These displacement sensors include integrated optical waveguide devices such as Bragg gratings, ring resonators, race track resonators and waveguide Michelson interferometers fabricated on a cantilever to measure the displacement of the cantilever tip due to the forces between surface and the tip. The displacement of the cantilever tip is measured directly from the change of the transmission characteristics of the optical device. As the cantilever tip displaces, the stress on the cantilever surface changes the refractive index of the materials that make up the integrated optical device which cause variations in its optical transmission characteristics. We have also studied an optical waveguide grating coupler fabricated on the cantilever for the same purpose. In two different embodiments of this device, light is either coupled in or out of the waveguide via the waveguide grating coupler. The displacement of the cantilever alters the direction of the scattered light and measuring the power of the scattered light with a position sensitive detector allows for the detection of cantilever i tip displacement. The novel design proposed in this work provides very high displacement sensitivity of the order of 10−4˚A−1 .
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 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.