A new issue of this journal has just
been published. To see abstracts of the papers it contains (with links through
to the full papers) click here:
Selected
papers from the latest issue:
Infrared motion sensing system for human-following robots
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Guodong Feng, Xuemei Guo, Guoli Wang
This paper presents an infrared motion sensing system for human-following robots. The proposed sensing system consists of two layers: a geometric sensing layer and a cooperative sensing layer. Through a modulation of the sensor field of view (FOV), the geometric sensing layer can generate bearing measurements of a moving human target from multiple perspectives. Through a fusion of bearing measurements from multiple perspectives, the cooperative sensing layer can localize the target and predict its moving direction for the robot to perform related actions. In this study, pyroelectric infrared (PIR) sensor arrays and Fresnel lenses are used for geometric sensing. The least square method is used for data fusion. The performance of the sensing system is evaluated through experiments of human localization and human following.
Source:Sensors and Actuators A: Physical, Volume 185
Guodong Feng, Xuemei Guo, Guoli Wang
This paper presents an infrared motion sensing system for human-following robots. The proposed sensing system consists of two layers: a geometric sensing layer and a cooperative sensing layer. Through a modulation of the sensor field of view (FOV), the geometric sensing layer can generate bearing measurements of a moving human target from multiple perspectives. Through a fusion of bearing measurements from multiple perspectives, the cooperative sensing layer can localize the target and predict its moving direction for the robot to perform related actions. In this study, pyroelectric infrared (PIR) sensor arrays and Fresnel lenses are used for geometric sensing. The least square method is used for data fusion. The performance of the sensing system is evaluated through experiments of human localization and human following.
Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Frederic Surre, Richard H. Scott, Pradipta Banerji, P.A.M. Basheer, Tong Sun, Kenneth T.V. Grattan
In this paper, the reliability and thus the suitability of optical fibre strain sensors for surface strain measurement in concrete structures was investigated. Two different configurations of optical strain sensors were used each having different mountings making them suitable for different uses in various structures. Due to the very limited time available to install the sensors and take result, commercially packaged sensors were used. In the tests carried out each sensor was mounted onto a concrete beam which was then subjected to a range of known and calibrated loadings. The performance of the optical strain sensors thus evaluated was compared with the results of conventional techniques. This comparison allows for selecting the best performing combination of sensor/mounting, i.e. long-gauge sensor with mounts bolted to threaded rods glued into the concrete for use in future work in a field test where a limited time window was available for installation, testing and post-test demounting.
Source:Sensors and Actuators A: Physical, Volume 185
Frederic Surre, Richard H. Scott, Pradipta Banerji, P.A.M. Basheer, Tong Sun, Kenneth T.V. Grattan
In this paper, the reliability and thus the suitability of optical fibre strain sensors for surface strain measurement in concrete structures was investigated. Two different configurations of optical strain sensors were used each having different mountings making them suitable for different uses in various structures. Due to the very limited time available to install the sensors and take result, commercially packaged sensors were used. In the tests carried out each sensor was mounted onto a concrete beam which was then subjected to a range of known and calibrated loadings. The performance of the optical strain sensors thus evaluated was compared with the results of conventional techniques. This comparison allows for selecting the best performing combination of sensor/mounting, i.e. long-gauge sensor with mounts bolted to threaded rods glued into the concrete for use in future work in a field test where a limited time window was available for installation, testing and post-test demounting.
Highlights
► Long gauge length fiber optic sensors can measure higher strain. ► Short-gauge length fiber optic sensors underead strain values. ► Best fibre optic strain sensor attachment on concrete surface. ► Validation of optical sensor system for field test application.Impact of silicon nitride thickness on the infrared sensitivity of silicon nitride–aluminum microcantilevers
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Matthew R. Rosenberger, Beomjin Kwon, David G. Cahill, William P. King
This paper investigates how silicon nitride thickness impacts the performance of silicon nitride–aluminum bimaterial cantilever infrared sensors. A model predicts cantilever behavior by considering heat transfer within and from the cantilever, cantilever optical properties, cantilever bending mechanics, and thermomechanical noise. Silicon nitride–aluminum bimaterial cantilevers of different thicknesses were designed and fabricated. Cantilever sensitivity and noise were measured when exposed to infrared laser radiation. For cantilever thickness up to 1200nm, thicker silicon nitride results in improved signal to noise ratio due to increased absorptivity and decreased noise. The best cantilever had an incident flux sensitivity of 2.1×10−3 VW−1 m2 and an incident flux signal to noise ratio of 406Hz1/2 W−1 m2, which is more than an order of magnitude improvement compared to the best commercial cantilever.
Source:Sensors and Actuators A: Physical, Volume 185
Matthew R. Rosenberger, Beomjin Kwon, David G. Cahill, William P. King
This paper investigates how silicon nitride thickness impacts the performance of silicon nitride–aluminum bimaterial cantilever infrared sensors. A model predicts cantilever behavior by considering heat transfer within and from the cantilever, cantilever optical properties, cantilever bending mechanics, and thermomechanical noise. Silicon nitride–aluminum bimaterial cantilevers of different thicknesses were designed and fabricated. Cantilever sensitivity and noise were measured when exposed to infrared laser radiation. For cantilever thickness up to 1200nm, thicker silicon nitride results in improved signal to noise ratio due to increased absorptivity and decreased noise. The best cantilever had an incident flux sensitivity of 2.1×10−3 VW−1 m2 and an incident flux signal to noise ratio of 406Hz1/2 W−1 m2, which is more than an order of magnitude improvement compared to the best commercial cantilever.
Highlights
► In bimaterial cantilever infrared sensors, silicon nitride thickness affects cantilever absorptivity, sensitivity, and noise. ► We model and measure bimaterial cantilever sensors of several thicknesses and geometries. ► Optimization of the silicon nitride thickness improves the cantilever performance by 10× compared to commercial microcantilevers.Effects of scaling and geometry on the performance of piezoelectric microphones
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Stephen B. Horowitz, Adam D. Mathias, Jon R. Fox, J.P. Cortes, Mohan Sanghadasa, Paul Ashley
Recent advances in microfabrication and nanofabrication techniques have allowed for the construction of ever-smaller sensors for the measurement of acoustic signals. The physics of sensor transduction and acoustics however place fundamental constraints on performance and limit the benefits of continual reductions in size. Key operating parameters such as sensitivity, minimum detectable signal (MDS) and resonant frequency are directly affected by device scale. Besides overall scale, relative sensor geometry (e.g. thickness ratio) can drastically alter performance. Through finite element and lumped element modeling, we study the effects of sensor geometry and scale on the sensitivity and noise performance of a piezoelectric microphone. The results indicate optimal relative geometric parameters for maximum performance and demonstrate the strong dependence on device geometry.
Source:Sensors and Actuators A: Physical, Volume 185
Stephen B. Horowitz, Adam D. Mathias, Jon R. Fox, J.P. Cortes, Mohan Sanghadasa, Paul Ashley
Recent advances in microfabrication and nanofabrication techniques have allowed for the construction of ever-smaller sensors for the measurement of acoustic signals. The physics of sensor transduction and acoustics however place fundamental constraints on performance and limit the benefits of continual reductions in size. Key operating parameters such as sensitivity, minimum detectable signal (MDS) and resonant frequency are directly affected by device scale. Besides overall scale, relative sensor geometry (e.g. thickness ratio) can drastically alter performance. Through finite element and lumped element modeling, we study the effects of sensor geometry and scale on the sensitivity and noise performance of a piezoelectric microphone. The results indicate optimal relative geometric parameters for maximum performance and demonstrate the strong dependence on device geometry.
A simple, low-cost, high-sensitivity fiber-optic tilt sensor
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Jovan S. Bajić, Dragan Z. Stupar, Lazo M. Manojlović, Miloš P. Slankamenac, Miloš B. Živanov
The paper presents a simple, low-cost and high-sensitivity fiber-optic tilt sensor. The sensor consists of two optical fibers and a container filled with transparent liquid to the half of the total volume of the container. The sensor principle is based on the change in angle of the liquid surface with respect to the fibers with the tilt angle. The achieved sensor sensitivity and resolution are 1V/° and 0.02°, respectively.
Source:Sensors and Actuators A: Physical, Volume 185
Jovan S. Bajić, Dragan Z. Stupar, Lazo M. Manojlović, Miloš P. Slankamenac, Miloš B. Živanov
The paper presents a simple, low-cost and high-sensitivity fiber-optic tilt sensor. The sensor consists of two optical fibers and a container filled with transparent liquid to the half of the total volume of the container. The sensor principle is based on the change in angle of the liquid surface with respect to the fibers with the tilt angle. The achieved sensor sensitivity and resolution are 1V/° and 0.02°, respectively.
Flexible PVDF-TrFE pyroelectric sensor driven by polysilicon thin film transistor fabricated on ultra-thin polyimide substrate
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
A. Pecora, L. Maiolo, F. Maita, A. Minotti
In this work we present a flexible pyroelectric sensor composed by a PVDF-TrFE capacitor realized on ultra-thin polyimide film (5μm thick), integrated with a n-channel low temperature polysilicon thin film transistor also fabricated on ultra-thin polyimide (8μm thick). Exploiting a multi-foil approach, the pyroelectric capacitors and the transistors were attached one over the other reaching a final thickness of about 15μm. The bottom contact of the sensor capacitance was connected to the gate of the transistor by a silver ink, while, for bias and load resistances, we used external elements. The active sensor area was defined by a circular capacitor with a diameter of about 2mm. In order to enhance PVDF-TrFE pyroelectric properties, an external stepwise voltage was applied to the structure up to values of 160V at a temperature of about 80°C. The devices were then tested, at different working frequencies (up to 800Hz) under a specific infrared radiation provided by a He–Ne laser, with a wavelength of 632nm and maximum power of 5mW. An output signal of tens of millivolt was observed at 10Hz, exploiting the pre-amplification of polysilicon thin film transistor.
Source:Sensors and Actuators A: Physical, Volume 185
A. Pecora, L. Maiolo, F. Maita, A. Minotti
In this work we present a flexible pyroelectric sensor composed by a PVDF-TrFE capacitor realized on ultra-thin polyimide film (5μm thick), integrated with a n-channel low temperature polysilicon thin film transistor also fabricated on ultra-thin polyimide (8μm thick). Exploiting a multi-foil approach, the pyroelectric capacitors and the transistors were attached one over the other reaching a final thickness of about 15μm. The bottom contact of the sensor capacitance was connected to the gate of the transistor by a silver ink, while, for bias and load resistances, we used external elements. The active sensor area was defined by a circular capacitor with a diameter of about 2mm. In order to enhance PVDF-TrFE pyroelectric properties, an external stepwise voltage was applied to the structure up to values of 160V at a temperature of about 80°C. The devices were then tested, at different working frequencies (up to 800Hz) under a specific infrared radiation provided by a He–Ne laser, with a wavelength of 632nm and maximum power of 5mW. An output signal of tens of millivolt was observed at 10Hz, exploiting the pre-amplification of polysilicon thin film transistor.
Using ring strain sensors to measure dynamic forces in wind-tunnel testing
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Raquel A.B. Almeida, Daniel C. Vaz, António P.V. Urgueira, A.R. Janeiro Borges
The paper deals with the use of strain-gage based ring-sensors to measure the dynamic forces involved in wind-tunnel testing for research of aeroelastic instabilities. In these experiments, the model has to be supported by an elastic suspension system that allows it to move in response to the flow. The motivation for the work here reported was the assessment of the possibility of occurrence of aeroelastic instabilities in a sectional model of a bridge deck under the action of lateral wind. The model is suspended by helical springs linked to four ring-sensors and aerodynamic drag is measured by two other ring-sensors. The entire measuring system stands outside the wind-tunnel and proved to be practical, low-cost and adaptable to other sectional models. The paper describes the development process and evaluation results of the ring sensors. They feature strain gages arranged in full Wheatstone bridge circuit. The measured time series of force values were translated into lift, pitch moment and drag, as well as linear and angular displacements of the model. High quality results were obtained with the assembly, which allowed obtaining the aerodynamic parameters sought.
Source:Sensors and Actuators A: Physical, Volume 185
Raquel A.B. Almeida, Daniel C. Vaz, António P.V. Urgueira, A.R. Janeiro Borges
The paper deals with the use of strain-gage based ring-sensors to measure the dynamic forces involved in wind-tunnel testing for research of aeroelastic instabilities. In these experiments, the model has to be supported by an elastic suspension system that allows it to move in response to the flow. The motivation for the work here reported was the assessment of the possibility of occurrence of aeroelastic instabilities in a sectional model of a bridge deck under the action of lateral wind. The model is suspended by helical springs linked to four ring-sensors and aerodynamic drag is measured by two other ring-sensors. The entire measuring system stands outside the wind-tunnel and proved to be practical, low-cost and adaptable to other sectional models. The paper describes the development process and evaluation results of the ring sensors. They feature strain gages arranged in full Wheatstone bridge circuit. The measured time series of force values were translated into lift, pitch moment and drag, as well as linear and angular displacements of the model. High quality results were obtained with the assembly, which allowed obtaining the aerodynamic parameters sought.
Mechanical model of flex sensors used to sense finger movements
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Giovanni Saggio
Flex sensors change in their electrical resistance value depending on the amount of bend they are subjected. These sensors can be realized with different techniques, but the mostly adopted are based on a resistive element film, which can be made of a PEDOT:PSS polymer or of a carbon-based element, printed on a plastic substrate. We investigated from a theoretical point of view the mechanical aspect of these sensors related to their utilization to sense finger movements, to determine the relationship with the electrical behavior. This was to provide enhanced degrees of understanding and predictability in performances. Experiments were conducted on custom-made flex sensors based on PEDOT:PSS polymer, to measure the resistance variations vs. the amount of bend radius induced in the sensors, in either of two opposing directions (outward and inward). Results demonstrated that the mechanical behavior influences the electrical counterpart but linearly, the more the bent the more the increase in the resistance, in a direct proportion. When a nonlinear behavior is measured, as in the case of commercially available Flexpoint sensors, it was found to depend only to causes strictly related to physical changes in the resistive element (cracks under stress).
Source:Sensors and Actuators A: Physical, Volume 185
Giovanni Saggio
Flex sensors change in their electrical resistance value depending on the amount of bend they are subjected. These sensors can be realized with different techniques, but the mostly adopted are based on a resistive element film, which can be made of a PEDOT:PSS polymer or of a carbon-based element, printed on a plastic substrate. We investigated from a theoretical point of view the mechanical aspect of these sensors related to their utilization to sense finger movements, to determine the relationship with the electrical behavior. This was to provide enhanced degrees of understanding and predictability in performances. Experiments were conducted on custom-made flex sensors based on PEDOT:PSS polymer, to measure the resistance variations vs. the amount of bend radius induced in the sensors, in either of two opposing directions (outward and inward). Results demonstrated that the mechanical behavior influences the electrical counterpart but linearly, the more the bent the more the increase in the resistance, in a direct proportion. When a nonlinear behavior is measured, as in the case of commercially available Flexpoint sensors, it was found to depend only to causes strictly related to physical changes in the resistive element (cracks under stress).
A broadband optical fiber based inline polarizer for telecom wavelength range
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Hamid Esmaeilzadeh, Ezatollah Arzi, Morteza Mozafari, Alireza Hassani
A broadband optical fiber based inline polarizer (OFIP) for telecom wavelength division multiplexing (WDM) systems is fabricated by coating of Al and Au layers on opposite sides of an etched multimode fiber. We demonstrated that the cladding residual thickness δ =0μm optimizes the OFIP design for the maximum extinction ratio (ER) of 17.1dB/cm, at both telecom wavelengths of 1550nm and 1310nm. In addition to the broadband characteristics of this OFIP, the optimal ER value which is identical for both telecom regimes makes our OFIP even more desirable for WDM systems. Finally, our OFIP is very cheap and miniaturized which also makes it very attractive in commercialization point of view.
Source:Sensors and Actuators A: Physical, Volume 185
Hamid Esmaeilzadeh, Ezatollah Arzi, Morteza Mozafari, Alireza Hassani
A broadband optical fiber based inline polarizer (OFIP) for telecom wavelength division multiplexing (WDM) systems is fabricated by coating of Al and Au layers on opposite sides of an etched multimode fiber. We demonstrated that the cladding residual thickness δ =0μm optimizes the OFIP design for the maximum extinction ratio (ER) of 17.1dB/cm, at both telecom wavelengths of 1550nm and 1310nm. In addition to the broadband characteristics of this OFIP, the optimal ER value which is identical for both telecom regimes makes our OFIP even more desirable for WDM systems. Finally, our OFIP is very cheap and miniaturized which also makes it very attractive in commercialization point of view.
Thick macroporous silicon membranes: Influence of the masking layer on the underetching characteristics
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Margherita Bassu, Gilles Scheen, Laurent A. Francis
Macroporous silicon (MPS) has been demonstrated as an interesting material to be used in different applications including micromachining and chemical sensing. In most of these applications the formation of MPS in patterned areas is required or preferable. In this work we report the results of a study on the selective anodization of patterned p-type silicon substrates to form thick MPS layers. Two challenging issues were identified: (1) overetching at the edge of Si3N4 layers, which causes are principally associated with the electrical properties of the interface between the mask and the substrate and the distribution of carriers across the patterned area; (2) adherence of organic masking layers at the silicon during the anodization. Metallic Au/Ti masking layer was demonstrated to be a valuable solution to both issues. SEM cross-sectional views of macroporous layers formed on silicon substrates patterned using different materials are shown and analyzed. Experimental results are supported by two-dimensional (2D) simulations of the silicon/mask/electrolyte interface.
Source:Sensors and Actuators A: Physical, Volume 185
Margherita Bassu, Gilles Scheen, Laurent A. Francis
Macroporous silicon (MPS) has been demonstrated as an interesting material to be used in different applications including micromachining and chemical sensing. In most of these applications the formation of MPS in patterned areas is required or preferable. In this work we report the results of a study on the selective anodization of patterned p-type silicon substrates to form thick MPS layers. Two challenging issues were identified: (1) overetching at the edge of Si3N4 layers, which causes are principally associated with the electrical properties of the interface between the mask and the substrate and the distribution of carriers across the patterned area; (2) adherence of organic masking layers at the silicon during the anodization. Metallic Au/Ti masking layer was demonstrated to be a valuable solution to both issues. SEM cross-sectional views of macroporous layers formed on silicon substrates patterned using different materials are shown and analyzed. Experimental results are supported by two-dimensional (2D) simulations of the silicon/mask/electrolyte interface.
Highlights
► In this work we report the results of a study on the selective formation of macropores on p-type silicon. ► The observed overetching at the edges of Si3N4 layers was imputed to the charge distribution at the interface. ► Loss of adhesion of organic masking layers at the silicon during the anodization was observed. ► Metal HF resistant masking layers were demonstrated to be a solution to the formation of localized macroporous silicon layer.Schottky diode properties of CuInSe2 films prepared by a two-step growth technique
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
H. Tecimer, S. Aksu, H. Uslu, Y. Atasoy, E. Bacaksız, Ş. Altındal
CuInSe2 films were synthesized by a thermal evaporation method on both glass and Mo coated glass substrates. To obtain Al/CuInSe2/Mo Schottky diode, Al metal was evaporated on the upper surface of CuInSe2 as a front contact and electrical properties of the structure were analyzed. The structural and optical behaviors of the CuInSe2 thin films were also investigated. The X-ray diffraction studies showed that the chalcopyrite CuInSe2 was obtained with a preferential orientation in the (112) plane with lattice parameters a and c as 0.577 and 1.161nm, respectively. Mo back contact layer had a preferential orientation in the (110) plane. Scanning electron microscopy equipped with energy dispersive spectroscopy revealed an irregular and rough surface morphology with Cu-rich protruding regions. Optical studies showed the existence of three different band gaps, which were determined as 1.06, 1.17 and 1.39eV, respectively. From the Hall Effect measurements, we determined the carrier concentration of CuInSe2 films as 4.0×1017 cm−3. The electrical properties of the CuInSe2 films were further studied by fabricating Al/p-CuInSe2/Mo structures and obtaining their forward and reverse bias current–voltage characteristics in a wide temperature range of 100–300K, in steps of 25K. A thorough analysis of the forward bias current–voltage characteristics based on thermionic emission theory showed that the zero bias barrier height increases while series resistance and ideality factor decreases with an increase in temperature. After a barrier height inhomogeneity correction, the Richardson constant and mean barrier height were found to be 34.71A/cm2 K2 and 0.72eV, respectively.
Source:Sensors and Actuators A: Physical, Volume 185
H. Tecimer, S. Aksu, H. Uslu, Y. Atasoy, E. Bacaksız, Ş. Altındal
CuInSe2 films were synthesized by a thermal evaporation method on both glass and Mo coated glass substrates. To obtain Al/CuInSe2/Mo Schottky diode, Al metal was evaporated on the upper surface of CuInSe2 as a front contact and electrical properties of the structure were analyzed. The structural and optical behaviors of the CuInSe2 thin films were also investigated. The X-ray diffraction studies showed that the chalcopyrite CuInSe2 was obtained with a preferential orientation in the (112) plane with lattice parameters a and c as 0.577 and 1.161nm, respectively. Mo back contact layer had a preferential orientation in the (110) plane. Scanning electron microscopy equipped with energy dispersive spectroscopy revealed an irregular and rough surface morphology with Cu-rich protruding regions. Optical studies showed the existence of three different band gaps, which were determined as 1.06, 1.17 and 1.39eV, respectively. From the Hall Effect measurements, we determined the carrier concentration of CuInSe2 films as 4.0×1017 cm−3. The electrical properties of the CuInSe2 films were further studied by fabricating Al/p-CuInSe2/Mo structures and obtaining their forward and reverse bias current–voltage characteristics in a wide temperature range of 100–300K, in steps of 25K. A thorough analysis of the forward bias current–voltage characteristics based on thermionic emission theory showed that the zero bias barrier height increases while series resistance and ideality factor decreases with an increase in temperature. After a barrier height inhomogeneity correction, the Richardson constant and mean barrier height were found to be 34.71A/cm2 K2 and 0.72eV, respectively.
Modelling trilayer conjugated polymer actuators for their sensorless position control
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Chuc Huu Nguyen, Gursel Alici, Gordon G. Wallace
In this paper, we present a new model to describe the displacement response of a trilayer conjugated polymer actuator that can operate in dry environments. The proposed model based on the working principle of conjugated polymer actuators includes diffusion impedances combined with double layer capacitors and charge transfer resistors. The parameters of the model are estimated by using a nonlinear least square estimation method by comparing simulation and experimental results. The proposed model is very useful in predicting the impedance as well as the displacement response of the polymer actuators accurately. Based on the proposed model, an inversion-based controller not requiring an external sensor for position feedback data is implemented and compared with the experimental results. The experimental position control results have confirmed the feasibility and efficacy of the proposed model in describing the time response of the actuators and their position control without using externally provided position data.
Source:Sensors and Actuators A: Physical, Volume 185
Chuc Huu Nguyen, Gursel Alici, Gordon G. Wallace
In this paper, we present a new model to describe the displacement response of a trilayer conjugated polymer actuator that can operate in dry environments. The proposed model based on the working principle of conjugated polymer actuators includes diffusion impedances combined with double layer capacitors and charge transfer resistors. The parameters of the model are estimated by using a nonlinear least square estimation method by comparing simulation and experimental results. The proposed model is very useful in predicting the impedance as well as the displacement response of the polymer actuators accurately. Based on the proposed model, an inversion-based controller not requiring an external sensor for position feedback data is implemented and compared with the experimental results. The experimental position control results have confirmed the feasibility and efficacy of the proposed model in describing the time response of the actuators and their position control without using externally provided position data.
Evaluation of generated micro droplets using micropore plates oscillated by ultrasonic torsional transducers
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Yusuke Kiyama, Yoshiyuki Tominaga, Takefumi Kanda, Koichi Suzumori, Toru Kishi, Yoshiaki Yamada, Norihisa Seno
This paper reports on generating micro and uniform droplets in various viscosity liquids by using a micropore plate oscillated by an ultrasonic torsional transducer. When the micropore plate was not oscillated, generated droplet diameter was not stable. On the other hand, when the micropore plate was oscillated, generated droplets became small and uniform by ruffling the liquid column surface. Droplets were generated experimentally in the air by using pure water and silicone oil of various viscosities and then evaluated. We have designed the ultrasonic torsional transducer and a droplet generation device to apply a high pressure for the use of higher viscosity liquids. We have succeeded in generating droplets by using pure water when the ultrasonic torsional transducer and the micropore plate that had an 18-μm-diameter micropore were used. The average diameter of droplets was 30.0μm and the standard deviation was 0.98. We have also succeeded in generating 50-cSt silicone oil droplets by using the droplet generation device and the micropore plate that had the 50-μm-diameter micropore. The average diameter of droplets was 98.0μm and the standard deviation was 0.76.
Source:Sensors and Actuators A: Physical, Volume 185
Yusuke Kiyama, Yoshiyuki Tominaga, Takefumi Kanda, Koichi Suzumori, Toru Kishi, Yoshiaki Yamada, Norihisa Seno
This paper reports on generating micro and uniform droplets in various viscosity liquids by using a micropore plate oscillated by an ultrasonic torsional transducer. When the micropore plate was not oscillated, generated droplet diameter was not stable. On the other hand, when the micropore plate was oscillated, generated droplets became small and uniform by ruffling the liquid column surface. Droplets were generated experimentally in the air by using pure water and silicone oil of various viscosities and then evaluated. We have designed the ultrasonic torsional transducer and a droplet generation device to apply a high pressure for the use of higher viscosity liquids. We have succeeded in generating droplets by using pure water when the ultrasonic torsional transducer and the micropore plate that had an 18-μm-diameter micropore were used. The average diameter of droplets was 30.0μm and the standard deviation was 0.98. We have also succeeded in generating 50-cSt silicone oil droplets by using the droplet generation device and the micropore plate that had the 50-μm-diameter micropore. The average diameter of droplets was 98.0μm and the standard deviation was 0.76.
Tunable mechanical properties of layer-by-layer self-assembled carbon nanotube/polymer nanocomposite membranes for M/NEMS
03 September 2012,
08:38:13
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 185
Dongzhi Zhang, Tianhong Cui
This paper presents layer-by-layer (LbL) self-assembly of single-walled carbon nanotube (SWNT)/polymer membranes with a well-dispersed wide-range tunable volume fraction of functionalized SWNTs. The surface morphology of the SWNT/polymer membranes shows a high strength, dense and random network structures. The quartz crystal microbalance (QCM) characterization illustrates that the deposition thickness and the SWNT loading fraction in SWNT nanocomposites can be controlled in a large range based on LbL sequential deposition process. The Young's modulus of the self-assembled SWNT/polymer composite membranes is characterized by a combinative approach of piezoelectric excitation and laser vibrometer measurement. The Young's modulus of SWNT/polymer nanocomposites is tunable from hundreds to tens of GPa, as a function of the SWNT volume fraction. Such significant enhancement of LbL self-assembled SWNTs offers a way in which the embedded SWNTs can realize the true potential to strengthen SWNT/polymer nanocomposites. Conventional mixture models such as rule-of-mixture model and Halpin–Tsai model fail to explain the structure–property regime in nanoscale at a high SWNT fraction ratio. This observed tunability can serve as a benchmark to tailor the design of nanocomposite thin films for potential applications to MEMS and NEMS devices.
Source:Sensors and Actuators A: Physical, Volume 185
Dongzhi Zhang, Tianhong Cui
This paper presents layer-by-layer (LbL) self-assembly of single-walled carbon nanotube (SWNT)/polymer membranes with a well-dispersed wide-range tunable volume fraction of functionalized SWNTs. The surface morphology of the SWNT/polymer membranes shows a high strength, dense and random network structures. The quartz crystal microbalance (QCM) characterization illustrates that the deposition thickness and the SWNT loading fraction in SWNT nanocomposites can be controlled in a large range based on LbL sequential deposition process. The Young's modulus of the self-assembled SWNT/polymer composite membranes is characterized by a combinative approach of piezoelectric excitation and laser vibrometer measurement. The Young's modulus of SWNT/polymer nanocomposites is tunable from hundreds to tens of GPa, as a function of the SWNT volume fraction. Such significant enhancement of LbL self-assembled SWNTs offers a way in which the embedded SWNTs can realize the true potential to strengthen SWNT/polymer nanocomposites. Conventional mixture models such as rule-of-mixture model and Halpin–Tsai model fail to explain the structure–property regime in nanoscale at a high SWNT fraction ratio. This observed tunability can serve as a benchmark to tailor the design of nanocomposite thin films for potential applications to MEMS and NEMS devices.
No comments:
Post a Comment