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Selected
papers from the latest issue:
An improved sensitivity normalization technique of PGC demodulation with low minimum phase detection sensitivity using laser modulation to generate carrier signal
11 January 2013,
10:50:59
1 March 2013
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
The phase carrier signal of the PGC demodulation in fiber optic interferometric sensors (FOIS) may be generated by using laser current modulation to achieve all-fiber structures in long-distance and outdoor applications. An optical intensity modulation with carrier frequency induced from the laser modulation will cause the instability and distortion in the PGC demodulation output. Additionally, since the optical intensity attenuation of the FOIS will degrade the PGC demodulation output, proper sensitivity compensation on the PGC demodulator is necessary for the field applications. In this paper, we propose an improved technique by using a balanced photoreceiver in the FOIS to attain significant improvements in the instability and distortion of the PGC demodulation output. Moreover, we choose a small phase scrambler signal amplitude of 1rad to achieve improved the minimum phase detection sensitivity (MPDS) as well as sensitivity normalization because the improvement of the MPDS is very important to the advanced FOIS. The experimental results show that the improved values of the best MPDS are 5.7dB (for DFB laser diode) and 4.3dB (for EP1550 laser diode), respectively, by using the improved technique. From the sensitivity normalization experiment results, the relative error is shown to be less than 0.5% when the optical intensity attentuation is no more than 15dB. It verifies the effectiveness of the sensitivity normalization technique proposed in our improved PGC demodulation system.
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
The phase carrier signal of the PGC demodulation in fiber optic interferometric sensors (FOIS) may be generated by using laser current modulation to achieve all-fiber structures in long-distance and outdoor applications. An optical intensity modulation with carrier frequency induced from the laser modulation will cause the instability and distortion in the PGC demodulation output. Additionally, since the optical intensity attenuation of the FOIS will degrade the PGC demodulation output, proper sensitivity compensation on the PGC demodulator is necessary for the field applications. In this paper, we propose an improved technique by using a balanced photoreceiver in the FOIS to attain significant improvements in the instability and distortion of the PGC demodulation output. Moreover, we choose a small phase scrambler signal amplitude of 1rad to achieve improved the minimum phase detection sensitivity (MPDS) as well as sensitivity normalization because the improvement of the MPDS is very important to the advanced FOIS. The experimental results show that the improved values of the best MPDS are 5.7dB (for DFB laser diode) and 4.3dB (for EP1550 laser diode), respectively, by using the improved technique. From the sensitivity normalization experiment results, the relative error is shown to be less than 0.5% when the optical intensity attentuation is no more than 15dB. It verifies the effectiveness of the sensitivity normalization technique proposed in our improved PGC demodulation system.
Simplified analytical inductance model for a single turn eddy current sensor
11 January 2013,
10:50:59
1 March 2013
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
Analytical solutions for the inductance can be easily obtained for coils with rectangular cross sections having multiple turns realizing a homogeneous current distribution. These models have at least six parameters and do not consider the self-capacitance of the coil. The inner magnetic field is partially included, so that the accuracy of the static impedance is limited especially at higher frequencies. Even at lower frequencies, reference measurements without target are generally needed for self-calibration. By direct evaluation of the magnetic vector potential at the contour of the coil wire, a coil inductance model with a simpler mathematical structure can be obtained, which allows a consideration of the self-capacitance and the inner inductance. This avoids the need for reference measurements and the influence of distance, conductivity and permeability can be easier quantified. Inductance calculation requires 250ms on a standard personal computer for 100 frequencies resulting in a deviation of at most 5% for the static inductance. This is a good result with respect to the low impedances in the μΩ range, which are generally hard to measure. The proposed model represents a good basis for models of multiple turns with a precisely defined geometry including the self-capacitance effects.
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
Analytical solutions for the inductance can be easily obtained for coils with rectangular cross sections having multiple turns realizing a homogeneous current distribution. These models have at least six parameters and do not consider the self-capacitance of the coil. The inner magnetic field is partially included, so that the accuracy of the static impedance is limited especially at higher frequencies. Even at lower frequencies, reference measurements without target are generally needed for self-calibration. By direct evaluation of the magnetic vector potential at the contour of the coil wire, a coil inductance model with a simpler mathematical structure can be obtained, which allows a consideration of the self-capacitance and the inner inductance. This avoids the need for reference measurements and the influence of distance, conductivity and permeability can be easier quantified. Inductance calculation requires 250ms on a standard personal computer for 100 frequencies resulting in a deviation of at most 5% for the static inductance. This is a good result with respect to the low impedances in the μΩ range, which are generally hard to measure. The proposed model represents a good basis for models of multiple turns with a precisely defined geometry including the self-capacitance effects.
A compact opto-fluidic platform for chemical sensing with photonic crystal fibers
11 January 2013,
10:50:59
1 March 2013
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
We report a compact opto-fluidic platform capable of continuous analyte loading and unloading with a 3dB optical insertion loss. The customized opto-fluidic manipulator enabled infiltration of photonic crystal fibers (PCFs) at ten times the rate achievable by capillary action. Additionally, it is to our knowledge, the first demonstration of complete and rapid evacuation performed with a syringe pump for extended lengths (>100mm) of PCF. These properties render the device highly promising for continuous real-time sensing applications. Study was conducted on a PCF under macro-bending, taking advantage of its wavelength-dependent bending losses that red-shifted with the increasing refractive indices of the infiltrated analytes. The flexibility of the platform also facilitated the selection of an optimal bending radius (12.5mm) for the analysis, based on sensitivity (Δλ/Δn) and signal to noise ratio (Q-factor). The subsequent comparison of experiment with simulation results was noted to show good coherence. Moreover, experimental results showed repeatability throughout the multiple cycles of infiltration and evacuation executed. The further employment of the device in the chemical sensing of ethanol solutions exhibited good consistency with calibrated data for concentrations up to 50% by weight.
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
We report a compact opto-fluidic platform capable of continuous analyte loading and unloading with a 3dB optical insertion loss. The customized opto-fluidic manipulator enabled infiltration of photonic crystal fibers (PCFs) at ten times the rate achievable by capillary action. Additionally, it is to our knowledge, the first demonstration of complete and rapid evacuation performed with a syringe pump for extended lengths (>100mm) of PCF. These properties render the device highly promising for continuous real-time sensing applications. Study was conducted on a PCF under macro-bending, taking advantage of its wavelength-dependent bending losses that red-shifted with the increasing refractive indices of the infiltrated analytes. The flexibility of the platform also facilitated the selection of an optimal bending radius (12.5mm) for the analysis, based on sensitivity (Δλ/Δn) and signal to noise ratio (Q-factor). The subsequent comparison of experiment with simulation results was noted to show good coherence. Moreover, experimental results showed repeatability throughout the multiple cycles of infiltration and evacuation executed. The further employment of the device in the chemical sensing of ethanol solutions exhibited good consistency with calibrated data for concentrations up to 50% by weight.
Modified two prism SPR sensor configurations to improve the sensitivity of measurement
11 January 2013,
10:50:59
1 March 2013
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
A modified two prism optical configuration to improve the performance of surface plasmon resonance based sensor systems in bio and chemical analysis is proposed in this paper. This proposed cost effective approach improves the surface plasmon detection sensitivity by keeping the SP interrogation spot stationary during SPR angular rotation. The proposed concept is validated both theoretically as well as experimentally.
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
A modified two prism optical configuration to improve the performance of surface plasmon resonance based sensor systems in bio and chemical analysis is proposed in this paper. This proposed cost effective approach improves the surface plasmon detection sensitivity by keeping the SP interrogation spot stationary during SPR angular rotation. The proposed concept is validated both theoretically as well as experimentally.
A high performance strain gage based on the stressimpedance effect in magnetic amorphous wires
11 January 2013,
10:50:59
1 March 2013
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
The paper presents a study on the possibilities of using the Co based magnetic amorphous wires (MAWs) with nearly zero magnetostriction for measuring strains by exploiting the stressimpedance (SI) effect occurring on them. It is known that the SI is a particularization of the magnetoimpedance (MI) effect when a MAW is driven by an ac current and is subjected to mechanical stresses under constant magnetic field. Several parameters of influence have been investigated in order to obtain the best performances for a strain gage (SG) that is intended to be developed for finally building a high performance landslide transducer. Using a MAW of 20mm length which is driven by a current of 10mA and of frequency of 1MHz, under induced initial torsional stress of 5πrad/m and a residual axial tensile stress of 55MPa, we obtained a high sensitivity SG showing a gage constant of about 2100 and a linear range of ±200ppm.
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
The paper presents a study on the possibilities of using the Co based magnetic amorphous wires (MAWs) with nearly zero magnetostriction for measuring strains by exploiting the stressimpedance (SI) effect occurring on them. It is known that the SI is a particularization of the magnetoimpedance (MI) effect when a MAW is driven by an ac current and is subjected to mechanical stresses under constant magnetic field. Several parameters of influence have been investigated in order to obtain the best performances for a strain gage (SG) that is intended to be developed for finally building a high performance landslide transducer. Using a MAW of 20mm length which is driven by a current of 10mA and of frequency of 1MHz, under induced initial torsional stress of 5πrad/m and a residual axial tensile stress of 55MPa, we obtained a high sensitivity SG showing a gage constant of about 2100 and a linear range of ±200ppm.
Highlights
► A highly sensitive device for measuring strain is proposed in the paper. ► The working principle is based on the stressimpedance effect in amorphous wires. ► A sensitivity of over 10 times higher than that of semiconductor gages is achieved. ► The sensor has a linearity under 1% for a range of 200ppm. ► The sensor must be supplied with 1MHz ac current.Sensor characterization for multisensor odor-discrimination system
11 January 2013,
10:50:59
1 March 2013
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
In recent years, with the advent of new and cheaper sensors, the use of olfactory systems in homes, industries, and hospitals has a new start. Multisensor systems can improve the ability to distinguish between complex mixtures of volatile substances. To develop multisensor systems that are accurate and reliable, it is important to take into account the anomalies that may arise because of electronic instabilities, types of sensors, and air flow. In this approach, 32 metal oxide semiconductor sensors of 7 different types and operating at different temperatures have been used to develop a multisensor olfactory system. Each type of sensor has been characterized to select the most suitable temperature combinations. In addition, a prechamber has been designed to ensure a good air flow from the sample to the sensing area. The multisensor system has been tested with good results to perform multidimensional information detection of two fruits, based on obtaining sensor matrix data, extracting three features parameters from each sensor curve and using these parameters as the input to a pattern recognition system.
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
In recent years, with the advent of new and cheaper sensors, the use of olfactory systems in homes, industries, and hospitals has a new start. Multisensor systems can improve the ability to distinguish between complex mixtures of volatile substances. To develop multisensor systems that are accurate and reliable, it is important to take into account the anomalies that may arise because of electronic instabilities, types of sensors, and air flow. In this approach, 32 metal oxide semiconductor sensors of 7 different types and operating at different temperatures have been used to develop a multisensor olfactory system. Each type of sensor has been characterized to select the most suitable temperature combinations. In addition, a prechamber has been designed to ensure a good air flow from the sample to the sensing area. The multisensor system has been tested with good results to perform multidimensional information detection of two fruits, based on obtaining sensor matrix data, extracting three features parameters from each sensor curve and using these parameters as the input to a pattern recognition system.
Two forward-flow regimes in actuator nozzles with large-amplitude pulsation
11 January 2013,
10:50:59
1 March 2013
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
Extensive systematic investigations were made of pulsatile flows in a wide range of frequencies (extending over more than a decimal order) in a small nozzle of simple shape and size representative of actuator nozzles generating hybrid-synthetic jets – i.e. with return flow into the nozzle during a part of the cycle. In a synergetic approach, data from hot-wire anemometer measurements are supported and explained by results of numerical flowfield computations. Several effects not previously mentioned in literature were discovered. Particularly interesting among them is the existence of two different characters of the flowfield inside the nozzle in the forward-flow part of the period. In the transition between them, the initial annular-flow dominated configuration changes at a later stage into central-dominated flow.
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
Extensive systematic investigations were made of pulsatile flows in a wide range of frequencies (extending over more than a decimal order) in a small nozzle of simple shape and size representative of actuator nozzles generating hybrid-synthetic jets – i.e. with return flow into the nozzle during a part of the cycle. In a synergetic approach, data from hot-wire anemometer measurements are supported and explained by results of numerical flowfield computations. Several effects not previously mentioned in literature were discovered. Particularly interesting among them is the existence of two different characters of the flowfield inside the nozzle in the forward-flow part of the period. In the transition between them, the initial annular-flow dominated configuration changes at a later stage into central-dominated flow.
Design and fabrication of LTCC electro-magnetic energy harvester for low rotary speed
11 January 2013,
10:50:59
1 March 2013
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
This study focuses on the design and fabrication of a planar rotary electromagnetic energy harvester with a low rotary speed for bicycle dynamos. The primary components of a dynamo system include planar multilayer and multipole coils, a soft magnet (iron) used to enhance magnetic efficiency, and a multipole Nd/Fe/B (neodymium, iron, and boron) permanent magnet. Finite element analysis and the Taguchi method were used to design this dynamo system. The optimal parameters of the magnet, coil, and soft magnet were determined by using the Taguchi method. Low temperature co-fired ceramics (LTCC) technology was applied to fabricate silver planar multilayer coils with 10 and 20 layers, respectively. Nd/Fe/B was sintered to obtain the desired characteristics of a permanent magnet. A 28-pole magnet Nd/Fe/B with an outer diameter of 50mm and a thickness of 2mm was also sintered and magnetized, creating a magnetic field of 1.4T. Simulation results show that a harvester with 20-layer and 22 poles coils, a linewidth of 200μm, an interspace of 100μm, and a layer thickness of 40μm can generate voltages of 1.796V at a rotary speeds of 300rpm. This harvester system was approximately 50mm×50mm×3mm in volume (including 20-layer micro-coils+magnet+spacing between the coil and magnet surface). The experimentally induced voltages of 20-layer coils were 1.539V. Measurements show a similar trend with finite element simulations. The power output was 0.788mW with an external resistance load of 737Ω. This harvester is capable of powering 200 LEDs (forward voltage (VF)<2.2V and 20mA) using a rotary speed of 250rpm, and could be used for bicycle dynamo lighting.
Publication year: 2013
Source:Sensors and Actuators A: Physical, Volume 191
This study focuses on the design and fabrication of a planar rotary electromagnetic energy harvester with a low rotary speed for bicycle dynamos. The primary components of a dynamo system include planar multilayer and multipole coils, a soft magnet (iron) used to enhance magnetic efficiency, and a multipole Nd/Fe/B (neodymium, iron, and boron) permanent magnet. Finite element analysis and the Taguchi method were used to design this dynamo system. The optimal parameters of the magnet, coil, and soft magnet were determined by using the Taguchi method. Low temperature co-fired ceramics (LTCC) technology was applied to fabricate silver planar multilayer coils with 10 and 20 layers, respectively. Nd/Fe/B was sintered to obtain the desired characteristics of a permanent magnet. A 28-pole magnet Nd/Fe/B with an outer diameter of 50mm and a thickness of 2mm was also sintered and magnetized, creating a magnetic field of 1.4T. Simulation results show that a harvester with 20-layer and 22 poles coils, a linewidth of 200μm, an interspace of 100μm, and a layer thickness of 40μm can generate voltages of 1.796V at a rotary speeds of 300rpm. This harvester system was approximately 50mm×50mm×3mm in volume (including 20-layer micro-coils+magnet+spacing between the coil and magnet surface). The experimentally induced voltages of 20-layer coils were 1.539V. Measurements show a similar trend with finite element simulations. The power output was 0.788mW with an external resistance load of 737Ω. This harvester is capable of powering 200 LEDs (forward voltage (VF)<2.2V and 20mA) using a rotary speed of 250rpm, and could be used for bicycle dynamo lighting.
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