Showing papers in "Sensors and Actuators A-physical in 2000"
TL;DR: This work presents an overview of progress and developments in the field of fiber optic sensor technology, highlighting the major issues underpinning recent research and illustrating a number of important applications and key areas of effective Fiber optic sensor development.
Abstract: This work presents an overview of progress and developments in the field of fiber optic sensor technology, highlighting the major issues underpinning recent research and illustrating a number of important applications and key areas of effective fiber optic sensor development.
823 citations
TL;DR: In this article, hot embossing is used as a flexible, low-cost microfabrication method for polymer microstructures, which uses the replication of a micromachined emplossing master to generate micro-structures on a polymer substrate.
Abstract: Polymer microfabrication methods are becoming increasingly important as low-cost alternatives to the silicon or glass-based MEMS technologies We present in this paper the technology of hot embossing as a flexible, low-cost microfabrication method for polymer microstructures, which uses the replication of a micromachined embossing master to generate microstructures on a polymer substrate With this fabrication technology high aspect ratio structures can be fabricated over large surface areas, which allows a commercially successful manufacturing of polymer microcomponents
686 citations
TL;DR: In this paper, a magnetohydrodynamic (MHD) based micropump was proposed, in which the Lorentz force is the pumping source of conductive, aqueous solutions in the microchannel.
Abstract: This paper presents a novel micropump of which pumping mechanism is based upon magnetohydrodynamic (MHD) principles. MHD is the study of flow of electrically conducting liquids in electric and magnetic fields. Lorentz force is the pumping source of conductive, aqueous solutions in the MHD micropump. Conducting fluid in the microchannel of the MHD micropump is driven by Lorentz force in the direction perpendicular to both magnetic and electric fields. The performance of the micropump is obtained by measuring the pressure head difference and flow rate as the applied voltage changes from 10 to 60 VDC at 0.19 and 0.44 Tesla (T). The pressure head difference is 18 mm at 38 mA and the flow rate is 63 μl/min at 1.8 mA when the inside diameter of inlet/outlet tube is 2 mm and the magnetic flux density is 0.44 T. Bubble generation by the electrolysis of the conducting liquid can be observed. The performance of the MHD micropump obtained theoretically in single phase is compared with the experimental results.
429 citations
TL;DR: Silicon carbide (SiC) is a material with very attractive properties for microsystems applications as discussed by the authors, its mechanical strength, high thermal conductivity, ability to operate at high temperatures and extreme chemical inertness in several liquid electrolytes, make SiC an attractive candidate for MEMS applications, both as structural material and as coating layer.
Abstract: Silicon carbide (SiC) is a material with very attractive properties for microsystems applications Its mechanical strength, high thermal conductivity, ability to operate at high temperatures and extreme chemical inertness in several liquid electrolytes, make SiC an attractive candidate for MEMS applications, both as structural material and as coating layer The recently reported progress in material growth and processing techniques has strengthened the potential of this material for MEMS, especially for applications requiring operation at high temperature or in severe environments Examples of SiC microsensors and microstructures are given and interesting development in both material characteristics and micromachining processes are discussed
414 citations
TL;DR: In this paper, self-assembled monolayers are used as release and anti-stiction coatings for micro-electro-mechanical systems (MEMS) and their formation mechanism, microstructure coating process, and the characteristics of the coated microstructures are described.
Abstract: Despite significant advances in surface micromachining technology, stiction remains a key problem, severely limiting the realization and reliability of many micro-electro-mechanical systems (MEMS) devices. In this article, we focus on self-assembled monolayers as release and anti-stiction coatings for MEMS. Their formation mechanism, the microstructure coating process, and the characteristics of the coated microstructures are described, followed by a discussion of the current limitations, areas for improvements and recent progress for this coating technology.
399 citations
TL;DR: The ElectroMechanical Film (EMFi) as mentioned in this paper is a thin, cellular, biaxially oriented polypropylene film that can be used as an electret, having a special voided internal structure and high resistivity, it is capable of storing large permanent charge.
Abstract: The ElectroMechanical Film (EMFi) is a thin, cellular, biaxially oriented polypropylene film that can be used as an electret. Having a special voided internal structure and high resistivity, it is capable of storing large permanent charge. The charge is injected by a corona method using ∼10 kV cm−1 fields, thus creating internal electrical discharges inside the cellular structure. Films of different thickness and elasticity can be manufactured. The thickness in sensor and actuator applications is typically 30–70 μm. When metallized on both sides, EMFi is capable of measuring pressure and force changes offering large application potential in different fields of technology including microphones and also actuators. New loudspeaker panels based on EMFi are only a few millimeters thick.
290 citations
TL;DR: In this article, the authors compared the anisotropic etching properties of KOH and TMAH solutions and concluded that the two etchants have different etching mechanisms at least in an area including these two planes.
Abstract: We compared the anisotropic etching properties of KOH and TMAH solutions. We used hemispherical specimens of single-crystal silicon whose surface exhibited every crystallographic orientation, in order to evaluate the etching properties as a function of the orientation. We carried out a series of experiments using different etchant concentrations and etching temperatures. The orientation dependence in the etching rates of the surface crystals significantly differed between the two etchants, especially for the (111) and (221) planes. We conclude that the two etchants have different etching mechanisms at least in an area including these two planes. The etching rates varied with etchant concentration and etching temperature. The concentrations that maximized the etching rate were 25 wt.% for KOH and 20 wt.% for TMAH. The activation energies in KOH and TMAH were almost the same for the (100), (110), and (320) planes but not for the (221) and (111) planes. Etchant circulation had a significant effect on the etching rates in diluted TMAH solution but not in KOH solution. The roughness of the (100) plane in KOH was one order smaller than that in TMAH.
238 citations
TL;DR: In this paper, a polysilicon fracture mechanics specimen is fabricated using standard microelectro-mechanical systems (MEMS) processing techniques, with characteristic dimensions comparable to typical MEMS devices.
Abstract: Polysilicon fracture mechanics specimens have been fabricated using standard microelectro-mechanical systems (MEMS) processing techniques, with characteristic dimensions comparable to typical MEMS devices. These specimens are fully integrated with simultaneously fabricated electrostatic actuators that are capable of providing sufficient force to ensure catastrophic crack propagation. Thus, the entire fracture experiment takes place on-chip, eliminating the difficulties associated with attaching the specimen to an external loading source. The specimens incorporate atomically sharp cracks created by indentation, and fracture is initiated using monotonic electrostatic loading. The fracture toughness values are determined using finite element analysis (FEA) of the experimental data, and show a median value of 1.1 MPa m 1/2 .
199 citations
TL;DR: In this paper, the authors describe a small-scale, ultrasonic piezoelectric transducers that exert a directed body force on the fluid via acoustic attenuation, which is a type of acoustic streaming termed quartz wind in microfluidics applications.
Abstract: Miniature acousto-fluidic devices are described that operate as pumps without valves in channel widths of millimeters and below These devices can also be configured to produce mixing in low-Reynolds-number flows The prototypes are based on radio-frequency, ultrasonic piezoelectric transducers that exert a directed body force on the fluid via acoustic attenuation The process is a type of acoustic streaming termed quartz wind In microfluidics applications, this mechanism has the advantages of insensitivity to the chemical state of the fluid or walls and greatly reduced crosstalk in a multichannel system The observed pump flow velocities are on the order of 1 mm/s in 16×16 mm 2 channels and with a calculated maximum backpressure that can be pumped against of 013 Pa Due to the low backpressure, quartz wind devices are not competitive pumps for open-loop and high-impedance microfluidics systems but could find application in pumping in low-impedance planar and closed-loop systems and for mixing in reservoirs and channels
198 citations
TL;DR: In this article, a thermopneumatic actuator with a corrugated diaphragm, which is more flexible than a flat one, is presented, and the maximum flow rate of the micropump is about 14 μl/min at 4 Hz.
Abstract: This paper presents a thermopneumatic micropump fabricated by micromachining. The micropump consists of a p + silicon diaphragm, a micro heater and a pair of nozzle/diffuser. The thermopneumatic actuator of this paper is characterized by a corrugated diaphragm, which is more flexible than a flat one. The diaphragm is driven by the air cavity pressure variation caused by the ohmic heating and the natural cooling. If the diaphragm of the micropump vibrates, the fluid flows in one direction through a nozzle/diffuser. The experimental result illustrates that the deflection of the corrugated diaphragm is about three times that of the flat one. The maximum flow rate of the micropump with the corrugated diaphragm is about 14 μl/min at 4 Hz when the input voltage and duty ratio are 8 V and 40%, respectively.
194 citations
TL;DR: In this paper, the flow-directing capability of flat-walled diffuser elements for valve-less micropumps is investigated and the results are compared with previously published results on pump performance.
Abstract: An investigation of flat-walled diffuser elements for valve-less micropumps is presented. The diffuser element is a small angle flow channel with a rounded inlet and a preferably sharp outlet. The diverging-wall direction is the positive flow direction. The flow-directing capability under steady flow conditions was determined experimentally for several different diffuser elements. The flow-pressure characteristic was studied in detail for one of them. The result is compared with previously published results on pump performance. Numerical simulations were done using the Computational Fluid Dynamics program ANSYS/Flotran. The simulations show the flow-directing capability of the diffuser elements and predict the flow-pressure characteristics well for Reynolds numbers below 300-400. For higher Reynolds numbers, the simulations show the flow-directing capability, but there is a larger discrepancy between simulations and measurements. Simulations were also done for a nozzle element, a wide-angle flow channel with sharp inlet and outlets used in the micropump with dynamic passive-valves. A nozzle element has the converging-wall direction as positive flow direction. The simulations show differences in the flow patterns for diffuser elements and nozzle elements that explain the opposite positive flow directions. The diffuser element has an ordered flow and takes advantage of the pressure recovery in the diverging-wall direction. The nozzle element has gross flow separation in the diverging-wall direction and there is a vena-contracta effect instead of pressure recovery. The effective cross-sectional area is smaller in the diverging-wall direction than in the converging-wall direction.
TL;DR: In this article, an approach for simultaneous compensation of the hysteretic and creep transfer characteristics of a piezoelectric stack actuator by interposing an inverse system in an open loop control is described.
Abstract: An approach for the simultaneous compensation of the hysteretic and creep transfer characteristics of a piezoelectric stack actuator by interposing an inverse system in an open loop control is described. The basis of the inverse control paradigm is formed by complex creep and hysteresis operators. Both operators consist of weighted superpositions of elementary operators which can easily be described mathematically and which reflect the qualitative properties of the transfer characteristic. This operator-based actuator model allows the prediction of the transfer characteristic within the inverse control paradigm in order to calculate the compensation signal in real-time. As a result, the maximum linearity error caused by hysteresis and creep effects is lowered by an order of magnitude.
TL;DR: In this article, the authors investigated the possibility of replacing the rotary type of fan in some noise-sensitive electronic devices by different vibrating metal plates and found that the resonant frequency of the vibrating plate decreases with the increase of its length ( l ) if the length of the piezoelectric ceramic bimorph (L ) is kept constant.
Abstract: Several types of piezoelectric fans for cooling electronic devices were constructed and tested at 60 Hz, 110 V and 220 V, respectively. The aim of the work is to investigate the possibility of replacing the rotary type of fan in some noise-sensitive electronic devices. Different vibrating metal plates were tested and analyzed theoretically. It is found that the resonant frequency of the vibrating plate decreases with the increase of its length ( l ) if the length of the piezoelectric ceramic bimorph ( L ) is kept constant. The series-type fan with l =31.8 mm, made of phosphor bronze vibrating plate (S6), shows the highest value of fan tip displacement of 35.5 mm and produced wind velocity of 3.1 m/s driven by a 220 V, 60 Hz power source.
TL;DR: In this paper, a uniaxial tension test was designed to accommodate micro-scale test requirements such as sample handling, sample alignment, and friction elimination, and stress and strain were measured using a commercial load cell and a laser interferometry system, respectively.
Abstract: The mechanical properties of single-crystalline silicon are measured by uniaxial tension tests from microscale beam specimens patterned by four different common silicon etchants — KOH, EDP, TMAH and XeF2. SOI wafers are used to prepare test samples, which are 3–5 μm thick, 20–100 μm wide, and 6 mm long beam specimens; these are monolithically mounted on a temporary frame. A uniaxial tension test has been designed to accommodate microscale test requirements such as sample handling, sample alignment, and friction elimination. Stress and strain are measured using a commercial load cell and a laser interferometry system, respectively. Young's modulus of silicon in the 〈110〉 direction is measured to be 169.2±3.5 GPa, very close to the widely accepted value of 168.9 GPa obtained from a macroscale sample by an ultrasonic method. The fracture strength in the 〈110〉 direction is measured to vary from 0.6 to 1.2 GPa, and is apparently affected by the etching process employed to make the microscale specimen. As surface defects are expected to be the main factor determining the strength of the specimen, surface morphology is examined not only as a function of etchants but also as a function of mask-to-crystal direction misalignment after KOH etching. In the case of samples prepared by KOH etching, measured fracture strengths are 0.94 and 0.72 GPa from samples with 0° and 2° misalignments, respectively.
TL;DR: In this paper, a generic platform for the fabrication of multipurpose microprobes with integrated piezoresistive readout, built-in background filter and silicon tip was developed.
Abstract: We have developed a new generic platform for the fabrication of multipurpose microprobes with integrated piezoresistive read-out, built-in background filter and silicon tip. The probe fabrication is based on SOI wafers with buried boron etch-stop layers, which allow us to realize probes with fully encapsulated resistors and integrated silicon tips. The dimensions of the resistors are well defined and leak-current is eliminated. Probes with a force constant in the range of 0.8–4 N/m and with resonant frequencies in the range of 40–80 kHz have been fabricated. The probes typically display a deflection sensitivity of (ΔR/R)z−1=2.4×10−7 A−1, and a force sensitivity (ΔR/R)F−1=2.7×10−6 nN−1. The change in resistance of the piezoresistors is detected by a highly symmetrical on-chip Wheatstone bridge arrangement. The measured noise level in the Wheatstone bridge is in good agreement with the calculated noise limit and a minimum detectable cantilever deflection of 0.3 A has been predicted for a measurement bandwidth of 10 Hz. The symmetrical bridge configuration has been compared with a nonsymmetrical setup, and it is concluded that the symmetrical Wheatstone bridge significantly decreases nonlinearities in the output response. Finally, the probe has successfully been used for atomic force microscopy (AFM) imaging.
TL;DR: In this article, the authors present results on magneto-impedance in multilayers consisting essentially of two soft ferromagnetic films (F) and a conductive inner lead (M): F/M/F.
Abstract: This paper reviews results on magneto-impedance (MI) in multilayers consisting essentially of two soft ferromagnetic films (F) and a conductive inner lead (M): F/M/F. Multilayer film MI has a potential to be utilized for developing highly sensitive and quick-responding micro-magnetic sensors for advanced intelligent measurement and control systems and high-density magnetic recording. In materials with a uniform conductivity, a large change in impedance is accountable to a strong skin-effect, requiring the operation frequencies to be of the order of several gigahertz, for a submicron MI element. In the multilayer films F/M/F with sufficiently large difference between the conductivity values of layers M and F, the impedance can vary considerably at relatively low frequencies when the skin effect is not essential. The theory predicts that the MI ratio in multilayers 1-μm thick with a Cu inner lead and soft magnetic amorphous films (CoSiB) or permalloy (NiFe) films is as much as 400–500% at frequencies of 10–100 MHz; in the case of a sandwich 0.1-μm thick, the MI ratio, although drops considerably, is still large being 15–20% at frequencies of 300–400 MHz, which is in good agreement with the experimental results. On the other hand, in narrow films, the flux leakage across the inner conductor may result in a considerable drop in MI ratio if the film width is smaller than some critical value depending on the transverse permeability and the thickness of the M and F layers.
Abstract: A sensor embedded in the composite laminate can act as a temperature transducer during the composite cure mechanism. Once the composite is cured, the same sensor can be used to provide the information about the mechanical changes that influence the performance of the material. Fiber Bragg Grating (FBG) sensor is one such sensor which one can use for the composite cure monitoring. We present here the results obtained with an associated FBG sensor system for the cure monitoring of smart composites. The performance of the embedded FBG sensor smart composite specimens under 3- and 4-point bending conditions are also being investigated. Finally, the performance analysis has been extended to cantilever specimens.
IBM1
TL;DR: In this article, the authors report the microfabrication of a 32×32 (1024) 2D cantilever array chip and its electrical testing, which has been designed for ultrahigh-density, high-speed data storage applications using thermomechanical writing and readout in thin polymer film storage media.
Abstract: We report the microfabrication of a 32×32 (1024) 2D cantilever array chip and its electrical testing. It has been designed for ultrahigh-density, high-speed data storage applications using thermomechanical writing and readout in thin polymer film storage media. The fabricated chip is the first very large scale integration (VLSI)-NEMS (NanoEMS) for nanotechnological applications. For electrical and thermal stability, the levers are made of silicon, and the heater/sensor element is defined as a lower, doped platform with the tip on top. Freestanding cantilevers are obtained with surface-micromachining techniques, which yield better mechanical stability and heatsinking of the chip than bulk-micromachining releasing techniques do. Two-wiring levels interconnect the cantilevers for a time-multiplexed row/column addressing scheme. By integrating a Schottky diode in series with each cantilever, a considerable reduction of crosstalk between cantilevers has been achieved.
TL;DR: An elastic wave model is presented that describes the sensor response as a function of the frictional forces acting upon the sensor surface.
Abstract: Magnetically soft, magnetostrictive metallic glass ribbons are used as in-situ remote query viscosity sensors. When immersed in a liquid, changes in the resonant frequency of the ribbon-like sensors are shown to correlate with the square root of the liquid viscosity and density product. An elastic wave model is presented that describes the sensor response as a function of the frictional forces acting upon the sensor surface.
TL;DR: In this article, a 3×3×5 mm 3 size gas microvalve with a shape memory alloy (SMA) thin film with stress-optimized shape is presented.
Abstract: Gas microvalves of about 3×3×5 mm 3 size are presented, which are actuated by a microdevice of shape memory alloy (SMA) thin film with stress-optimized shape. By variation of the chemical composition of the material system Ti–Ni–Pd, the phase transformation temperatures have been adjusted in a range below 405 K in order to design the operation temperature of the valves. The main fabrication technologies were magnetron sputtering and electrolytic photoetching of the thin films and hybrid integration of the valve components. The SMA microvalves work in a normally open mode and allow control of pressure differences below 2500 hPa at gas flows below 360 standard ccm (sccm).
TL;DR: In this article, an integrated three-dimensional tactile sensor with robust MEMS structure and soft contact surface suitable for robotic applications was developed, which includes 4×8 sensing cells each exhibiting an independent, linear response to the three components of forces applied on the cells.
Abstract: An integrated three-dimensional tactile sensor with robust MEMS structure and soft contact surface suitable for robotic applications was developed. The sensor has a maximum force range of 50 N in the vertical direction and ±10 N in the x and y horizontal directions. The tactile sensor includes 4×8 sensing cells each exhibiting an independent, linear response to the three components of forces applied on the cells. By finite element analysis, optimal cell structures and piezoresistor positions were determined. Post bulk-micromachining was performed on foundry-fabricated CMOS chips to produce the sensor cells. With neural network training, the tactile sensor produced reliable three-dimensional force measurements and repeatable response on tactile images. Design analysis, fabrication procedures, and experimental results are presented in this paper.
TL;DR: In this paper, a powder-blasted accelerometer was used for biochemical separations, the realisation of microfluidic chips, and the micropatterning of composite hard magnetic layers for mechatronic and magnetic sensor applications.
Abstract: We introduce powder blasting using a pressurised nozzle and a metallic mask as a new promising technology for microsystem fabrication. We study basic parameters of this powder blasting erosion process as well as mask-geometry effects on the erosion rate. We demonstrate the application potential of this technique in three important fields of microsystems research: (i) the realisation of microfluidic chips for biochemical separations, (ii) the micropatterning of composite hard magnetic layers for mechatronic and magnetic sensor applications, and (iii) the realisation of inertial sensors in glass. We present for the first time a mechanical and electrical characterisation of powder-blasted accelerometer devices.
TL;DR: In this article, an inductively coupled plasma reactive ion etching (ICP RIE) using SF 6 gas has been applied to the Deep RIE of quartz plate to achieve high etch rate (∼0.5 μm/min) and mirror surface (roughness, ∼2 nm) were achieved at the conditions of low process pressure (2 mTorr) and high self-bias voltage (−340 V).
Abstract: In this paper, we present a one-chip multichannel quartz crystal microbalance (QCM) sensor fabricated by deep reactive ion etching (Deep RIE). An inductively coupled plasma reactive ion etching (ICP RIE) using SF 6 gas has been applied to the Deep RIE of quartz. High etch rate (∼0.5 μm/min) and mirror surface (roughness, ∼2 nm) were achieved at the conditions of low process pressure (2 mTorr) and high self-bias voltage (−340 V). The multichannel QCM sensor, which has different resonance frequencies, was formed by fabricating diaphragms of different thicknesses on a single crystal of quartz plate. The resonance frequencies ranged from 21.7 to 20.75 MHz. The Q factors of each peak were approximately 2000 in air and the resolution for mass change was ±1 ng on 2-mm-diameter electrode. We have successfully shown that the sensor with different coating films can be applied to chemometric odor sensor.
TL;DR: In this article, a single crystal silicon ultrathin cantilever with thickness 60 and 170 nm and length 5-120 μm has been fabricated from a SIMOX wafer.
Abstract: Mechanical characteristics of a single crystal silicon ultrathin cantilever and their dependence on the geometry was investigated in this paper. The cantilevers with thickness 60 and 170 nm and length 5–120 μm have been fabricated from 〈100〉-oriented SIMOX wafer. Preliminary results show that the longer cantilevers (L>30 μm) have higher mechanical quality factor, Q (>104) than the shorter ones (L<30 μm), since the shorter one is more susceptible to the energy loss, i.e., support loss and surface loss (oxide layer). Furthermore, multimode resonance of the longer cantilever was observable within the measurable range, and all of them have the Q factor higher than 104. By using the high resonance mode, these cantilevers are theoretically capable of detecting the force as small as 2×10−17 N. In addition, the atomic scale mass resolution (1.4×10−22 g) is also expected by these cantilevers if it is used for sensing the mass load. Using the dynamic detection method, water vapor adsorption was detected, and the mass resolution of the cantilever is roughly estimated to be 2.9×10−17 g.
TL;DR: In this article, a prototype tactile sensing system with only three sensing elements is presented, where the magnitude and position of the applied force is obtained by utilising triangulation approach combined with membrane stress.
Abstract: This paper reports on a prototype tactile sensing system with only three sensing elements. The magnitude and position of the applied force is obtained by utilising triangulation approach combined with membrane stress. Some information about the shape of the contacted object is obtained. The polyvinylidene fluoride (PVDF) sensor is designed to overcome the problems of cross talk between sensing elements and to reduce the complexity associated with some PVDF tactile sensors arranged in matrix form. A theoretical analysis of the sensor is made and compared with experimental results. The limitation of the sensor is also reported. The sensor in miniaturised form can also be integrated into an endoscopic grasper and a prosthetic finger.
TL;DR: The JPL micro-valve is expected to have an extremely low leak rate, limited susceptibility to particulates, vibration or radiation, as well as a wide operational temperature range as discussed by the authors.
Abstract: We report on the development of a micro-electro-mechanical systems (MEMS) valve that is designed to meet the rigorous performance requirements for a variety of space applications, such as micro-propulsion, in situ chemical analysis of other planets, or microbiology. These systems often require very small yet reliable silicon valves with extremely low leak rates and long shelf lives. Also, they must survive the perils of space travel, which include unstoppable radiation, monumental shock and vibration forces, as well as extreme variations in temperature. Currently, no commercial MEMS valve meets these requirements. At JPL, we are developing a piezoelectric MEMS valve that attempts to address the unique problem of space. We begin with proven configurations that may seem familiar. However, we have implemented some major design innovations that should produce a superior valve. The JPL micro-valve is expected to have an extremely low leak rate, limited susceptibility to particulates, vibration or radiation, as well as a wide operational temperature range.
TL;DR: In this article, a micro gripper of 2×3.9×0.1 mm3 size is presented consisting of a single device microfabricated from a shape memory alloy (SMA) thin sheet.
Abstract: A microgripper of 2×3.9×0.1 mm3 size is presented consisting of a single device microfabricated from a shape memory alloy (SMA) thin sheet. The device consists of two integrated actuation units of a stress-optimized shape, which actuate in opposite directions and thus form an antagonistic pair. The fabrication procedure is reduced to one micromachining step of a rolled SMA sheet and subsequent bonding onto a substrate. The maximum displacement of the gripping jaws is 180 μm, the maximum gripping force 17 mN. For an electrical power of 22 mW, a response time of 32 ms is observed.
TL;DR: In this article, the authors introduce the technique and discuss the mechanism behind the process on the base of theoretical models, and present the versatility of powder blasting as well as well-controllable etching process for a wide range of brittle materials.
Abstract: The old technique of sandblasting has recently been developed into a versatile etching technique for brittle materials, capable of producing structures larger than 100 μm. The paper introduces the technique and discusses the mechanism behind the process on the base of theoretical models. The characteristics of patterned etching are illustrated by the evolution of trench-like structures and by the wear of mask patterns, while also some technological aspects will be addressed. With both experimental results and theoretical considerations, it will present the versatility of powder blasting as well-controllable etching process for a wide range of brittle materials.
TL;DR: In this paper, the phase reveals abrupt jumps in response to a minute increase in the effective thickness of a receptor layer that binds analyte particles on the sensor surface, which forms the basis for biosensing with sensitivity much higher as compared to traditional SPR sensors.
Abstract: Interferometry that detects the phase of a beam reflected under surface plasmon resonance (SPR) has been developed for bio and chemical sensing. The conditions have been found, under which the phase reveals abrupt jumps in response to a minute increase in the effective thickness of a receptor layer that binds analyte particles on the sensor surface. This forms the basis for biosensing with sensitivity much higher as compared to traditional SPR sensors. Besides, SPR interferometry (SPRI) provides spatial resolution at the micron scale. The enhanced sensitivity attributed to the phase jump and interferometric imaging of variations of the phase over the surface are demonstrated, which open up new avenues for micro-array biosensing.
TL;DR: In this paper, a capacitive single-chip silicon microphone with very low-stress polysilicon membrane was fabricated and a mechanism for stress-releasing due to the high stress of the perforated membrane was introduced.
Abstract: A capacitive single-chip silicon microphone with very low-stress polysilicon membrane was fabricated. A mechanism for stress-releasing due to the high stress of the perforated membrane was introduced. With the achieved stress level of 2 MPa, a microphone with the membrane area of 1 mm 2 can be optimally designed, although the measured components did not show the optimal resolution due to excessive acoustic resistance. With a membrane area of 1 mm 2 , the acoustical sensitivity was 4 mV/Pa (at 1 kHz) and the noise equivalent sound level was 33.5 dB (A), which are adequate values for many applications. The packaged components were tested with a thermal cycle between −40°C and +60°C, and due to low packaging-related stresses, no buckling of the membranes was observed.