Showing papers in "Sensors and Actuators A-physical in 1991"
TL;DR: In this paper, a brief review of applications of piezoelectric bimorphs is presented, and the constituent equations which describe the behavior of bimomorphs for various mechanical boundary conditions are derived.
Abstract: A brief review of applications of piezoelectric bimorphs is presented. The constituent equations which describe the behavior of piezoelectric bimorphs for various mechanical boundary conditions are derived. The internal energy density of infinitesimally small volume elements in thermodynamic equilibrium is calculated in the presence of a voltage on the electrodes, a clamped cantilever beam condition on one side of the beam and a set of three different classical boundary conditions on the other side of the beam. These are a mechanical moment M at the end of the beam, a force F perpendicular to the beam, applied at its tip, and a uniformly distributed body force p.
The total internal energy content is calculated by integrating over the entire volume of the beam. Two different beam configurations are considered: parallel polarizations of the two adjoining elements of the beam with an internal electrode; and antiparallel orientation without an internal electrode.
The canonical conjugate of the moment is calculated as the angular deflection at the tip of the beam α, while that of the force at the tip is the local vertical deflection δ. The canonical conjugate of the uniform load on the beam is found to be the volume displacement V of the beam. The canonical conjugate of the voltage across the electrodes is the charge on the electrodes. The equations are given in the direct form, with external parameters (M, V), (F, V), and (p, V) as independent variables and also in a linear combination with (M, F, p, V) as variables.
These constituent equations can be used to calculate the behavior of the bimorph under any condition that can be described as a linear combination of forces at the tip, moments at the tip and uniform loads on the entire beam. This allows us to use the bimorph as a black box, without having to consider its internal movement or charges.
401 citations
TL;DR: In this paper, a graphical representation of the piezoresistance effect on crystallographic orientations and the effect of impurity concentration on the PR are given for n- and p-Si.
Abstract: The principle of the piezoresistance effect (PR) of n- and p-Si is explained by the carrier-transfer mechanism and the effective mass change. The origin of the shear piezoresistance coefficient π 44 in n-Si is also a stress-induced effective mass change. A graphical representation of the PR on crystallographic orientations and the effect of impurity concentration on the PR are given for n- and p-Si. The non-linearity of the PR is also mentioned.
379 citations
TL;DR: In this paper, a micromachined electrohydrodynamic (EHD) injection pump is presented, which mainly consists of two facing grids, which are micro-machined from s
Abstract: A new micromachined electrohydrodynamic (EHD) injection pump is presented. The pump mainly consists of two facing grids, which are micromachined from s
214 citations
TL;DR: In this paper, an absolute pressure transducers with four diaphragms, two active and two inactive, have been constructed and optimized towards manufacturability, and the measured performance is excellent and agrees with the predictions of the design algorithm.
Abstract: Typical IC processing is fundamentally two dimensional; sensors are three-dimensional structures. In surface micromachining, two-dimensional IC processing is extended to sensor structures by the addition of one or more sacrificial layers which are removed by lateral etching. The resulting sensor structures involve the substrate and one or more deposited films which form the intended micromechanical component. The concepts of this type of sensor manufacturing are readily demonstrated by considering absolute pressure transducers in some detail. Absolute pressure transducers involve a vacuum-sealed cavity and a deformation sensing technique. The cavity is formed from the substrate and a low-pressure chemical vapor deposited polycrystalline silicon film. The mechanical properties of this film must be controlled well enough to allow the device to be designed. This implies morphological control during processing. Optimized films which do exhibit controlled compressive or tensile strains exclude oxygen or nitrogen and are therefore not modified by extended hydrofluoric acid etches. Their mechanical behavior is monitored by micromechanical test structures which measure Euler buckling and thereby determine the value of the built-in strain. The cavity vacuum is established by reactive sealing. Long-term vacuum integrity is achieved by a low-stress silicon nitride barrier which also acts as a dielectric isolation barrier. Sensing is accomplished via deposited polysilicon resistors. These devices behave like metal resistors in terms of their temperature coefficient of resistance and noise figure. Their piezoresistive behavior is larger than that of typical metal film structures and smaller than that of single-crystal resistors. Pressure sensors with four diaphragms, two active and two inactive, have been constructed and optimized towards manufacturability. The measured performance is excellent and agrees with the predictions of the design algorithm.
166 citations
TL;DR: The theoretical interpretation and models of the piezoresistivity in poly-Si and experimental results are presented in this paper, where the calculation of the longitudinal and transverse gauge factors and their correlation with the crystallographic structure of the polySi film are discussed.
Abstract: Polycrystalline Si (poly-Si) has found various applications in microelectronics and micromechanical devices such as pressure sensors, accelerometers and actuators. Poly-Si films deposited on an oxidized Si substrate can combine the excellent mechanical properties of Si with the efficient electrical insulation of poly-Si piezoresistors, so that improved stability and high-temperature operation can be obtained. Different poly-Si fabrication techniques are reviewed with emphasis on their applications to pressure sensors. The theoretical interpretation and models of the piezoresistivity in poly-Si and experimental results are presented. The calculation of the longitudinal and transverse gauge factors and their correlation with the crystallographic structure of the poly-Si film are discussed. The possibility of sensor performance optimization including mechanical, temperature and piezoresistive properties of a device is demonstrated. Two examples of commercially manufactured poly-Si sensors and an example of a new poly-Si technology are also presented.
149 citations
TL;DR: In this article, three types of sensors based on amorphous ribbons are discussed and the principle of sensor operation is based on the dependence of the ribbon properties on the magnetic field intensity.
Abstract: New sensitive sensors suitable for measuring weak magnetic fields and based on amorphous ribbons are described. Three types of sensors are discussed in the paper. The principle of sensor operation is based on the dependence of the ribbon properties on the magnetic field intensity. The advantage of the sensors is the minimal use of active elements, and consequently their high reliability, thermal stability and small size.
132 citations
TL;DR: The techniques of silicon micromachining have been used to fabricate a second-generation Fabry-Perot interferometer for use in the near infrared spec.
Abstract: The techniques of silicon micromachining have been used to fabricate a second-generation Fabry—Perot interferometer for use in the near infrared spec
101 citations
TL;DR: In this article, two silicon gas flow sensors fabricated by combining silicon micromachining with either standard CMOS or standard bipolar technology are reported. But they are based on the Seebeck effect and cannot measure the temperature difference between the heated tip of the beam and the bulk silicon.
Abstract: We report two silicon gas flow sensors fabricated by combining silicon micromachining with either standard CMOS or standard bipolar technology. Both sensors are based on the Seebeck effect. An integrated thermopile is placed on a free-standing cantilever beam and measures the temperature difference between the heated tip of the beam and the bulk silicon, which depends on the gas flow. For the CMOS sensor we report an output voltage sensitivity to the gas flow velocity of 1.78 V(m/s) −1/2 W −1 . The sensitivity of the bipolar sensor is 0.26 V (m/s) −1/2 W −1 .
97 citations
TL;DR: In this paper, a novel technique for the simultaneous determination of the strain and Young's modulus of a silicon microresonator is reported, where the lowest two symmetric vibration modes of a single resonator are excited and their frequencies measured.
Abstract: A novel technique for the simultaneous determination of the strain and Young's modulus of a silicon microresonator is reported. The lowest two symmetric vibration modes of a single resonator are excited and their frequencies measured. The measured frequencies are compared with a theoretical model. The strain is determined by substituting the ratio of the two frequencies into the model. The calculated strain is then substituted into a characteristic equation to yield Young's modulus. The measured value for Young's modulus is 1.31×1011 Pa, which is close to that of pure silicon, 1.30×1011 Pa.
95 citations
TL;DR: Some examples of tactile sensor technology and application are discussed, with the aim of giving the reader a feeling of what has been achieved and some hints are given on the research directions to pursue in order to obtain useful results in this field.
Abstract: This paper presents some considerations on the motivation for the development and use of tactile sensing in robotics. Some examples of tactile sensor technology and application are discussed, with the aim of giving the reader a feeling of what has been achieved, and some hints are given on the research directions to pursue in order to obtain useful results in this field.
81 citations
TL;DR: In this paper, a movable mass suspended on a cantilever which can be used as a capacitive acceleration sensor is presented, and the movability of these microstructures is demonstrated by applying electrical and magnetic fields.
Abstract: By combination of the LIGA (German Acronym for Lithografie, Galvanoformung, Abformung) process with a sacrificial layer technique, movable microstructures with great structural heights can be fabricated. As a first example, a movable mass suspended on a cantilever which can be used as a capacitive acceleration sensor is presented. Calculation of the sensor characteristics shows that a capacitor gap width of 3 μm is needed. This capacitor has been fabricated up to a height of more than 100 μm. The movability of these microstructures is demonstrated by applying electrical and magnetic fields.
TL;DR: In this article, a brief history of crystal sensing techniques is presented and simple resonator equivalent circuits are outlined and expanded upon for cases of crystal immersion in liquids, conditions for oscillation and choice of appropriate oscillator are discussed.
Abstract: A brief history of crystal sensing techniques is presented. Simple resonator equivalent circuits are outlined and expanded upon for cases of crystal immersion in liquids. Conditions for oscillation and choice of appropriate oscillator are discussed. Several well-known recently published sensor oscillator circuits are briefly reviewed and some suggestions for improvements are made. Details are given of two new oscillator circuits developed and employed by the author. Uniquely, these new circuits allow total immersion of the exposed crystal plate in hitherto impossible media, such as viscous liquids of viscosity up to 40 cP and in electrolytes and buffers of several millimolar ionic strength. Finally, suggestions for gain and stability control of oscillators in practical ‘under-liquid’ sensing situations are made in relation to the future potential of these techniques.
TL;DR: In this article, the authors report the reduction of package stresses by introducing a decoupling zone directly around a sensor structure, using the finite element method (FEM) and analytical models.
Abstract: The authors report the reduction of package stresses by introducing a decoupling zone directly around a sensor structure. Different geometries of the decoupling zones are compared, using the finite element method (FEM) and analytical models. Reduction factors over 1000 and higher can be realized by using an axisymmetrical V-corrugation. A design rule to optimize the reduction for the V-corrugation is given. This rule is based on analytical calculations and verified by FEM-simulations. Finally, it is shown that the thickness of a backplate, mounted to the sensor chip, can be optimized for minimal thermal stresses in the sensor. >
TL;DR: In this article, the geometrical shapes resulting from anisotropic etching of crystalline substances are investigated and a simulator has been built that constructs boundary representations of the polyhedral models of such shapes starting from an etch rate polar diagram.
Abstract: The geometrical shapes resulting from anisotropic etching of crystalline substances are investigated. A simulator has been built that constructs boundary representations of the polyhedral models of such shapes starting from an etch rate polar diagram. Special attention is given to situations in which new faces emerge that were not previously present. >
TL;DR: In this paper, a radiation thermopile made of p-(Bi 1− x Sb x ) 2 Te 3 and n-Bi 1 − sb x S b x films is presented.
Abstract: A radiation thermopile made of p-(Bi 1− x Sb x ) 2 Te 3 and n-Bi 1− x Sb x films is presented. The technological steps
TL;DR: In this article, a wide range of such sensors, including micromachined, gravimetric and large-volume resonator sensors, are compared and their properties are discussed.
Abstract: Resonant sensors configured to have a mechanical resonance frequency are a subject of special practical interest. They are sensors with outputs based on a quasidigital frequency signal. This is a great advantage over conventional analog sensors. This paper reviews a wide range of such sensors, including micromachined, gravimetric and large-volume resonator sensors. They are compared and their properties are discussed.
TL;DR: In this article, a 16-contact spinning-current Hall plate was proposed to reduce the offset in silicon Hall plates by multiple orthogonal switching of a single symmetrical spinning current Hall plate.
Abstract: The offset in silicon Hall plates is reduced by multiple orthogonal switching of a single symmetrical spinning-current Hall plate. The offset virtually cancels out when the current direction is made to spin with steps of π/8, while the consecutively available Hall voltages are averaged over time. The novel 16-contact spinning-current Hall plate shows less than 50 μ V (100 μ T) residual offset. A combination of the spinning-current Hall plate and the hybrid electronic circuitry obtains a 10 times lower offset (at maximum 200 μ T) when compared to optimized commercially available Hall plates without electronics.
TL;DR: In this article, different chemically sensitive coatings such as amines, siloxanes and supramolecular compounds for quartz microbalance sensors to detect polar and apolar organic and inorganic compounds such as CO 2, CO, NO 2, Cl 2 C CHCl, Cl 2C CCl 2 and C 8 H 18 in the gas phase.
Abstract: We have studied different chemically sensitive coatings such as amines, siloxanes and supramolecular compounds for quartz microbalance sensors to detect polar and apolar organic and inorganic compounds such as CO 2 , CO, NO 2 , Cl 2 C CHCl, Cl 2 C CCl 2 and C 8 H 18 in the gas phase.
TL;DR: In this article, a planar grating spectrograph with a self-focusing reflection grating has been fabricated together with fiber-fixing grooves, which shows an excellent dispersion of the light.
Abstract: A three-layer resist system has been developed which can be used for light guiding. By structuring these layers with deep-etch X-ray lithography, high-precision multimode lightguide components with a relatively low attenuation can be produced. As a first example, a planar grating spectrograph with a self-focusing reflection grating has been fabricated together with fibre-fixing grooves. The spectro-graph shows an excellent dispersion of the light as well as a low cross-talk between the channels.
TL;DR: In this paper, concepts of actuators and sensors are introduced and applied to the controllability and observability of systems described by partial differential equations, and developed results are illustrated by many examples of specific geometries and systems.
Abstract: The purpose of this paper is to give some results related to the link between actuator and sensor structures and systems analysis. concepts of actuators and sensors are introduced and applied to the controllability and observability of systems described by partial differential equations. The developed results are illustrated by many examples of specific geometries and systems.
TL;DR: In this paper, the authors presented integrated capacitive humidity sensors fabricated with the industrial SACMOS (self-aligned contact CMOS) technology, which are based on different interdigitated microelectrodes.
Abstract: We present integrated capacitive humidity sensors fabricated with the industrial SACMOS (self-aligned contact CMOS) technology. The devices are based on different interdigitated microelectrodes. Some of these include a new, photosensitive as well as humidity-sensitive, polyimide layer which offers the advantage of easy patterning and processing. The capacitances and phase angles of the sensors have been measured as a function of the relative humidity (RH) of the ambient air for different polyimide thicknesses, temperatures and frequencies in an environmental chamber. Their fast response to humidity is linear over a wide range of RH. Good reproducibility over the prototype batch is obtained.
TL;DR: In this paper, a sensor fabrication method using silicon surface-micromachining was proposed to construct tactile sense elements, with the integration of readout circuitry, upon a single silicon wafer in an entirely single-sided fabrication set-up, which has the potential for reduced weakening of the supporting substrate.
Abstract: The fabrication of a capacitive tactile sensor is examined Therefore, the different transduction methods for converting tactile forces to an electrical signal, and the different manufacturing methods used by other researchers in the last 30 years will be summarized We propose a sensor fabrication method using silicon surface-micromachining This comparatively new microfabrication technology allows us to construct the tactile sense elements, with the integration of readout circuitry, upon a single silicon wafer in an entirely single-sided fabrication set-up, which also has the potential for reduced weakening of the supporting substrate The structure and the fabrication of the sensor and the measured readout characteristic are described
TL;DR: In this paper, the authors describe the development of a threshold accelerometer for sensing very high acceleration levels, which comprises an array of eight normally open switches, each having a different acceleration threshold.
Abstract: This paper describes the development of a threshold accelerometer for sensing very high acceleration levels. The device, which is fabricated by silicon micromachining techniques, comprises an array of eight normally open switches, each having a different acceleration threshold. Each switch is a miniature silicon dioxide cantilever beam, only 2.2 μm in thickness, with metallization running along its length and fabricated on the surface of a silicon wafer. Under an applied acceleration, the cantilever beam deflects across a 2.5 μm gap and makes contact with another electrode, thus closing a switch. Electrostatic and static centrifuge testing have been performed on the devices. Closing the switches (beams 120 to 400 μm long and 80 μm wide) electrostatically with voltages in the 10 to 70 V region provides a convenient way to pre-test the beams for closure. Under static centrifuge testing, a maximum of 20 000 g was measured with a cantilever beam 180 μm long and 80 μm wide.
TL;DR: In this article, a simple capacitive displacement sensor based on the application of spatial sampling and Doppler measurement techniques is presented, which shows a resolution and repeatability of 1 μm.
Abstract: This paper presents a simple capacitive displacement sensor based on the application of spatial sampling and Doppler measurement techniques. The theoretical performance of the sensor has been predicted and simulated on a PC, and confirmed experimentally. The prototype sensor shows a resolution and repeatability of 1 μm. A linear measurement range up to a few meters can be achieved.
TL;DR: In this paper, a computer program is described which simulates silicon single-crystal etching in KOH, starting from a 2D mask layout, the program finds the relevant etching planes and delivers a 3D output of the etched structure with the etch time (or etch depth) as parameter.
Abstract: A computer program is describe which simulates silicon single-crystal etching in KOH. Starting from a 2-D mask layout, the program finds the relevant etching planes and delivers a 3-D output of the etched structure with the etch time (or etch depth) as parameter. The resulting output plot is compared with realized test structures.
TL;DR: In this paper, the authors describe the development of integrated silicon thermal vacuum sensors with much reduced sizes, compared with previously described versions, which can achieve a sensitivity of 12.4%/Pa for nitrogen and a pressure range of 1 mPa to 10 kPa absolute pressure.
Abstract: This paper describes the development of integrated silicon thermal vacuum sensors with much reduced sizes, compared with previously described versions. After a short expose of the physics of thermal vacuum measurement, the general sensor structure is elucidated. Then the novel structure is described, seven times smaller but three times more sensitive than previous versions. The experimental results show a sensitivity of 12.4%/Pa for nitrogen and a pressure range of 1 mPa to 10 kPa absolute pressure. The sensor can be mounted in a small TO-5 housing.
TL;DR: The combination of integrated optics and micromechanics on silicon offers new integration potentials for sensor applications as discussed by the authors, where the SiON optical strip waveguides are fabricated by low-temperature (570 K) PECVD and RIE processes on microbridges, cantilevers and resonators based on field oxide.
Abstract: The combination of integrated optics and micromechanics on silicon offers new integration potentials for sensor applications. Silicon oxinitride (SiON) optical strip waveguides are fabricated by low-temperature (570 K) PECVD and RIE processes on microbridges, cantilevers and resonators based on field oxide. The single-mode strip waveguides with a refractive index n=1.52 of the SiON layer show 0.5 dB/cm attenuation at 0.633 μm wavelength. The micromechanical elements are delineated by anisotropic KOH etching. They are built up with SiO2SiONSiO2 triple layers and exhibit low internal stress.
TL;DR: In this paper, a silicon condenser microphone with an integrated field effect transistor (FET) is described and the measured sensitivities are in the range 0.1-1 mV/Pa, which is about 15 dB lower than calculated values.
Abstract: A silicon condenser microphone is described, which works with an integrated field-effect transistor (FET). The gate of the transistor corresponds to the membrane of the microphone. Between the membrane and the gate oxide is a small air gap. The drain current of the transistor is controlled by the deflections of the membrane. The structure, which carries the FET and which is placed beyond the membrane, can have very small lateral dimensions. This results in small values of air-gap streaming losses and high air-gap compliances, thus yielding a good acoustic behaviour. The design of a silicon microphone with suspended-gate FET is described and experimental results of frequency response and noise are presented. The measured sensitivities are in the range 0.1–1 mV/Pa, which is about 15 dB lower than the calculated values. The reduction in sensitivity is caused by the silicon fabrication process of the microphones and can be eliminated. The frequency response is smooth up to 30 kHz. The noise measurement shows a 1/ f slope, which is typical for the noise behaviour of the FET.
TL;DR: In this paper, the thermal modeling of a flow sensor that operates on the principle of detecting flow-induced temperature differences is described in detail, and the authors describe in detail the thermal model of the flow sensor.
Abstract: This paper describes in detail the thermal modelling of a flow sensor that operates on the principle of detecting flow-induced temperature differences
TL;DR: Theoretical and experimental study on thermal excitation of micromechanical resonators is presented in this article, where it is shown that there is a turnover frequency, ωt, which is related to the square of the ratio of the penetration depth of the thermal wave into the structure and its thickness.
Abstract: theoretical and experimental study is presented on thermal excitation of micromechanical resonators. It is shown that there is a turnover frequency, ωt, which is related to the square of the ratio of the penetration depth of the thermal wave into the structure and its thickness. For constant power dissipation at the surface of the structure, the bending moment is independent of the frequency ω at ω > ωt, it is proportional to ω-1. At high frequency we obtain a phase shift of -π/2. Vibration amplitudes and turnover frequencies measured on clamped beam structures agree well with the theory.