Browsing by Subject "Strain sensing"

Now showing 1 - 5 of 5

Open Access
Flexible metamaterials for wireless strain sensing
(American Institute of Physics, 2009-11-04) Melik, R.; Unal, E.; Perkgoz, N. K.; Puttlitz, C.; Demir, Hilmi Volkan
We proposed and demonstrated flexible metamaterial-based wireless strain sensors that include arrays of split ring resonators (SRRs) to telemetrically measure strain. For these metamaterial sensors, we showed that a flexible substrate (e.g., Kapton tape) delivers greater sensitivity and a more linear response as compared to using silicon substrates. Specifically, these tape-based flexible SRR sensors exhibit a significantly improved sensitivity level of 0.292 MHz/kgf with a substantially reduced nonlinearity error of 3% for externally applied mechanical loads up to 250 kgf. These data represent a sixfold increase in sensitivity and a 16-fold reduction in error percentage.
Open Access
Flexible strain sensors based on electrostatically actuated graphene flakes
(Institute of Physics Publishing, 2015) Fardindoost, S.; Alipour, A.; Mohammadi, S.; Gökyar, S.; Sarvari, R.; Iraji Zad, A.; Demir, Hilmi Volkan
In this paper we present flexible strain sensors made of graphene flakes fabricated, characterized, and analyzed for the electrical actuation and readout of their mechanical vibratory response in strain-sensing applications. For a typical suspended graphene membrane fabricated with an approximate length of 10 μm, a mechanical resonance frequency around 136 MHz with a quality factor (Q) of ∼60 in air under ambient conditions was observed. The applied strain can shift the resonance frequency substantially, which is found to be related to the alteration of physical dimension and the built-in strain in the graphene flake. Strain sensing was performed using both planar and nonplanar surfaces (bending with different radii of curvature) as well as by stretching with different elongations. © 2015 IOP Publishing Ltd.
Open Access
Metamaterial based telemetric strain sensing in different materials
(Optical Society of American (OSA), 2010) Melik, R.; Unal, E.; Perkgoz, N.K.; Puttlitz, C.; Demir, Hilmi Volkan
We present telemetric sensing of surface strains on different industrial materials using split-ring-resonator based metamaterials. For wireless strain sensing, we utilize metamaterial array architectures for high sensitivity and low nonlinearity-errors in strain sensing. In this work, telemetric strain measurements in three test materials of cast polyamide, derlin and polyamide are performed by observing operating frequency shift under mechanical deformation and these data are compared with commercially-available wired strain gauges. We demonstrate that hard material (cast polyamide) showed low slope in frequency shift vs. applied load (corresponding to high Young's modulus), while soft material (polyamide) exhibited high slope (low Young's modulus).
Open Access
Nested metamaterials for wireless strain sensing
(IEEE, 2009-12-28) Melik, R.; Unal, E.; Perkgoz, N. K.; Santoni, B.; Kamstock, D.; Puttlitz, C.; Demir, Hilmi Volkan
We designed, fabricated, and characterized metamaterial-based RF-microelectromechanical system (RF-MEMS) strain sensors that incorporate multiple split ring resonators (SRRs) in a compact nested architecture to measure strain telemetrically. We also showed biocompatibility of these strain sensors in an animal model. With these devices, our bioimplantable wireless metamaterial sensors are intended, to enable clinicians, to quantitatively evaluate the progression of long-bone fracture healing by monitoring the strain on the implantable fracture fixation hardware in real time. In operation, the transmission spectrum of the metamaterial sensor attached to the implantable fixture is changed when an external load is applied to the fixture, and from this change, the strain is recorded remotely. By employing telemetric characterizations, we reduced the operating frequency and enhanced the sensitivity of our novel nested SRR architecture compared to the conventional SRR structure. The nested SRR structure exhibited a higher sensitivity of 1.09 kHz/kgf operating at lower frequency compared to the classical SRR that demonstrated a sensitivity of 0.72 kHz/kgf. Using soft tissue medium, we achieved the best sensitivity level of 4.00 kHz/kgf with our nested SRR sensor. Ultimately, the laboratory characterization and in vivo biocompatibility studies support further development and characterization of a fracture healing system based on implantable nested SRR.
Open Access
Wireless thin-film microwave resonators for sensing and marking
(2017-05) Alipour, Akbar
Rapid progress in wireless microwave technology has attracted increasing interest for high-performance wireless devices. The thin- lm microwave technology is now evolving into the mainstream of applications but signi cant advances are required in resonator architectures and processing for operation in the desired frequency ranges. This dissertation studies the thin- lm microwave technology to develop wireless resonators and describes the core elements that give rise to resonators for high performance in wireless sensing and marking. Speci c to wireless sensing, we proposed and developed a novel wireless microwave resonator scheme that enables telemetric strain sensing avoiding the need for calibration at di erent interrogation distances. In this work, we showed that by using both the proposed sensor architecture and wireless measurement method, strain can be successfully extracted independent of the interrogation distance for the rst time. The experimental results indicate high sensitivity and linearity for the proposed system. This approach enables mobile wireless sensing with varying interrogation distance. For wireless marking, we investigated an ultra-thin, exible, passive radio frequency (RF) based resonator compatible with magnetic resonance imaging (MRI) that successfully was tested in clinic. The ultra-thin and exible architecture of the device o ers an e ective and safe MR visualization and improves the feasibility and reliability of anatomic marking at various surfaces of the body. Results show that, at low background ip angles, the proposed structure enables precise and rapid visibility with high marker-to-background contrast as well as high signal-to-noise ratio (SNR). Also clinical studies have led to a successful biopsy procedure using marking functionality of our device. In another work related to marking, we proposed a new method to enhance local SNR and resolution without disturbing the B1- eld. Here we used our passive RF resonator in the inductively uncoupled mode for endocavity MR imaging. T1- and T2-weighted sequences were employed for phantom and in vivo experiments. The obtained images show the feasibility of the proposed technique to improve the SNR and the resolution in the vicinity of the device. These ndings will allow for new possibilities in applications using wireless sensing and marking approaches shown in this thesis.