In this paper, a magnetic field sensor with simple fabrication, high sensitivity and wide measurement range is proposed. The sensor consists of fiber Bragg grating, sensitivity enhancement structure (SES), magnetostrictive particles and epoxy resin matrix. Metal tube with length of 5 mm is glued onto both sides of the grating as SES, and the mental tube is covered with grooves. The FBG with mental tubes is coated with the matrix made of magnetostrictive particles and resin. During the curing process of matrix, a uniform magnetic field with 200mT and parallel to the fiber is applied to make the orientation of magnetostrictive particles constant. It also can make particles have uniform spatial distribution. Firstly, by comparing the performances of sensors made of three different resin without mental tube with the sensor made by gluing FBG onto Terfenol-D rod directly, it is found that the sensor with epoxy crystal adhesive has the highest sensitivity reaching 0.58 pm/mT. Secondly the sensor based on epoxy crystal adhesive with SES is evaluated. Compared with the sensor without SES and gluing diretly, the sensitivity increases 5.17 times to 3.58 pm/mT and the measurement expands ranging from 0 mT to 226 mT.
Lithium-ion batteries have become a most promising energy storage candidate in power station and electric vehicles because of its high power capability, high energy-conversion efficiency, and environmental friendliness. It is significant to diagnose the security of battery by monitoring the its state parameters. Wherein, temperature and strain are the two of the important ones. In this work, a sensitivity-enhanced FBG strain sensor was designed for the strain measurement of lithium-ion batteries. This proposed sensor consists of two FBGs and a lever mechanism. The lever mechanism works as a displacement amplifier. The amplified deformation of battery act on the functional FBG and induce the larger wavelength shift. The thermal compensation FBG can eliminate the influence of ambient temperature. The calibration test shows that this sensor has a high sensitivity of 11.55 pm/με and a good linearity. Application test on a battery illustrates that the strain responses of the sensor has a good repeatability in three cycles. Then, artificial neural networks were used for state of charge (SOC) estimation. When the strain and temperature data were set as input parameters, SOC can be well predicted. Therefore, this sensor can monitor the strain on the cell with high sensitivity and accuracy. This research demonstrated a new solution for SOC estimation especially based on strain signals, which can provide more informative data for battery management system.
In this paper, we developed a new kind of ionic polymer metal composite (IPMC) actuator by doping sulfonated carbon nanotube (SCNT) into Nafion matrix to overcome some major drawbacks, such as low output force and short air-operation time, which restrict applications of conventional Nafion IPMC actuators. Firstly, SCNT was synthesized by coupled reaction of multi-walled carbon nanotubes and azo compounds and then doped into Nafion matrix by casting method. Subsequently, several key parameters of the SCNT-reinforced Nation matrix, water uptake ratio and equivalent stiffness, were revealed and the inner morphology of the membranes were observed by scanning electron microscopy. Finally, the effects of the SCNT on the electromechanical properties of IPMC actuators, especially the actuating performance, were evaluated experimentally and analyzed systematically. The results showed that SCNT was evenly dispersed in Nafion matrix and a small amount of SCNT could improve the performance of IPMC actuators significantly.
In this paper, the emerging technology of energy harvesting based on dielectric elastomers (DE), a new type of
functional materials belonging to the family of Electroactive Polymers (EAPs), is presented with emphasis on its
performance characteristics and some key influencing factors. At first, on the basic principle of DE energy harvesting,
the effects of some control parameters are theoretically analyzed under certain mechanical and electrical constraints.
Then, a type of annular DE generator using the commercial elastomers of VHB 4910 (3M, USA), is specially designed
and fabricated. A series of experimental tests for the device’s energy harvesting performance are implemented at
different pre-stretch ratios, stretch amplitudes (displacements), and bias voltages in the constant charge (open-circuit)
condition. The experiment results demonstrate the associated influence laws of the above control parameters on the
performance of the DE generator, and have good consistent with those obtained from the theoretical analysis. This study
is expected to provide a helpful guidance for the design and operation of practical DE energy harvesting devices/systems.
As a new kind of ionic-driven smart materials, ionic polymer metal composite (IPMC ) is normally fabricated by
depositing noble metal (gold, platinum, palladium etc.) on both sides of base membrane (Nafion, Flemion etc.) and
shows large bending deflection under low voltage. In the process of fabricating IPMC, surface roughening of base
membrane has a significant effect on the performance of IPMC. At present, there are many ways to roughen the base
membrane, including physical and chemical ways. In this paper, we analyze the effects of different surface treatment
time by plasma etching on surface resistance and mechanical properties of IPMCs fabricated by the treated base
membranes. Experimental results show that the base membrane treated by plasma etching displays uniform surface
roughness, consequently reducing IPMC’s surface resistance effectively and forming more uniform and homogeneous
external and penetrative electrodes. However, due to the use of reactive gas, the plasma treatment leads to complex
chemical reaction on Nafion surface, changing element composition and material properties and resulting in the
performance degradation of IPMC. And sandblast way should be adopted and improved without any changes on element
and material structure.
DE (dielectric elastomer) is one of the most promising artificial muscle materials for its large strain over 100% under driving voltage. However, to date, dielectric elastomer actuators (DEAs) are prone to failure due to the temperature-dependent electric breakdown. Previously studies had shown that the
electrical breakdown strength was mainly related to the temperature-dependent elasticity modulus and
the permittivity of dielectric substances. This paper investigated the influence of ambient temperature
on the electric breakdown strength of DE membranes (VHB4910 3M). The electric breakdown experiment of the DE membrane was conducted at different ambient temperatures and pre-stretch levels. The real breakdown strength was obtained by measuring the deformation and the breakdown
voltage simultaneously. Then, we found that with the increase of the environment temperature, the electric breakdown strength decreased obviously. Contrarily, the high pre-stretch level led to the large
electric breakdown strength. What is more, we found that the deformations of DEs were strongly dependent on the ambient temperature.
A novel optical acceleration sensor based on optical fiber and MEMS technology is presented in this paper. It can
effectively solve the problem of low immunity of inertial sensors and can be used in navigation system towards the
Electro Magnetic Interference (EMI) and Electro Magnetic Pulse (EMP). A Fresnel diffractive micro lens is fabricated
with a glass substrate. A reflecting membrane is placed behind the diffractive micro lens in parallel and its displacement
is determined by acceleration. The sensing principle of the sensor is to calculate acceleration by measuring variousl light
intensity at the frontal focal point of the diffractive micro lens. Moreover, the performance of sensor was analyzed. The
results of analysis and computer simulation indicated that the design is logical and feasible. The results of proof-of-principle
experiments indicate that the principle of this novel sensor is true and it has merits of simple structure and high
When a small reflecting membrane is paralleled to a special Fresnel diffractive lens, the light intensity at the focal point of the diffractive lens is highly sensitive to the position of the membrane. Based on this principle, the authors put forward a new optical acceleration sensor which can largely meet the development of the fly-by-fight system used in flight control system. In addition, the sensing principle is described and the computer simulation of the sensor is carried out. The results show how the light intensity depends on the membrane position and the influence of error on conclusion. The sensor has realized the mutual supplement with each other's advantages of optical fiber and Micro Electro Mechanical System (MEMS).
A novel phase unwrapping algorithm of DSPI for complex structure is proposed in this paper. An image of the object to be measured with very high contrast can be obtained by the subtraction of two speckle pattern interferograms, whose optical phases are opposite. The complete image area of object to be measured can be correctly obtained from this high contrast image. By controlling the phase unwrapping procedure to be inside the image area of the object, the wrapped phase map of complex structure can be unwrapped. This novel phase unwrapping algorithm makes DSPI be able to be used to measure the complex structure in practical engineering, and will enlarge the application field of DSPI.
A novel speckle averaging technique for DSPI static deformation measurement is proposed in this paper. This method combines the speckle averaging and phase-shifting technique. A speckle averaging mechanism is designed and fabricated. Its stability and repeatability is high, so it can meet the requirement of the DSPI static deformation measurement. Using this technique, the quality of result of DSPI static deformation measurement is improved greatly. The algorithm of speckle averaging is described in detail. The comparison of results of different speckle averaging times is presented in this paper.
A novel digital speckle pattern interferometry system including multi lower power He-Ne lasers to measure large object is presented in this paper. Multi lower power He-Ne lasers and optical switches are set in it. Through the control of computer, the different laser can illuminate the different area of large object at different time. Then the phase maps corresponding to different area are jointed together to obtain the measurement result of entire object by using proper image mosaic algorithm. Using this method, the contradiction between laser power and size of object to be measured is overcome. In this system, the high coherence of He-Ne laser and the power of multi lasers are comprehensively used, which makes it be able to measure the large object in practical engineering. At the same time, the speckle pattern fringes with high quality can be obtained.
This paper reports on the design, fabrication and performance of some novel MEMS (Micro-electro-mechanical system) optical switches. We have developed a new kind of MEMS electromagnetic micro actuator, which can drive mirrors enter or leave the optical path of switch. The 1 X 2, 2 X 2, 1 X 4 and 1 X 8 single mode optic-fiber switches have been fabricated. The switching voltage is less than 8 V and the switching time is no more than 5 ms. Using optic-fiber collimator for light coupling, we obtain small insertion loss (> -0.8 dB), considering the length of the light path is 40 mm. The cross-talk is less than -60 dB, extinction ratio is -60 dB.
A time-average DSPI method for nanometer vibration mode measurement is presented in this paper. The phase continuous scan technique is combined with the Bessel fringe-shifting technique to quantitatively analyze the vibration mode by time-average DSPI is used in measurement system. Through the phase continuous scan, the background and speckle items are completely eliminated, which improves the fringe quality and enhances the signal-to-noise ratio of interferogram. There is no need to calibrate the optical phase-shifter exactly in this method. The anti-disturbance capability of this method is higher than that of the phase-stepping technique, so it is robust and easy to be used. In the vibration measurement system, the speckle average technology is used, so the high quality measuring results are obtained.
A new error-correcting algorithm of phase unwrapping is proposed in this paper. This method can eliminate the propagation of phase errors in the unwrapped phase map. It is simple, effective, and has been successfully used in the deformation measurement and the quantitative analysis of vibration mode by DSPI.
The phase continuous scan technique is combined with the Bessel fringe-shifting technique to quantitatively analyze the vibration mode by time-averaging DSPI. Through the phase continuous scan, the background and speckle items are completely eliminated, which improves the fringe quality and enhances the signal-to-noise ratio of interferogram. There is no need to calibrate the optical phase-shifter exactly in this method. The anti-disturbance capability of this method is higher than that of the phase-stepping technique, so it is robust and easy to be used.