Microstrain Sensors Research Articles

In situ detection of spatial distribution information of temperature-pH-strain of sandstone cultural relics

To monitor in situ the temperature, pH, and micro-strain change information of sandstone artifacts in the process of oxalic acid corrosion, the temperature, pH, and micro-strain fiber Bragg grating (FBG) sensors are developed. A theoretical model of the sensors is established. The surface morphology, material composition, pore structure, temperature, pH, and micro-strain of sandstone corroded by oxalic acid solutions of different concentrations are investigated. The experimental results show that the higher the concentration of oxalic acid, the stronger the corrosiveness of the sandstone. Ferrous oxalate and calcium oxalate produced by corrosion continuously precipitate from the inside of the rock, and the dual reaction of crystallization and dissolution occurs, reducing the proportion of fine pores in the rock pore suction and gravity. The oxalic acid solution is transported to the middle of the sandstone (3 cm) and undergoes the strongest chemical reaction with ore particles and debris, resulting in the maximum wavelength drift of the temperature, pH, and micro-strain sensors. The results of this study provide important support for analyzing the acid dissolution mechanism of stone cultural relics and the preventive protection of cultural relics.

Pushing the Electrochemical Performance Limits of Polypyrrole Toward Stable Microelectronic Devices

HighlightsOptimizing the current collectors with rGO and the addition of CNT in PPy, and the structural pulverization is prevented significantly.Areal capacitances of 65.9 to 70 mF cm−2 are achieved for PPy-CNT@rGO microsupercapacitors (MSCs) with 79% capacitance retention after 10,000 cycles.The MSC-derived capacitive micro-strain sensor is capable of biosignals detection.The micro strain sensor is capable of detecting wide levels of applied strain with short response/recovery time and excellent reliability.

Real-Time Micro-Monitoring of Surface Temperature and Strain of Magnesium Hydrogen Tank through Self-Made Two-In-One Flexible High-Temperature Micro-Sensor.

The adsorption and desorption of hydrogen in the magnesium powder hydrogen tank should take place in an environment with a temperature higher than 250 °C. High temperature and high strain will lead to reactive hydrogen leakage from the magnesium hydrogen tank due to tank rupture. Therefore, it is very important to monitor in real time the volume expansion, temperature change, and strain change on the surface of the magnesium hydrogen tank. In this study, the micro-electro-mechanical systems (MEMS) technology was used to innovatively integrate the micro-temperature sensor and the micro-strain sensor into a two-in-one flexible high-temperature micro-sensor with a small size and high sensitivity. It can be placed on the surface of the magnesium hydrogen tank for real-time micro-monitoring of the effect of hydrogen pressure and powder hydrogen absorption expansion on the strain of the hydrogen storage tank.

Vertical Graphene Canal Mesh for Strain Sensing with a Supereminent Resolution.

The development of microstrain sensors offers significant prospects in diverse applications, such as microrobots, intelligent human-computer interaction, health monitoring, and medical rehabilitation. Among strain sensor materials, vertical graphene (VG) has demonstrated considerable potential as a resistive material; however, VG-based strain sensors with high resolution are yet to be developed. In addition, the detection mechanism of VG has not been extensively investigated. Herein, we developed a VG canal mesh (VGCM) to fabricate a flexible strain sensor for ultralow strain sensing, achieving an accurate response to strains as low as 0.1‰ within a total strain range of 0%-4%. The detection of such low strains is due to the rigorous structural design and strain concentration effect of the three-dimensional micronano structure of the VGCM. Through experimental results and theoretical simulation, the evolution of microcracks in VG and the sensing mechanism of VG and VGCM are elaborated, and the unique advantages of VGCM are revealed. Finally, the VGCM-based strain sensors are proposed as portable breathing test equipment for rapid breathing detection.

Real-time microscopic monitoring of temperature and strain on the surface of magnesium hydrogen storage tank by high temperature resistant flexible integrated microsensor

Magnesium hydrogen storage tanks shrink and expand due to different states of hydrogen absorption and desorption, so it is important to monitor the body expansion, temperature change and stress change on the surface of magnesium hydrogen storage tank in real time. At present, commercially available temperature sensors and strain gauges are bulky, and the two sensors are not easy to be placed on the surface of magnesium hydrogen storage tanks for accurate measurement. Therefore, this study used micro-electromechanical systems (MEMS) technology to innovate and integrate micro-temperature sensor and micro-strain sensor, and make a small volume but high sensitivity high temperature resistant flexible integrated microsensor, which can be placed on the surface of the magnesium hydrogen storage tank to monitor the temperature, expansion and stress changes in real time, thus providing a reference for improving the optimal design of the magnesium hydrogen storage tank.

A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes

A fully inkjet-printed strain sensor based on carbon nanotubes (CNTs) was fabricated in this study for microstrain and microcrack detection. Carbon nanotubes and silver films were used as the sensing layer and conductive layer, respectively. Inkjet-printed CNTs easily undergo agglomeration due to van der Waals forces between CNTs, resulting in uneven films. The uniformity of CNT film affects the electrical and mechanical properties. Multi-pass printing and pattern rotation provided precise quantities of sensing materials, enabling the realization of uniform CNT films and stable resistance. Three strain sensors printed eight-layer CNT film by unidirectional printing, rotated by 180° and 90° were compared. The low density on one side of eight-layer CNT film by unidirectional printing results in more disconnection and poor connectivity with the silver film, thereby, significantly increasing the resistance. For 180° rotation eight-layer strain sensors, lower sensitivity and smaller measured range were found because strain was applied to the uneven CNT film resulting in non-uniform strain distribution. Lower resistance and better strain sensitivity was obtained for eight-layer strain sensor with 90° rotation because of uniform film. Given the uniform surface morphology and saturated sheet resistance of the 20-layer CNT film, the strain performance of the 20-layer CNT strain sensor was also examined. Excluding the permanent destruction of the first strain, 0.76% and 1.05% responses were obtained for the 8- and 20-layer strain sensors under strain between 0% and 3128 µε, respectively, which demonstrates the high reproducibility and recoverability of the sensor. The gauge factor (GF) of 20-layer strain sensor was found to be 2.77 under strain from 71 to 3128 µε, which is higher than eight-layer strain sensor (GF = 1.93) due to the uniform surface morphology and stable resistance. The strain sensors exhibited a highly linear and reversible behavior under strain of 71 to 3128 µε, so that the microstrain level could be clearly distinguished. The technology of the fully inkjet-printed CNT-based microstrain sensor provides high reproducibility, stability, and rapid hardness detection.

Axial Micro-Strain Sensor Based on FM-FBG via Dual-Mode ML-FMF in Sensor Networks

An in-fiber axial micro-strain sensor based on a Few Mode Fiber Bragg Grating (FM-FBG) is proposed and experimentally characterized. This FM-FBG is in inscribed in a multi-layer few-mode fiber (ML-FMF), and could acquire the change of the axial strain along fibers, which depends on the transmission dips. On account of the distinct dual-mode property, a good stability of this sensor is realized. The two transmission dips could have the different sensing behaviors. Both the propagation characteristics and operation principle of such a sensor are demonstrated in detail. High sensitivity of the FM-FBG, ~4 pm/με and ~4.5 pm/με within the range of 0 με - 1456 με, is experimentally achieved. FM-FBGs could be easily scattered along one fiber. So this sensor may have a great potential of being used in sensor networks.

Practical research on photonic crystal fiber micro-strain sensor

Abstract In this paper, we study the principle and application of a micro-strain sensor with a single mode fiber – tapered photonic crystal fiber – single mode fiber (SMF-TPCF-SMF) structure. The fabrication process and sensing principle of strain sensor are introduced in detail, and the key problems in the application process are solved. A kind of intermittent cooling tapering technique is proposed, which can obtain high quality interference spectrum. We verified that tapering the photonic crystal fiber in the sensor could effectively improve the sensitivity of the sensor. Experimental results showed that the strain sensitivity of the sensor before tapering is 2.75 p m / μ e , and its linear fit is 98.35%; after tapering, the strain sensitivity of the sensor is 5.46 p m / μ e , and its linear fit is 98.59% when the strain range is 109.860 - 559.287 μ e . The improved strain sensor with an SMF-TPCF-SMF structure has high sensitivity, good stability, quick response speed, good invertibility, simple manufacturing process, and low cost. Thus, it has broad application value.

Design and analysis of a prototypical sensory Z-slide for machine tools

Due to the advancements in high speed and high performance cutting, further improvements of machine component design and process monitoring are necessary. For this purpose, new machine components with process monitoring capabilities have to be developed. In this paper, a new spindle carrying Z-slide for a 5-axis machining center with integrated sensing capabilities for process monitoring is presented. First, the overall system design is described. The sensing capabilities to enable process monitoring are realized by application of a micro-strain gauges network on to the structure of the slide. The optimal sensor positions are computed by application of a special sensor placement algorithm. The prototype of the slide has been built up to investigate the system behavior. The electronic system of the prototype to realize the signal amplification and the communication via an industrial bus are presented. Furthermore, the results of the system analysis of the prototype are described. Because the sensor amplitudes, which can be monitored by strain gauges on stiff structures, are generally small, a method to increase these amplitudes by use of the notch effect and new micro-strain sensors is discussed. With this method, the signal amplitudes can be increased significantly, without degrading the stiffness noticeably. At the end of the paper a method to manufacture notches in the prototype by a milling process is presented. The surface roughness of plan notch ground, measured with a laserprofilometer, shows roughness values lower than 3 μm.

Fabrication and Characterization of Microscale Sensors for Strain Measurement in Flexible Polymer Heart Valve Leaflet

Flexible polymer heart valves are promising clinical prostheses for replacement of diseased or malfunctioned natural heart valves. However, the flexible polymer leaflets are prone to fatigue fracture, which hinders their practicality in clinical applications. In this study, microstrain sensor (gauge) for strain measurement is designed in the polyurethane (PU) thin film to measure the stress/strain in situ. In our design, the strain gauge is embedded in PU, which is different than the commercial strain gauge of sticking to the sample. The metal layer of strain gauge used in this study is gold. The overall size of the designed strain gauge is 1 mm × 1 mm × 0.1 µm, and the resistance value was measured to be 200 ±30Ω. The static test of strain gauge without damp proof shows that gauge sensitivity G was measured to be 4 and 1.8, when strain range is less than 1% and between 1–1.5%, respectively, while the static test of strain gauge with damp proof shows that gauge sensitivity G was measured to be 2.6 when strain range is less than 1.2%. The dynamic test of strain gauge was also applied in this study.

Motion analysis of sun salutation using magnetometer and accelerometer

Background:Sun salutation is a part of yoga. It consists of a sequence of postures done with synchronized breathing. The practice of few cycles of sun salutation is known to help in maintaining good health and vigor. The practice of sun salutation does not need any extra gadgets. Also it is very much aerobic and invigorates the body and the mind. sun salutation, which comprises 10 postures, involves most of the joints of the body. Understanding the transition phase during motion is a challenging task, and thus, new convenient methods need to be employed.Aims:The purpose of this study was to get an insight into the motion analysis of sun salutation during the transition from each of the 10 postures.Materials and Methods:A device MicroStrain sensor 3DM-GX1, which is a combination of magnetometers, accelerometers, and gyroscopes was used to measure the inclination and the acceleration of the body along the three axes. The acceleration obtained was then separated into gravitational and kinematic components.Results and Conclusions:The value of the gravitational component helps us to understand the position of the body and the kinematic component helps us to analyze the grace of the motion.

柔軟基板上に形成した磁気弾性歪センサ

Micro-strain sensors using the magnetostrictive properties of FeCeSiB films were investigated. To avoid the effects of the rigidity of the substrate on the stress sensitivity, a sensor was formed on thin polyimide ribbons (50 μm thick), which have superior heat resistance, wide elastic region, and excellent flexibility. By using the large difference in the coefficient of thermal expansion between FeCoSiB and polyimide, the residual stress in the magnetostrictive FeCoSiB patterned film was controlled. The sensor was formed under optimized conditions, and had an extremely high value of the figure of merit F = (ΔZ/Z)/Δε (change in film impedance Z per unit ε) of about 1500 at a carrier current frequency of 700 MHz. In addition, the point of stress representing the largest sensitivity of the sensor was controlled by controlling the field annealing conditions.

Strain sensitivity of highly magnetostrictive amorphous films for use in microstrain sensors

Strain sensitivity of amorphous (Fe90Co10)78Si12B10 sputtered film was studied in detail, so as to examine the potential of film for highly sensitive microstrain gauges. The film exhibited the figure of merit F=(Δμ/μ)/ε (change in film permeability μ per unit strain ε) of 1.2×105, the value of which is comparable to that of amorphous ribbons. Reflecting the large value of F, the high-frequency impedance of the film was also subjected to change due to strain: the change in impedance of 46% was observed at 100 MHz applying a strain of 300×10−6. It is also demonstrated that utilizing the strain-dependent impedance, a small strain of 0.2×10−6 can be detected with the film.

Deformation measurements of mortars at early ages and of large concrete components on site by means of embedded fiber-optic microstrain sensors

The paper demonstrates the application of fiber-optic microstrain gages to steel components of prestressed and reinforced concrete structures in order to measure deformations caused by proof loads or induced by constraints during the hardening period of large concrete sections. The use of embedded micro sensors for assessment of volume changes of cementitious building materials at early ages, and corresponding deformations due to heat, shrinkage, etc. in matured mortars, is also discussed. A resolution of 0.01 με was achieved. Theoretical aspects for the design of surface-mounted and embedded sensors are briefly addressed. We have investigated the behavior of embedded optical fibers, micro sensors and their coatings in cementitious mortars. Initial findings regarding the bond between sensor and the mortar matrix, as well as preferred coating materials, are presented.