Effects of Binder and Substrate Materials on the Performance and Reliability of Stretchable Nanocomposite Strain Sensors

2021 ◽  
Vol 21 (5) ◽  
pp. 2969-2979
Author(s):  
Hyun Jin Nam ◽  
Jin Yeong Park ◽  
Van-Phu Vu ◽  
Sung-Hoon Choa
Keyword(s):  
Strain Sensors ◽  
Pdms Substrate ◽  
Response Delay ◽  
Multiwalled Carbon ◽  
Bending Tests ◽  
Hysteresis Behavior ◽  
Response Characteristics ◽  
Large Hysteresis ◽  
Bending Angles

In stretchable strain sensors, highly elastic elastomers such as polydimethylsiloxane (PDMS), Ecoflex, and polyurethane are commonly used for binder materials of the nanocomposite and substrates. However, the viscoelastic nature of the elastomers and the interfacial action between nanofillers and binders influence the critical sensor performances, such as repeatability, response, and hysteresis behavior. In this study, we developed a stretchable nanocomposite strain sensor composed of multiwalled carbon nanotubes and a silicone elastomer binder. The effects of binder and substrate materials on the repeatability, response, hysteresis behavior, and long-term endurance of the strain sensors were systematically investigated using stretching, bending, and repeated cyclic bending tests. Three different binder and substrate materials including PDMS, Ecoflex, and a mixture of PDMS/Ecoflex were tested. The stretchable strain sensors showed an excellent linearity and stretchability of more than 130%. Therefore, the long-term endurance of the strain sensors fabricated with Ecoflex binder should be improved. The strain sensors fabricated with Ecoflex binder showed a relatively large variation in electrical resistance during 10,000-cycle bending tests and repeatability errors at large bending angles. The strain sensors fabricated with PDMS binder showed repeatability errors at small bending angles and a slight response delay of 1 second. On the contrary, the strain sensors fabricated with a mixture of PDMS/Ecoflex binder showed excellent repeatability and response characteristics. The PDMS material showed hysteresis behavior; therefore, the strain sensors fabricated with PDMS binder on PDMS substrate exhibited a large hysteresis behavior in the first stretch–release cycle. It was found that the hysteresis behavior of the strain sensors was mainly dependent on substrate materials than on binder materials. The stretchable strain sensors made of the mixture of PDMS/Ecoflex exhibited excellent repeatability, response, hysteresis behavior, and excellent capability in detecting finger and wrist bending.

scholarly journals A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Waris Obitayo ◽  
Tao Liu
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Composite Films ◽  
Strain Sensors ◽  
Voltage Response ◽  
Strain Sensing ◽  
Multiwalled Carbon ◽  
Sensing Applications ◽  
Mechanical Deformations ◽  
Electrical Resistivities

The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

Long-Term Reliability Assessment of Bioceramics for Artificial Joints Using Microdamage Monitoring by AE

2006 ◽  
Vol 309-311 ◽  
pp. 1191-1194
Author(s):  
Shuichi Wakayama ◽  
Teppei Kawakami ◽  
Junji Ikeda
Keyword(s):  
Critical Stress ◽  
Reliability Assessment ◽  
Physiological Saline ◽  
Bending Test ◽  
Unstable Fracture ◽  
Artificial Joints ◽  
Bending Tests ◽  
Four Point Bending

Microfracture process during bending tests of alumina ceramics used for artificial joints was evaluated by acoustic emission (AE) technique. Four-point bending tests were carried out in air, refined water, physiological saline and simulated body fluid. AE behavior during bending test inhibited the rapid increasing point of AE events and energy prior to the final unstable fracture. It was understood that the bending stress at the increasing point corresponds to the critical stress for maincrack formation. The critical stress was affected by water in environments more strongly than fracture strength. Consequently, it was suggested that the characterization of maincrack formation is essential for the long-term reliability assessment of load-bearing bioceramics.

The effect of washing on the electrical performance of knitted textile strain sensors for quantifying joint motion

2021 ◽  
pp. 152808372110592
Author(s):  
Cristina Isaia ◽  
Simon McMaster ◽  
Donal McNally
Keyword(s):  
Elbow Flexion ◽  
Strain Sensors ◽  
Electrical Performance ◽  
Market Penetration ◽  
Maximum Extension ◽  
Maximum Flexion ◽  
Flexion Extension ◽  
Textile Sensor ◽  
Simulated Training

Successful market penetration of textile-based strain sensors requires long-term reliability which in turn relies on the washability of the sensor. First, this paper presents an evaluation of the effect of 5 washing cycles on the electrical performance of a knitted conductive transducer, over 1500 cycles of repetitive elongation. The promising behaviour of the textile sensor in this study showed that it might be possible to make a smart garment, capable of quantifying elbow flexion-extension motion, by integrating it into an elbow sleeve. Second, a prototype sleeve, incorporating a knitted sensor (the so-called smart sleeve), was tested in a simulated training/clinical setting by performing 50 flexion-extension cycles after 1, 5, 15, 25, 50 and 75 washes. In both studies, the electrical resistance of the sensor increased with the number of washes in a predictable manner and exhibited a repeatable, reliable and prompt response to elongation. In particular, the electrical pattern representing flexion-extension motion measured using the sleeve was clear and distinguishable up to the 75th wash. Moreover, resistance measurements within the same trial were repeatable at maximum flexion (≤2% variation) and at maximum extension (≤3% variation) and predictable with increasing washes (R2 = 0.992 at maximum flexion and R2 = 0.989 at maximum extension). The good washability of the smart sleeve, evidenced by its ability to detect, distinguish and measure parameters of flexion-extension motion up to 75 washes, makes it a suitable and sustainable choice for applications, such as strength conditioning or rehabilitation, where repetition count and speed are useful.

scholarly journals Evaluation of Strain Transition Properties between Cast-In Fibre Bragg Gratings and Cast Aluminium during Uniaxial Straining

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6276
Author(s):  
Florian Heilmeier ◽  
Robert Koos ◽  
Michael Singer ◽  
Constantin Bauer ◽  
Peter Hornberger ◽  
...  
Keyword(s):  
Bragg Gratings ◽  
Tensile Specimen ◽  
Strain Sensors ◽  
Fe Model ◽  
Plastic Strains ◽  
Closing The Gap ◽  
Optical Strain ◽  
Structural Parts ◽  
Fibre Bragg Gratings

Current testing methods are capable of measuring strain near the surface on structural parts, for example by using strain gauges. However, stress peaks often occur within the material and can only be approximated. An alternative strain measurement incorporates fibre-optical strain sensors (Fiber Bragg Gratings, FBG) which are able to determine strains within the material. The principle has already been verified by using embedded FBGs in tensile specimens. The transition area between fibre and aluminium, however, is not yet properly investigated. Therefore, strains in tensile specimens containing FBGs were measured by neutron diffraction in gauge volumes of two different sizes around the Bragg grating. As a result, it is possible to identify and decouple elastic and plastic strains affecting the FBGs and to transfer the findings into a fully descriptive FE-model of the strain transition area.We thus accomplished closing the gap between the external load and internal straining obtained from cast-in FBG and generating valuable information about the mechanisms within the strain transition area.It was found that the porosity within the casting has a significant impact on the stiffness of the tensile specimen, the generation of excess microscopic tensions and thus the formation of permanent plastic strains, which are well recognized by the FBG. The knowledge that FBG as internal strain sensors function just as well as common external strain sensors will now allow for the application of FBG in actual structural parts and measurements under real load conditions. In the future, applications for long-term monitoring of cast parts will also be enabled and are currently under development.

Two-dimensional a-Si:H/a-SiC:H n-i-p sensor array with ITO/a-SiNx antireflection coating

2005 ◽  
Vol 862 ◽  
Author(s):  
Yu. Vygranenko ◽  
J. H. Chang ◽  
A. Nathan
Keyword(s):  
Reverse Bias ◽  
Spectral Response ◽  
Charge Trapping ◽  
Optical Excitation ◽  
Antireflection Coating ◽  
Two Dimensional ◽  
Device Structure ◽  
Response Characteristics ◽  
Photodiode Array

AbstractThis paper presents a two-dimensional a–Si:H/a-SiC:H n–i–p photodiode array with switching diode readout, developed specifically for fluorescence-based bio-assays. Both device structure and fabrication processing has enabled enhancement of the external quantum efficiency of the encapsulated device up to 80%, reduction of the photodiode leakage down to 10 pA/cm2 at -1V reverse bias, and increase of the rectification current ratio of the switching diodes up to 109. The critical fabrication issues associated with deposition of device-quality materials, tailoring of defects at the i–p interface, device patterning with dry etching, junction passivation, and contact formation will be discussed. Both sensing and switching diodes were characterized. While the observed dark current in the photodiodes at low reverse bias voltages is primarily due to carrier emission from deep states in the a–Si:H bulk, the leakage in the small switching diodes stems from peripheral defects along junction sidewalls. Optical losses in the photodiodes with ITO/a–SiNx:H antireflection coating were evaluated using numerical modeling, and the calculated transmission spectra correlated well with the spectral response characteristics. Measurements of the charge transfer time and output linearity demonstrated the efficiency of the single-switching diode readout configuration. The response of the array to optical excitation was also investigated. The observed long term retardation in the signal rise and decay at illumination levels less than 1010 photons/cm2-s can be associated with charge trapping in the undoped layer.

Empirical Procedures for Long-Term Prediction of Fatigue Damage for an Instrumented Marine Riser

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
C. Shi ◽  
L. Manuel ◽  
M. A. Tognarelli
Keyword(s):  
Fatigue Damage ◽  
Field Measurements ◽  
Damage Estimation ◽  
Current Profile ◽  
Short Term ◽  
Response Characteristics ◽  
Damage Rate ◽  
Using Data ◽  
Analytical Approaches

Slender marine risers used in deepwater applications can experience vortex-induced vibration (VIV). It is becoming increasingly common for field monitoring campaigns to be undertaken wherein data loggers such as strain sensors and/or accelerometers are installed on such risers to aid in VIV-related fatigue damage estimation. Such damage estimation relies on the application of empirical procedures that make use of the collected data. This type of damage estimation can be undertaken for different current profiles encountered. The empirical techniques employed make direct use of the measurements and key components in the analyszes (such as participating riser modes selected for use in damage estimation) are intrinsically dependent on the actual current profiles. Fatigue damage predicted in this manner is in contrast to analytical approaches that rely on simplifying assumptions on both the flow conditions and the response characteristics. Empirical fatigue damage estimates conditional on current profile type can account explicitly even for complex response characteristics, participating riser modes, etc. With significant amounts of data, it is possible to establish “short-term” fatigue damage rate distributions conditional on current type. If the relative frequency of different current types is known from metocean studies, the short-term fatigue distributions can be combined with the current distributions to yield integrated “long-term” fatigue damage rate distributions. Such a study is carried out using data from the Norwegian Deepwater Programme (NDP) model riser subject to several sheared and uniform current profiles and with assumed probabilities for different current conditions. From this study, we seek to demonstrate the effectiveness of empirical techniques utilized in combination with field measurements to predict the long-term fatigue damage and the fatigue failure probability.

Flexible and Transparent Strain Sensors with Embedded Multiwalled Carbon Nanotubes Meshes

2017 ◽  
Vol 9 (46) ◽  
pp. 40681-40689 ◽  
Author(s):  
Bangbang Nie ◽  
Xiangming Li ◽  
Jinyou Shao ◽  
Xin Li ◽  
Hongmiao Tian ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Strain Sensors ◽  
Multiwalled Carbon

scholarly journals Different Cellular Response of Human Mesothelial Cell MeT-5A to Short-Term and Long-Term Multiwalled Carbon Nanotubes Exposure

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Li Ju ◽  
Wei Wu ◽  
Min Yu ◽  
Jianlin Lou ◽  
Hao Wu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Cell Motility ◽  
Multiwalled Carbon Nanotubes ◽  
Mesothelial Cell ◽  
Continuous Exposure ◽  
Short Term ◽  
Multiwalled Carbon ◽  
Long Term Treatment ◽  
Human Mesothelial Cell

Despite being a commercially important product, multiwalled carbon nanotubes (MWCNTs) continue to raise concerns over human health due to their structural similarity to asbestos. Indeed, exposure to MWCNT has been shown to induce lung cancer and even mesothelioma, but contradictory results also exist. To clarify the potentially carcinogenic effects of rigid and rod-like MWCNT and to elucidate the underlying mechanisms, the effects of MWCNT on human mesothelial cell MeT-5A were examined throughout 3 months of continuous exposure, including cytotoxicity, genotoxicity, and cell motility. It was found that MWCNT did not affect MeT-5A cell proliferation at 10 μg/cm2 within 72 h treatment, but under the same condition, MWCNT induced genotoxicity and perturbed cell motility. In addition, MeT-5A cells demonstrated different cellular responses to MWCNT after short-term and long-term exposure. Taken together, our results indicated a possible carcinogenic potential for MWCNT after long-term treatment, in which Annexin family proteins might be involved.

Empirical Procedures for Long-Term Prediction of Fatigue Damage for an Instrumented Marine Riser

2011 ◽  
Author(s):  
C. Shi ◽  
L. Manuel ◽  
M. A. Tognarelli
Keyword(s):  
Fatigue Damage ◽  
Field Measurements ◽  
Damage Estimation ◽  
Current Profile ◽  
Short Term ◽  
Response Characteristics ◽  
Damage Rate ◽  
Using Data ◽  
Analytical Approaches

Slender marine risers used in deepwater applications can experience vortex-induced vibration (VIV). It is becoming increasingly common for field monitoring campaigns to be undertaken wherein data loggers such as strain sensors and/or accelerometers are installed on such risers to aid in VIV-related fatigue damage estimation. Such damage estimation relies on the application of empirical procedures that make use of the collected data. This type of damage estimation can be undertaken for different current profiles encountered. The empirical techniques employed make direct use of the measurements and key components in the analyses (such as participating riser modes selected for use in damage estimation) are intrinsically dependent on the actual current profiles. Fatigue damage predicted in this manner is in contrast to analytical approaches that rely on simplifying assumptions on both the flow conditions and the response characteristics. Empirical fatigue damage estimates conditional on current profile type can account explicitly even for complex response characteristics, participating riser modes, etc. With significant amounts of data, it is possible to establish “short-term” fatigue damage rate distributions conditional on current type. If the relative frequency of different current types is known from metocean studies, the short-term fatigue distributions can be combined with the current distributions to yield integrated “long-term” fatigue damage rate distributions. Such a study is carried out using data from the Norwegian Deepwater Programme (NDP) model riser subject to several sheared and uniform current profiles and with assumed probabilities for different current conditions. From this study, we seek to demonstrate the effectiveness of empirical techniques utilized in combination with field measurements to predict long-term fatigue damage and life.

Sign in / Sign up

Export Citation Format

Share Document