Calibration of Piezoresistive Cantilever Force Sensors Using the NIST Electrostatic Force Balance

2003 ◽  
Author(s):  
Jon R. Pratt ◽  
David B. Newell ◽  
John A. Kramar ◽  
Eric Whitenton
Keyword(s):  
Mechanical Performance ◽  
Electrostatic Force ◽  
International System ◽  
National Standards ◽  
Force Balance ◽  
Force Sensitivity ◽  
System Of Units ◽  
Load Cells ◽  
Optical Lever

The characterization of material properties and mechanical performance of micro-electromechanical devices often hinges on the accurate measurement of small forces. Calibrated load cells of appropriate size and range are used, but are often not calibrated in a fashion traceable to the International System of Units (SI). Recently, we calibrated a piezoresistive cantilever in terms of SI force sensitivity. Here, we employ this device as a secondary force standard to calibrate another, optical lever based sensor in a force probe instrument, demonstrating an unbroken tracability chain to appropriate national standards.

Progress toward Système International d'Unités traceable force metrology for nanomechanics

2004 ◽  
Vol 19 (1) ◽  
pp. 366-379 ◽  
Author(s):  
Jon R. Pratt ◽  
Douglas T. Smith ◽  
David B. Newell ◽  
John A. Kramar ◽  
Eric Whitenton
Keyword(s):  
Atomic Force Microscope ◽  
Electrostatic Force ◽  
Standard Uncertainty ◽  
National Standards ◽  
Force Balance ◽  
Traceability Chain ◽  
Relative Standard Uncertainty ◽  
Force Sensitivity ◽  
Atomic Force ◽  
Relative Standard

Recent experiments with the National Institute of Standards and Technology (NIST) Electrostatic Force Balance (EFB) have achieved agreement between an electrostatic force and a gravitational force of 10−5 N to within a few hundred pN/μN. This result suggests that a force derived from measurements of length, capacitance, and voltage provides a viable small force standard consistent with the Système International d’Unités. In this paper, we have measured the force sensitivity of a piezoresistive microcantilever by directly probing the NIST EFB. These measurements were linear and repeatable at a relative standard uncertainty of 0.8%. We then used the calibrated cantilever as a secondary force standard to transfer the unit of force to an optical lever–based sensor mounted in an atomic force microscope. This experiment was perhaps the first ever force calibration of an atomic force microscope to preserve an unbroken traceability chain to appropriate national standards. We estimate the relative standard uncertainty of the force sensitivity at 5%, but caution that a simple model of the contact mechanics suggests errors may arise due to friction.

A Piezoresistive Cantilever Force Sensor for Direct AFM Force Calibration

2007 ◽  
Vol 1021 ◽  
Author(s):  
Jon R. Pratt ◽  
John A. Kramar ◽  
Gordon A. Shaw ◽  
Douglas T. Smith ◽  
John M. Moreland
Keyword(s):  
Atomic Force Microscope ◽  
Contact Force ◽  
Electrostatic Force ◽  
International System ◽  
Force Sensor ◽  
Force Balance ◽  
Atomic Force ◽  
International System Of Units ◽  
System Of Units ◽  
Force Calibration

AbstractWe describe the design, fabrication, and calibration testing of a new piezoresistive cantilever force sensor suitable for the force calibration of atomic force microscopes in a range between tens of nanonewtons to hundreds of micronewtons. The sensor is calibrated using the NIST Electrostatic Force Balance (EFB) and functions either as a force reference or stiffness artifact that is traceable to the International System of Units. The cantilever has evenly spaced fiducial marks along its length. We report stiffnesses that vary quadratically with location, from a high of 12.1 N/m at the first fiducial to a low of 0.394 N/m at the last; with force sensitivities that vary linearly, ranging from 18.1 Ù/mN to 106 Ù/mN. We also test the device to transfer the unit of force to an atomic force microscope, finding that force and stiffness based approaches yield independent estimates of the contact force consistent within 2 % of each other.

The BIPM Mycotoxin Metrology Capacity Building and Knowledge Transfer Program: Accurate Characterization of a Pure Aflatoxin B1 Material to Avoid Calibration Errors

2019 ◽  
Vol 102 (6) ◽  
pp. 1740-1748
Author(s):  
Ralf D Josephs ◽  
Xiaomin Li ◽  
Xiuqin Li ◽  
Zhen Guo ◽  
Bruno Garrido ◽  
...  
Keyword(s):  
Knowledge Transfer ◽  
Aflatoxin B1 ◽  
Developing Economies ◽  
International System ◽  
Impurity Content ◽  
Transfer Program ◽  
Measurement Capability ◽  
System Of Units ◽  
Food And Feed

Abstract Background: The contamination of food and feed by mycotoxins, Aflatoxin B1 (AfB1) being one of the most prominent examples, is of imminent concern to many countries. Regulatory limits for mycotoxins have been implemented, and these need to be supported by a sound measurement infrastructure for mycotoxin analysis in order to enforce and verify products, protect populations, and avoid technical barriers to trade in food stuffs. Objective: A Capability Building and Knowledge Transfer program on Metrology for Safe Food and Feed in Developing Economies was started at the International Bureau of Weights and Measures to allow National Metrology Institutes or Designated Institutes to work together to strengthen their national mycotoxin metrology infrastructure. Methods: Knowledge transfer to scientists is provided to enable the characterization of selected pure mycotoxin materials and the production of corresponding certified reference material solutions. Results: This higher-order measurement capability can in turn support mycotoxin testing laboratories within their countries through the provision, for example, of standard solutions of critical analytes that are traceable to the International System of Units (SI). Conclusions and Highlights: The purity characterization and value assignment for a high-purity AfB1 material (979.6 ± 2.3 mg/g, k = 2) intended to be used for the gravimetric production of SI traceable calibration solutions for AfB1 is described using an approach combining quantitative NMR and LC–diode array detection–tandem MS for the correction of the mycotoxin-related impurity content.

Traceability of DC and AC high voltage measurements using voltage divider calibration

2018 ◽  
Vol 55 (2) ◽  
pp. 109-119 ◽  
Author(s):  
Hala M Abdel Mageed ◽  
Faisal Q Alenezi
Keyword(s):  
High Voltage ◽  
International System ◽  
Voltage Divider ◽  
Calibration Method ◽  
Industrial Applications ◽  
Theory And Practice ◽  
National Standards ◽  
Dc Voltage ◽  
Acceptable Accuracy ◽  
System Of Units

This paper focuses on achieving traceability of high voltage measurements up to 200 kV at the Egyptian National Institute of Standards. The measurement system consists of an AC/DC voltmeter and a universal resistive/capacitive high voltage divider. The voltmeter shows measured voltage values based on the scale factor of the voltage divider. The divider ensures a stable capacitance for AC voltage measurements and an additional resistive parallel path for DC voltage measurements. Both the divider and the voltmeter are calibrated in AC and DC modes. All uncertainty components are taken into account to obtain measured values with an acceptable accuracy. The calibration results in traceability to the national standards, which make measurements using the international system of units. The proposed calibration method is useful for the theory and practice of high voltage measurements in education, industrial applications, and electrical metrology studies.

scholarly journals International System of Units (SI) Traceable Noise-Equivalent Power and Responsivity Characterization of Continuous Wave ErAs:InGaAs Photoconductive Terahertz Detectors

Photonics ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 15 ◽  
Author(s):  
Anuar Fernandez Olvera ◽  
Axel Roggenbuck ◽  
Katja Dutzi ◽  
Nico Vieweg ◽  
Hong Lu ◽  
...  
Keyword(s):  
Continuous Wave ◽  
International System ◽  
Noise Equivalent Power ◽  
National Metrology Institute ◽  
International System Of Units ◽  
System Of Units ◽  
Experimental Values ◽  
Power Measurements ◽  
Thz Power

A theoretical model for the responsivity and noise-equivalent power (NEP) of photoconductive antennas (PCAs) as coherent, homodyne THz detectors is presented. The model is validated by comparison to experimental values obtained for two ErAs:InGaAs PCAs. The responsivity and NEP were obtained from the measured rectified current, the current noise floor in the PCAs, and the incoming THz power for the same conditions. Since the THz power measurements are performed with a pyroelectric detector calibrated by the National Metrology Institute of Germany (PTB), the experimentally obtained values are directly traceable to the International System of Units (SI) for the described conditions. The agreement between the presented model and the experimental results is excellent using only one fitting parameter. A very low NEP of 1.8 fW/Hz at 188.8 GHz is obtained at room temperature.

scholarly journals Characterization of blackbody inhomogeneity and its effect on the retrieval results of the GLORIA instrument

2018 ◽  
Vol 11 (7) ◽  
pp. 3871-3882 ◽  
Author(s):  
Anne Kleinert ◽  
Isabell Krisch ◽  
Jörn Ungermann ◽  
Albert Adibekyan ◽  
Berndt Gutschwager ◽  
...  
Keyword(s):  
Water Vapor ◽  
Temperature Distribution ◽  
International System ◽  
Vertical Resolution ◽  
Radiometric Calibration ◽  
Climate Trends ◽  
Trace Species ◽  
Calibration Uncertainty ◽  
System Of Units

Abstract. Limb sounding instruments play an important role in the monitoring of climate trends, as they provide a good vertical resolution. Traceability to the International System of Units (SI) via onboard reference or transfer standards is needed to compare trend estimates from multiple instruments. This study investigates the required uncertainty of these radiation standards to properly resolve decadal trends of climate-relevant trace species like ozone, water vapor, and temperature distribution for the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA). Temperature nonuniformities of the onboard reference blackbodies, used for radiometric calibration, have an impact on the calibration uncertainty. The propagation of these nonuniformities through the retrieval is analyzed. A threshold for the maximum tolerable uncertainty of the blackbody temperature is derived, so that climate trends can be significantly identified with GLORIA.

The BIPM Mycotoxin Metrology Capacity Building and Knowledge Transfer Program: Accurate Characterization of a Pure Aflatoxin B1 Material to Avoid Calibration Errors

2019 ◽  
Vol 102 (6) ◽  
pp. 1740-1748 ◽  
Author(s):  
Ralf D. Josephs ◽  
Xiaomin Li ◽  
Xiuqin Li ◽  
Zhen Guo ◽  
Bruno Garrido ◽  
...  
Keyword(s):  
Knowledge Transfer ◽  
Developing Economies ◽  
International System ◽  
Impurity Content ◽  
Transfer Program ◽  
Measurement Capability ◽  
Weights And Measures ◽  
System Of Units ◽  
Food And Feed

Background: The contamination of food and feed by mycotoxins, Aflatoxin B1 (AfB1) being one of the most prominent examples, is of imminent concern to many countries. Regulatory limits for mycotoxins have been implemented, and these need to be supported by a sound measurement infrastructure for mycotoxin analysis in order to enforce and verify products, protect populations, and avoid technical barriers to trade in food stuffs. Objective: A Capability Building and Knowledge Transfer program on Metrology for Safe Food and Feed in Developing Economies was started at the International Bureau of Weights and Measures to allow National Metrology Institutes or Designated Institutes to work together to strengthen their national mycotoxin metrology infrastructure. Methods: Knowledge transfer to scientists is provided to enable the characterization of selected pure mycotoxin materials and the production of corresponding certified reference material solutions. Results: This higher-order measurement capability can in turn support mycotoxin testing laboratories within their countries through the provision, for example, of standard solutions of critical analytes that are traceable to the International System of Units (SI). Conclusions and Highlights: The purity characterization and value assignment for a high-purity AfB1 material (979.6 ± 2.3 mg/g, k = 2) intended to be used for the gravimetric production of SI traceable calibration solutions for AfB1 is described using an approach combining quantitative NMR and LC–diode array detection–tandem MS for the correction of the mycotoxin-related impurity content.

Design of a MEMS Force Sensor for Quantitative Measurement in the Nano- to Pico-Newton Range

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001841-001868
Author(s):  
Li-Anne Liew ◽  
John M. Moreland ◽  
Jonathan R. Pratt
Keyword(s):  
Single Molecule ◽  
Quantitative Measurement ◽  
Electrostatic Force ◽  
Force Sensor ◽  
Force Balance ◽  
Glass Wafer ◽  
Quantitative Measurements ◽  
Force Sensitivity ◽  
Si Traceability ◽  
Silicon Tethers

We describe the design and fabrication of a MEMS nano- to pico-Newton force sensor with SI traceability. There has been much recent interest in developing instrumentation for the quantitative measurement of forces in the nano- to pico-Newton range. Forces in this range are frequently encountered when investigating mechanical properties of nanomaterials, in nanobiotechnology, and in single-molecule biophysics. Various methods of measuring forces at these levels include using AFM cantilevers, scanning probe microscopy, and nanoindentation. However, such measurements are relative, and in order to obtain precise quantitative measurements, it is necessary to be able to calibrate such sensors in a manner that is traceable to fundamental SI units. One such method of calibration is using an Electrostatic Force Balance (EFB) that has been established at NIST. We thus describe the design and fabrication of a MEMS-based force sensor that may be directly calibrated with the EFB and thus has the potential to measure nano- to pico-Newtons of force with SI traceability. The sensor consists of a silicon rigid arm supported on silicon tethers and which are attached to capacitive electrodes. The bar, tethers and electrodes are made from the device layer of a double side SOI wafer. A glass wafer with patterned metal electrodes is anodically bonded on both the top and bottom of the wafer to form symmetrical capacitive electrodes. An external force moves the silicon arm and the resulting capacitive force gradient of the electrodes is measured with the EFB. The mechanical structure and electrodes are designed for force sensitivity in the nano- to pico-Newton ranges and for operation in UHV to reduce thermomechanical noise. We discuss the design, initial fabrication and testing of this force sensor as a step toward the ultimate goals of quantitative nanomechanical testing of materials, NEMS, and engineered surfaces at the nanoscale.

Dimensions of plane and solid angles and their units in the International System of Units (SI)

2020 ◽  
pp. 26-32
Author(s):  
M. I. Kalinin ◽  
L. K. Isaev ◽  
F. V. Bulygin
Keyword(s):  
Solid Angle ◽  
International System ◽  
International Committee ◽  
Plane Angle ◽  
Arc Length ◽  
Weights And Measures ◽  
International System Of Units ◽  
System Of Units ◽  
In Series ◽  
Solid Angles

The situation that has developed in the International System of Units (SI) as a result of adopting the recommendation of the International Committee of Weights and Measures (CIPM) in 1980, which proposed to consider plane and solid angles as dimensionless derived quantities, is analyzed. It is shown that the basis for such a solution was a misunderstanding of the mathematical formula relating the arc length of a circle with its radius and corresponding central angle, as well as of the expansions of trigonometric functions in series. From the analysis presented in the article, it follows that a plane angle does not depend on any of the SI quantities and should be assigned to the base quantities, and its unit, the radian, should be added to the base SI units. A solid angle, in this case, turns out to be a derived quantity of a plane angle. Its unit, the steradian, is a coherent derived unit equal to the square radian.

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