First Vertical Hall Device in standard 0.35 μm CMOS technology

In order to lower the short-circuit effect due to the measurement contacts, Vertical Hall Devices (VHDs) are generally designed either in bulky N-type silicon or in the deep N-well of high-voltage CMOS technologies. In this last case, VHD can benefit from on chip circuitry for offset and 1/f noise reduction, but HVCMOS remains a costly technology. Using spinning-current, HVCMOS compatible VHDs with a resolution of 76 μT rms over a 1.6-kHz bandwidth have been demonstrated. The VHD presented here is designed in the shallow N-well of a low-cost 0.35 μm standard CMOS technology. Unlike conventional VHD, its measurement contacts are located outside the sensor active area. FEM simulations and experimental results show that the new geometry suppresses the short-circuit effect and strongly reduces the intrinsic offset and noise. Thus, without any noise and offset reduction method, this new small VHD (63 μm²) reaches a resolution of 79 μT rms over a (5 Hz–1.6 kHz) bandwidth, and opens the way to the integration of 3D Hall sensors in low-cost standard CMOS technologies.     

Measurement of the pressure broadening coefficients of the oxygen A-band using a low cost, polarization stabilized, widely tunable vertical-cavity surface-emitting laser

Vertical-cavity surface-emitting lasers (VCSELs) are used for oxygen monitoring via tunable diode laser spectroscopy at 760 nm wavelength. For the desired application, novel polarization-stable laser diodes based on AlGaAs were developed. We present measurements of the pressure-broadening coefficients of the electric dipole forbidden oxygen A-band b ¹ Σ₊ ^g → X ³ Σ₊ ^g transition at 760 nm. The time the pressure-broadening coefficients were determined with a temperature tuned VCSEL. Generally temperature tuning has the disadvantage of frequent mode-hops, but the advantage of a wider tuning range in comparison to current tuning. Because of special techniques of polarization stabilization with a combination of a dielectric surface grating and a surface relief the VCSELs have a mode hop-free tuning range of more than 7 nm and a sidemode suppression of more than 30 dB. This provides a low cost laser diode system with a wide tuning range, which enables the possibility of simultaneous measurement of temperature, pressure and oxygen concentration in air, high pressure measurements and also a higher accuracy of oxygen concentration measurements.     

Controlled synthesis and gas-sensing properties of hollow sea urchin-like α-Fe2O3 nanostructures and α-Fe2O3 nanocubes

Hollow sea urchin-like α-Fe₂O₃ nanostructures were successfully synthesized by a hydrothermal approach using FeCl₃ and Na₂SO₄ as raw materials, and subsequent annealing in air at 600 °C for 2 h. The hollow sea urchin-like α-Fe₂O₃ nanostructures with the diameters of 2–4.5 μm consist of well-aligned α-Fe₂O₃ nanorods with an average length of about 1 μm growing radially from the centers of the nanostructures, have a hollow interior with a diameter of about 2 μm. α-Fe₂O₃ nanocubes with a diameter of 700–900 nm were directly obtained by a hydrothermal reaction of FeCl₃ at 140 °C for 12 h. The response S_r (S_r = R_a/R_g) of the hollow sea urchin-like α-Fe₂O₃ nanostructures reached 2.4, 7.5, 5.9, 14.0 and 7.5 to 56 ppm ammonia, 32 ppm formaldehyde, 18 ppm triethylamine, 34 ppm acetone, and 42 ppm ethanol, respectively, which was excess twice that of the α-Fe₂O₃ nanocubes and the nanoparticle aggregations. Our results demonstrated that the hollow sea urchin-like α-Fe₂O₃ nanostructures were very promising for gas sensors for the detection of flammable and/or toxic gases with good-sensing characteristics.     

Completeness of Continuation Models for λμ-Calculus

We show that a certain simple call-by-name continuation semantics of Parigot's λ_μ-calculus is complete. More precisely, for every λ_μ-theory we construct a cartesian closed category such that the ensuing continuation-style interpretation of λ_μ, which maps terms to functions sending abstract continuations to responses, is full and faithful. Thus, any λ_μ-category in the sense of L. Ong (1996, in “Proceedings of LICS '96,” IEEE Press, New York) is isomorphic to a continuation model (Y. Lafont, B. Reus, and T. Streicher, “Continuous Semantics or Expressing Implication by Negation,” Technical Report 93-21, University of Munich) derived from a cartesian-closed category of continuations. We also extend this result to a later call-by-value version of λ_μ developed by C.-H. L. Ong and C. A. Stewart (1997, in “Proceedings of ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages, Paris, January 1997,” Assoc. Comput. Mach. Press, New York).     

A large-displacement 65Pb(Mg1/3Nb2/3)O3–35PbTiO3/Pt bimorph actuator prepared by screen printing

In this paper we present a novel approach to preparing large-displacement 65Pb(Mg_1/3Nb_2/3)O₃–35PbTiO₃/Pt (65/35 PMN–PT/Pt) bimorph actuators. These “substrate-free”, bending-type actuators were prepared by screen-printing the 65/35 PMN–PT and Pt thick-film pastes as the electrodes on alumina substrates. After this screen printing and the subsequent firing the 65/35 PMN–PT/Pt composites were peeled off from the substrates. Displacements of nearly 100 μm at 18 V were achieved for actuators with dimensions of 1.8 cm × 2.5 mm × 50 μm for the 65/35 PMN–PT layer. The normalized displacement (the displacement per unit length) was 40 μm/cm at 18 V. The experimental results together with a computation procedure were used to obtain the material parameters for a finite-element analysis of the 65/35 PMN–PT/Pt bimorph actuators.     

Invited Paper: Surface‐emitting‐diode lasers and laser arrays for displays

Abstract— High‐power red, green, and blue laser light sources made from vertically emitting arrays of intracavity doubled IR lasers is reported. The emitted infrared light from a monolithic array of large‐aperture vertical cavity lasers is converted into visible light using a PPLN doubling crystal in an external cavity. A volume Bragg grating provides simultaneous feedback for all emitters in the array and sets the laser wavelength. Increased diffraction losses for higher‐order modes result in quasi‐Gaussian beams with excellent conversion efficiency. Green 532‐nm lasers with more than 5.8‐W visible power have been demonstrated at a base temperature of 40°C. Blue 465‐nm lasers with 4.4‐W power at 40°C are unmatched in performance and wavelength when compared to competing GaN‐based edge emitters. Typical wall‐plug efficiencies are higher than 8%. We have measured single‐emitter operating lifetimes to be more than 28,000 hours. Red lasers based on highly strained InGaAs achieve record laser powers of 2.0W at 618 nm in the same form factor as the green and blue lasers. Red single‐emitter lifetimes of more than 10,000 hours have been attained. The technology described in this paper delivers on a full suite of cost efficient and reliable red, green, and blue lasers that meet the demands of the display markets.     

Micromachined widely tunable vertical cavity laser diodes

Wavelength tunable vertical-cavity surface-emitting lasers (VCSELs) are potentially useful for future optical communications. Traditionally, the emission wavelength of a vertical cavity laser was tuned by modulating the active region temperature. However, thermal tuning is slow, and the realized tuning range is quite limited. Micromachined tunable VCSELs (Mi-T-VCSELs) combine the traditional vertical cavity laser structure with a monolithically micromachined deformable membrane, enabling continuous wavelength tuning without mode hopping. In addition to a large wavelength tuning range, this technique does not suffer from the shortcomings of the thermal tuning technique. This paper presents the background theory, processing sequence, and experimental results for Mi-T-VCSELs     

An efficient cell count method using a lattice molded on indents of a culture dish

Cell count is an important task for obtaining biological and medical information. In this paper, a novel cell count method is presented for improving the efficiency of the procedure as well as reducing microbial contamination compared to the conventional cell count method using a hemocytometer. The proposed method involves a lattice array consisting of a 50 μm × 50 μm square with lines of 2-μm width and 1.4-μm depth on a surface indented from a culture dish bottom. This configuration enables observation of cells at the same focus as the lattice. Therefore, an instant cell count during incubation is possible without the tedious, error-prone preparation steps such as harvesting and loading required in conventional methods. In addition, cells can be preserved with minimal contact with the external environment. These advantages become magnified with a periodic long-term cell count. A polystyrene culture dish, 35 mm in diameter, was fabricated by injection molding using a nickel mold, wherein indents of 3 mm × 3 mm in area and 1 mm in height were electroplated based on microfabrication technology. For easy separation from the nickel mold, the four sides of the indents in the mold are inclined at 54.74° via anisotropic silicon etching. The usefulness of the suggested method was verified using adhering HeLa (cervical carcinoma cell) cells and floating Jurkat cells. Both were placed in culture dishes and cultivated for 3 days in a carbon dioxide incubator (5% CO₂, 95% air) at 37 °C, and then successfully observed through the divided lattice using an inverted microscope. The dish was also assessed with a hemocytometer by counting HEK 293T (human embryonic kidney) cells and yeast cells.     

The μFill: A New 96-/384- Well Microplate Reagent Dispenser for HTS and Drug Discovery

Today's biomedical research requires instrumentation that is both functional and versatile. While high throughput screening (HTS) and drug discovery laboratories require instrumentation that can be automated, pilot assay laboratories may not necessarily need total automation. Towards that end, Bio-Tek has developed the μFill, a 96-/384- well microplate reagent dispenser capable of running stand-alone or computer-controlled as part of a robotics system. The μFill is compatible with both 96- and 384-well microplates, and using a specially designed adaptor can also dispense to deep-well microplates. It is capable of dispensing from 10-3000 μl for 96- well plates and 5-1500 μl for 384-well plates in 1-μl increments. The μFill can dispense 20 μl into a 96-well plate in four seconds and into a 384-well microplate in 12 seconds. The microprocessor-controlled syringe pump is based on a tested, low-maintenance design that requires no calibration, yet provides a high degree of accuracy and precision. The accuracy with an 80 μl dispense is within 1 μl with a percentage CV of less than 2%, and with a dispense volume of 20 μl, the percentage CV is still less than 5%. For those needing to dispense organic solvents or sterile aqueous solutions, a model that is autoclavable and has increased solvent resistance is also available. The programming allows for the control of flow rates from 225 μl/well/sec, for dispensing to cell cultures, and to 1000 μl/well/sec for rapid and vigorous reagent dispensing. The flexible software provides complete programming capabilities from the keypad. For more complete automation, robotics interfaces can be developed using ActiveX® software commands. The μFill's size, with a 14 x 14-inch footprint and a height of seven inches, allows it to be used almost anywhere.     

高功率窄线宽可调谐 1 064 nm 环形腔激光

文章采用了三镜环形腔内插入标准具获取高功率窄线宽可调谐1064 nm 激光。对环形腔的单向运行、标准具压窄线宽与调谐波长及激光大基模体积运转进行了理论分析与计算,结合实验优化了腔镜曲率与输出耦合率。在808 nm 半导体激光泵浦功率151 W 条件下,获得输出功率33.7 W、光束质量因子 M 2＝1.28、线宽0.1 GHz 的单向1064 nm 激光输出,相应的光转换效率22.3%。采用高精度控温仪对标准具进行精确温控,实现激光波长的精密调谐。改变标准具温度获得1064 nm 波长调谐范围72.6 GHz,调谐精度为220 MHz。波长调谐过程中1064 nm 激光输出功率变化约10%。整个系统稳定可靠,而且相对简单,较易实现,为获得可调谐窄线宽1064 nm 激光提供了实用有效的技术手段。     

A sensitive nonenzymatic hydrogen peroxide sensor based on DNA–Cu complex electrodeposition onto glassy carbon electrode

In this paper, DNA–Cu²⁺ complex was electrodeposited onto the surface of glassy carbon (GC) electrode, which fabricated a DNA–Cu²⁺/GC electrode sensor to detect H₂O₂ with nonenzyme. Cyclic voltammogram of DNA–Cu²⁺/GC electrode showed a pair of well-defined redox peaks for Cu²⁺/Cu⁺. Moreover, the electrodeposited DNA–Cu²⁺ complex exhibited excellent electrocatalytic behavior and good stability for the detection of H₂O₂. The effects of Cu²⁺ concentration, electrodeposition time and determination conditions such as pH value, applied potential on the current response of the DNA–Cu²⁺/GC electrode toward H₂O₂ were optimized to obtain the maximal sensitivity. The linear range for the detection of H₂O₂ is 8.0 × 10⁻⁷ M to 4.5 × 10⁻³ M with a high sensitivity of −40.25 μA mM⁻¹, a low detection limit of 2.5 × 10⁻⁷ M and a fast response time of within 4 s. In addition, the sensor has good reproducibility and long-term stability and is interference free.     

New gas sensitive MIS structures Pt/Al2O3(M = Pt, Rh)/Si with a granular dielectric layer

New gas sensitive MIS structures Pt/Al₂O₃(M)/p-Si, where M = Pt, Rh, with granular dielectric Al₂O₃ layers doped with noble metals were obtained by an aerosol pyrolysis method. Surface morphology and composition of the structures were studied by TEM, AFM and EPMA. Sensor properties of the MIS structures were studied towards reducing gases (1000 ppm H₂, 300 ppm CO, 1000 ppm CH₄ in air) at 100 and 200 °C. The Pt/Al₂O₃(M = Pt, Rh)/Si structures showed a very high sensor response to reducing gases. A shift of C–V characteristics was up to 2.5 V under CO, 2.2 V under hydrogen and 0.7 V under methane. High values of shift of C–V curves can be related with cooperative influence of a change of surface state density in dielectric layer, reduction of platinum electrode and dipole layer formation.     

Simulation, fabrication and characterization of a 3D piezoresistive force sensor

In this contribution we report on a miniaturized bulk micro-machined three-axes piezoresistive force sensor. The force sensor consists of a full membrane with 16 conventional two terminal p-type diffused piezoresistors on the surface of the membrane. The die size of the chip is 6.5 mm × 6.5 mm. Piezoresistors with four different designs were placed on the membrane. Sensitivities were found to be in the range of 0.37–0.79 mV/(V mN) and 1.68–2.92 mV/(V mN) in Z-direction and X- or Y-direction, respectively. The stiffness of the measured microprobes in the range of 5–8 mN/μm and 0.27–0.48 mN/μm were obtained in vertical and lateral direction, respectively. Various single and twin membranes designs were simulated to calculate stiffness of the microprobe. The measurement results show a cross-axis sensitivity of <2.5% at full scale of 25 mN.     

Tensile and high cycle fatigue test of Al–3% Ti thin films

This paper presents the results of tensile and high cycle fatigue tests with stress ratio R = 0.1 for an Al–3% Ti thin film of 1 μm thickness in atmospheric air at room temperature. Specimens with three different widths (50, 100, and 150 μm) were fabricated to study the width effects of each sample. Test results show that tensile and fatigue properties for the Al–3% Ti thin film with different widths are very close, and, thus, width effects were found to be minimal. The elastic moduli ranged from 80 to 82 GPa, and the tensile strengths ranged from 369 to 379 MPa. Fatigue strength coefficients of the specimens with 50, 100, and 150 μm width were 193, 181, and 164 MPa, respectively. In addition, fatigue strength exponents of the specimens with 50, 100, and 150 μm width were −0.023, −0.020, and −0.013, respectively. When present test results are compared with typical properties of bulk aluminium, the Al–3% Ti thin film is found to have longer life at the same stress, but it is more sensitive to the stress level.     

Canonical completeness of infinitary μ

This paper presents a new model construction for a natural cut-free infinitary version of the propositional modal μ-calculus. Based on that the completeness of and the related system K_ω(μ) can be established directly – no detour, for example through automata theory, is needed. As a side result we also obtain a finite, cut-free sound and complete system for the propositional modal μ-calculus.     

Estimation of soil clay and calcium carbonate using laboratory, field and airborne hyperspectral measurements

This paper examines how reflectance spectrometry used in the laboratory to estimate clay and calcium carbonate (CaCO₃) soil contents can be applied to field and airborne measurements for soil property mapping. A continuum removal (CR) technique quantifying specific absorption features of clay (2206 nm) and CaCO₃ (2341 nm) was applied to laboratory, field and airborne HYMAP reflectance measurements collected in 2003 (33 sites) and 2005 (19 sites) over bare soil sites of a few meters within the La Peyne Valley area, southern France. Nine intermediate stages from the laboratory up to HYMAP sensor measurements were considered for separately evaluating the possible degradation of estimation performances when going across scales and sensors, e.g. radiometric calibration, spectral resolution, spatial variability, illumination conditions, and surface status including roughness, soil moisture and presence and nature of pebbles.Significant relationships were observed between clay and CaCO₃ contents and CR values computed respectively at 2206 nm and 2341 nm from reflectance measurements at the laboratory level with an ASD spectrophotometer up to the HYMAP spectro-imaging sensor. Performances of clay and CaCO₃ estimations decreased from the laboratory to airborne scales. The main factors inducing uncertainties in the estimates were radiometric and wavelength calibration uncertainties of the HYMAP sensor as well as possible residual atmospheric effects.     

基于TDLAS-WMS的近红外痕量CH_4气体传感器

为了对煤矿CH4气体进行实时监测,基于混合可调谐二极管激光吸收光谱(TDLAS)与波长调制光谱(WMS)的检测技术,采用中心波长为1.65μm的分布反馈(DFB)激光器,设计并研制出痕量CH4气体传感器。利用自主设计的DFB激光器温度控制器,通过调节激光器工作温度,进而使其发光光谱扫描CH4气体的吸收跃迁谱线。同时利用WMS检测技术将待测信号频率移至高频区,减小1/f噪声。利用该痕量CH4气体传感器,在被测气体体积分数为(0~106)×10-6的范围内,对二次谐波信号进行了提取。测试结果显示:在(0~106)×10-6范围内相对测量误差小于7%,检测下限为11×10-6。同时,研究人员可以通过更换其他波长的激光器,实现对其他气体的检测。     

Thin-film organic photodiodes for integrated on-chip chemiluminescence detection – application to antioxidant capacity screening

We demonstrate that solution processed thin-film organic photodiodes (OPDs) can be used as compact and sensitive integrated detectors for antioxidant capacity screening. The OPDs were fabricated with blends of regioregular poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C₆₁ butyric-acid methyl-ester (PCBM). The devices had a broadband photoresponse from 350 nm to 650 nm with a peak responsivity of 0.25 A/W at 550 nm and a dark current density of 0.59 μA/cm² under 10 mV bias for a device area of 1 mm². The signal rise and fall times of the detectors were 0.51 μs and 0.66 μs, respectively. The detectors were applied to an on-chip peroxyoxalate chemiluminescence (PO-CL) assay for antioxidant capacity determination. Antioxidant standards were injected into a stream of PO-CL reagents, resulting in a CL emission decrease that correlated with the antioxidant capacity. For the encountered CL signals the OPDs provided a comparable response to photomultiplier tubes (PMTs) commonly used in analytical applications. Antioxidant capacity screening results showed excellent consistency between the two detection methods. The compact and portable detection system is suited not only to low-cost in-the-field antioxidant capacity screening, but could have wider applications for chemiluminescence based diagnostic tests at the point-of-care.     

The rank one mixed μ problem and ‘kharitonov-type’ analysis

The general mixed μ problem has been shown to be NP hard, so that the exact solution of the general problem is computationally intractable, except for small problems. In this paper we consider not the general problem, but a particular special case of this problem, the rank one mixed μ problem. We show that for this case the mixed μ problem is equivalent to its upper bound (which is convex), and it can in fact be computed easily (and exactly). This special case is shown to be equivalent to the so-called ‘affine parameter variation’ problem (for a polynomial with perturbed coefficients) which has been examined in detail in the literature, and for which several celebrated ‘Kharitonov-type’ results have been proven.     

Electrochemical DNA biosensor for the detection of interaction between di[azino-di(5,6-azafluorene)-κ-NN′]dichlormanganous and DNA

A new Mn(II) complex of MnL₂Cl₂ (L = azino-di(5,6-azafluorene)-κ²-NN′) was synthesized and utilized as an electrochemical indicator for the determination of hepatitis B virus (HBV) based on its interaction with MnL₂Cl₂. The electrochemical behavior of interaction of MnL₂Cl₂ with salmon sperm DNA was investigated on glassy carbon electrode (GCE). In the presence of salmon sperm DNA, the peak current of [MnL₂]²⁺ was decreased and the peak potential was shifted positively without appearance of new peaks. The binding ratio between [MnL₂]²⁺ and salmon sperm DNA was calculated to be 2:1 and the binding constant was 3.72 × 10⁸ mol² L⁻². The extent of hybridization was evaluated on the basis of the difference between signals of [MnL₂]²⁺ with probe DNA before and after hybridization with complementary sequence. Control experiments performed with non-complementary and mismatch sequence demonstrated the good selectivity of the biosensor. With this approach, a sequence of the HBV could be quantified over the range from 1.76 × 10⁻⁸ to 1.07 × 10⁻⁶ mol L⁻¹, with a linear correlation of r = 0.9904 and a detection limit of 6.80 × 10⁻⁹ mol L⁻¹. Additionally, the binding mechanism was preliminarily discussed. The mode of interaction between MnL₂Cl₂ and DNA was found to be primary intercalation binding.