A Modular Test Platform for Micromechanical Tensile Testing of Soft Biomaterials

2018 ◽  
Author(s):  
Wilson Eng ◽  
Max Kim ◽  
Anand Ramasubramanian ◽  
Sang-Joon John Lee
Keyword(s):  
Force Measurement ◽  
Low Noise ◽  
Particle Tracing ◽  
Viscoelastic Parameters ◽  
Tensile Tester ◽  
Low Profile ◽  
Blood Clots ◽  
Microscope Imaging ◽  
Using Data ◽  
Soft Biomaterials

Mechanical properties of biomaterials are difficult to characterize experimentally because many relevant biomaterials such as hydrogels are very pliable and viscoelastic. Furthermore, test specimens such as blood clots retrieved from patients tend to be small in size, requiring fine positioning and sensitive force measurement. Mechanobiological studies require fast data recording, preferably under simultaneous microscope imaging, in order to monitor events such as structural remodeling or localized rupture while strain is being applied. A low-profile tensile tester that applies prescribed displacement up to several millimeters and measures forces with resolution on the order of micronewtons has been designed and tested, using alginate as a representative soft biomaterial. 1.5% alginate (cross-linked with 0.1 M and 0.2 M calcium chloride) has been chosen as a reference material because of its extensive use in tissue engineering and other biomedical applications. Prescribed displacement control with rates between 20 μm/s and 60 μm/s were applied using a commercial low-noise nanopositioner. Force data were recorded using data acquisition and signal conditioning hardware with sampling rates as high as 1 kHz. Elongation up to approximately 10 mm and force in the range of 250 mN were measured. The data were used to extract elastic and viscoelastic parameters for alginate specimens. Another biomaterial, 2% agarose, was also tested to show versatility of the apparatus for slightly stiffer materials. The apparatus is modular such that different load cells ranging in capacity from hundreds of millinewtons to tens of newtons can be used. The apparatus furthermore is compatible with real-time microscope imaging, particle tracing, and programmable positioning sequences.

Tensile Test of Bulk- and Surface-Micromachined 0.1-νm Thick Silicon Film using Electrostatic Force Grip System

2001 ◽  
Vol 687 ◽  
Author(s):  
Toshiyuki Tsuchiya ◽  
Jiro Sakata ◽  
M. Shikida ◽  
K. Sato
Keyword(s):  
Thin Film ◽  
Force Measurement ◽  
Electrostatic Force ◽  
Silicon Film ◽  
Single Crystal Silicon ◽  
Surface Micromachining ◽  
Crystal Silicon ◽  
Release Process ◽  
Tensile Tester ◽  
Small Force

AbstractSingle-crystal silicon films of sub-micrometer thicknesses were tensile tested using a thin film tensile tester with an electrostatic force grip. The tester has been newly designed for this thin film. It uses a servo-controlled balance for small-force measurement with a resolution of less than 100 νN. The specimens were fabricated using bulk- and surface-micromachining starting with a SIMOX wafer, and an epi-SOI wafer. The bulk micromachined specimens were released from a wafer by anisotropic etching from the backside of the wafer. The specimen size was 0 to 500 νm long, 20 or 50 νm wide and 0.14 νm thick. The thinner specimens were fabricated by surface micromachining and dry release process using XeF2 and vapor HF etching to avoid stiction of the specimens. The size was 0 to 600 νm long, 1 to 20 νm wide and 0.05 νm thick. These wafers were (100) oriented and the loading axis of the specimen was <110>. The tensile strength of the bulk micromachined specimens ranged from 1.4 to 4.8 GPa for twelve samples and that of the surface micromachined specimens ranged from 1.0 to 6.8 GPa for seven samples.

scholarly journals An effective method for the detection of trace species demonstrated using the MetOp Infrared Atmospheric Sounding Interferometer

2010 ◽  
Vol 3 (5) ◽  
pp. 4531-4569
Author(s):  
J. C. Walker ◽  
A. Dudhia ◽  
E. Carboni
Keyword(s):  
Brightness Temperature ◽  
Sulphur Dioxide ◽  
Atmospheric Temperature ◽  
Quantitative Information ◽  
Low Noise ◽  
Target Species ◽  
Trace Species ◽  
Atmospheric Sounding ◽  
The Difference ◽  
Using Data

Abstract. A detection method is demonstrated for volcanic sulphur dioxide and ammonia from agriculture using data from the MetOp Infrared Atmospheric Sounding Interferometer (IASI). The method is an extension of the Brightness Temperature Difference (BTD) technique which uses the difference in brightness temperature between a small number of channels sensitive to the target species and spectral background to determine the presence of the target species. The method described here allows instead for the use of large numbers of channels with an optimal set of linear weights which effectively suppress the spectral background allowing low-noise filters to be produced which are capable of distinguishing the target species from other parameters such as interfering species, surface and atmospheric temperature, and cloudiness without retrieving these parameters explicitly. Once generated, the filters can be applied quickly and easily to identify events of interest over a large global dataset, in near-real-time if required, and in some circumstances a degree of quantitative information can be extracted about the abundance of the target species. The theory behind the generation of the filters is first described. The filters are then used in the detection of volcanic sulphur dioxide from the eruption of the Kasatochi volcano in Alaska, beginning in August 2008, and in the detection of ammonia emissions related to agriculture over Southern Asia in May 2008. The performance of new the filters is compared against that obtained using existing filters.

scholarly journals Estimating Optimum Compaction Level for Dense-Graded Hot-Mix Asphalt Mixtures

2010 ◽  
Vol 7 (1) ◽  
pp. 11 ◽  
Author(s):  
Khalid Al Shamsi ◽  
Louay N. Mohammad
Keyword(s):  
Force Measurement ◽  
Asphalt Mixtures ◽  
Air Voids ◽  
Superpave Gyratory Compactor ◽  
Field Compaction ◽  
Traffic Level ◽  
Compaction Energy ◽  
High Structural Stability ◽  
Compaction Force ◽  
Using Data

 A critical step in the design of asphalt mixtures is laboratory compaction. Laboratory compaction should reflect field compaction and should produce mixtures that are economical and possess high structural stability. During the compaction process, asphalt mixtures are subjected to certain amount of compaction energy in order to achieve the required density. The Superpave volumetric mix design is based on compacting HMA mixtures to a specified compaction level described by the number of gyrations from the Superpave gyratory compactor (SGC). This level is termed Ndes and represents the required energy (based on the traffic level expected) to densify the mixture to a 4% air voids level. This paper re-examines the Superpave compaction requirements through extensive laboratory investigation of the response of a number of asphalt mixtures to the applied compaction energy. It also presents an alternative method to estimate the number of gyrations at which a mixture first reaches an optimum aggregate interlock and hence prevents overcompaction problems that might result in unstable aggregate structures or dry asphalt mixtures. A total of 12 HMA mixtures were studied. During compaction, force measurement was made using the pressure distribution analyzer (PDA). The compaction characteristics of the mixtures were analyzed using data from the PDA and the traditional Superpave Gyratory Compactor (SGC) results. 

Mistuning and Damping Experiments at Design Speed Combined With Computational Tools

2017 ◽  
Author(s):  
Kiran D’Souza ◽  
Mike Dunn ◽  
Bogdan I. Epureanu
Keyword(s):  
Data Storage ◽  
Nonlinear Damping ◽  
Noise Signal ◽  
Low Noise ◽  
Computational Tools ◽  
Air Jets ◽  
Engine Order ◽  
Light Probe ◽  
Design Speed ◽  
Using Data

This paper describes a combined experimental/analytical effort which will provide measurements specifically designed to verify computational tools developed for turbomachinery applications. The hardware used for these measurements is engine-type hardware that will be operated at design speed. The specific hardware to be used is NASA Rotor 67 and the measurements will be performed in the confines of an underground spin pit facility. The experiments are aimed at identifying damping and mistuning properties of the rotor while it rotates at predetermined speed values within the facility. In addition, experiments using a modified Rotor 67 configuration containing added frictional damping elements are described. Light probe and strain gauge data will be obtained in order to compare their individual effectiveness. The response data storage is based on wide bandwidth, low noise signal conditioners used in conjunction with a high sampling-frequency data acquisition system. The rotor can be excited at specific engine-order crossings using air-jets with the number of specific active air-jets and the corresponding force transmitted by each jet estimated from computations. The experimental effort enables the identification of key parameters used in a series of computational tools that have been developed recently. The computational tools include various mistuning and (nonlinear) damping identification methods that have not yet been verified using data obtained from rotating hardware.

scholarly journals Calibration and Evaluation of a Force Measurement Glove for Field-Based Monitoring of Manual Wheelchair Users

2020 ◽  
Author(s):  
Anthony Anderson ◽  
Alexander W. Hooke ◽  
Chandrasekaran Jayaraman ◽  
Adam Burns ◽  
Emma Fortune ◽  
...  
Keyword(s):  
Force Measurement ◽  
Relative Magnitude ◽  
Force Measurements ◽  
Data Logger ◽  
Wheelchair Users ◽  
Manual Wheelchair ◽  
Sensing Systems ◽  
Palmar Surface ◽  
Strong Linear Correlation ◽  
Using Data

AbstractManual wheelchair users exhibit pain related to repetitive and demanding shoulder activities of daily living. Wearable sensing systems like force measurement gloves can provide insights about upper extremity loading in the community and home environments. We calibrated and evaluated the accuracy of a novel force measurement glove with a body-worn data logger. The device was calibrated with loads of 0-800 N applied to the palmar surface of the glove. Calibration conditions were tested that varied the stiffness of the material in the glove, the temperature, and the curvature of the force applicator. Calibration equations from each condition were evaluated by comparing the glove’s force prediction with the output of an instrumented wheelchair rim during propulsion and weight relief exercises. The force measurement glove detected 72.7% of 355 propulsion peaks and had a strong linear correlation with the instrumented rim force measurements (r=0.80). The most accurate calibration equation was constructed using data from all conditions, with an RMS force measurement error of 64.7 N and 31.7 N for weight relief exercise and propulsion, respectively. The force measurement glove design described here may serve as a useful tool for detection of loading events and relative magnitude changes.

scholarly journals Validity of the AdMos, Advanced Sport Instruments, GNSS Sensor for Use in Alpine Skiing

2021 ◽  
Vol 14 (1) ◽  
pp. 22
Author(s):  
Petter Andre Husevåg Jølstad ◽  
Robert Cortas Reid ◽  
Jon Glenn Omholt Gjevestad ◽  
Matthias Gilgien
Keyword(s):  
Accuracy Assessment ◽  
Satellite System ◽  
Low Noise ◽  
Alpine Skiing ◽  
Performance Parameters ◽  
Position Data ◽  
Turn Radius ◽  
Using Data ◽  
Global Navigation Satellite ◽  
Over Time

The AdMos receiver from Advanced Sport Instruments is a global navigation satellite system (GNSS) frequently used in alpine ski racing, with users from national and professional teams. Therefore, a validation was conducted for use of the AdMos in alpine skiing, using data from both recreational and competitive skiers. Athletes skied a total of 60 km in different measurement and skiing conditions, while carrying both an AdMos and a differential GNSS, which was used as the gold standard. From the GNSS position data, speed, acceleration, turn radius, trajectory incline and impulse were calculated as instantaneous and turn average measures for both GNSS systems and errors between the systems were calculated. The median and interquartile range (IQR) for the instantaneous errors were below 3.5 (3.5) m for horizontal plane position and below 7.0 (4.3) m for the 3D position. The median and IQR for instantaneous errors and turn average errors, respectively, were below 0.04 (0.24)/0.04 (0.16) m/s for speed, below 0.23 (1.06)/0.35 (0.63) m/s2 for acceleration, below 0.47 (5.65)/0.73 (5.3) m for turn radius, and below 0.043 (1.96)/0.42 (1.42) degrees for trajectory incline. The median and IQR for turn average impulse were 0.025 (0.099) BWs. The position error changed gradually and randomly over time, with low noise levels causing smooth trajectories of similar shape but spatially shifted from the true trajectory that allowed the position–time derivation of the performance parameters, and detection of turns with 3% median and 5% IQR error. The accuracy assessment revealed that (1) the error levels were comparable to other consumer-grade standalone GNSS units designed for sport; (2) the trajectories closely resembled the true trajectories but with a random shift that changed over time and had a low noise level; (3) there was a very low instantaneous speed error that may allow the detection of many performance aspects of skiing and other sports; and (4) there were larger instantaneous errors for the remaining performance parameters, which decreased substantially when averaged over a turn.

Distribution of R- and S-Process Elements in the Galactic Halo

1988 ◽  
Vol 132 ◽  
pp. 501-506
Author(s):  
C. Sneden ◽  
C. A. Pilachowski ◽  
K. K. Gilroy ◽  
J. J. Cowan
Keyword(s):  
Heavy Element ◽  
Galactic Halo ◽  
Low Noise ◽  
Heavy Elements ◽  
Process Synthesis ◽  
Element Abundances ◽  
Halo Stars ◽  
Abundance Patterns ◽  
R Process ◽  
Process Elements

Current observational results for the abundances of the very heavy elements (Z&gt;30) in Population II halo stars are reviewed. New high resolution, low noise spectra of many of these extremely metal-poor stars reveal general consistency in their overall abundance patterns. Below Galactic metallicities of [Fe/H] Ã −2, all of the very heavy elements were manufactured almost exclusively in r-process synthesis events. However, there is considerable star-to-star scatter in the overall level of very heavy element abundances, indicating the influence of local supernovas on element production in the very early, unmixed Galactic halo. The s-process appears to contribute substantially to stellar abundances only in stars more metal-rich than [Fe/H] Ã −2.

Polar Magnetic Field Reversals of the Sun in Maunder Minimum

2000 ◽  
Vol 179 ◽  
pp. 193-196
Author(s):  
V. I. Makarov ◽  
A. G. Tlatov
Keyword(s):  
Magnetic Field ◽  
Maunder Minimum ◽  
The Sun ◽  
Annual Rings ◽  
Field Reversal ◽  
Polar Magnetic Field ◽  
Pine Trees ◽  
Using Data ◽  
Magnetic Field Reversal

AbstractA possible scenario of polar magnetic field reversal of the Sun during the Maunder Minimum (1645–1715) is discussed using data of magnetic field reversals of the Sun for 1880–1991 and the14Ccontent variations in the bi-annual rings of the pine-trees in 1600–1730 yrs.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Quality films from carbon fiber evaporation for thorough coverage of TEM grids

1988 ◽  
Vol 46 ◽  
pp. 418-419
Author(s):  
N. Tempel ◽  
M. C. Ledbetter
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Carbon Films ◽  
Low Noise ◽  
Vacuum Evaporation ◽  
High Yield ◽  
Good Adhesion ◽  
Noise Structure ◽  
Resolution Electron ◽  
Carbon Foils

Carbon films have been a support of choice for high resolution electron microscopy since the introduction of vacuum evaporation of carbon. The desirable qualities of carbon films and methods of producing them has been extensively reviewed. It is difficult to get a high yield of grids by many of these methods, especially if virtually all of the windows must be covered with a tightly bonded, quality film of predictable thickness. We report here a method for producing carbon foils designed to maximize these attributes: 1) coverage of virtually all grid windows, 2) freedom from holes, wrinkles or folds, 3) good adhesion between film and grid, 4) uniformity of film and low noise structure, 5) predictability of film thickness, and 6) reproducibility.Our method utilizes vacuum evaporation of carbon from a fiber onto celloidin film and grid bars, adhesion of the film complex to the grid by carbon-carbon contact, and removal of the celloidin by acetone dissolution. Materials must be of high purity, and cleanliness must be rigorously maintained.

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