Reducing the Uncertainty of Industrial Trace Humidity Generators through NIST Permeation-Tube Calibration

Permeation-tube moisture generators (PTGs) are commonly used by the semiconductor industry as transfer standards for the calibration of hygrometer systems measuring trace amounts of water vapor in gases (water vapor mole fractions typically below 1 × 10⁻⁶). They are relatively simple devices that generate a steady stream of humidified gas by diluting water vapor delivered at a constant rate from a permeable capsule with precisely metered purified gas, usually nitrogen. Here a new calibration service enabling the measurement of PTG permeation rates directly in terms of NIST primary standards of trace humidity generation is described. Rather than using commonly employed gravimetric methods for permeation-tube calibration, the method applied here links the permeation rate of the permeation tube to the thermodynamic properties of ice. Using a hygrometer based on cavity ringdown spectroscopy, we compare the water vapor concentrations produced by the NIST low frost-point generator (LFPG) and a specially constructed PTG containing the permeation tube undergoing calibration. A least squares fit of the data determines the permeation rate of the tube under test. We describe the calibration system, experimental procedure and present sample calibration data. The expanded relative uncertainty of NIST permeation-tube calibrations is 1.8% with a coverage factor k = 2, dominated by the Type A uncertainties.     

MEMS Young’s Modulus and Step Height Measurements With Round Robin Results

This paper presents the results of a microelectromechanical systems (MEMS) Young’s modulus and step height round robin experiment, completed in April 2009, which compares Young’s modulus and step height measurement results at a number of laboratories. The purpose of the round robin was to provide data for the precision and bias statements of two \ related Semiconductor Equipment and Materials International (SEMI) standard test methods for MEMS. The technical basis for the test methods on Young’s modulus and step height measurements are also provided in this paper.Using the same test method, the goal of the round robin was to assess the repeatability of measurements at one laboratory, by the same operator, with the same equipment, in the shortest practical period of time as well as the reproducibility of measurements with independent data sets from unique combinations of measurement setups and researchers. Both the repeatability and reproducibility measurements were done on random test structures made of the same homogeneous material.The average repeatability Young’s modulus value (as obtained from resonating oxide cantilevers) was 64.2 GPa with 95 % limits of ± 10.3 % and an average combined standard uncertainty value of 3.1 GPa. The average reproducibility Young’s modulus value was 62.8 GPa with 95 % limits of ± 11.0 % and an average combined standard uncertainty value of 3.0 GPa.The average repeatability step height value (for a metal2-over-poly1 step from active area to field oxide) was 0.477 μm with 95 % limits of 7.9 % and an average combined standard uncertainty value of 0.014 μm. The average reproducibility step height value was 0.481 μm with 95 % limits of ± 6.2 % and an average combined standard uncertainty value of 0.014 μm.In summary, this paper demonstrates that a reliable methodology can be used to measure Young’s modulus and step height. Furthermore, a micro and nano technology (MNT) 5-in-1 standard reference material (SRM) can be used by industry to compare their in-house measurements using this methodology with NIST measurements thereby validating their use of the documentary standards.     

C波段热噪声标准

Ｃ波段热噪声标准是用来校准噪声发生器的，本文给出噪声源校准原理及其数学模型，并进一步分析测量不确定度。     

粘质沙雷氏菌测量方法研究

粘质沙雷氏菌是生物防护评价的指示菌。对粘质沙雷氏菌营养琼脂平板涂布法进行了方法验证和协同实验验证以及不确定度分析。结果显示,该方法重复性和复现性均较好,室内重复性相对标准偏差为8.93%,室间相对标准偏差为14.95%。经统计分析,营养琼脂平板涂布法相对扩展不确定度为12.60%（k=2）,适用于粘质沙雷氏菌定量测量。     

Nanoflow gradient generator for capillary high-performance liquid chromatography

A novel method of generating a nanoflow gradient elution for a capillary high-performance liquid chromatography (HPLC) system has been developed. An important feature of this system is that any gradient (GR) profile generated by a conventional microflow GR pump can be asymptotically traced and converted as a corresponding nanoflow GR profile simply by using a 10-port switching valve with two injection loops installed. Consequently, it has been called an "asymptotic trace 10-port valve" (AT10PV) nanoflow GR generator. Performance of the AT10PV nanoflow GR generator was tested in the range of flow rates from 50 to 500 nL/min. The test demonstrated that the AT10PV nanoflow GR generator can asymptotically trace the original gradient profile with good reproducibility. A capillary HPLC system using the AT10PV nanoflow GR generator provides reasonably good repeatability of peak retention times on the chromatogram of the tryptic digest of a BSA sample, RSD of less than 0.3% at a flow rate of 200 nL/min. It also enables sequential running of a series of sample injections in the same manner as conventional analysis at microflow rates.     

Moisture content estimation in paper pulp using fringing field impedance spectroscopy

Currently used methods for estimation of moisture content in paper pulp are restricted to levels of moisture concentration below 90%. Some of the existing methods require less practical double-sided contact measurements. A few other methods make restrictive assumptions, such as the constituents of the pulp that determine its conductance. This paper presents a technique that uses fringing field interdigital sensors to measure moisture concentration in paper pulp at levels as high as 96%. The method proposed in this paper uses single-sided measurements, offers high sensitivity, and does not require special operating conditions. The accuracy of the proposed method is also demonstrated. The repeatability and reproducibility of the sensor measurements are also shown.     

PZT和磁致伸缩孤立波传感器的性能研究与分析

孤立波方法被证实可用于测量均匀与非均匀材料的杨氏模量,而用于采集信号的孤立波传感器的性能直接决定测量结果的精度。介绍了两种基于不同原理的孤立波传感器,分别为采用压电材料制成的圆柱传感器,与基于维拉里与法拉第效应的磁致伸缩传感器。利用两种传感器分别测量了同一批水灰比分别为0.42、0.45与0.50的混凝土样本,将两者100次的测量结果均值与标准参考值相对比,从而对比两种传感器测量的精度。同时,分别分析了两者测量值的标准偏差,对比两者的可重复性强度。实验结果表明,三种水灰比样本的测量值相对于标准参考值,圆柱压力传感器的偏差率分别为6.48%、5.04%与1.85%,磁致伸缩传感器的偏差率分别为0.78%、3.08%与4.94%,因此两种传感器的误差率均低于10%,均可用与实际测量中,但后者的精度略高于前者,同时后者的标准偏差低于前者,因此具有更高的可重复性。     

枯草芽孢杆菌黑色变种芽孢测量方法研究

枯草芽孢杆菌黑色变种芽孢是生物防护和灭菌效果评价的重要指示微生物,其量值准确可以保证评价的有效性和可比性。对枯草芽孢杆菌涂布平板法进行了方法验证和协同实验验证以及不确定度分析。结果显示,当平板上的菌落数在30～300CFU之间时,该方法重复性和再现性均较好,室内重复性相对标准偏差为10.0%,室间相对标准偏差为14.1%。经统计分析,胰蛋白胨大豆琼脂培养基平板涂布法相对扩展不确定度为12.0%(k=2),适用于枯草芽孢杆菌黑色变种芽孢定量测量,对于人员防护装备防护性能评价、消毒剂检测及灭菌质量控制具有重要意义。     

Some relationships between gage R&R criteria

In this paper, several commonly used gage repeatability and reproducibility (R&R) acceptance criteria are discussed. The number of distinct categories (ndc) is equivalent to an acceptance criterion based on another standard metric, the ratio of the estimated measurement system standard deviation to the estimated overall standard deviation of the measurements. This implies that the criterion based on ndc could be considered redundant. Several acceptance criteria are revisited and compared, including a discussion of more objective measures of capability based on misclassification rates. The relationship between ndc and the discrimination ratio is also given. Copyright © 2007 John Wiley & Sons, Ltd.     

Reproducibility of regional pulse-wave velocity in uremic subjects

Despite the clinical importance of pulse-wave velocity (PWV), there are no standards for accurate carotid-radial pulse-wave measurement in uremic patients with respect to carotid-femoral measurement. We assessed the reproducibility of PWV values using the carotid-radial PWV measurement. We have measured the carotid-femoral PWV and carotid-radial PWV with an automated system (Pulse Pen, DiaTecne) using 2 different blind operators in 105 hemodialysis (HD) patients. The carotid-femoral waveforms were acquired by the first blind operator simultaneously with 2 pressure-sensitive transducers and the transit time of the pulse was calculated using the system software. Similarly, the second blind operator acquired the carotid-radial waveforms. The two operators performed 2 consecutive measurements from the same subject, in a random order. In fact, after the first operator had completed 2 consecutive measurements from 1 subject, all of the sensors were detached, and the second operator attached sensors again to the same subject. The measurements were performed during interval of a midweek dialysis-free day. To evaluate the reproducibility of the system, both within-observer and between-observer analyses were performed. We studied 105 dialysis patients (HD) and 20 controls. All HD patients had three dialysis sessions lasting at least 4 h/wk. A total of 28 patients (26.7%) had diabetic nephropathy. The mean age of HD was 64.6 ± 16.1 years, the body weight was 71.1 ± 15.1 kg, and the height was 164.6 ± 6.1 cm. All population studied is referral at a tertiary care from at least 6 months (mean 11.1 ± 2.1 months). A total of 45% of patients are smokers or ex-smokers. The PWV of carotid-femoral is 8.58 ± 3.99 and the PWV of carotid-radial is 8.70 ± 4.01 m/sec, respectively, by the first and the second operator; the difference of PWV (femoral-radial measure) is -0.037 ± 0.99 m/sec. The linear correlation of carotid-femoral vs. carotid-radial PWV measurements is the highest (R(2) =0.90). The results regarding reproducibility, including mean differences and standard deviations, standard errors, and correlation coefficients were analyzed for each regional PWV value for the between-observer and within-observer studies. All of the measurements showed significant correlation coefficients, ranging from 0.94 to 0.98. The reproducibility of regional PWV values for 2 consecutive measurements from the same subject was also analyzed using Bland-Altman plots, with the reproducibility expressed as the mean difference and 2 standard deviations between the measurements obtained by the 2 operators during carotid-femoral and carotid-radial measurements. Carotid-radial PWV measurement provides an accurate analysis with a high reproducibility with respect to carotid-femoral PWV measurement, and it can be used for arterial stiffness analysis in hemodialysis patients.     

Upgradation of a spectral irradiance measurement facility at National Physical Laboratory,India

This report describes the details of a recently upgraded spectral irradiance measurement facility in optical radiation standards at National Physical Laboratory, India. This facility provides the calibration of spectral irradiance in the wavelength range 280 nm – 2500 nm. PTB, Braunschweig, Germany calibrated five numbers of 1000 W quartz halogen lamps, which are used as reference standards for spectral irradiance scale. In addition to providing the details of instruments, the procedure of calibration and evaluation of uncertainties is also described. For checking the fidelity, repeatability and reproducibility of the upgraded system, calibration of one of the PTB calibrated lamps, was done against the other four PTB calibrated lamps. These measurements not only provide confidence on the upgraded system but also verify the retention of the PTB certificate values after a lapse of two years after their calibration.     

A New Attempt on a Coulometric Trace Humidity Generator

This paper describes the improved PTB coulometric trace humidity generator designed to extend the calibration capabilities at PTB down to 5?nL/L water-vapor volume fraction. The generation of defined water-vapor concentrations is based on the generation of defined quantities of hydrogen and oxygen by electrolysis of water according to Faraday??s law and the catalytic recombination of the generated hydrogen and oxygen back into water, which is then added to a flow of ultrapure or zero gas. The inherent uncertainties associated with the main subsystems are discussed, especially as concern the electrolysis of water. The expanded relative uncertainty of the water-vapor concentration is calculated and shown to be about 0.5?% to 1 % in the range above 100?nL/L volume fraction. For lower concentrations, the expanded uncertainty in volume fraction is about 0.6?nL/L to 0.9?nL/L caused by the blank level of the zero gas.     

基于静力称重法的微小容量光学检测系统标定

实验室常用静力称重法对微量液体容量进行检测,该方法在1μL容量的精确度达到2.18%,重复性为1.85%,但该方法无法在实验室外进行。现有的光学测量微量液体容量法的在1μL的精度为6.09%,重复性为1.31%。该法可实现在线检测,但其精度不如静力称重法。对光学测量微量液体容量的方法进行研究分析,提出了一种新的标定容量参照标准的方法,该标定方法将静力称重法与光学测量法两者结合,以静力称重法容量测量结果为参照标准,代替光学法原先的标准液。新的标定方法在原理上将参照标准由点扩展到线,可将光学测量法在10μL点的精度提高到2.014%,重复性1.30%。     

介入法测量工业X射线光机管电压的研究

建立了基于分压箱介入法测量工业X射线光机管电压的方法,测量了工业X射线光机MG165的管电压。结果显示管电压纹波小于4%,其中35 kV以上,纹波小于1%;7.5～150 kV范围内平均管电压与标称值偏差小于1.8%,多次测量管电压重复性好于0.01%,测试重新出束和开机条件下的管电压重复性,结果好于0.02%,达到了低能X射线空气比释动能国家基准量值复现、量值传递和国际比对的要求。     

Microwave Determination of Water Mole Fraction in Humid Gas Mixtures

A small volume (65?cm³) gold-plated quasi-spherical microwave resonator has been used to measure the water vapor mole fraction x _w of H₂O/N₂ and H₂O/air mixtures. This experimental technique exploits the high precision achievable in the determination of the cavity microwave resonance frequencies and is particularly sensitive to the presence of small concentrations of water vapor as a result of the high polarizability of this substance. The mixtures were prepared using the INRIM standard humidity generator for frost-point temperatures T _fp in the range between 241?K and 270?K and a commercial two-pressure humidity generator operated at a dew-point temperature between 272?K and 291?K. The experimental measurements compare favorably with the calculated molar fractions of the mixture supplied by the humidity generators, showing a normalized error lower than 0.8.     

自动标准压力发生器控制原理及检定方法研究

自动标准压力发生器以其准确度等级高、操作简单、可自动检定等优点被计量检定部门作为计量标准器使用,与数字压力计的主要区别是其具有控制功能.本文通过介绍自动标准压力发生器控制功能的工作原理提出了能够提高控制功能的方法,结合检定软件和检定数据进一步诠释检定规程的要求,对更好地开展检定工作具有一定的参考价值.     

平均值-极差控制图在地面放射性测量模型标准装置核查中的应用

地面放射性测量模型标准装置在国内属于最高计量标准,无法直接溯源。为确认其系列标准量值处于受控状态,本文采用了定期核查的方法,对核查测量结果通过制作平均值-极差控制图来反映标准量值复现的重复性和稳定性,进而确认标准量值的受控状态。     

基于时域分光法的微小容量测量方法研究

为了实现微小容量的在线测量,研究了一种基于时域分光法的微小容量检测方法。该方法基于溶液吸光度与溶液浓度的关系定理,通过双波长测量减小了实验耗材的加工误差影响。基于时域分光的模式,采用光栅分光将复色光源在时间域上分离出单色光后由探测器检测溶液吸光度变化。最后计算出溶液体积,同时可以通过配制不同浓度的溶液实现多次测量,提高实验耗材的利用率。在100μL和50μL的液体容量测量值分别为99.67μL和50.11μL,重复性为0.35%和1.22%,与传统的重力法进行比较获得了同样的结论,证明了基于时域分光法的微小容量测量方法的可行性。     

Comparative Study of Humidity Analyzers in Nitrogen Below 1?μ mol/mol

A precision trace humidity calibration system using permeation tubes has been implemented, and measurements have been performed in the range between 100?nmol/mol (100 ppb_v) and 245?nmol/mol (245 ppb_v) with flow rates between ${1\,{\rm L}{\cdot}{\min}^{-1}}$ and ${5\, {\rm L}{\cdot} {min}^{-1}}$ . The preliminary results of the commissioning of the permeation tube generator and its use in the comparison of humidity analyzers based on different measurement principles are presented and discussed. The work reported comprises the first stage in establishing the detailed design and operational characteristics of the future standard moisture generation to extend the range currently covered by Spanish national humidity standards. A precision optical dew-point hygrometer, a quartz crystal microbalance moisture analyzer, and a cavity ringdown spectrometer have been compared, and the response times and repeatability have been investigated. The design criteria and the characterization of the system as well as the estimation of measurement uncertainty in each case are presented.     

High dynamic range measurement of linear birefringence with an electro-optic modulated circular polariscope

This paper presents a common-path electro-optic modulated circular polariscope capable of performing the sequential measurements of the principal axis and retardance of the linearly birefringent media with high accuracy by means of two phase-locked extractions, and with a high dynamic range obtained by the design of optical configuration and the derivation of an easy algorithm. There exist an absolute error of 0.10° on average in the principal axis measurement of 36 times within the range of 0°–180°, and a relative error of 1.10% in the retardance measurement of a λ/2-wave plate by this method. Consequently, the standard deviations for the principal axis angle and retardance measurements are determined to be 0.0033° and 0.086°, respectively, triple standard deviations to the average values of principal axis angle and retardance are just 0.10% and 0.14% with high repeatability, respectively, and corresponding dynamic ranges of 0°–180°.