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strain-sensors
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Study and Fabrication of Electrical & Electromechanical Resonators Based on Nanostructures for Sensing Application
, Ph.D. Dissertation Sharif University of Technology ; Iraji Zad, Azam (Supervisor) ; Sarvari, Reza (Supervisor) ; Mohajerzadeh, Shamsoddin (Co-Advisor)
Abstract
In this thesis we present fabrication, characterization, and experimental results describing electrical actuation and readout of the mechanical vibratory response of PVP, graphene-doped and ZnO fibers by employing electrical actuation. For a fiber resonator with an approximate radius of 850 nm and length of 100 µm, we observed a resonance frequency around 580 kHz with a quality factor (Q) of about 2511 in air at ambient conditions. Through the use of finite element simulations, we show that the reported frequency of resonance is relevant. Also, the measurements were performed in an enclosed chamber with controlled levels of ethanol vapor. The adsorption of ethanol causes a shift in the...
Graphene based strain sensors: A comparative study on graphene and its derivatives
, Article Applied Surface Science ; Volume 448 , 2018 , Pages 71-77 ; 01694332 (ISSN) ; Bidmeshkipour, S ; Abdi, Y ; Arzi, E ; Mohajerzadeh, S ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In this study, we have experimentally investigated the electrical properties of graphene and its derivatives (Exfoliated graphene, CVD synthesized graphene, graphene oxide and hydrogenated graphene oxide) under uniaxial strain. We have used gauge factor as a common representation of the sensitivity of the strain sensors and found that the hydrogenated graphene oxide shows significantly higher responsivity comparing to other samples under study. Reproducibility, reliability and lack of hysteresis in the responses of the graphene based samples make them a good candidate to be used in the strain sensors. © 2018
A review on the features, performance and potential applications of hydrogel-based wearable strain/pressure sensors
, Article Advances in Colloid and Interface Science ; Volume 298 , 2021 ; 00018686 (ISSN) ; Shojaei, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Over the past few years, development of wearable devices has gained increasing momentum. Notably, the demand for stretchable strain sensors has significantly increased due to many potential and emerging applications such as human motion monitoring, prosthetics, robotic systems, and touch panels. Recently, hydrogels have been developed to overcome the drawbacks of the elastomer-based wearable strain sensors, caused by insufficient biocompatibility, brittle mechanical properties, complicated fabrication process, as the hydrogels can provide a combination of various exciting properties such as intrinsic electrical conductivity, suitable mechanical properties, and biocompatibility. There are...
Enhanced resolution fiber optic strain sensor based on Mach-Zehnder interferometer and displacement sensing principles
, Article ELECO 2009 - 6th International Conference on Electrical and Electronics Engineering, 5 November 2009 through 8 November 2009 ; 2009 , Pages II302-II306 ; 9789944898188 (ISBN) ; Nurmohammadi, T ; Ounie, S ; Sadighi Bonabi, R ; Sharif University of Technology
Abstract
In this study, a novel scheme for fiber optic strain sensor has been introduced. This scheme is indeed a Mach-Zehnder interferometer followed by a displacement sensor. The strain is applied to an optical fiber which is the main branch of the Mach-Zehnder interferometer and causes an alteration in the interferometer's output intensity. The output beam is then spread on a mirror located in front of the fiber head. The head of the fiber and the mirror form a displacement sensor configuration. The portion of the reflected beam, gathered by the fiber, is a function of the distance between the fiber head and the mirror. So, applying strain causes a new change in the gathered intensity due to the...
Potential application of single-layered graphene sheet as strain sensor
, Article Solid State Communications ; Volume 147, Issue 7-8 , August , 2008 , Pages 336-340 ; 00381098 (ISSN) ; Ahmadian, M. T ; Vafai, A ; Sharif University of Technology
2008
Abstract
Molecular structural mechanics is implemented to investigate the vibrational characteristics of defect-free single-layered graphene sheets (SLGSs), which have potential applications as strain sensors. The effect of strain on the fundamental frequencies of the defect-free zigzag and armchair models with clamped-clamped boundary condition is studied. The atomistic modeling results reveal while sensitivities of the strain sensors are not influenced significantly by chirality, they can be slightly increased by decreasing aspect ratios of the sheets. It is further shown that the SLGSs-based strain sensors are more sensitive to the applied stretch than the SWCNTs versions. © 2008 Elsevier Ltd. All...
Preparation and Characterization of the Shape Memory Polymers and Polymeric Nanocomposites and Investigation of their Applications
, Ph.D. Dissertation Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
The current research focuses on preparing conductive hydrogels with combined shape memory and actuating under the effect of external stimuli. Two studies were conducted in which hydrogels simultaneously showed shape memory and actuating behaviors. The magnetic carrageenan-based double network hydrogels were prepared in the first part. The presence of magnetic nanoparticles not only strengthened the mechanical properties, but also induced shape memory properties under a magnetic field. These hydrogels had good electrical conductivity and showed successful performance as strain sensors. The hydrogels performed well in simple and complex shape memory experiments in response to the temperature....