In situ reduction of gold nanoparticles in PDMS matrices and applications for large strain sensing

Ryu, Donghyeon,Loh, Kenneth J.,Ireland, Robert,Karimzada, Mohammad,Yaghmaie, Frank,Gusman, Andrea M. Techno-Press 2011 Smart Structures and Systems, An International Jou Vol.8 No.5

Various types of strain sensors have been developed and widely used in the field for monitoring the mechanical deformation of structures. However, conventional strain sensors are not suited for measuring large strains associated with impact damage and local crack propagation. In addition, strain sensors are resistive-type transducers, which mean that the sensors require an external electrical or power source. In this study, a gold nanoparticle (GNP)-based polymer composite is proposed for large strain sensing. Fabrication of the composites relies on a novel and simple in situ GNP reduction technique that is performed directly within the elastomeric poly(dimethyl siloxane) (PDMS) matrix. First, the reducing and stabilizing capacities of PDMS constituents and mixtures are evaluated via visual observation, ultraviolet-visible (UV-Vis) spectroscopy, and transmission electron microscopy. The large strain sensing capacity of the GNP-PDMS thin film is then validated by correlating changes in thin film optical properties (e.g., maximum UV-Vis light absorption) with applied tensile strains. Also, the composite's strain sensing performance (e.g., sensitivity and sensing range) is also characterized with respect to gold chloride concentrations within the PDMS mixture.

In situ reduction of gold nanoparticles in PDMS matrices and applications for large strain sensing

Donghyeon Ryu,Kenneth J. Loh,Robert Ireland,Mohammad Karimzada,Frank Yaghmaie,Andrea M. Gusman 국제구조공학회 2011 Smart Structures and Systems, An International Jou Vol.8 No.5

Various types of strain sensors have been developed and widely used in the field for monitoring the mechanical deformation of structures. However, conventional strain sensors are not suited for measuring large strains associated with impact damage and local crack propagation. In addition, strain sensors are resistive-type transducers, which mean that the sensors require an external electrical or power source. In this study, a gold nanoparticle (GNP)-based polymer composite is proposed for large strain sensing. Fabrication of the composites relies on a novel and simple in situ GNP reduction technique that is performed directly within the elastomeric poly(dimethyl siloxane) (PDMS) matrix. First, the reducing and stabilizing capacities of PDMS constituents and mixtures are evaluated via visual observation, ultraviolet-visible (UV-Vis) spectroscopy, and transmission electron microscopy. The large strain sensing capacity of the GNP-PDMS thin film is then validated by correlating changes in thin film optical properties (e.g., maximum UV-Vis light absorption) with applied tensile strains. Also, the composite’s strain sensing performance (e.g., sensitivity and sensing range) is also characterized with respect to gold chloride concentrations within the PDMS mixture.

Evolutionary learning based sustainable strain sensing model for structural health monitoring of high-rise buildings

Oh, Byung Kwan,Kim, Kyu Jin,Kim, Yousok,Park, Hyo Seon,Adeli, Hojjat Elsevier 2017 Applied soft computing Vol.58 No.-

<P>Strain sensor network-based structural health monitoring systems have been used to assess the safety of high-rise buildings. In consideration of life cycle of high-rise buildings, long-term measurement by sensors should be required. However, because of unpredictable problems such as the lack of durability of sensors and data loggers, disruption in communication, and loss of data, long-term strain measurement of major structural members is currently infeasible. For sustainable safety assessment of high-rise buildings, this paper presents a sustainable strain-sensing model that employs an artificial neural network (ANN) to estimate the strain responses of columns depending on the wind-induced behavior of high-rise buildings. The ANN model used in the paper is based on evolutionary learning consists of training in radial basis function neural network (RBFN) and evolving in genetic algorithm. In this evolutionary RBFN (ERBFN). Weights between layers are trained and variables of Gaussian function in the RBFN are evolved to estimate strain responses of the column of the high-rise building structure. A wind tunnel test was performed to produce wind data and strains in column members in a high-rise building model. In the wind tunnel test, a specimen consisting of a core, perimeter columns, and outriggers is used to simulate the conditions of typical high-rise buildings with a slenderness ratio of 5.0. The proposed model is trained and verified by using the wind data such as wind speeds and directions and the corresponding strains measured with fiber optic grating sensors. In addition to estimation of the maximum and minimum values of strains in vertical members in a high-rise building, it is found that the proposed model can build a relationship between the wind data and strain of vertical members. (C) 2017 Elsevier B.V. All rights reserved.</P>

Strain sensing skin-like film using zinc oxide nanostructures grown on PDMS and reduced graphene oxide

Satish, Tejus,Balakrishnan, Kaushik,Gullapalli, Hemtej,Nagarajaiah, Satish,Vajtai, Robert,Ajayan, Pulickel M. Techno-Press 2017 Structural monitoring and maintenance Vol.4 No.2

In this paper, we present a strain-sensitive composite skin-like film made up of piezoresistive zinc oxide (ZnO) nanorods embedded in a flexible poly(dimethylsiloxane) substrate, with added reduced graphene oxide (rGO) to facilitate connections between the nanorod clusters and increase strain sensitivity. Preparation of the composite is described in detail. Cyclic strain sensing tests are conducted. Experiments indicate that the resulting ZnO-PDMS/rGO composite film is strain-sensitive and thus capable of sensing cycling strain accurately. As such, it has the potential to be molded on to a structure (civil, mechanical, aerospace, or biological) in order to provide a strain sensing skin.

Noncontact strain sensing in cement-based material using laser-induced fluorescence from nanotube-based skin

Meng, Wei,Bachilo, Sergei M.,Parol, Jafarali,Weisman, R. Bruce,Nagarajaiah, Satish Techno-Press 2022 Structural monitoring and maintenance Vol.9 No.3

This study explores the use of the recently developed "strain-sensing smart skin" (S⁴) method for noncontact strain measurements on cement-based samples. S⁴ sensors are single-wall carbon nanotubes dilutely embedded in thin polymer films. Strains transmitted to the nanotubes cause systematic shifts in their near-infrared fluorescence spectra, which are analyzed to deduce local strain values. It is found that with cement-based materials, this method is hampered by spectral interference from structured near-infrared cement luminescence. However, application of an opaque blocking layer between the specimen surface and the nanotube sensing film enables interference-free strain measurements. Tests were performed on cement, mortar, and concrete specimens with such modified S⁴ coatings. When specimens were subjected to uniaxial compressive stress, the spectral peak separations varied linearly and predictably with induced strain. These results demonstrate that S⁴ is a promising emerging technology for measuring strains down to ca. 30 𝜇𝜀 in concrete structures.

Patch-type large strain sensor using elastomeric composite filled with carbon nanofibers

Tetsuo Yasuoka,Yoshinobu Shimamura,Akira Todoroki 한국항공우주학회 2013 International Journal of Aeronautical and Space Sc Vol.14 No.2

Carbon nanofibers (CNFs) are electrically conductive. When CNFs are used as fillers in resin, this electrical conductivity can be yielded without adversely affecting the mechanical properties of the resin. When an elastomer is adopted as the resin, a conductive elastomer can then be produced. Due to its flexibility and conductive properties, a large strain sensor based on changes in resistivity may be produced, for strain sensing in flexible structures. In this study, a patch-type large strain sensor using resistivity change in a CNF/elastomer composite was proposed. The measurement limits of the sensor were investigated experimentally, and the limit was found to be 40%, which greatly exceeded the limits of conventional metal-foiled strain gages. Also, the proposed CNF/elastomer large strain sensor can be used to measure flexible materials, while conventional strain gages cannot be used to measure such strains.

Battery-free slotted patch antenna sensor for wireless strain and crack monitoring

Xiaohua Yi,Chunhee Cho,Yang Wang,Manos M. Tentzeris 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.6

In this research, a slotted patch antenna sensor is designed for wireless strain and crack sensing. An off-the-shelf RFID (radiofrequency identification) chip is adopted in the antenna sensor design for signal modulation. The operation power of the RFID chip is captured from wireless reader interrogation signal, so the sensor operation is completely battery-free (passive) and wireless. For strain and crack sensing of a structure, the antenna sensor is bonded on the structure surface like a regular strain gage. Since the antenna resonance frequency is directly related with antenna dimension, which deforms when strain occurs on the structural surface, the deformation/strain can be correlated with antenna resonance frequency shift measured by an RFID reader. The slotted patch antenna sensor performance is first evaluated through mechanics-electromagnetics coupled simulation. Extensive experiments are then conducted to validate the antenna sensor performance, including tensile and compressive strain sensing, wireless interrogation range, and fatigue crack sensing.

Flexible and transparent strain sensor made with silver nanowire–coated cellulose

Mun, Seongcheol,Zhai, Lindong,Min, Seung-Ki,Yun, Youngmin,Kim, Jaehwan SAGE Publications 2016 Journal of intelligent material systems and struct Vol.27 No.8

<P>Simple and versatile method of layer-by-layer deposition is used to coat silver nanowire on a cellulose film to fabricate a flexible and transparent strain sensor. Strain-sensing behaviors of such a simply fabricated cellulose film are analyzed in both stretching and bending modes. When 0.01wt% silver nanowire is coated on the cellulose film, 70% transmittance is maintained with 2.4 k Omega/sq of sheet resistance, which is applicable for transparent electrode of the strain sensor. Conductivity of the transparent electrode is maintained after mechanical stretching, which demonstrates that the silver nanowire coating is securely adhered on the surface of cellulose film. The strain sensor shows high strain sensitivity and good gauge factor maintaining good transparency at low silver nanowire concentration, which might be associated with the tunneling resistance change in the silver nanowire. The morphology of the silver nanowire-coated cellulose strain sensor is investigated using an atomic force microscopy with an increase in silver nanowire concentration.</P>

건설안전분야 : PVDF 필름을 이용한 구조물의 동적 변형률 측정

김수민 ( Su Min Kim ),신성우 ( Sung Woo Shin ),이재용 ( Jae Yong Lee ),김남식 ( Nam Sik Kim ) 한국안전학회(구 한국산업안전학회) 2011 한국안전학회지 Vol.26 No.6

In this study, the applicability of PVDF films for measurements of dynamic strain in a structure was investigated. A relationship between the strain and the voltage response of a PVDF film was analytically derived. Free vibration test on a steel cantilever beam was performed and vibration response of the beam was measured both by a convential foil strain gauge and a PVDF film. Strain-voltage relationship obtained from the experiment was compared with the analytic relationship. Good agreement between the analytic and experimental relationships was observed. It was found that a tailored PVDF film can measure the dynamic strain of a structure as accurate as a conventional foil strain gauge.

Patch-type large strain sensor using elastomeric composite filled with carbon nanofibers

Yasuoka, Tetsuo,Shimamura, Yoshinobu,Todoroki, Akira The Korean Society for Aeronautical and Space Scie 2013 International Journal of Aeronautical and Space Sc Vol.14 No.2

Carbon nanofibers (CNFs) are electrically conductive. When CNFs are used as fillers in resin, this electrical conductivity can be yielded without adversely affecting the mechanical properties of the resin. When an elastomer is adopted as the resin, a conductive elastomer can then be produced. Due to its flexibility and conductive properties, a large strain sensor based on changes in resistivity may be produced, for strain sensing in flexible structures. In this study, a patch-type large strain sensor using resistivity change in a CNF/elastomer composite was proposed. The measurement limits of the sensor were investigated experimentally, and the limit was found to be 40%, which greatly exceeded the limits of conventional metal-foiled strain gages. Also, the proposed CNF/elastomer large strain sensor can be used to measure flexible materials, while conventional strain gages cannot be used to measure such strains.