scispace - formally typeset
Search or ask a question

Showing papers in "Sensors and Actuators A-physical in 2006"


Journal ArticleDOI
TL;DR: In this article, a comparison between four vibration-powered generators designed to power standalone transducers is presented, based on a particular processing of the voltage delivered by the piezoelectric material, which enhances the electromechanical conversion.
Abstract: This paper presents a comparison between four vibration-powered generators designed to power standalone systems, such as wireless transducers. Ambient vibrations are converted into electrical energy using piezoelectric materials. The originality of the proposed approaches is based on a particular processing of the voltage delivered by the piezoelectric material, which enhances the electromechanical conversion. The principle of each processing circuit is detailed. Experimental results confirm the predictions given by an electromechanical model: compared to usual generators, the proposed approaches dramatically increase the power of the generators.

644 citations


Journal ArticleDOI
TL;DR: A novel bio-mimetic micro robot with wireless control and wireless power supply using shape memory alloy (SMA) actuator is developed, which can move freely without limitation of working space and be fabricated easily.
Abstract: A novel bio-mimetic micro robot with wireless control and wireless power supply using shape memory alloy (SMA) actuator is developed. There have been many kinds of mobile micro robot using the micro actuators such as ionic polymer metal composite (IPMC), micro motors and piezo actuators. These actuators generally require electric cable for power supply, which might highly influence the mobility of the micro robot. Therefore, a perfect wireless micro robot comprising telemetry and batteries is realized using only one SMA spring actuator and one silicone bellow. The SMA actuator and bellow play a role in contraction and extension of an earthworm muscle respectively. Based on theoretical analysis, specifications of a SMA actuator and a bellow are properly selected. For temporal stopping, setae of earthworm mimicked claws are employed. On the issue of control, the proposed robot is controlled according to On/Off signal via wireless communication. The operation is customized through tuning of on-/off-time of an actuator and using different type batteries such as a lithium, silver oxide and alkaline battery. After the design and experiment, we find out that the earthworm-like micro robot without wired power supply and control can move freely without limitation of working space and be fabricated easily.

294 citations


Journal ArticleDOI
TL;DR: Computationally-tractable algebraic expressions are suggested here in contrast to the commonly-used Bouc–Wen model, which involves internal dynamics represented by a non-linear differential equation.
Abstract: Non-linear hysteresis is a complicated phenomenon associated with magnetorheological (MR) fluid dampers. A new model for MR dampers is proposed in this paper. For this, computationally-tractable algebraic expressions are suggested here in contrast to the commonly-used Bouc–Wen model, which involves internal dynamics represented by a non-linear differential equation. In addition, the model parameters can be explicitly related to the hysteretic phenomenon. To identify the model parameters, a particle swarm optimization (PSO) algorithm is employed using experimental force–velocity data obtained from various operating conditions. In our algorithm, it is possible to relax the need for a priori knowledge on the parameters and to reduce the algorithmic complexity. Here, the PSO algorithm is enhanced by introducing a termination criterion, based on the statistical hypothesis testing to guarantee a user-specified confidence level in stopping the algorithm. Parameter identification results are included to demonstrate the accuracy of the model and the effectiveness of the identification process.

282 citations


Journal ArticleDOI
TL;DR: In this paper, a heterojunction of n-type zinc oxide (ZnO) nanowires and p-type silicon has been successfully constructed to demonstrate ultraviolet (UV) photodiodes.
Abstract: A heterojunction of n-type zinc oxide (ZnO) nanowires and p-type silicon has been successfully constructed to demonstrate ultraviolet (UV) photodiodes. The prototype device consists of naturally doped n-type ZnO nanowires grown on top of a (1 0 0) p-silicon substrate by the bottom-up growth process. The diameter of the nanowires is in the range of 70–120 nm, and the length is controlled by the growth time. The isolation is achieved by using spin-on glass (SOG) that also works as the foundation of the top electrode. The current–voltage (I–V) characteristics show the typical rectifying behavior of heterojunctions, and the photodiode exhibits response of ∼0.07 A/W for UV light (365 nm) under a 20 V reverse bias.

261 citations


Journal ArticleDOI
TL;DR: In this article, a class of electromechanical transducers consisting of an ionomeric substrate with metal-plated electrodes is presented. But this effect is small compared to the increase in strain produced by maximizing the capacitance.
Abstract: Ionomeric polymers are a class of electromechanical transducer consisting of an ionomeric substrate with metal-plated electrodes. Application of a low-voltage ( 10 Hz), but this effect is small compared to the increase in strain produced by maximizing the capacitance. Increasing capacitance produces a transducer that is able to achieve >2% strain (ɛ) at voltage levels of ±3 V.

238 citations


Journal ArticleDOI
TL;DR: GMR spin valve sensors designed for detection of superparamagnetic nanoparticles as potential biomolecular labels in magnetic biodetection technology are presented and it is found that sensor signal increases linearly with the number of nanoparticles.
Abstract: We present giant magnetoresistance (GMR) spin valve sensors designed for detection of superparamagnetic nanoparticles as potential biomolecular labels in magnetic biodetection technology. We discuss the sensor design and experimentally demonstrate that as few as approximately 23 monodisperse 16-nm superparamagnetic Fe(3)O(4) nanoparticles can be detected by submicron spin valve sensors at room temperature without resorting to lock-in detection. A patterned self-assembly method of nanoparticles, based on a polymer-mediated process and fine lithography, is developed for the detection. It is found that sensor signal increases linearly with the number of nanoparticles.

222 citations


Journal ArticleDOI
TL;DR: In this paper, a coiled-up thermoelectric micro power generator is presented using metal films sputtered on a thin polyimide foil, which yields higher voltages at a smaller generator area.
Abstract: A coiled-up thermoelectric micro power generator is presented using metal films sputtered on a thin polyimide foil. The principle of coiling-up yields higher voltages at a smaller generator area. Design optimizations were made for maximum long-term power output using the human body as heat source. It is shown that for low-power electronics like a wrist-watch even simple materials are sufficient and allow lowest-cost production, e.g. screen printing. Thermoelectrical screen-printing pastes were developed and results of first screen printed thermocouples are given.

221 citations


Journal ArticleDOI
TL;DR: In this paper, a polymer-based wafer level fabrication process for micro thermoelectric generators (μTEGs) for the application on non-planar surfaces is presented.
Abstract: We present a novel polymer based wafer level fabrication process for micro thermoelectric generators (μTEGs) for the application on non-planar surfaces The generators are fabricated by subsequent electrochemical deposition (ECD) of Cu and Ni in a 190-μm thick flexible polymer mold formed by photolithographic (PL) patterning of SU-8 First generators were tested and characterized The TEG generated a power of 120 ± 11 nW/cm 2 for a Δ T of 012 K at the μTEG interface, which is equivalent to a thermoelectric efficiency factor of 083 μW K −2 cm −2 The experimental data is in good accordance with a model introduced for the optimization of vertical micro thermoelectric generators It allows calculation of the optimal geometric design parameters for any given material and thermal interfaces The analysis reveals that the thermocouple length should be in the range of 80–150 μm when the best thermoelectric bulk material (BiTe) is used and realistic interface condition are assumed

214 citations


Journal ArticleDOI
TL;DR: A miniaturized high-resolution gas chromatography is under construction, which autonomously configures itself to a product specific supervision task based on data scanned by an RFID reader during freight loading.
Abstract: New sensor, communication and software technologies are used to broaden the facilities of tracing and tracing systems for food transports. An embedded assessing unit detects from sensor data collected by a wireless network potential risks for the freight quality. The estimation of the current maturing state of agricultural products will be supported by measurements of the gaseous hormone ethylene as an indicator for the ripening processes. A miniaturized high-resolution gas chromatography is under construction. The system autonomously configures itself to a product specific supervision task based on data scanned by an RFID reader during freight loading. Mobile software agents accompany the freight along the supply chain. They pre-process the vast sensor data and submit only substantial changes to the freight owner.

213 citations


Journal ArticleDOI
TL;DR: In this article, the authors used elastic beam theory to analyze the theoretical displacement amplification ratio of a bridge-type flexure hinge, and they showed that increasing the amplification ratio by decreasing the thickness of the flexure pivots led to a decrease in the mode shape frequency.
Abstract: The bridge-type flexure hinge is a classic displacement amplification mechanism The existing models of theoretic displacement amplification ratio of bridge-type flexure hinges are not perfect This makes it very difficult to design and manufacture a satisfactory structure using these models Kinematic theory was used to analyze the ideal displacement amplification ratio of a bridge-type flexure hinge in this paper, and the flexure hinge was regarded as a pure multi-rigid body with ideal pivots Elastic beam theory was used to analyze the theoretic displacement amplification ratio when considering the translational and rotational stiffness of the flexure pivots The model of theoretic displacement amplification ratio explains why the bridge-type displacement amplification mechanism has an amplification ratio extremum and where the threshold is The finite element method was used for comparison with the mathematical model, and similar results were obtained Finally, the finite element method was used to analyze the shape mode of the structure The result showed that increasing the amplification ratio by decreasing the thickness of the flexure pivots led to a decrease in the mode shape frequency of the bridge-type structure Thus, redesigning of the structure was needed to solve the problem

201 citations


Journal ArticleDOI
TL;DR: In this paper, a wearable cardiorespiratory signal sensor device for monitoring sleep condition at home is presented, which consists of a belt-type sensor head which is composed with a couple of conductive fabric sheets and a PVDF film, two signal acquisition circuits which are designed specially for conductive fabrics and PVDF films to obtain clear cardiorespiratory signals, and a USB communication module which is used to transmit the signal to computer for data display and analysis.
Abstract: This paper is concerned with the development of a novel wearable cardiorespiratory signal sensor device for monitoring sleep condition at home. The sensor device consists of a belt-type sensor head which is composed with a couple of conductive fabric sheets and a PVDF film, two signal acquisition circuits which are designed specially for conductive fabric and PVDF film to obtain clear cardiorespiratory signals, and a USB communication module which is used to transmit the signal to computer for data display and analysis. In order to design and construct the signal acquisition circuits efficiently and simply, modular design concept is adopted in this research. Three basic high quality and flexible modules, pre-amplifier module with 500 Hz low-pass filter, high quality band-pass filter module and VCVS band-rejection filter module, are designed and assembled together for satisfying each sensor. Furthermore, software data processing algorithms are also proposed for extraction of the reliable heartbeats and respiratory cycles from the obtained cardiorespiratory signals. To validate the performance and efficiency of the developed wearable belt-type sensor system, two commercial sensor devices, 3-lead ECG sensor and pneumography sensor, are used together in experimental test. The results demonstrated that the cardiorespiratory signals are obtained clearly and the information of the heartbeat and respiratory cycle are extracted successfully by the proposed simple data processing algorisms. In contrast to the commercial sensors, the developed belt-type sensor system shows a great potential to take over the commercial pneumography and 3-lead ECG sensors.

Journal ArticleDOI
TL;DR: In this paper, the performance of thin film bulk acoustic resonators (FBARs) operating in shear mode has been investigated for biosensing applications and it was found that the sensor performance ruled by the smallest detectable mass attachment, is already better than that of QCMs.
Abstract: Thin film bulk acoustic resonators (FBARs) operating in shear mode have been investigated for biosensing applications. Dynamic measurements in liquid were carried out and the adsorption of an antibody–antigen system was observed. Although this is the very first FBAR biosensor system operating in liquid environment it was found that the sensor performance ruled by the smallest detectable mass attachment, is already better (2.3 ng/cm 2 ) than that of QCMs. The ability of easy integration onto wafers together with readout-circuitry as well as the possibility of making up large arrays comprising pixels with different functionalities make these devices interesting for future acoustic biosensors.

Journal ArticleDOI
TL;DR: In this paper, a tactile sensor with standing piezoresistive cantilevers embedded in an elastic material was proposed to detect the shear stress applied on its surface, and the efficiency of this sensor was confirmed in the range of −5.0 to 5.0
Abstract: In this paper, we propose a tactile sensor with standing piezoresistive cantilevers embedded in an elastic material. The sensor detects the shear stress applied on its surface. Each standing piezoresistive cantilever in the elastic material detects a certain axial component of applied shear stress. By arranging this standing piezoresistive cantilever in orthogonal directions, the directions and the magnitudes of applied shear stress is detected. The efficiency of this sensor was confirmed in the range of −5.0 to 5.0 kPa. We measured the 2.45 kPa shear stress applied to this sensor from several directions and confirmed that the sensor has a high accuracy for the shear stress detection.

Journal ArticleDOI
TL;DR: In this paper, the piezoelectric coefficient d 33eff of aluminium nitride thin films was measured using both, piezoresponse force microscopy and an interferometric technique.
Abstract: The piezoelectric coefficient d 33eff of aluminium nitride thin films was measured using both, the piezoresponse force microscopy and an interferometric technique. Wurtzite AlN thin films were prepared on Si (1 1 1) substrates by reactive dc-sputtering and by metal organic chemical vapor deposition (MOCVD). Direct measurements of the inverse piezoelectric effect in the picometer range showed that the acceptable tolerance in the crystal orientation is much larger for MEMS applications than expected previously. The value of the effective piezoelectric coefficient d 33 for the prepared AlN thin films remained as high as 5.1 pm/V even for lower degrees of texture.

Journal ArticleDOI
TL;DR: In this article, two kinds of 3 × 3 force sensor arrays using fiber Bragg gratings (FBG) and transducers for tactile sensation to detect a distributed normal force are described.
Abstract: This paper describes two kinds of 3 × 3 force sensor arrays using fiber Bragg gratings (FBG) and transducers for tactile sensation to detect a distributed normal force. One array is developed for a large area tactile sensor that has good sensitivity but low spatial resolution, similar to human body skin. The other is for a small area tactile sensor that has good sensitivity and spatial resolution, similar to human finger skin. The transducer is designed such that it is not affected by chirping and light loss. We also present the fabrication process and experimental verification of the prototype sensors. Experimental tests show that the newly designed sensors have good performance: good sensitivity, repeatability, and no-hysteresis. The load calibration is accomplished by a verified uniaxial load cell. In order to provide a more precise measurement, temperature compensation is applied to all taxels. These force sensor arrays are flexible enough to be attached to a curved surface and they also have simple wiring compared with other types of small force sensors for tactile sensation.

Journal ArticleDOI
TL;DR: In this paper, the surface plasmon resonance (SPR) sensors with Au, Ag, Cu, and Al with a film thickness of 45nm were fabricated for the first time and the response curves and the properties of these sensors were investigated with a comparison of those of the sensors with AU and Ag.
Abstract: Metal-deposited optical fiber sensors with Cu and Al with a film thickness of 45 nm based on surface plasmon resonance (SPR) were fabricated for the first time. The response curves and the properties of these sensors were investigated with a comparison of those of the sensors with Au and Ag. The reflection properties of thin films of Au, Ag, Cu, and Al due to the SPR phenomenon were also measured and considered. The metal-deposited SPR optical fiber sensors with Au, Ag, and Cu have high sensitivities and good responses. Though the sensor with Al shows a lower sensitivity, it has a wider response range in the refractivity. The response curve of the sensor with Au calculated from SPR theoretical equations agreed well with that obtained by the experiment. However, the response curves of the sensors with Ag, Cu, and Al have the effects of the surface oxide layers. The surface characterization of these metal films by X-ray photoelectron spectroscopy (XPS) showed the presence of oxide layers on the films of Ag, Cu, and Al. A very thin (about 0.3 nm) oxide layer is present on Ag, while thick (about 2 nm) oxide layers are present on Cu and Al.

Journal ArticleDOI
TL;DR: In this paper, the pull-in instability of micro-structure under electrostatic loading is analyzed using one-mode analysis, which is a combination of Galerkin method and Cardan solution of cubic equation.
Abstract: The one-mode analysis method on the pull-in instability of micro-structure under electrostatic loading is presented. Taylor series are used to expand the electrostatic loading term in the one-mode analysis method, which makes analytical solution available. The one-mode analysis is the combination of Galerkin method and Cardan solution of cubic equation. The one-mode analysis offers a direct computation method on the pull-in voltage and displacement. In low axial loading range, it shows little difference with the established multi-mode analysis on predicting the pull-in voltages for three different structures (cantilever, clamped-clamped beams and the plate with four edges simply-supported) studied here. For numerical multi-mode analysis, we also show that using the structural symmetry to select the symmetric mode can greatly reduce both the computation effort and the numerical fluctuation.

Journal ArticleDOI
TL;DR: In this paper, the authors describe tests of a scaled-up laboratory model of a new actuator version, generating the hybrid-synthetic jets without any moving components, where self-excited flow oscillation is produced by aerodynamic instability in fixed-wall cavities.
Abstract: In contrast to usual synthetic jets, the “hybrid-synthetic jets” of non-zero time-mean nozzle mass flow rate are increasingly often considered for control of flow separation and/or transition to turbulence as well as heat and mass transfer. The paper describes tests of a scaled-up laboratory model of a new actuator version, generating the hybrid-synthetic jets without any moving components. Self-excited flow oscillation is produced by aerodynamic instability in fixed-wall cavities. The return flow in the exit nozzles is generated by jet-pumping effect. Elimination of the delicate and easily damaged moving parts in the actuator simplifies its manufacture and assembly. Operating frequency is adjusted by the length of feedback loop path. Laboratory investigations concentrated on the propagation processes taking place in the loop.

Journal ArticleDOI
TL;DR: In this article, a fabrication process of precisely controlled 3D microstructures using a maskless gray-scale lithography is described, where multilayered ultraviolet exposure patterns digitally generated by a commercialized maskless exposure system are superposed on a photoresist-coated substrate layer by layer so as to realize a 3D profile of the UV dose.
Abstract: A fabrication process of precisely controlled three-dimensional (3D) microstructures using a maskless gray-scale lithography is described. Multilayered ultraviolet (UV) exposure patterns digitally generated by a commercialized maskless exposure system are superposed on a photoresist-coated substrate layer by layer so as to realize a 3D profile of the UV dose. After a development with an appropriate time, 3D profile of photoresist corresponding to the profile of the UV dose is obtained. Changing the exposure patterns and the exposure time of each exposure makes the precise control of the profile of UV dose possible. The maskless exposure system realizes fabrication of variable three-dimensional patterns at low cost with saving time. As the result of the maskless gray-scale lithography, positive photoresist patterns of spherical and aspherical microlens array of 100 μm in each diameter and 17 μm in height are fabricated. The patterns are transferred into silicon substrates with reactive ion etching (RIE).

Journal ArticleDOI
TL;DR: This paper reports on the full realization of a garment embedded patient monitoring system, including wireless communication and inductive powering, primarily intended for the continuous monitoring of the electrocardiogram of children with an increased risk of Sudden Infant Death Syndrome.
Abstract: This paper reports on the full realization of a garment embedded patient monitoring system, including wireless communication and inductive powering. The developed system is primarily intended for the continuous monitoring of the electrocardiogram (ECG) of children with an increased risk of Sudden Infant Death Syndrome (SIDS). The sensors and the antenna are made out of textile materials. All electronics are mounted on a flexible circuit to facilitate integration in the baby's pajamas. A significant increase in the comfort of patient and nursing staff is achieved by this integration in textiles. A prototype baby suit was fabricated and successfully tested.

Journal ArticleDOI
TL;DR: In this article, a distributed temperature sensing (DTS) method was used for temperature detection in an XLPE insulated 154kV power cable, where the optical fiber itself behaves as a sensor.
Abstract: The power transfer capacity of an underground power cable is limited by high-temperature regions that occur along the cable. It is very difficult to determine and control these ‘hot spots’. Optimum use and temperature profile control of power cables before and during load transmission can be achieved with real-time processing of temperature data. There are various methods developed for this purpose such as conventional point temperature measurement method, where a large number of sensors and connectors are required, and methods based on mathematical models which can only approach real values by approximation. In this study, temperature detection in an XLPE insulated 154 kV power cable is performed using a distributed sensing method where the optical fiber itself behaves as a sensor. Therefore, there is no need for the devices of conventional method. Moreover, contrary to methods based on mathematical models, where it is difficult to predict environmental variations, this method considers the variations with a temperature resolution of ±1 °C. Distributed temperature sensing (DTS) method, detection system configuration and required system parameters are explained in the paper. Experimental results obtained for 126 and 412 m cables show a temperature resolution of ±1 °C and a spatial resolution of 1.22 m. Simulations for a 10 km cable are also given. Results show that DTS is a reliable method for both short and long range cable systems.

Journal ArticleDOI
TL;DR: In this article, the bending motion of the strip-type fourth generation polypyrrole polymer (PPy) actuators, which operate in a non-liquid medium, i.e. in the air, is characterized and modeled.
Abstract: Conducting polymer actuators are emerging new actuators with many promising features suitable to some cutting edge applications ranging from biomedical devices to micro/nano manipulation systems. These features are highly influenced by their interrelated mechanical, electrical and chemical properties. This makes their behavior complex, and difficult to understand and predict. In order to make use of their full potentials, there is an increasing need to investigate into their actuation mechanism in order to provide enhanced degrees of understanding and predictability. With this in mind, it is the object of this paper to characterize and model the bending motion of the strip-type fourth generation polypyrrole polymer (PPy) actuators, which operate in a non-liquid medium, i.e. in the air. After deriving a mathematical model approximately accounting for mechanical, electrical, and chemical properties and geometric parameters of the actuator, the model has been experimentally verified for two actuators with the dimensions of (20 mm × 1 mm × 0.16 mm) and (10 mm × 1 mm × 0.21 mm). Theoretical and experimental results are presented to demonstrate that the model is effective enough to predict the displacement output of the strip type-PPy actuator all along the edge of the actuator as a function of the applied voltage.

Journal ArticleDOI
TL;DR: In this article, a review of the state of the art in room temperature solid state magnetic sensors is presented, which includes magnetoresistive devices (AMR, GMR, spin valve, and spin dependent tunnelling device), giant magneto-inductive devices (GMDT), and non-solid, atomic vapor laser magnetometers.
Abstract: Conventional magnetic sensors, easy to use, are supposed to work mainly well over the nanotesla range, as due to the large magnetic environmental noise occurring in urban and industrial environments. On the other hand, a strange world exists, well below the nanotesla range, where the very efficient magnetic properties of superconducting materials have been used. It is the world investigated using cryogenic sensors, especially those of the SQUID's family. During a long time starting from the 1960s, SQUID people have refined their technologies, together with the use of advanced signal processing both analogue and digital, in order to input couple various external magnetic sources at room temperature, such the bio magnetic ones. State of the art of SQUID sensors is given. In the early 1990s, the dramatic improvement of the operating temperature led to the hope of lighter and lower costs systems with reduced cryogenic mount, designed to operate in open environment. An important target of multi SQUID systems using high critical temperature superconductors was and still is the magnetocardiography (MCG) mapping that could be daily used for improved diagnosis, as compared to conventional electrocardiography. It is known that such an important application is realistic only with noise spectral densities referred at the input lower than 100 fT/√Hz in a frequency bandwidth lying in between 1 Hz and 1 kHz and with a spatial resolution lower than 1 cm. The talk will review the recent advances in room temperature solid state sensors that could reach the above specified noise level. The review includes: magnetoresistive devices (AMR, GMR, spin valve, and spin dependent tunnelling device), Giant magneto-inductive devices. Non-solid, atomic vapor laser magnetometers, which have recently shown their ability to deliver very clear MCG signals, and start to be used to map the MCG signal above the chest just like SQUIDs systems, are reviewed. A simple, convenient energy resolution—volume is proposed, which allows a convenient way to compare high sensitivity magnetic sensors.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the resonant frequency and mode shapes of a fixed-free single-walled carbon nanotubes (SWCNTs) using a beam-bending model.
Abstract: Carbon nanotubes (CNTs) have good mechanical properties and unique structural, electronic, thermal, and optical characteristics. Fixed-free single-walled carbon nanotubes (SWCNTs) have attracted intense interest in recent years due to their suitability for a wide range of applications, such as field emission and vacuum microelectronic devices, nano-sensors and nano-actuators, etc. This paper investigates the resonant frequency and mode shapes of a SWCNT analytically and via continuum mechanics-based finite element method (FEM) simulations using a beam-bending model. Additionally, this study explores the resonant frequency shift of the fixed-free SWCNT caused by the addition of a nano-scale particle to the beam tip in order to explore the suitability of the SWCNT as a mass detector device. The simulation results for the resonant frequency are compared to the theoretical solutions and published experimental data. It is shown that the FEM simulation results are in good agreement with the theoretical and experimental data and hence the current modeling approach is suitable as a coupled-field design tool for the development of SWCNT-based NEMS applications.

Journal ArticleDOI
TL;DR: In this paper, a method to tune the wettability of a solid surface by changing its roughness was proposed, where the apparent contact angle (CA) can be continuously adjusted from the intrinsic contact angle.
Abstract: We proposed a method to tune the wettability of a solid surface by changing its roughness. With specific designed micro square pillar arrays, the apparent contact angle of a hydrophobic surface can be continuously adjusted from the intrinsic contact angle. The samples were fabricated by combining silicon micromachining and self-assembled monolayer modification. The experimental results were closer to Cassie's theoretical predictions on the superhydrophobic surfaces than that by Wenzel's. The apparent contact angle (CA) can be tuned from the intrinsic CA to a superhydrophobic CA. The largest apparent CA in our experiments can be up to 162°, with pillars of 9.45 μm × 9.45 μm × 16 μm (width × width × height), and the spacing of 26.34 μm. By controlling the size and layout of the square micropillars, we also formed a surface with a certain roughness gradient, on which spontaneous movement of a droplet has been observed.

Journal ArticleDOI
TL;DR: In this paper, a micro-hotplate (MHP) supported by six unequal beams is fabricated using surface silicon micromachining technique and a thermal model for the MHP is established by means of Fourier analysis, which takes account of internal heat source in the beams and pressure-dependent gaseous heat conduction above and below the MG.
Abstract: This paper presents a Pirani vacuum gauge based on a micro-hotplate (MHP) supported by six unequal beams. The MHP is fabricated using surface silicon micromachining technique. A thermal model for the gauge is established by means of Fourier analysis, which takes account of internal heat source in the beams and pressure-dependent gaseous heat conduction above and below the MHP. It is applied to determine the MHP operation temperature, temperature distributions along the supporting beams and heat losses through various mechanisms at different vacuum pressure. The measurements of gauge characteristics have been done and the results show good agreements with theoretical analysis. The measured sensitive range of the gauge is 10−1 to 105 Pa when driven by a constant current, 0.8 mA.

Journal ArticleDOI
TL;DR: In this article, a micro ultrasonic motor using a micro-machined bulk piezoelectric transducer is introduced, which is made of lead zirconate titanate (PZT) bulk ceramics.
Abstract: In this paper, a micro ultrasonic motor using a micro-machined bulk piezoelectric transducer is introduced. The cylindrical shaped bulk piezoelectric transducer, a diameter of 0.8 mm and a height of 2.2 mm, was developed as stator transducer for traveling wave type ultrasonic motor. The transducer was made of lead zirconate titanate (PZT) bulk ceramics, and formed by micro machining, Ni plating and laser beam cutting process. Using this stator transducer, we have fabricated a cylindrical micro ultrasonic motor, a diameter of 2.0 mm and a height of 5.9 mm. We have also evaluated some characteristics and succeeded in driving the micro ultrasonic motor.

Journal ArticleDOI
TL;DR: A planar, valveless, microfluidic pump using electrostrictive poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] based polymer as the actuator material is presented in this paper.
Abstract: A planar, valveless, microfluidic pump using electrostrictive poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] based polymer as the actuator material is presented. P(VDF-TrFE) thick films having a large electrostrictive strain ∼5–7% and high elastic energy density of 1 J/cm 3 have been used in a unimorph diaphragm actuator configuration. The microfluidic pump was realized by integrating a nozzle/diffuser type fluidic mechanical-diode structure with the polymer microactuator. The P(VDF-TrFE) unimorph diaphragm actuator, 80 μm thick and 2.2 mm × 2.2 mm in lateral dimensions, showed an actuation deflection of 80 μm for an applied electric field of 90 MV/m. The microfluidic pump could pump methanol at a flow rate of 25 μl/min at 63 Hz with a backpressure of 350 Pa. The flow rate of this pump could be easily controlled by external electrical field. Two different sizes of nozzle/diffuser elements were studied and the pumping efficiency of these structures is 11 and 16%, respectively.

Journal ArticleDOI
TL;DR: In this paper, the authors derived a mathematical model to predict the force induced at the tip of a trilayer bending type polypyrrole (PPy)-based actuator under input voltages and experimentally verified the model.
Abstract: This study aims at (i) deriving a mathematical model to predict the force induced at the tip of a trilayer bending type polypyrrole (PPy)-based actuator under input voltages and (ii) experimentally verifying the model. As opposed to the previous versions of these actuators, the actuator operates in air. The model has been extended to estimate the force produced by a robotic finger made up of the PPy actuator and a carbon fibre rigid link. All theoretical and experimental results presented show that the force model is accurate enough to predict the force at the tip of two actuators with the dimensions of (10 mm × 1 mm × 0.17 mm), and (5 mm × 1 mm × 0.17 mm), and the robotic finger with the dimensions of ((5 + 5) mm × 1 mm × 0.17 mm) under a wide range of input voltages. The response of the actuator and the finger under step input voltages is also evaluated and found that the actuator does not have any delay time, but has a large time constant. Two of the fingers are assembled to form a robotic gripping system, whose payload handling and positioning ability has been experimentally evaluated. The gripper can lift payloads as much as 50 times its total mass under a 1.5 V.

Journal ArticleDOI
TL;DR: In this article, the optical mouse is proposed for indoor odometry measurement in mobile robot applications, which has the advantage that the measured displacement is independent from the kinematics of the robot because the optical sensor uses external natural ground landmarks to obtain the effective relative displacement.
Abstract: In this work the optical mouse is proposed for indoor odometry measurement in mobile robot applications The optical mouse is a very low-cost sensor and has the advantage that the measured displacement is independent from the kinematics of the robot because the optical sensor uses external natural microscopic ground landmarks to obtain the effective relative displacement In this work the sensor is calibrated and evaluated for odometry measurement It was found that the original conception inside a visual feedback loop precludes its use as an isolated displacement sensor although its impressive speed and parts, with a CMOS camera and a digital signal processor embedded on the same chip, suggests that an improved design can be a good alternative for accurate mobile robot odometry measurement