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Sample records for in-situ cantilever beam

  1. SEM in situ MiniCantilever Beam Bending of U-10Mo/Zr/Al Fuel Elements

    SciTech Connect

    Mook, William; Baldwin, Jon K.; Martinez, Ricardo M.; Mara, Nathan A.

    2014-06-16

    In this work, the fracture behavior of Al/Zr and Zr/dU-10Mo interfaces was measured via the minicantilever bend technique. The energy dissipation rates were found to be approximately 3.7-5 mj/mm2 and 5.9 mj/mm2 for each interface, respectively. It was found that in order to test the Zr/U-10Mo interface, location of the hinge of the cantilever was a key parameter. While this test could be adapted to hot cell use through careful alignment fixturing and measurement of crack lengths with an optical microscope (as opposed to SEM, which was used here out of convenience), machining of the cantilevers via MiniMill in such a way as to locate the interfaces at the cantilever hinge, as well as proper placement of a femtosecond laser notch will continue to be key challenges in a hot cell environment.

  2. Dual-Cantilever-Beam Accelerometer

    NASA Technical Reports Server (NTRS)

    Reynolds, Emmitt A.; Speckhart, Frank H.

    1988-01-01

    Sensitivity to velocity changes along beam axis reduced. Weighted-end cantilever beams of accelerometer deflected equally by acceleration in y direction. When acceleration to right as well as up or down, right beam deflected more, while left beam deflected less. Bridge circuit averages outputs of strain gauges measuring deflections, so cross-axis sensitivity of accelerometer reduced. New device simple and inexpensive.

  3. In situ mass measurement of electron-beam-induced nanometer-sized W-related deposits using a carbon nanotube cantilever

    SciTech Connect

    Sawaya, Shintaro; Akita, Seiji; Nakayama, Yoshikazu

    2006-11-06

    Using a carbon nanotube oscillator, the authors performed in situ measurements of densities of electron-beam-induced tungsten compounds with size of less than 100 nm. Total mass of the deposit was proportional to the deposition time. A higher deposition rate was obtained at lower electron-beam acceleration voltage. Density of the deposit decreased from 2.7 to 1.4 g/cm{sup 3} with increasing acceleration voltage from 5 to 15 kV. These results indicate that the increased density with low-acceleration voltage produces effective decomposition of W(CO){sub 6}.

  4. In-situ piezoresponse force microscopy cantilever mode shape profiling

    SciTech Connect

    Proksch, R.

    2015-08-21

    The frequency-dependent amplitude and phase in piezoresponse force microscopy (PFM) measurements are shown to be a consequence of the Euler-Bernoulli (EB) dynamics of atomic force microscope (AFM) cantilever beams used to make the measurements. Changes in the cantilever mode shape as a function of changes in the boundary conditions determine the sensitivity of cantilevers to forces between the tip and the sample. Conventional PFM and AFM measurements are made with the motion of the cantilever measured at one optical beam detector (OBD) spot location. A single OBD spot location provides a limited picture of the total cantilever motion, and in fact, experimentally observed cantilever amplitude and phase are shown to be strongly dependent on the OBD spot position for many measurements. In this work, the commonly observed frequency dependence of PFM response is explained through experimental measurements and analytic theoretical EB modeling of the PFM response as a function of both frequency and OBD spot location on a periodically poled lithium niobate sample. One notable conclusion is that a common choice of OBD spot location—at or near the tip of the cantilever—is particularly vulnerable to frequency dependent amplitude and phase variations stemming from dynamics of the cantilever sensor rather than from the piezoresponse of the sample.

  5. Oscillations of end loaded cantilever beams

    NASA Astrophysics Data System (ADS)

    Macho-Stadler, E.; Elejalde-García, M. J.; Llanos-Vázquez, R.

    2015-09-01

    This article presents several simple experiments based on changing transverse vibration frequencies in a cantilever beam, when acted on by an external attached mass load at the free end. By using a mechanical wave driver, available in introductory undergraduate laboratories, we provide various experimental results for end loaded cantilever beams that fit reasonably well into a linear equation. The behaviour of the cantilever beam’s weak-damping resonance response is studied for the case of metal resonance strips. As the mass load increases, a more pronounced decrease occurs in the fundamental frequency of beam vibration. It is important to note that cantilever construction is often used in architectural design and engineering construction projects but current analysis also predicts the influence of mass load on the sound generated by musical free reeds with boundary conditions similar to a cantilever beam.

  6. Forced Vibrations of a Cantilever Beam

    ERIC Educational Resources Information Center

    Repetto, C. E.; Roatta, A.; Welti, R. J.

    2012-01-01

    The theoretical and experimental solutions for vibrations of a vertical-oriented, prismatic, thin cantilever beam are studied. The beam orientation is "downwards", i.e. the clamped end is above the free end, and it is subjected to a transverse movement at a selected frequency. Both the behaviour of the device driver and the beam's weak-damping…

  7. Inner Crack Detection Method for Cantilever Beams

    NASA Astrophysics Data System (ADS)

    Li, Zheng; Zhang, Wei; Li, Yixuan; Su, Xianyue

    2008-02-01

    In this paper, continuous wavelet transform has been performed to extract the inner crack information from the guided waves in cantilever beams, and the location and size of crack can be detected exactly. Considering its best time-frequency property, Gabor continuous wavelet transform is employed to analyze the complicated flexible wave signals in cantilever beam, which is inspirited by an impact on the free end. Otherwise, in order to enhance the sensitivity of detection for some small cracks, an improved method is discussed. Here, both computational and experimental methods are carried out for comparing the influence of different crack location in beam. Therefore, the method proposed can be expected to expand to a powerful damage detection method in a broad engineering application.

  8. 41. Fixed Span, Floor Beam 1, showing the cantilever; looking ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Fixed Span, Floor Beam 1, showing the cantilever; looking N. (The splice between the original beam and the 1960 extension (widening) is between the two stringers to the left of the bottom chord tension members). - Pacific Shortline Bridge, U.S. Route 20,spanning Missouri River, Sioux City, Woodbury County, IA

  9. Investigation of fiber bridging in double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Managalgiri, P. D.

    1986-01-01

    The possibility to eliminate fiber bridging or at least to reduce it, and to evaluate an alternative approach for determination of in situ mode 7 fracture toughness values of composite matrix materials were investigated. Double cantilever beam (DCB) specimens were made using unidirectional lay-ups of T6C/Hx205 composite material in which the delaminating halves were placed at angles of 0, 1.5, and 3 degrees to each other. The small angles between the delaminating plies were used to avoid fiber nesting without significantly affecting mode I teflon insert. The DCB specimens were fabricated and it was found that: (1) the extent which fiber bridging and interlaminar toughness increase with crack length can be reduced by slight cross ply at the delamination plane to reduce fiber nesting; (2) some fiber bridging may occur even in the absence of fiber nesting; (3) the first values of toughness measured ahead of the thin teflon insert are very close to the toughness of the matrix material with no fiber bridging; (4) thin adhesive bondline of matrix material appears to give toughness values equal to the interlaminar toughness of the composite matrix without fiber bridging.

  10. Atomic force microscope cantilever calibration using a focused ion beam.

    PubMed

    Slattery, Ashley D; Quinton, Jamie S; Gibson, Christopher T

    2012-07-20

    A calibration method is presented for determining the spring constant of atomic force microscope (AFM) cantilevers, which is a modification of the established Cleveland added mass technique. A focused ion beam (FIB) is used to remove a well-defined volume from a cantilever with known density, substantially reducing the uncertainty usually present in the added mass method. The technique can be applied to any type of AFM cantilever; but for the lowest uncertainty it is best applied to silicon cantilevers with spring constants above 0.7 N m(-1), where uncertainty is demonstrated to be typically between 7 and 10%. Despite the removal of mass from the cantilever, the calibration method presented does not impair the probes' ability to acquire data. The technique has been extensively tested in order to verify the underlying assumptions in the method. This method was compared to a number of other calibration methods and practical improvements to some of these techniques were developed, as well as important insights into the behavior of FIB modified cantilevers. These results will prove useful to research groups concerned with the application of microcantilevers to nanoscience, in particular for cases where maintaining pristine AFM tip condition is critical.

  11. Accurate Method for Determining Adhesion of Cantilever Beams

    SciTech Connect

    Michalske, T.A.; de Boer, M.P.

    1999-01-08

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying.

  12. Vibration Characteristics of Partially Covered Double-Sandwich Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Chen, Qinghua; Levy, Cesar

    1996-01-01

    The differential equations of motion together with the boundary conditions for a partially covered, double-sandwich cantilever beam are derived. Bending and extension, rotational and longitudinal inertia of damping layers, and shear deformation and rotational and longitudinal inertia of the constraining layers and the primary beam are included in the equations. The theory is applicable for long as well as short, soft, or stiff damping layer, double-sandwich beams. Also, the effects of different parameters on the system loss factor and resonance frequency are discussed. Differences are found to exist with the previous beam model (called the Euler beam model) when the damping layers are stiff, when the thickness of the damping layer is large compared to the primary-beam thickness, and in the case of higher modes of vibration.

  13. Dynamic modelling and experimental study of cantilever beam with clearance

    NASA Astrophysics Data System (ADS)

    Li, B.; Jin, W.; Han, L.; He, Z.

    2012-05-01

    Clearances occur in almost all mechanical systems, typically such as the clearance between slide plate of gun barrel and guide. Therefore, to study the clearances of mechanisms can be very important to increase the working performance and lifetime of mechanisms. In this paper, rigid dynamic modelling of cantilever with clearance was done according to the subject investigated. In the rigid dynamic modelling, clearance is equivalent to the spring-dashpot model, the impact of beam and boundary face was also taken into consideration. In ADAMS software, the dynamic simulation was carried out according to the model above. The software simulated the movement of cantilever with clearance under external excitation. Research found: When the clearance is larger, the force of impact will become larger. In order to study how the stiffness of the cantilever's supporting part influences natural frequency of the system, A Euler beam which is restricted by a draught spring and a torsion spring at its end was raised. Through numerical calculation, the relationship between natural frequency and stiffness was found. When the value of the stiffness is close to the limit value, the corresponding boundary condition is illustrated. An ADAMS experiment was carried out to check the theory and the simulation.

  14. Double Cantilever Beam Fracture Toughness Testing of Several Composite Materials

    NASA Technical Reports Server (NTRS)

    Kessler, Jeff A.; Adams, Donald F.

    1992-01-01

    Double-cantilever beam fracture toughness tests were performed by the Composite Materials Research Group on several different unidirectional composite materials provided by NASA Langley Research Center. The composite materials consisted of Hercules IM-7 carbon fiber and various matrix resin formulations. Multiple formulations of four different families of matrix resins were tested: LaRC - ITPI, LaRC - IA, RPT46T, and RP67/RP55. Report presents the materials tested and pertinent details supplied by NASA. For each material, three replicate specimens were tested. Multiple crack extensions were performed on each replicate.

  15. Large Area Microcorrals and Cavity Formation on Cantilevers using a Focused Ion Beam

    SciTech Connect

    Saraf, Laxmikant V.; Britt, David W.

    2011-09-14

    We utilize focused ion beam (FIB) to explore various sputtering parameters to form large area microcorrals and cavities on cantilevers. Microcorrals were rapidly created by modifying ion beam blur and overlaps. Modification in FIB sputtering parameters affects the periodicity and shape of corral microstructure. Cantilever deflections show ion beam amorphization effects as a function of sputtered area and cantilever base cavities with or without side walls. The FIB sputtering parameters address a method for rapid creation of a cantilever tensiometer with integrated fluid storage and delivery.

  16. Design and characterization of nanoknife with buffering beam for in situ single-cell cutting

    NASA Astrophysics Data System (ADS)

    Shen, Yajing; Nakajima, Masahiro; Yang, Zhan; Kojima, Seiji; Homma, Michio; Fukuda, Toshio

    2011-07-01

    A novel nanoknife with a buffering beam is proposed for single-cell cutting. The nanoknife was fabricated from a commercial atomic force microscopy (AFM) cantilever by focused-ion-beam (FIB) etching technique. The material identification of the nanoknife was determined using the energy dispersion spectrometry (EDS) method. It demonstrated that the gallium ion pollution of the nanoknife can be ignored during the etching processes. The buffering beam was used to measure the cutting force based on its deformation. The spring constant of the beam was calibrated based on a referenced cantilever by using a nanomanipulation approach. The tip of the nanoknife was designed with a small edge angle 5° to reduce the compression to the cell during the cutting procedure. For comparison, two other nanoknives with different edge angles, i.e. 25° and 45°, were also prepared. An in situ single-cell cutting experiment was performed using these three nanoknives inside an environmental scanning electron microscope (ESEM). The cutting force and the sample slice angle for each nanoknife were evaluated. It showed the compression to the cell can be reduced when using the nanoknife with a small edge angle 5°. Consequently, the nanoknife was capable for in situ single-cell cutting tasks.

  17. Four-beam model for vibration analysis of a cantilever beam with an embedded horizontal crack

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Zhu, Weidong; Charalambides, Panos G.; Shao, Yimin; Xu, Yongfeng; Wu, Kai; Xiao, Huifang

    2016-01-01

    As one of the main failure modes, embedded cracks occur in beam structures due to periodic loads. Hence it is useful to investigate the dynamic characteristics of a beam structure with an embedded crack for early crack detection and diagnosis. A new four-beam model with local flexibilities at crack tips is developed to investigate the transverse vibration of a cantilever beam with an embedded horizontal crack; two separate beam segments are used to model the crack region to allow opening of crack surfaces. Each beam segment is considered as an Euler-Bernoulli beam. The governing equations and the matching and boundary conditions of the four-beam model are derived using Hamilton's principle. The natural frequencies and mode shapes of the four-beam model are calculated using the transfer matrix method. The effects of the crack length, depth, and location on the first three natural frequencies and mode shapes of the cracked cantilever beam are investigated. A continuous wavelet transform method is used to analyze the mode shapes of the cracked cantilever beam. It is shown that sudden changes in spatial variations of the wavelet coefficients of the mode shapes can be used to identify the length and location of an embedded horizontal crack. The first three natural frequencies and mode shapes of a cantilever beam with an embedded crack from the finite element method and an experimental investigation are used to validate the proposed model. Local deformations in the vicinity of the crack tips can be described by the proposed four-beam model, which cannot be captured by previous methods.

  18. The stress intensity factor for the double cantilever beam

    NASA Technical Reports Server (NTRS)

    Fichter, W. B.

    1983-01-01

    Fourier transforms and the Wiener-Hopf technique are used in conjunction with plane elastostatics to examine the singular crack tip stress field in the double cantilever beam (DCB) specimen. In place of the Dirac delta function, a family of functions which duplicates the important features of the concentrated forces without introducing unmanageable mathematical complexities is used as a loading function. With terms of order h-squared/a-squared retained in the series expansion, the dimensionless stress intensity factor is found to be K (h to the 1/2)/P = 12 to the 1/2 (a/h + 0.6728 + 0.0377 h-squared/a-squared), in which P is the magnitude of the concentrated forces per unit thickness, a is the distance from the crack tip to the points of load application, and h is the height of each cantilever beam. The result is similar to that obtained by Gross and Srawley by fitting a line to discrete results from their boundary collocation analysis.

  19. Electromechanical decoupled model for cantilever-beam piezoelectric energy harvesters

    NASA Astrophysics Data System (ADS)

    Tan, T.; Yan, Z.; Hajj, M.

    2016-09-01

    Analysis of cantilever-based piezoelectric energy harvesting systems is usually performed using coupled equations that represent the mechanical displacement and the voltage output. These equations are then solved simultaneously. In contrast to this representation, we use analytical solutions of the governing equation to derive an algebraic equation of the power as a function of the beam displacement, electromechanical coefficients, and the load resistance. Such an equation can be more useful in the design of such harvesters. Particularly, the mechanical displacement is computed from a mechanical governing equation with modified natural frequency and damping ratio that account for the electromechanical coupling. The voltage and the harvested power are then obtained by relating them directly to the mechanical displacement. We validate the proposed analysis by comparing its solution including the tip displacement and harvested power with those of numerical simulations of the governing equations. To demonstrate the generality of the proposed approach, we consider the cases of base excitation, galloping, and autoparametric vibration. The model proposed in this study simplifies the electromechanical coupling problem for practical applications of cantilever-beam piezoelectric energy harvesting systems.

  20. Micromachined silicon cantilever beam accelerometer incorporating an integrated optical waveguide

    NASA Technical Reports Server (NTRS)

    Burcham, Kevin E.; De Brabander, Gregory N.; Boyd, Joseph T.

    1993-01-01

    A micromachined cantilever beam accelerometer is described in which beam deflection is determined optically. A diving board structure is anisotropically etched into a silicon wafer. This diving board structure is patterned from the wafer backside so as to leave a small gap between the tip of the diving board and the opposite fixed edge on the front side of the wafer. In order to sense a realistic range of accelerations, a foot mass incorporated onto the end of the beam is found to provide design flexibility. A silicon nitride optical waveguide is then deposited by low pressure chemical vapor deposition (LPCVD) onto the sample. Beam deflection is measured by the decrease of light coupled across the gap between the waveguide sections. In order to investigate sensor response and simulate deflection of the beam, we utilized a separate beam and waveguide section which could be displaced from one another in a precisely controlled manner. Measurements were performed on samples with gaps of 4.0, 6.0, and 8.0 micron and the variation of the fraction of light coupled across the gap as a function of displacement and gap spacing was found to agree with overlap integral calculations.

  1. Bending stresses due to torsion in cantilever box beams

    NASA Technical Reports Server (NTRS)

    Kuhn, Paul

    1935-01-01

    The paper beings with a brief discussion on the origin of the bending stresses in cantilever box beams under torsion. A critical survey of existing theory is followed by a summary of design formulas; this summary is based on the most complete solution published but omits all refinements considered unnecessary at the present state of development. Strain-gage tests made by NACA to obtained some experimental verification of the formulas are described next. Finally, the formulas are applied to a series of box beams previously static-tested by the U.S. Army Air Corps; the results show that the bending stresses due to torsion are responsible to a large extent for the free-edge type of failure frequently experienced in these tests.

  2. Detection of atomic force microscopy cantilever displacement with a transmitted electron beam

    NASA Astrophysics Data System (ADS)

    Wagner, R.; Woehl, T. J.; Keller, R. R.; Killgore, J. P.

    2016-07-01

    The response time of an atomic force microscopy (AFM) cantilever can be decreased by reducing cantilever size; however, the fastest AFM cantilevers are currently nearing the smallest size that can be detected with the conventional optical lever approach. Here, we demonstrate an electron beam detection scheme for measuring AFM cantilever oscillations. The oscillating AFM tip is positioned perpendicular to and in the path of a stationary focused nanometer sized electron beam. As the tip oscillates, the thickness of the material under the electron beam changes, causing a fluctuation in the number of scattered transmitted electrons that are detected. We demonstrate detection of sub-nanometer vibration amplitudes with an electron beam, providing a pathway for dynamic AFM with cantilevers that are orders of magnitude smaller and faster than the current state of the art.

  3. Strain energy release rate distributions for double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Crews, J. H., Jr.; Shivakumar, K. N.; Raju, I. S.

    1991-01-01

    A 24-ply composite double cantilever-beam specimen under mode I (opening) loading has been analyzed by a 3D FEM code that calculated along a straight delamination starter for several different specimen materials. An isotropic specimen was found to have a strain-energy release rate distribution which varied along its delamination front due to the boundary-layer effect and another effect associated with the anticlastic curvature of the bent specimen arms. A 0-deg graphite-reinforced epoxy specimen had a nearly-uniform strain-energy release rate distribution which dropped only near the edge, due to the boundary-layer effect, and a +/- 45-deg graphite/epoxy specimen exhibited a pronounced strain-energy release rate variation across the specimen width.

  4. A Novel Approach to the Sensing of Liquid Density Using a Plastic Optical Fibre Cantilever Beam

    ERIC Educational Resources Information Center

    Kulkarni, Atul; Kim, Youngjin; Kim, Taesung

    2009-01-01

    This article reports for the first time the use of a plastic optical fibre (POF) cantilever beam to measure the density of a liquid. The sensor is based on the Archimedes buoyancy principle. The sensor consists of a POF bonded on the surface of a metal beam in the form of a cantilever configuration, and at the free end of the beam a displacer is…

  5. Mechanical behavior simulation of MEMS-based cantilever beam using COMSOL multiphysics

    SciTech Connect

    Acheli, A. Serhane, R.

    2015-03-30

    This paper presents the studies of mechanical behavior of MEMS cantilever beam made of poly-silicon material, using the coupling of three application modes (plane strain, electrostatics and the moving mesh) of COMSOL Multi-physics software. The cantilevers playing a key role in Micro Electro-Mechanical Systems (MEMS) devices (switches, resonators, etc) working under potential shock. This is why they require actuation under predetermined conditions, such as electrostatic force or inertial force. In this paper, we present mechanical behavior of a cantilever actuated by an electrostatic force. In addition to the simplification of calculations, the weight of the cantilever was not taken into account. Different parameters like beam displacement, electrostatics force and stress over the beam have been calculated by finite element method after having defining the geometry, the material of the cantilever model (fixed at one of ends but is free to move otherwise) and his operational space.

  6. AFM cantilever vibration detection with a transmitted electron beam

    NASA Astrophysics Data System (ADS)

    Woehl, Taylor; Wagner, Ryan; Keller, Robert; Killgore, Jason

    Cantilever oscillations for dynamic atomic force microscopy (AFM) are conventionally measured with an optical lever system. The speed of AFM cantilevers can be increased by decreasing the size of the cantilever; however, the fastest AFM cantilevers are currently nearing the smallest size that can be detected with the current optical lever approach. Here we demonstrate an electron detection scheme in an SEM for detecting AFM cantilever oscillations. An oscillating AFM tip is positioned perpendicular to the propagation direction of a stationary ~ 1 nm diameter electron probe, and the oscillatory change in electron scattering resulting from the changing thickness of the electron irradiated area of the AFM tip is detected with a transmitted electron detector positioned below the AFM tip. We perform frequency sweep and ring-down experiments to determine the first resonant frequency and Q factor of an AFM cantilever.

  7. Research of fiber Bragg grating geophone based on cantilever beam

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Chen, Shao-hua; Tao, Guo; Lu, Gui-wu; Zhao, Kun

    2009-07-01

    Along with the development of seismic exploration, the demand of frequency, dynamic range, precision and resolution ration is increased. However, the traditional geophone has disadvantages of narrower bandwidth, lower dynamic range and resolution, and cannot meet the new needs of seismic exploration. Geophone technology is a choke point, which constrains the development of petroleum prospecting in recent years. Fiber Bragg Grating seism demodulation technology is the newest kind of seism demodulation technology. The sensing probe of the Fiber Bragg Grating geophone is made up of Fiber Bragg Gating. The information which it collects is embodied by wavelength. The modulation-demodulation is accomplished by Fiber Bragg Gating geophone directly. In this paper, we design different size Fiber Bragg Grating geophones based on the transmission properties of Fiber Bragg Grating and cantilever beam method. Beryllium bronze and stainless steel are chosen as the elastic beam and shell materials, respectively. The parameters such as response function and sensitivity are given theoretically. In addition, we have simulated the transmission characteristics of Fiber Bragg Grating geophone by virtue of finite element analysis. The influences of wavelength, mass block, fiber length on the characteristics of geophones are discussed in detail, and finally the appropriate structural parameters are presented.

  8. Forced response of a cantilever beam with a dry friction damper attached. I - Theory. II - Experiment

    NASA Technical Reports Server (NTRS)

    Dowell, E. H.; Schwartz, H. B.

    1983-01-01

    A theoretical and experimental study of the forced vibration response of a cantilevered beam with Coulomb damping nonlinearity is described. Viscous damping in the beam is neglected. Beam and dry friction damper configurations of interest for applications to turbine blade vibrations are considered. It is shown that the basic phenomena found by Dowell (1983) for a simply supported beam with an attached dry friction damper of specific geometry also apply to a cantilevered beam and a more general representation of the dry friction damper and its associated mass and stiffness.

  9. Factors influencing elastic stresses in double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Crews, J. H., Jr.; Shivakumar, K. N.; Raju, I. S.

    1986-01-01

    An elastic stress analysis was conducted for a double cantilever beam (DCB) specimen using finite-element methods. The purpose of this study was to identify the important parameters that influence stresses ahead of the delamination front. The study focused on an aluminum DCB specimen, typical of adhesively-bonded joints, and on a graphite/epoxy specimen representing a cocured composite. Opening mode sigma sub y stresses ahead of the crack tip were calculated and compared with those for a monolithic reference specimen. Beyond the singularity-dominated region very near the crack tip, the sigma sub y distribution was elevated compared to the monolithic case. Both the adhesive thickness and the adherend transverse (thickness-direction) stiffness were found to influence the elevation of sigma sub y. In contrast, adherend thickness and longitudinal stiffness has very little effect on this stress distribution. Estimates for adhesive yielding beyond the aluminum DCB crack tip showed that both the area and height of the plastic zone increased to a peak value for increasing adhesive thicknesses. Results from this study would provide insight for comparing data from different DCB specimens and for designing new DCB specimens.

  10. Factors influencing elastic stresses in double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Crews, J. H., Jr.; Shivakumar, K. N.; Raju, I. S.

    1988-01-01

    An elastic stress analysis was conducted for a double cantilever beam (DCB) specimen using finite-element methods. The purpose of this study was to identify the important parameters that influence stresses ahead of the delamination front. The study focused on an aluminum DCB specimen, typical of adhesively-bonded joints, and on a graphite/epoxy specimen representing a cocured composite. Opening mode sigma sub y stresses ahead of the crack tip were calculated and compared with those for a monolithic reference specimen. Beyond the singularity-dominated region very near the crack tip, the sigma sub y distribution was elevated compared to the monolithic case. Both the adhesive thickness and the adherend transverse (thickness-direction) stiffness were found to influence the elevation of sigma sub y. In contrast, adherend thickness and longitudinal stiffness has very little effect on this stress distribution. Estimates for adhesive yielding beyond the aluminum DCB crack tip showed that both the area and height of the plastic zone increased to a peak value for increasing adhesive thicknesses. Results from this study would provide insight for comparing data from different DCB specimens and for designing new DCB specimens.

  11. Design of in situ sample rotation mechanism for angle-dependent study of cantilever-detected high-frequency ESR.

    PubMed

    Ohmichi, E; Hirano, S; Ohta, H

    2013-02-01

    Cantilever detected electron spin resonance (ESR) technique is combined with a precise rotation stage for angle-dependent ESR study of a tiny single crystalline sample on the order of 1 μg. Generally speaking, sample rotation in transmission-type ESR measurement is quite difficult. However, high angle resolution Δθ(min)∼0.2° and compact design of our stage allow in situ sample rotation in strong magnetic fields at low temperatures. As a result, a systematic study of ESR spectra for different field orientations can be easily obtained without sample extraction from a cryostat. As an example, angle-dependent ESR study of Co Tutton salt in the millimeter wave region is demonstrated at liquid helium temperature.

  12. Dynamic analysis and temperature measurements of concrete cantilever beam using fibre Bragg gratings

    NASA Astrophysics Data System (ADS)

    da Silva, Jean Carlos Cardozo; Martelli, Cicero; Kalinowski, Hypolito José; Penner, Elisabeth; Canning, John; Groothoff, Nathaniel

    2007-01-01

    We analyzed the action of fire, causing degradation in a concrete cantilever beam using dynamic testing. The structure was fitted with two fibre Bragg gratings (FBG) sensors. One of them measured vibration and the other measured the temperature inside of the cantilever beam, while the beam was exposed to fire. A high-temperature probe based on a simple packaging system, which isolates the sensing FBG from any mechanical action, was developed. A low-cost fibre Bragg grating interrogation system, including easy assembly and maintenance, was used for the measurements. The temperature in the cantilever beam increased until 150 °C and a reduction in the strength of concrete was observed through modal analysis. Results reveal a considerable reduction in strength occurs even with exposures to moderate temperatures (less than 90 °C).

  13. Effect of Centrifugal Force on the Elastic Curve of a Vibrating Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Simpkinson, Scott H; Eatherton, Laurel J; Millenson, Morton B

    1948-01-01

    A study was made to determine the effect of rotation on the dynamic-stress distribution in vibrating cantilever beams. The results of a mathematical analysis are presented together with experimental results obtained by means of stroboscopic photographs and strain gages. The theoretical analysis was confined to uniform cantilever beams; the experimental work was extended to include a tapered cantilever beam to simulate an aircraft propeller blade. Calculations were made on nondimensional basis for second and third mode vibration; the experiments were conducted on beams of various lengths, materials, and cross sections for second-mode vibration. From this investigation it was concluded that high vibratory-stress positions are unaffected by the addition of centrifugal force. Nonrotating vibration surveys of blades therefore are valuable in predicting high vibratory-stress locations under operating conditions.

  14. Design Optimization of PZT-Based Piezoelectric Cantilever Beam by Using Computational Experiments

    NASA Astrophysics Data System (ADS)

    Kim, Jihoon; Park, Sanghyun; Lim, Woochul; Jang, Junyong; Lee, Tae Hee; Hong, Seong Kwang; Song, Yewon; Sung, Tae Hyun

    2016-08-01

    Piezoelectric energy harvesting is gaining huge research interest since it provides high power density and has real-life applicability. However, investigative research for the mechanical-electrical coupling phenomenon remains challenging. Many researchers depend on physical experiments to choose devices with the best performance which meet design objectives through case analysis; this involves high design costs. This study aims to develop a practical model using computer simulations and to propose an optimized design for a lead zirconate titanate (PZT)-based piezoelectric cantilever beam which is widely used in energy harvesting. In this study, the commercial finite element (FE) software is used to predict the voltage generated from vibrations of the PZT-based piezoelectric cantilever beam. Because the initial FE model differs from physical experiments, the model is calibrated by multi-objective optimization to increase the accuracy of the predictions. We collect data from physical experiments using the cantilever beam and use these experimental results in the calibration process. Since dynamic analysis in the FE analysis of the piezoelectric cantilever beam with a dense step size is considerably time-consuming, a surrogate model is employed for efficient optimization. Through the design optimization of the PZT-based piezoelectric cantilever beam, a high-performance piezoelectric device was developed. The sensitivity of the variables at the optimum design is analyzed to suggest a further improved device.

  15. Damping analysis of a flexible cantilever beam containing an internal fluid channel: Experiment, modeling and analysis

    NASA Astrophysics Data System (ADS)

    Wang, Ya; Masoumi, Masoud; Gaucher-Petitdemange, Matthias

    2015-03-01

    Passive structural damping treatments have been applied with the use of high-viscosity fillings (in practice) and have been the focus of numerous research studies and papers. However, internal viscoelastic fluid leading to passive damping of flexible cantilever beams, has not yet been investigated in the literature. Although structures containing internal fluid channels provide multifunctional solutions to many engineering issues, they also raise damping control requests caused by unacceptable vibrations due to ambient environmental changes. In this paper, we examine ambient effects on damping properties of flexible cantilever beams, each conveying an internal high-viscosity fluid channel. Experiments are conducted to investigate how the internal fluids provide damping to the system under varied temperatures, frequencies and base-acceleration levels. While the vibration analysis of pipes conveying internal flow has been extensively studied, internal high-viscosity fluids in relation to passive damping of flexible cantilever beams and their ambient, environment-dependent behaviors have not been well-investigated. Originally motivated by research, which uses internal fluid channels to provide the cooling of multifunctional composite structures, we aim to research the damping behaviors of cantilever beams. We will conduct an experimental study and modeling analysis, examining the vibrations and frequency responses of the cantilever beams when filled with three types of internal fluids.

  16. Comparison of Theory with Experimental Data For a Partially Covered Double-Sandwich Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Chen, Qinghua; Levy, Cesar

    1998-01-01

    In this paper, vibration characteristics of a partially covered, double-sandwich cantilever beam are evaluated experimentally and compared to the theoretical results of Levy and Chen for partially covered beams with and without end mass. The results obtained indicate that the theoretical models serve very well in providing the frequency factors and loss factors for the system being investigated.

  17. Theoretical and experimental study on the transverse vibration properties of an axially moving nested cantilever beam

    NASA Astrophysics Data System (ADS)

    Duan, Ying-Chang; Wang, Jian-Ping; Wang, Jing-Quan; Liu, Ya-Wen; Shao, Fei

    2014-06-01

    An axially moving nested cantilever beam is a type of time-varying nonlinear system that can be regarded as a cantilever stepped beam. The transverse vibration equation for the axially moving nested cantilever beam with a tip mass is derived by D'Alembert's principle, and the modified Galerkin's method is used to solve the partial differential equation. The theoretical model is modified by adjusting the theoretical beam length with the measured results of its first-order vibration frequencies under various beam lengths. It is determined that the length correction value of the second segment of the nested beam increases as the structural length increases, but the corresponding increase in the amplitude becomes smaller. The first-order decay coefficients are identified by the logarithmic decrement method, and the decay coefficient of the beam decreases with an increase in the cantilever length. The calculated responses of the modified model agree well with the experimental results, which verifies the correctness of the proposed calculation model and indicates the effectiveness of the methods of length correction and damping determination. Further studies on non-damping free vibration properties of the axially moving nested cantilever beam during extension and retraction are investigated in the present paper. Furthermore, the extension movement of the beam leads the vibration displacement to increase gradually, and the instantaneous vibration frequency and the vibration speed decrease constantly. Moreover, as the total mechanical energy becomes smaller, the extension movement of the nested beam remains stable. The characteristics for the retraction movement of the beam are the reverse.

  18. Investigation of fiber bridging in double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Mangalgiri, P. D.

    1987-01-01

    The possibility to eliminate fiber bridging or at least to reduce it, and to evaluate an alternative approach for determination of in situ mode 7 fracture toughness values of composite matrix materials were investigated. Double cantilver beam (DCB) specimens were made using unidirectional lay-ups of T6C/Hx205 composite material in which the delaminating halves were placed at angles of 0, 1.5, and 3 degrees to each other. The small angles between the delaminating plies were used to avoid fiber nesting without significantly affecting mode I teflon insert. The DCB specimens were fabricated and it was found that: (1) the extent which fiber bridging and interlaminar toughness increase with crack length can be reduced by slight cross ply at the delamination plane to reduce fiber nesting; (2) some fiber bridging may occur even in the absence of fiber nesting; (3) the first values of toughness measured ahead of the thin teflon insert are very close to the toughness of the matrix material with no fiber bridging; (4) thin adhesive bondline of matrix material appears to give toughness values equal to the interlaminar toughness of the composite matrix without fiber bridging.

  19. Response of long, flexible cantilever beams applied root motions. [spacecraft structures

    NASA Technical Reports Server (NTRS)

    Fralich, R. W.

    1976-01-01

    Results are presented for an analysis of the response of long, flexible cantilever beams to applied root rotational accelerations. Maximum values of deformation, slope, bending moment, and shear are found as a function of magnitude and duration of acceleration input. Effects of tip mass and its eccentricity and rotatory inertia on the response are also investigated. It is shown that flexible beams can withstand large root accelerations provided the period of applied acceleration can be kept small relative to the beam fundamental period.

  20. Active H ∞ control of the vibration of an axially moving cantilever beam by magnetic force

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Chen, Huai-hai; He, Xu-dong

    2011-11-01

    An H ∞ method for the vibration control of an iron cantilever beam with axial velocity using the noncontact force by permanent magnets is proposed in the paper. The transverse vibration equation of the axially moving cantilever beam with a tip mass is derived by D'Alembert's principle and then updated by experiments. An experimental platform and a magnetic control system are introduced. The properties of the force between the magnet and the beam have been determined by theoretic analysis and tests. The H ∞ control strategy for the suppression of the beam transverse vibration by initial deformation excitations is put forward. The control method can be used for the beam with constant length or varying length. Numerical simulation and actual experiments are implemented. The results show that the control method is effective and the simulations fit well with the experiments.

  1. A case study of analysis methods for large deflections of a cantilever beam

    NASA Technical Reports Server (NTRS)

    Craig, L. D.

    1994-01-01

    A load case study of geometric nonlinear large deflections of a cantilever beam is presented. The bending strain must remain elastic. Closed form solution and finite element methods of analysis are illustrated and compared for three common load cases. A nondimensional nomogram for each case is presented in the summary.

  2. Flexural Vibration Test of a Cantilever Beam with a Force Sensor: Fast Determination of Young's Modulus

    ERIC Educational Resources Information Center

    Digilov, Rafael M.

    2008-01-01

    We describe a simple and very inexpensive undergraduate laboratory experiment for fast determination of Young's modulus at moderate temperatures with the aid of a force sensor. A strip-shaped specimen rigidly bolted to the force sensor forms a clamped-free cantilever beam. Placed in a furnace, it is subjected to free-bending vibrations followed by…

  3. SEMICONDUCTOR TECHNOLOGY Supercritical carbon dioxide process for releasing stuck cantilever beams

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Chaoqun, Gao; Lei, Wang; Yupeng, Jing

    2010-10-01

    The multi-SCCO2 (supercritical carbon dioxide) release and dry process based on our specialized SCCO2 semiconductor process equipment is investigated and the releasing mechanism is discussed. The experiment results show that stuck cantilever beams were held up again under SCCO2 high pressure treatment and the repeatability of this process is nearly 100%.

  4. Simulation of large motions of nonuniform beams in orbit. I - The cantilever beam

    NASA Technical Reports Server (NTRS)

    Levinson, D. A.; Kane, T. R.

    1981-01-01

    An algorithm is developed for producing numerical simulations of large motions of a nonuniform cantilever beam in orbit. Special emphasis is given to the effective formulation of equations of motion and to the use of the finite element method to construct modal functions. Finite element methods are used to generate modal functions in such a way as to permit a particularly harmonious relationship to be established between the disciplines of rigid body dynamics and structural analysis. Sufficient information is provided to enable a reader to create, with relatively little effort, his own simulation program; simulation results are reported, both to provide check cases for other investigators and to illustrate certain important facets of the behavior of flexible spacecraft.

  5. An approximate solution for the free vibrations of rotating uniform cantilever beams

    NASA Technical Reports Server (NTRS)

    Peters, D. A.

    1973-01-01

    Approximate solutions are obtained for the uncoupled frequencies and modes of rotating uniform cantilever beams. The frequency approximations for flab bending, lead-lag bending, and torsion are simple expressions having errors of less than a few percent over the entire frequency range. These expressions provide a simple way of determining the relations between mass and stiffness parameters and the resultant frequencies and mode shapes of rotating uniform beams.

  6. Neutral beam species measurements using in situ Rutherford backscatter spectrometry

    SciTech Connect

    Kugel, H.W.; Kaita, R.; Gammel, G.; Williams, M.D.

    1984-12-01

    This work describes a new in situ method for measuring the neutral particle fractions in high power deuterium neutral beams, used to heat magnetically confined fusion plasmas. Deuterium beams, of variable energies, pulse lengths, and powers up to 47 keV, 100 msec, 1.6 MW, were Rutherford backscattered at 135/sup 0/ from TiC inner neutral beam armor of the PDX, and detected using an electrostatic analyzer with microchannel plates. Complete energy scans were made every 20 msec and data were obtained simultaneously from five different positions across the beam profile. The neutral particle fractions were measured to be D/sup 0/(E):D/sup 0/(E/2):D/sup 0/(E/3)=53:32:15. The corresponding neutral power fractions were P/sup 0/(E):P/sup 0/(E/2):P/sup 0/(E/3)=72:21:7, and the associated ionic fractions at the output of the ion source were D/sub 1//sup +/(E):D/sub 2//sup +/(E):D/sub 3//sup +/(E)=74:20:6. The measured neutral particle fractions were relatively constant over more than 70% of the beam power distribution. A decrease in the yield of the full energy component in the outer regions of the beam was observed. Other possible experimental configurations and geometries are discussed.

  7. Neutral beam species measurements using in situ Rutherford backscatter spectrometry

    SciTech Connect

    Kugel, H.W.; Kaita, R.; Gammel, G.; Williams, M.D.

    1985-05-01

    This work describes a new in situ method for measuring the neutral particle fractions in high-power deuterium neutral beams, used to heat magnetically confined fusion plasmas. Deuterium beams, of variable energies, pulse lengths, and powers up to 47 keV, 100 ms, 1.6 MW, were Rutherford backscattered at 135/sup 0/ from the TiC inner neutral beam armor of the PDX, and detected using an electrostatic analyzer with a microchannel plate. Complete energy scans were made every 20 ms and data were obtained simultaneously from five different positions across the beam profile. The neutral particle fractions were measured to be D/sup 0/(E):D/sup 0/(E/2):D/sup 0/(E/3) = 53:32:15. The corresponding neutral power fractions were P/sup 0/(E):P/sup 0/(E/2):P/sup 0/(E/3) = 72:21:7, and the associated ionic fractions at the output of the ion source were D/sup +//sub 1/ (E):D/sup +//sub 2/ (E):D/sup +//sub 3/ (E) = 74:20:6. The measured neutral particle fractions were relatively constant over more than 70% of the beam power distribution. A decrease in the yield of the full-energy component in the outer regions of the beam was observed.

  8. Neutral beam species measurements using in situ Rutherford backscatter spectrometry

    NASA Astrophysics Data System (ADS)

    Kugel, H. W.; Kaita, R.; Gammel, G.; Williams, M. D.

    1985-05-01

    This work describes a new in situ method for measuring the neutral particle fractions in high-power deuterium neutral beams, used to heat magnetically confined fusion plasmas. Deuterium beams, of variable energies, pulse lengths, and powers up to 47 keV, 100 ms, 1.6 MW, were Rutherford backscattered at 135° from the TiC inner neutral beam armor of the PDX, and detected using an electrostatic analyzer with a microchannel plate. Complete energy scans were made every 20 ms and data were obtained simultaneously from five different positions across the beam profile. The neutral particle fractions were measured to be D0(E):D0(E/2):D0(E/3)=53:32:15. The corresponding neutral power fractions were P0(E):P0(E/2):P0(E/3)=72:21:7, and the associated ionic fractions at the output of the ion source were D+1 (E):D+2 (E):D+3 (E)=74:20:6. The measured neutral particle fractions were relatively constant over more than 70% of the beam power distribution. A decrease in the yield of the full-energy component in the outer regions of the beam was observed.

  9. A molecular beam epitaxy facility for in situ neutron scattering

    SciTech Connect

    Dura, J. A.; LaRock, J.

    2009-07-15

    A molecular beam epitaxy (MBE) facility has been built to enable in situ neutron scattering measurements during growth of epitaxial layers. While retaining the full capabilities of a research MBE chamber, this facility has been optimized for polarized neutron reflectometry measurements. Optimization includes a compact lightweight portable design, a neutron window, controllable magnetic field, deposition across a large 76 mm diameter sample with exceptional flux uniformity, and sample temperatures continuously controllable from 38 to 1375 K. A load lock chamber allows for sample insertion, storage of up to 4 samples, and docking with other facilities. The design and performance of this chamber are described here.

  10. A performance-enhanced energy harvester for low frequency vibration utilizing a corrugated cantilevered beam

    NASA Astrophysics Data System (ADS)

    Kim, In-Ho; Jin, SeungSeop; Jang, Seon-Jun; Jung, Hyung-Jo

    2014-03-01

    This note proposes a performance-enhanced piezoelectric energy harvester by replacing a conventional flat cantilevered beam with a corrugated beam. It consists of a proof mass and a sinusoidally or trapezoidally corrugated cantilevered beam covered by a polyvinylidene fluoride (PVDF) film. Compared to the conventional energy harvester of the same size, it has a more flexible bending stiffness and a larger bonding area of the PVDF layer, so higher output voltage from the device can be expected. In order to investigate the characteristics of the proposed energy harvester, analytical developments and numerical simulations on its natural frequency and tip displacement are carried out. Shaking table tests are also conducted to verify the performance of the proposed device. It is clearly shown from the tests that the proposed energy harvester not only has a lower natural frequency than an equivalent sized standard energy harvester, but also generates much higher output voltage than the standard one.

  11. Application of a passive/active autoparametric cantilever beam absorber with PZT actuator for Duffing systems

    NASA Astrophysics Data System (ADS)

    Silva-Navarro, G.; Abundis-Fong, H. F.; Vazquez-Gonzalez, B.

    2013-04-01

    An experimental investigation is carried out on a cantilever-type passive/active autoparametric vibration absorber, with a PZT patch actuator, to be used in a primary damped Duffing system. The primary system consists of a mass, viscous damping and a cubic stiffness provided by a soft helical spring, over which is mounted a cantilever beam with a PZT patch actuator actively controlled to attenuate harmonic and resonant excitation forces. With the PZT actuator on the cantilever beam absorber, cemented to the base of the beam, the auto-parametric vibration absorber is made active, thus enabling the possibility to control the effective stiffness and damping associated to the passive absorber and, as a consequence, the implementation of an active vibration control scheme able to preserve, as possible, the autoparametric interaction as well as to compensate varying excitation frequencies and parametric uncertainty. This active vibration absorber employs feedback information from a high resolution optical encoder on the primary Duffing system and an accelerometer on the tip beam absorber, a strain gage on the base of the beam, feedforward information from the excitation force and on-line computations from the nonlinear approximate frequency response, parameterized in terms of a proportional gain provided by a voltage input to the PZT actuator, thus modifying the closed-loop dynamic stiffness and providing a mechanism to asymptotically track an optimal, robust and stable attenuation solution on the primary Duffing system. Experimental results are included to describe the dynamic and robust performance of the overall closed-loop system.

  12. Research on vibration measurement of a cantilever beam by twin-core fiber

    NASA Astrophysics Data System (ADS)

    Geng, Tao; Liu, Tao; Peng, Feng; Dai, Qiang; Yang, Yuan

    2009-05-01

    A novel interference transducer based on the measurement principle of multicore fiber interference for vibration measurement of a cantilever beam is designed in the paper. Twin-core fiber is special designed fiber, which contains a pair of parallel fiber core. Two paths integrated in one fiber not only greatly decreases sensor's volume, but also makes environment temperature effect approximately equal to each. A twin-core fiber which is pasted on the cantilever beam with epoxy resin is used as the sensing element. The twin-core fiber act as a two-beam in-fiber integrated interferometer that has a far-field interferometric fringe pattern which shift thereupon with the cantilever beam oscillates. CCD was used to measure the displacement of interferometer fringes instead of the traditional photodetector. The continuous capture of interference fringes was realized. The design of low pass filter and image smoothing were finished according to the characteristics of interference fringes. Orientation error of interference fringe center was removed. Displacement of fringe center was calculated and the spectrum of the displacement was analyzed with Fourier Transform. The system uses high-speed CCD camera as the photoelectric transformer. By using the high sensitivity twin-core fiber, the system realizes high precision measurement of vibration frequency, and ensures real-time performance. The experiment results show that the vibration measurement method is feasible and possesses potential application prospect in tiny vibration measure.

  13. A novel approach to the sensing of liquid density using a plastic optical fibre cantilever beam

    NASA Astrophysics Data System (ADS)

    Kulkarni, Atul; Kim, Youngjin; Kim, Taesung

    2009-01-01

    This article reports for the first time the use of a plastic optical fibre (POF) cantilever beam to measure the density of a liquid. The sensor is based on the Archimedes buoyancy principle. The sensor consists of a POF bonded on the surface of a metal beam in the form of a cantilever configuration, and at the free end of the beam a displacer is attached. Due to the apparent loss of the true weight of the displacer there is a deflection in the cantilever beam, which causes macro bending in the POF. The loss of intensity due to macro bending of the POF is a measure of the density of the liquid under test. The variation of weight loss with the density of different liquids showed that the weight loss is proportional to density. This sensor is capable of detecting the weight loss with respect to their densities even for liquids having close values of density like distilled water, tap water, and milk of various brands. The resolution of the sensor is observed to be 1.1 mg cm-3.

  14. Analytical determination of coupled bending-torsion vibrations of cantilever beams by means of station functions

    NASA Technical Reports Server (NTRS)

    Mendelson, Alexander; Gendler, Selwyn

    1951-01-01

    A method based on the concept of station functions is presented for calculating the modes and the frequencies of nonuniform cantilever beams vibrating in torsion, bending, and coupled bending-torsion motion. The method combines some of the advantages of the Rayleigh-Ritz and Stodola methods, in that a continuous loading function for the beam is used, with the advantages of the influence-coefficient method, in that the continuous loading function is obtained in terms of the displacements of a finite number of stations along the beam.

  15. In situ, in-liquid, all-electrical detection of Salmonella typhimurium using lead titanate zirconate/gold-coated glass cantilevers at any dipping depth.

    PubMed

    Zhu, Qing; Shih, Wan Y; Shih, Wei-Heng

    2007-06-15

    Most biosensing techniques are indirect, slow, and require labeling. Even though silicon-based microcantilever sensors are sensitive and label-free, they are not suitable for in-liquid detection. More recently lead zirconate titanate (PZT) thin-film-based microcantilevers are shown to be sensitive and in situ. However, they require microfabrication and must be electrically insulated. In this study, we show that highly sensitive, in situ, Salmonella typhimurium detection can be achieved at 90% relative humidity using a lead zirconate titanate (PZT)/gold-coated glass cantilever 0.7 mm long with a non-piezoelectric 2.7 mm long gold-coated glass tip by partially dipping the gold-coated glass tip in the suspension at any depth without electrically insulating the PZT. In particular, we showed that at 90% relative humidity and with a dipping depth larger than 0.8mm the PZT/gold-coated glass cantilever showed virtually no background resonance frequency up-shift due to water evaporation and exhibited a mass detection sensitivity of Deltam/Deltaf=-5 x 10(-11)g/Hz. The concentration sensitivities of this PZT/gold-coated glass cantilever were 1 x 10(3) and 500 cells/ml in 2 ml of liquid with a 1 and 1.5mm dipping depth, respectively, both more than two orders of magnitude lower than the infectious dose and more than one order of magnitude lower than the detection limit of a commercial Raptor sensor.

  16. An analytical investigation of delamination front curvature in double cantilever beam specimens

    NASA Technical Reports Server (NTRS)

    Davidson, B. D.

    1990-01-01

    An analytical investigation is conducted to determine the shape of a growing delamination and the distribution of the energy release rate along the delamination front in a laminated composite double cantilever beam specimen. Distributions of the energy release rate for specimens with straight delamination fronts and delamination front contours for delaminations whose growth is governed by the fracture criterion that G = Gc at all points are predicted as a function of material properties and delamination length. The predicted delamination front contours are utilized to ascertain the effect of the changing shape of the delamination front on the value of the critical strain energy release rate as computed from double cantilever beam fracture toughness test data.

  17. Note: Determination of torsional spring constant of atomic force microscopy cantilevers: combining normal spring constant and classical beam theory.

    PubMed

    Álvarez-Asencio, R; Thormann, E; Rutland, M W

    2013-09-01

    A technique has been developed for the calculation of torsional spring constants for AFM cantilevers based on the combination of the normal spring constant and plate/beam theory. It is easy to apply and allow the determination of torsional constants for stiff cantilevers where the thermal power spectrum is difficult to obtain due to the high resonance frequency and low signal/noise ratio. The applicability is shown to be general and this simple approach can thus be used to obtain torsional constants for any beam shaped cantilever.

  18. Mechanics of cantilever beam: Implementation and comparison of FEM and MLPG approach

    NASA Astrophysics Data System (ADS)

    Trobec, Roman

    2016-06-01

    Two weak form solution approaches for partial differential equations, the well known meshbased finite element method and the newer meshless local Petrov Galerkin method are described and compared on a standard test case - mechanics of cantilever beam. The implementation, solution accuracy and calculation complexity are addressed for both approaches. We found out that FEM is superior in most standard criteria, but MLPG has some advantages because of its flexibility that results from its general formulation.

  19. Large deflections of a cantilever beam under arbitrarily directed tip load

    NASA Technical Reports Server (NTRS)

    Mccomb, H. E., Jr.

    1985-01-01

    The nonlinear beam equation was integrated numerically in a direct fashion to obtain results for large deflections of cantilevers under tip loads of arbitrary direction. A short BASIC computer program for performing this integration is presented. Results for selected load cases are presented. The numerical process is performed rapidly on a modern microcomputer, and comparisons with results from closed form solutions show that the process is accurate.

  20. Piezoresistive AFM cantilevers surpassing standard optical beam deflection in low noise topography imaging

    PubMed Central

    Dukic, Maja; Adams, Jonathan D.; Fantner, Georg E.

    2015-01-01

    Optical beam deflection (OBD) is the most prevalent method for measuring cantilever deflections in atomic force microscopy (AFM), mainly due to its excellent noise performance. In contrast, piezoresistive strain-sensing techniques provide benefits over OBD in readout size and the ability to image in light-sensitive or opaque environments, but traditionally have worse noise performance. Miniaturisation of cantilevers, however, brings much greater benefit to the noise performance of piezoresistive sensing than to OBD. In this paper, we show both theoretically and experimentally that by using small-sized piezoresistive cantilevers, the AFM imaging noise equal or lower than the OBD readout noise is feasible, at standard scanning speeds and power dissipation. We demonstrate that with both readouts we achieve a system noise of ≈0.3 Å at 20 kHz measurement bandwidth. Finally, we show that small-sized piezoresistive cantilevers are well suited for piezoresistive nanoscale imaging of biological and solid state samples in air. PMID:26574164

  1. Piezoresistive AFM cantilevers surpassing standard optical beam deflection in low noise topography imaging

    NASA Astrophysics Data System (ADS)

    Dukic, Maja; Adams, Jonathan D.; Fantner, Georg E.

    2015-11-01

    Optical beam deflection (OBD) is the most prevalent method for measuring cantilever deflections in atomic force microscopy (AFM), mainly due to its excellent noise performance. In contrast, piezoresistive strain-sensing techniques provide benefits over OBD in readout size and the ability to image in light-sensitive or opaque environments, but traditionally have worse noise performance. Miniaturisation of cantilevers, however, brings much greater benefit to the noise performance of piezoresistive sensing than to OBD. In this paper, we show both theoretically and experimentally that by using small-sized piezoresistive cantilevers, the AFM imaging noise equal or lower than the OBD readout noise is feasible, at standard scanning speeds and power dissipation. We demonstrate that with both readouts we achieve a system noise of ≈0.3 Å at 20 kHz measurement bandwidth. Finally, we show that small-sized piezoresistive cantilevers are well suited for piezoresistive nanoscale imaging of biological and solid state samples in air.

  2. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam.

    PubMed

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-01-01

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m³), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively. PMID:26402682

  3. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam

    PubMed Central

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-01-01

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m3), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively. PMID:26402682

  4. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam.

    PubMed

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-09-22

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m³), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively.

  5. Flow structure interaction between a flexible cantilever beam and isotropic turbulence

    NASA Astrophysics Data System (ADS)

    Vogel, Andrew; Morvan, Thomas; Goushcha, Oleg; Andreopoulos, Yiannis; Elvin, Niell

    2015-11-01

    In the present experimental work we consider the degree of distortion of isotropy and homogeneity of grid turbulence caused by the presence of a thin flexible cantilever beam immersed in the flow aligned in the longitudinal direction. Beams of various rigidities and lengths were used in the experiments. Piezoelectric patches were attached to the beams which provided an output voltage proportional to the strain and therefore proportional to the beam's deflection. The experiments were carried out in a large scale wind tunnel and hot-wires were used to measure turbulence intensity in the vicinity of the beams for various values of the ratio of aerodynamic loading to beam's rigidity. It was found that the flow field distortion depends on the rigidity of the beam. For very rigid beams this distortion is of the order of the boundary layer thickness developing over the beam while for very flexible beams the distorted region is of the order of the beam's tip deflection. Analysis of the time-dependent signals indicated some correlation between the frequency of beam's vibration and flow structures detected. Supported by NSF Grant: CBET #1033117.

  6. Application of GRASP to nonlinear analysis of a cantilever beam. [General Rotorcraft Aeromechanical Stability Program

    NASA Technical Reports Server (NTRS)

    Hinnant, Howard E.; Hodges, Dewey H.

    1987-01-01

    The General Rotorcraft Aeromechanical Stability Program (GRASP) was developed to analyze the steady-state and linearized dynamic behavior of rotorcraft in hovering and axial flight conditions. Because of the nature of problems GRASP was created to solve, the geometrically nonlinear behavior of beams is one area in which the program must perform well in order to be of any value. Numerical results obtained from GRASP are compared to both static and dynamic experimental data obtained for a cantilever beam undergoing large displacements and rotations caused by deformation. The correlation is excellent in all cases.

  7. Application of GRASP (General Rotorcraft Aeromechanical Stability Program) to nonlinear analysis of a cantilever beam

    NASA Technical Reports Server (NTRS)

    Hinnant, Howard E.; Hodges, Dewey H.

    1987-01-01

    The General Rotorcraft Aeromechanical Stability Program (GRASP) was developed to analyse the steady-state and linearized dynamic behavior of rotorcraft in hovering and axial flight conditions. Because of the nature of problems GRASP was created to solve, the geometrically nonlinear behavior of beams is one area in which the program must perform well in order to be of any value. Numerical results obtained from GRASP are compared to both static and dynamic experimental data obtained for a cantilever beam undergoing large displacements and rotations caused by deformations. The correlation is excellent in all cases.

  8. Finite Element Analysis of Micro-cantilever Beam Experiments in UO2

    NASA Astrophysics Data System (ADS)

    Gong, Bowen

    Uranium Dioxide (UO2) is a significant nuclear fission fuel, which is widely used in nuclear reactors. Understanding the influence of microstructure on thermo-mechanical behavior of UO2 is extremely important to predict its performance. In particular, evaluating mechanical properties, such as elasticity, plasticity and creep at sub-grain length scales is key to developing this understanding as well as building multi-scale models of fuel behavior with predicting capabilities. In this work, modeling techniques were developed to study effects of microstructure on Young's modulus, which was selected as a key representative property that affects overall mechanical behavior, using experimental data obtained from micro-cantilever bending testing as benchmarks. Beam theory was firstly introduced to calculate Young's modulus of UO2 from the experimental data and then three-dimensional finite element models of the micro-cantilever beams were constructed to simulate bending tests in UO2 at room temperature. The influence of the pore distribution was studied to explain the discrepancy between predicted values and experimental results. Results indicate that results of tests are significantly affected by porosity given that both pore size and spacing in the samples are of the order of the micro-beam dimensions. Microstructure reconstruction was conducted with images collected from three-dimensional serial sectioning using focused ion beam (FIB) and electron backscattering diffraction (EBSD) and pore clusters were placed at different locations along the length of the beam. Results indicate that the presence of pore clusters close to the substrate, i.e., the clamp of the micro-cantilever beam, has the strongest effect on load-deflection behavior, leading to a reduction of stiffness that is the largest for any location of the pore cluster. Furthermore, it was also found from both numerical and i analytical models that pore clusters located towards the middle of the span and close

  9. A versatile cantilever beam magnetometer for ex situ characterization of magnetic materials.

    PubMed

    Adhikari, R; Sarkar, A; Das, A K

    2012-01-01

    We have designed, fabricated, and made operational an ex situ cantilever beam magnetometer (CBM), which is versatile in the sense that it can measure most of the magnetic properties of a material in all probable shapes. The working principle of a CBM is discussed considering the magnetic torque into the beam theory. The individual components of the instrument are described in details and experiments were performed on the bulk materials, pellets of nanoparticles, ribbon samples, and thin films, and the magnetization, magnetostriction, and magnetocrystalline anisotropy were studied. This magnetometer is inexpensive, but versatile and would be suitable for the research as well as teaching laboratories.

  10. Evaluation of the split cantilever beam for mode III delamination testing

    NASA Technical Reports Server (NTRS)

    Martin, Roderick, H.

    1991-01-01

    A test rig for testing a thick split cantilever beam for scissoring delamination (mode 3) fracture toughness was developed. A 3-D finite element analysis was conducted on the test specimen to determine the strain energy release rate, G, distribution along the delamination front. The virtual crack closure technique was used to calculate the G components resulting from interlaminar tension, GI, interlaminar sliding shear, GII, and interlaminar tearing shear, GIII. The finite element analysis showed that at the delamination front no GI component existed, but a GII component was present in addition to a GIII component. Furthermore, near the free edges, the GII component was significantly higher than the GIII component. The GII/GIII ratio was found to increase with delamination length but was insensitive to the beam depth. The presence of GII at the delamination front was verified experimentally by examination of the failure surfaces. At the center of the beam, where the failure was in mode 3, there was significant fiber bridging. However, at the edges of the beam where the failure was in mode 3, there was no fiber bridging and mode 2 shear hackles were observed. Therefore, it was concluded that the split cantilever beam configuration does not represent a pure mode 3 test. The experimental work showed that the mode 2 fracture toughness, GIIc, must be less than the mode 3 fracture toughness, GIIIc. Therefore, a conservative approach to characterizing mode 3 delamination is to equate GIIIc to GIIc.

  11. Evaluation of the split cantilever beam for Mode 3 delamination testing

    NASA Technical Reports Server (NTRS)

    Martin, Roderick H.

    1989-01-01

    A test rig for testing a thick split cantilever beam for scissoring delamination (mode 3) fracture toughness was developed. A 3-D finite element analysis was conducted on the test specimen to determine the strain energy release rate, G, distribution along the delamination front. The virtual crack closure technique was used to calculate the G components resulting from interlaminar tension, GI, interlaminar sliding shear, GII, and interlaminar tearing shear, GIII. The finite element analysis showed that at the delamination front no GI component existed, but a GII component was present in addition to a GIII component. Furthermore, near the free edges, the GII component was significantly higher than the GIII component. The GII/GIII ratio was found to increase with delamination length but was insensitive to the beam depth. The presence of GII at the delamination front was verified experimentally by examination of the failure surfaces. At the center of the beam, where the failure was in mode 3, there was significant fiber bridging. However, at the edges of the beam where the failure was in mode 3, there was no fiber bridging and mode 2 shear hackles were observed. Therefore, it was concluded that the split cantilever beam configuration does not represent a pure mode 3 test. The experimental work showed that the mode 2 fracture toughness, GIIc, must be less than the mode 3 fracture toughness, GIIIc. Therefore, a conservative approach to characterizing mode 3 delamination is to equate GIIIc to GIIc.

  12. Measurements of the solidification process of resins from cantilever beams resonances

    NASA Astrophysics Data System (ADS)

    Arenas, Gustavo F.; Duchowicz, Ricardo

    2013-01-01

    In this work, we introduce a technique to infer elastic and mechanical properties of light-curing resins by using cantilever beams. The methodology includes vibration resonance measurements performed with a fiber optic Fizeau interferometer. As is known, the natural resonance frequency of cantilever beams depends strongly on any variation in its physical properties and geometry. Following this idea, square shaped solid aluminum beams with a short transverse deep crack drilled near its fixed end were studied. The slot was filled with photo-curing resins and resonance frequency was monitored as polymerization proceeded. In order to track resonance peaks, we adopted a simple electromagnetic actuator to force the beam into oscillations of variable frequencies. Beams were scanned periodically around its natural resonance as photo-curing was carried out. Due to the small vibrations amplitude present at the free end of beams (tens of microns typically), we used a Fizeau interferometric fiber optic sensor placed near the free end. Its extremely high sensitivity and resolution are its outstanding features, yielding a non-invasive sensor that ensures natural evolution and distortionless amplitude and frequency measurements. Results show that liquid resin in the slot did not produce changes on beam resonance prior to curing. On the other hand, photo-polymerization partially recovered original properties of the beam in a few tens of seconds, suggesting that vitrification of resins is completely achieved while photoreaction is still occurring. Moreover, additional information of volumetric shrinkage of polymers can be extracted from these measurements. In summary, this powerful and simple technique enables to evaluate the static resonance of beams as well as polymer shrinkage and solidification time evolution in one single measurement.

  13. Numerical analysis and control for cantilever flexible beams using PZT patches

    NASA Astrophysics Data System (ADS)

    Yan, Shi; Zhang, Hao

    2008-03-01

    This paper presents a numerical study on a vibration control of a cantilever flexible beam using PZT patches. The PZT patches used as both actuators and sensors were adopted in the forms of surface-bond devices on the flexible aluminum beam to control actively the vibration responses. The beam was actuated electrically by the PZT actuator to generate the vibration and the feedback signals were collected by the PZT sensors during the numerical analysis and experimental validation. A finite element method (FEM) in which the materials of the beam and PZTs were coupled was used numerically to analyze the vibration and structural control. A compare study between the numerical simulation and experiment results was finished. The results of the FEM simulation showed that it was effective to use PZT patches to control the responses of flexible structure and the proposed numerical method was also successful in analyzing the vibration responses of the coupled material structures.

  14. Sensitivity of inelastic response to numerical integration of strain energy. [for cantilever beam

    NASA Technical Reports Server (NTRS)

    Kamat, M. P.

    1976-01-01

    The exact solution to the quasi-static, inelastic response of a cantilever beam of rectangular cross section subjected to a bending moment at the tip is obtained. The material of the beam is assumed to be linearly elastic-linearly strain-hardening. This solution is then compared with three different numerical solutions of the same problem obtained by minimizing the total potential energy using Gaussian quadratures of two different orders and a Newton-Cotes scheme for integrating the strain energy of deformation. Significant differences between the exact dissipative strain energy and its numerical counterpart are emphasized. The consequence of this on the nonlinear transient responses of a beam with solid cross section and that of a thin-walled beam on elastic supports under impulsive loads are examined.

  15. The small length scale effect for a non-local cantilever beam: a paradox solved.

    PubMed

    Challamel, N; Wang, C M

    2008-08-27

    Non-local continuum mechanics allows one to account for the small length scale effect that becomes significant when dealing with microstructures or nanostructures. This paper presents some simplified non-local elastic beam models, for the bending analyses of small scale rods. Integral-type or gradient non-local models abandon the classical assumption of locality, and admit that stress depends not only on the strain value at that point but also on the strain values of all points on the body. There is a paradox still unresolved at this stage: some bending solutions of integral-based non-local elastic beams have been found to be identical to the classical (local) solution, i.e. the small scale effect is not present at all. One example is the Euler-Bernoulli cantilever nanobeam model with a point load which has application in microelectromechanical systems and nanoelectromechanical systems as an actuator. In this paper, it will be shown that this paradox may be overcome with a gradient elastic model as well as an integral non-local elastic model that is based on combining the local and the non-local curvatures in the constitutive elastic relation. The latter model comprises the classical gradient model and Eringen's integral model, and its application produces small length scale terms in the non-local elastic cantilever beam solution. PMID:21730658

  16. Dynamic crack propagation and arrest in orthotropic DCB fiber composite specimens. [Double Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Williams, J. H., Jr.; Lee, S. S.; Kousiounelos, P. N.

    1981-01-01

    An orthotropic double cantilever beam (DCB) model is used to study dynamic crack propagation and arrest in 90 deg unidirectional Hercules AS/3501-6 graphite fiber epoxy composites. The dynamic fracture toughness of the composite is determined from tests performed on the long-strip specimen and DCB crack arrest experiments are conducted. By using the dynamic fracture toughness in a finite-difference solution of the DCB governing partial differential equations, a numerical solution of the crack propagation and arrest events is computed. Excellent agreement between the experimental and numerical crack arrest results are obtained.

  17. Characterization of Interlaminar Crack Growth in Composites with the Double Cantilever Beam Specimen

    NASA Technical Reports Server (NTRS)

    Hunston, D. L.

    1984-01-01

    A project to examine the double cantilever beam specimen as a quantitative test method to assess the resistance of various composite materials to interlaminar crack growth is discussed. A second objective is to investigate the micromechanics of failure for composites with tough matrix resins from certain generic types of polymeric systems: brittle thermosets, toughened thermosets, and thermoplastics. Emphasis is given to a discussion of preliminary results in two areas: the effects of temperature and loading rate for woven composites, and the effects of matrix toughening in woven and unidirectional composites.

  18. Analysis of the FELIX experiments with cantilevered beams and hollow cylinders

    SciTech Connect

    Turner, L.R.; Hua, T.Q.; Lee, S.Y.

    1986-01-01

    Experiments have been performed with the FELIX facility at Argonne National Laboratory to study the coupling between eddy currents and deflections and to provide data for validating eddy current computer programs. Experiments with cantilevered beams in crossed steady and decaying magnetic fields verify that coupling effects act to alleviate the large currents, deflections, and stresses predicted by uncoupled analyses. Measurements of magnetic fields induced in conducting hollow cylinders are analyzed by exponential fitting and by transfer functions. Spatial variation in the parameters of the exponential fit and in those of the one- and two-pole transfer functions suggests that several eddy current modes are acting in the cylinder test pieces.

  19. Three-dimensional elastic analysis of a composite double cantilever beam specimen

    NASA Technical Reports Server (NTRS)

    Raju, I. S.; Shivakumar, K. N.; Crews, J. H., Jr.

    1988-01-01

    Attention is given to the stresses and the strain energy release rate along the delamination front in the present three-dimensional elastic analysis of a 24-ply, cocured double-cantilever beam specimen by means of 20-noded parabolic-isoparametric finite elements. At the free surface, the strain energy release rate was found to be substantially smaller than the plane strain value; this is suggested to be due to the free-surface effect that exists where the delamination meets the surface edge.

  20. Nonlinear Elastic J-Integral Measurements in Mode I Using a Tapered Double Cantilever Beam Geometry

    NASA Technical Reports Server (NTRS)

    Macon, David J.

    2006-01-01

    An expression for the J-integral of a nonlinear elastic material is derived for an advancing crack in a tapered double cantilever beam fracture specimen. The elastic and plastic fracture energies related to the test geometry and how these energies correlates to the crack position are discussed. The dimensionless shape factors eta(sub el and eta(sub p) are shown to be equivalent and the deformation J-integral is analyzed in terms of the eta(sub el) function. The fracture results from a structural epoxy are interpreted using the discussed approach. The magnitude of the plastic dissipation is found to strongly depend upon the initial crack shape.

  1. Thermoelastic Analysis of a Vibrating TiB/Ti Cantilever Beam Using Differential Thermography

    SciTech Connect

    Byrd, Larry; Wyen, Travis; Byrd, Alex

    2008-02-15

    Differential thermography has been used to detect the fluctuating temperatures due the thermoelastic effect for a number of years. This paper examines functionally graded TiB/Ti cantilever beams excited on an electromechanical shaker in fully reversed bending. Finite difference analysis of specimens was used to look at the effect of heat conduction, convection and the fundamental frequency on the surface temperature distribution and compared to experimental data. The thermoelastic effect was also used to detect cracking and the stress field at the tip of the fixture during fatigue.

  2. Note: High-efficiency broadband acoustic energy harvesting using Helmholtz resonator and dual piezoelectric cantilever beams

    SciTech Connect

    Yang, Aichao; Li, Ping Wen, Yumei; Lu, Caijiang; Peng, Xiao; He, Wei; Zhang, Jitao; Wang, Decai; Yang, Feng

    2014-06-15

    A high-efficiency broadband acoustic energy harvester consisting of a compliant-top-plate Helmholtz resonator (HR) and dual piezoelectric cantilever beams is proposed. Due to the high mechanical quality factor of beams and the strong multimode coupling of HR cavity, top plate and beams, the high efficiency in a broad bandwidth is obtained. Experiment exhibits that the proposed harvester at 170–206 Hz has 28–188 times higher efficiency than the conventional harvester using a HR with a piezoelectric composite diaphragm. For input acoustic pressure of 2.0 Pa, the proposed harvester exhibits 0.137–1.43 mW output power corresponding to 0.035–0.36 μW cm{sup −3} volume power density at 170–206 Hz.

  3. Note: High-efficiency broadband acoustic energy harvesting using Helmholtz resonator and dual piezoelectric cantilever beams.

    PubMed

    Yang, Aichao; Li, Ping; Wen, Yumei; Lu, Caijiang; Peng, Xiao; He, Wei; Zhang, Jitao; Wang, Decai; Yang, Feng

    2014-06-01

    A high-efficiency broadband acoustic energy harvester consisting of a compliant-top-plate Helmholtz resonator (HR) and dual piezoelectric cantilever beams is proposed. Due to the high mechanical quality factor of beams and the strong multimode coupling of HR cavity, top plate and beams, the high efficiency in a broad bandwidth is obtained. Experiment exhibits that the proposed harvester at 170-206 Hz has 28-188 times higher efficiency than the conventional harvester using a HR with a piezoelectric composite diaphragm. For input acoustic pressure of 2.0 Pa, the proposed harvester exhibits 0.137-1.43 mW output power corresponding to 0.035-0.36 μW cm(-3) volume power density at 170-206 Hz. PMID:24985867

  4. Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission

    SciTech Connect

    Chrystal, C.; Burrell, K. H.; Pace, D. C.; Grierson, B. A.

    2015-10-15

    Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination (CER) diagnostic at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain information about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. The methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.

  5. Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission.

    PubMed

    Chrystal, C; Burrell, K H; Grierson, B A; Pace, D C

    2015-10-01

    Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination (CER) diagnostic at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain information about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. The methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.

  6. Rapid serial prototyping of magnet-tipped attonewton-sensitivity cantilevers by focused ion beam manipulation1

    PubMed Central

    Longenecker, Jonilyn G.; Moore, Eric W.; Marohn, John A.

    2011-01-01

    The authors report a method for rapidly prototyping attonewton-sensitivity cantilevers with custom-fabricated tips and illustrate the method by preparing tips consisting of a magnetic nanorod overhanging the leading edge of the cantilevers. Micron-long nickel nanorods with widths of 120–220 nm were fabricated on silicon chips by electron beam lithography, deposition, and lift-off. Each silicon chip, with its integral nanomagnet, was attached serially to a custom-fabricated attonewton-sensitivity cantilever using focused ion beam manipulation. The magnetic nanorod tips were prepared with and without an alumina capping layer, and the minimum detectable force and tip magnetic moment of the resulting cantilevers was characterized by cantilever magnetometry. The results indicate that this serial but high-yield approach is an effective way to rapidly prepare and characterize magnetic tips for the proposed single-electron-spin and single-proton magnetic resonance imaging experiments. The approach also represents a versatile route for affixing essentially any vacuum-compatible sample to the leading edge of an attonewton-sensitivity cantilever. PMID:23028212

  7. Stiffening and damping capacity of an electrostatically tuneable functional composite cantilever beam

    NASA Astrophysics Data System (ADS)

    Ginés, R.; Bergamini, A.; Motavalli, M.; Ermanni, P.

    2015-09-01

    The damping capacity of a novel composite film, designed to exhibit high dielectric strength and a high friction coefficient for an electrostatic tuneable friction damper, is tested on a cantilever beam. Such a system consists of a carbon fibre reinforced polymer stiffening element which is reversibly laminated onto a host structure with a dielectric material by means of electrostatic fields. Damping is achieved when the maximum shear at the interface between the stiffening element and structure exceeds the shear strength of the electrostatically laminated interface. The thin films tested consist of barium titanate particles and alumina platelets in an epoxy matrix. Their high dielectric constant and high coefficient of friction compared to a commercial available polymer film, polyvinylidene fluoride, lead to a reduction of the required electric field to stiffen and damp the cantilever beam. Reducing the operating voltage affects different aspects of the studied damper. The cost of possible applications of the frictional damper can be reduced, as the special components necessary at high voltages become redundant. Furthermore, the enhanced security positively affects the damping system’s appeal as an alternative damping method.

  8. Height-tapered double cantilever beam specimen for study of rate effects on fracture toughness of composites

    NASA Technical Reports Server (NTRS)

    Yaniv, Gershon; Daniel, Isaac M.

    1988-01-01

    Loading rate effects on the mode I delamination fracture toughness of AS4/3501-6 graphite/epoxy are presently studied by means of a height-tapered double-cantilever beam specimen whose height contour is designed to furnish a slightly decreasing compliance with increasing crack length, in order to yield a stable and smooth crack propagation at high loading rates. This specimen geometry also allows much higher crack propagation velocities to be obtained with either uniform or width-tapered double cantilever beam specimens.

  9. Out-of-resonance vibration modulation of ultrasound with a nonlinear oscillator for microcrack detection in a cantilever beam

    SciTech Connect

    He, Qingbo Xu, Yanyan; Lu, Siliang; Dai, Daoyi

    2014-04-28

    This Letter reports an out-of-resonance vibro-acoustic modulation (VAM) effect in nonlinear ultrasonic evaluation of a microcracked cantilever beam. We design a model to involve the microcracked cantilever beam in a nonlinear oscillator system whose dynamics is introduced to extend the operating vibration excitation band of the VAM out of resonance. The prototype model exhibits an effective bandwidth four times that of the traditional linear model. The reported VAM effect allows efficiently enhancing the detection, localization, and imaging of various types of microcracks in solid materials at out-of-resonance vibration excitation frequencies.

  10. Mimicking the cochlear amplifier in a cantilever beam using nonlinear velocity feedback control

    NASA Astrophysics Data System (ADS)

    Joyce, Bryan S.; Tarazaga, Pablo A.

    2014-07-01

    The mammalian cochlea exhibits a nonlinear amplification which allows mammals to detect a large range of sound pressure levels while maintaining high frequency sensitivity. This work seeks to mimic the cochlea’s nonlinear amplification in a mechanical system. A nonlinear, velocity-based feedback control law is applied to a cantilever beam with piezoelectric actuators. The control law reduces the linear viscous damping of the system while introducing a cubic damping term. The result is a system which is positioned close to a Hopf bifurcation. Modelling and experimental results show that the beam with this control law undergoes a one-third amplitude scaling near the resonance frequency and an amplitude-dependent bandwidth. Both behaviors are characteristic of data obtained from the mammalian cochlea. This work could provide insight on the biological cochlea while producing bio-inspired sensors with a large dynamic range and sharp frequency sensitivity.

  11. In-situ determination of energy species yields of intense particle beams

    DOEpatents

    Kugel, Henry W.; Kaita, Robert

    1987-01-01

    An arrangement is provided for the in-situ determination of energy species yields of intense particle beams. The beam is directed onto a target surface of known composition, such that Rutherford backscattering of the beam occurs. The yield-energy characteristic response of the beam to backscattering from the target is analyzed using Rutherford backscattering techniques to determine the yields of energy species components of the beam.

  12. In-situ determination of energy species yields of intense particle beams

    DOEpatents

    Kugel, Henry W.; Kaita, Robert

    1987-03-03

    An arrangement is provided for the in-situ determination of energy species yields of intense particle beams. The beam is directed onto a target surface of known composition, such that Rutherford backscattering of the beam occurs. The yield-energy characteristic response of the beam to backscattering from the target is analyzed using Rutherford backscattering techniques to determine the yields of energy species components of the beam.

  13. A dynamic model of a cantilever beam with a closed, embedded horizontal crack including local flexibilities at crack tips

    NASA Astrophysics Data System (ADS)

    Liu, J.; Zhu, W. D.; Charalambides, P. G.; Shao, Y. M.; Xu, Y. F.; Fang, X. M.

    2016-11-01

    As one of major failure modes of mechanical structures subjected to periodic loads, embedded cracks due to fatigue can cause catastrophic failure of machineries. Understanding the dynamic characteristics of a structure with an embedded crack is helpful for early crack detection and diagnosis. In this work, a new three-segment beam model with local flexibilities at crack tips is developed to investigate the vibration of a cantilever beam with a closed, fully embedded horizontal crack, which is assumed to be not located at its clamped or free end or distributed near its top or bottom side. The three-segment beam model is assumed to be a linear elastic system, and it does not account for the nonlinear crack closure effect; the top and bottom segments always stay in contact at their interface during the beam vibration. It can model the effects of local deformations in the vicinity of the crack tips, which cannot be captured by previous methods in the literature. The middle segment of the beam containing the crack is modeled by a mechanically consistent, reduced bending moment. Each beam segment is assumed to be an Euler-Bernoulli beam, and the compliances at the crack tips are analytically determined using a J-integral approach and verified using commercial finite element software. Using compatibility conditions at the crack tips and the transfer matrix method, the nature frequencies and mode shapes of the cracked cantilever beam are obtained. The three-segment beam model is used to investigate the effects of local flexibilities at crack tips on the first three natural frequencies and mode shapes of the cracked cantilever beam. A stationary wavelet transform (SWT) method is used to process the mode shapes of the cracked cantilever beam; jumps in single-level SWT decomposition detail coefficients can be used to identify the length and location of an embedded horizontal crack.

  14. Transverse vibration and buckling of a cantilevered beam with tip body under constant axial base acceleration

    NASA Technical Reports Server (NTRS)

    Storch, J.; Gates, S.

    1983-01-01

    The planar transverse bending behavior of a uniform cantilevered beam with rigid tip body subject to constant axial base acceleration was analyzed. The beam is inextensible and capable of small elastic transverse bending deformations only. Two classes of tip bodies are recognized: (1) mass centers located along the beam tip tangent line; and (2) mass centers with arbitrary offset towards the beam attachment point. The steady state response is studied for the beam end condition cases: free, tip mass, tip body with restricted mass center offset, and tip body with arbitrary mass center offset. The first three cases constitute classical Euler buckling problems, and the characteristic equation for the critical loads/accelerations are determined. For the last case a unique steady state solution exists. The free vibration response is examined for the two classes of tip body. The characteristic equation, eigenfunctions and their orthogonality properties are obtained for the case of restricted mass center offset. The vibration problem is nonhomogeneous for the case of arbitrary mass center offset. The exact solution is obtained as a sum of the steady state solution and a superposition of simple harmonic motions.

  15. Improved Beam Diagnostic Spatial Calibration Using In-Situ Measurements of Beam Emission

    NASA Astrophysics Data System (ADS)

    Chrystal, C.; Burrell, K. H.; Pace, D. C.; Grierson, B. A.; Pablant, N. A.

    2014-10-01

    A new technique has been developed for determining the measurement geometry of the charge exchange recombination spectroscopy diagnostic (CER) on DIII-D. This technique removes uncertainty in the measurement geometry related to the position of the neutral beams when they are injecting power. This has been accomplished by combining standard measurements that use in-vessel calibration targets with spectroscopic measurements of Doppler shifted and Stark split beam emission to fully describe the neutral beam positions and CER views. A least squares fitting routine determines the measurement geometry consistent with all the calibration data. The use of beam emission measurements allows the position of the neutral beams to be determined in-situ by the same views that makeup the CER diagnostic. Results indicate that changes in the measurement geometry are required to create a consistent set of calibration measurements. However, changes in quantities derived from the geometry, e.g. ion temperature gradient and poloidal rotation, are small. Work supported by the US DOE under DE-FG02-07ER54917, DE-FC02-04ER54698, and DE-AC02-09H11466.

  16. Damage detection in a cantilever beam under dynamic conditions using a distributed, fast, and high spatial resolution Brillouin interrogator

    NASA Astrophysics Data System (ADS)

    Motil, A.; Davidi, R.; Bergman, A.; Botsev, Y.; Hahami, M.; Tur, M.

    2016-05-01

    The ability of Brillouin-based fiber-optic sensing to detect damage in a moving cantilever beam is demonstrated. A fully computerized, distributed and high spatial resolution (10cm) Fast-BOTDA interrogator (50 full-beam Brillouin-gain-spectra per second) successfully directly detected an abnormally stiffened (i.e., `damaged') 20cm long segment in a 6m Aluminum beam, while the beam was in motion. Damage detection was based on monitoring deviations of the measured strain distribution along the beam from that expected in the undamaged case.

  17. Finite difference analysis of torsional vibrations of pretwisted, rotating, cantilever beams with effects of warping

    NASA Technical Reports Server (NTRS)

    Subrahmanyam, K. B.; Kaza, K. R. V.

    1985-01-01

    Theoretical natural frequencies of the first three modes of torsional vibration of pretwisted, rotating cantilever beams are determined for various thickness and aspect ratios. Conclusions concerning individual and collective effects of warping, pretwist, tension-torsion coupling and tennis racket effect (twist-rotational coupling) terms on the natural frequencies are drawn from numerical results obtained by using a finite difference procedure with first order central differences. The relative importance of structural warping, inertial warping, pretwist, tension-torsion and twist-rotational coupling terms is discussed for various rotational speeds. The accuracy of results obtained by using the finite difference approach is verified by a comparison with the exact solution for specialized simple cases of the equation of motion used in this paper.

  18. The width-tapered double cantilever beam for interlaminar fracture testing

    NASA Technical Reports Server (NTRS)

    Bascom, W. D.; Jensen, R. M.; Bullman, G. W.; Hunston, D. L.

    1984-01-01

    The width-tapered double-cantilever-beam (WTDCB) specimen configuration used to determine the Mode-I interlaminar fracture energy (IFE) of composites has special advantages for routine development work and for quality-assurance purposes. These advantages come primarily from the simplicity of testing and the fact that the specimen is designed for constant change in compliance with crack length, so that the computation of Mode-I IFE is independent of crack length. In this paper, a simplified technique for fabrication and testing WTDCB specimens is described. Also presented are the effects of fiber orientation and specimen dimensions, a comparison of data obtained using the WTDCB specimens and other specimen geometries, and comparison of data obtained at different laboratories. It is concluded that the WTDCB gives interlaminar Mode-I IFE essentially equal to other type specimens, and that it can be used for rapid screening in resin-development work and for quality assurance of composite materials.

  19. An improved finite-difference analysis of uncoupled vibrations of tapered cantilever beams

    NASA Technical Reports Server (NTRS)

    Subrahmanyam, K. B.; Kaza, K. R. V.

    1983-01-01

    An improved finite difference procedure for determining the natural frequencies and mode shapes of tapered cantilever beams undergoing uncoupled vibrations is presented. Boundary conditions are derived in the form of simple recursive relations involving the second order central differences. Results obtained by using the conventional first order central differences and the present second order central differences are compared, and it is observed that the present second order scheme is more efficient than the conventional approach. An important advantage offered by the present approach is that the results converge to exact values rapidly, and thus the extrapolation of the results is not necessary. Consequently, the basic handicap with the classical finite difference method of solution that requires the Richardson's extrapolation procedure is eliminated. Furthermore, for the cases considered herein, the present approach produces consistent lower bound solutions.

  20. Fatigue fracture of the stem-cement interface with a clamped cantilever beam test.

    PubMed

    Heuer, D A; Mann, K A

    2000-12-01

    A clamped cantilever beam test was developed to determine the fatigue crack propagation rate of the CoCr alloy/PMMA cement interface at high crack tip phase angles. A combination of finite element and experimental methods was used to determine the fatigue crack growth rates of two different CoCr alloy/PMMA cement surfaces. A crack tip phase angle of 69 deg was found, indicating that loading at the crack tip was mixed-mode with a large degree of in-plane shear loading. The energy required to propagate a crack at the interface was much greater for the plasma-sprayed CoCr surface when compared to the PMMA-precoated satin finish (p < 0.001). Both interface surfaces could be modeled using a Paris fatigue crack growth law over crack propagation rates of 10(-4) to 10(-9) m/cycle.

  1. Sizing Single Cantilever Beam Specimens for Characterizing Facesheet/Core Peel Debonding in Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.

    2010-01-01

    This paper details part of an effort focused on the development of a standardized facesheet/core peel debonding test procedure. The purpose of the test is to characterize facesheet/core peel in sandwich structure, accomplished through the measurement of the critical strain energy release rate associated with the debonding process. The specific test method selected for the standardized test procedure utilizes a single cantilever beam (SCB) specimen configuration. The objective of the current work is to develop a method for establishing SCB specimen dimensions. This is achieved by imposing specific limitations on specimen dimensions, with the objectives of promoting a linear elastic specimen response, and simplifying the data reduction method required for computing the critical strain energy release rate associated with debonding. The sizing method is also designed to be suitable for incorporation into a standardized test protocol. Preliminary application of the resulting sizing method yields practical specimen dimensions.

  2. Experimental evaluation of a piezoelectric vibration absorber using a simplified fuzzy controller in a cantilever beam

    NASA Astrophysics Data System (ADS)

    Lin, J.; Liu, Wei-Zheng

    2006-09-01

    This study presents a novel resonant fuzzy logic controller (FLC) to minimize structural vibration using collocated piezoelectric actuator/sensor pairs. The proposed fuzzy controller increases the damping of the structures to minimize certain resonant responses. The vibration absorber is first experimentally examined by a cantilever beam test bed for impulse and near-resonant excitation cases. Moreover, the effectiveness of the new fuzzy control design to a state-of-the-art control scheme is compared through the experimental studies. The experimental results indicate the proposed controller is highly promising for this application field. Our results further demonstrate that the fuzzy approach is much better than traditional control methods. In summary, a novel vibration absorption scheme using fuzzy logic has been demonstrated to significantly enhance the performance of a flexible structure with resonant response.

  3. Double Cantilever Beam and End Notched Flexure Fracture Toughness Testing of Two Composite Materials

    NASA Technical Reports Server (NTRS)

    Kessler, Jeff A.; Adams, Donald F.

    1993-01-01

    Two different unidirectional composite materials were provided by NASA Langley Research Center and tested by the Composite Materials Research Group within the Department of Mechanical Engineering at the University of Wyoming. Double cantilever beam and end notched flexure tests were performed to measure the mode I (crack opening) and mode II (sliding or shear) interlaminar fracture toughness of the two materials. The two composites consisted of IM7 carbon fiber combined with either RP46 resin toughened with special formulation of LaRC IA resin, known as JJS1356; or PES chain extended thermoplastic resin known as JJS1361. Double Cantilever Beam Specimen Configuration and Test Methods As received from NASA, the test specimens were nominally 0.5 inch wide, 6 inches long, and 0.2 inch thick. A 1 inch long Kapton insert at the midplane of one end of the specimen (placed during laminate fabrication) facilitated crack initiation and extension. It was noted that the specimens provided were smaller than the nominal 1.5 inch wide, 9.0 inch long configuration specified. Similarly, the Kapton inserts were of greater length than those in the present specimens. Hence, the data below should not be compared directly to those generated with the referenced methods. No preconditioning was performed on the specimens prior to testing. In general, the methodology was used for the present work. Crack opening loads were introduced to the specimens via piano hinges attached to the main specimen faces at a single end of each specimen. Hinges were bolted to the specimens using the technique presented. The cracks were extended a small distance from the end of the Kapton insert prior to testing. Just before precracking, the sides of the specimens were coated with water-soluble typewriter correction fluid to aid in crack visualization. Scribe marks were then made in the coating at half-inch intervals.

  4. Stress and DNA assembly differences on cantilevers gold coated by resistive and e-beam evaporation techniques.

    PubMed

    Arroyo-Hernández, M; Tamayo, J; Costa-Krämer, J L

    2009-09-15

    Changes in the sign of differential surface stress of gold-coated cantilevers produced by thiol-derivatized single-stranded DNA immobilization are observed, depending on the method used to deposit the gold. While the DNA immobilization on e-beam gold-coated cantilevers produces a compressive differential surface stress in the metallic layer, the opposite is observed for resistively coated cantilevers under the same immobilization conditions. The gold films exhibit quite a similar morphology, and the immobilization differences seem to be related to the charge state of the metallic layer surface. This in turn produces a different distribution of the orientation of the DNA strands on the gold layer. A tentative explanation for the observed effect is proposed.

  5. Fault Diagnosis of Cantilever Beam Using Finite Element Analysis: A Case Study

    NASA Astrophysics Data System (ADS)

    Murthy, B. S. N.; Ratnam, C.; Kumar, K. A.

    2013-10-01

    Damage prediction in mechanical and structural systems is establishing a prominent role in modern engineering. Vibration based damage methods give ample flexibility to understand the extent of expected damages in the system. Measurement of vibration characteristics like natural frequencies and mode shapes, Fourier responses and transient responses can help in comprehending the present status of a system either by comparing with their baseline equivalents or by formulating residual functions and minimizing them. The minimization of residues is carried out using non-conventional optimization techniques like genetic algorithms. Genetic algorithms being a meta-heuristic method obtain global minimum values with implicitly defined constraints and objective. In all the residual functions considered in this paper, it is assumed that only the stiffness parameters are reduced individually in each element due to the damage. The amount of reduction in each element is an unknown parameter. The approach is attempted with a structural member like beam. Experimental analysis is carried out to test the natural frequencies and mode shapes of the damaged beams from finite element model considered. A cantilever beam with central slot of desired depth is selected and impact hammer analysis is performed to know the variation in modes when compared to undamaged counter part. Results are presented in the form of table and graphs.

  6. Investigation of the transient behavior of a cantilever beam using PVDF sensors.

    PubMed

    Ma, Chien-Ching; Huang, Yu-Hsi; Pan, Shan-Ying

    2012-01-01

    In this paper, a PVDF film sensor was used to measure the transient responses of a cantilever beam subjected to an impact loading. The measurement capability of a PVDF sensor is affected by the area of the PVDF film sensor and the signal conditioner (charge amplifier). The influences of these effects on the experimental measurements were investigated. The transient responses for the dynamic strain of the beam were measured simultaneously by the PVDF sensor and a conventional strain gauge. The resonant frequencies of the beam were determined by applying the Fast Fourier Transform on transient results in the time domain of the PVDF sensor and the strain gauge. The experimentally measured resonant frequencies from the PVDF sensor and the strain gauge were compared with those predicted from theoretical and FEM numerical calculations. Based on the comparison of the results measured for these two sensors, the PVDF film sensor proved capable of measuring transient responses for dynamic strain, and its sensitivity is better than that of the strain gauge. Furthermore, almost all the resonant frequencies can be obtained from the results of transient responses for PVDF film. PMID:22438754

  7. An experimental-theoretical correlation study of non-linear bending and torsion deformations of a cantilever beam

    NASA Technical Reports Server (NTRS)

    Dowell, E. H.; Traybar, J.; Hodges, D. H.

    1977-01-01

    An experimental study of the large deformation of a cantilevered beam under a gravity tip load has been made. The beam root is rotated so that the tip load is oriented at various angles with respect to the beam principal axes. Static twist and bending deflections of the tip and bending natural frequencies have been measured as a function of tip load magnitude and orientation. The experimental data are compared with the results of a recently developed non-linear structural theory. Agreement is reasonably good when bending deflections are small compared to the beam span, but systematic differences occur for larger deflections.

  8. Chemical sensor with oscillating cantilevered probe

    DOEpatents

    Adams, Jesse D

    2013-02-05

    The invention provides a method of detecting a chemical species with an oscillating cantilevered probe. A cantilevered beam is driven into oscillation with a drive mechanism coupled to the cantilevered beam. A free end of the oscillating cantilevered beam is tapped against a mechanical stop coupled to a base end of the cantilevered beam. An amplitude of the oscillating cantilevered beam is measured with a sense mechanism coupled to the cantilevered beam. A treated portion of the cantilevered beam is exposed to the chemical species, wherein the cantilevered beam bends when exposed to the chemical species. A second amplitude of the oscillating cantilevered beam is measured, and the chemical species is determined based on the measured amplitudes.

  9. On use of double cantilever beam for coatings and adhesion tests

    NASA Astrophysics Data System (ADS)

    Troczynski, Tom; Camire, Jean

    1995-05-01

    The compliance model of Double Cantilever Beam (DCB) for testing coatings and adhesion has been proposed and verified experimentally. The model is based on the assumption that the coating modifies the stiffness of a foundation of DCB onto which the beam is fixed, according to a simple series-spring law. The model includes multi-coated specimens, in particular the specimen with thermal sprayed ceramic coating, with an additional layer of epoxy adhesive for attachment of a symmetrical DCB arm. It was found, that the compliance of DCB specimens with a coating is significantly increased for a coating thickness larger than approximately 1% of the arm thickness, and a coating Young's modulus smaller than approximately 50% of the arm modulus. The model results, verified by experiment, have profound consequences on calculations of the strain energy release rate in fracture tests for coatings, brazed joints etc. The total compliance of the arm and coating assembly scales with the coating stiffness, and thus the model can be utilised for rigidity evaluation of a variety of coatings on standard substrates, e.g. paints or polymer coatings on metals.

  10. Optimization of a right-angle piezoelectric cantilever using auxiliary beams with different stiffness levels for vibration energy harvesting

    NASA Astrophysics Data System (ADS)

    Xu, Jia Wen; Liu, Yong Bing; Shao, Wei Wei; Feng, Zhihua

    2012-06-01

    This paper presents experiments and models of a piezoelectric cantilever generator with a right-angle structure. Analysis shows that the extended part provides a large torque to the main beam, which can dramatically smoothen the strain distribution of the main beam. The auxiliary beam was fabricated with half the length of the main beam. When the auxiliary beam has a stiffness which is 0.02 times that of the main beam the piezoelectric element has a highly uniform strain distribution; in addition, its relative utilization efficiency (RUE) is 93% at the initial resonant frequency, whereas it is 50% for a conventional rectangular piezoelectric cantilever. The performances of three right-angle generators with auxiliary beams having different levels of stiffness, but constant-stiffness main beams are studied. The RUE of the piezoelements increases as the auxiliary beam’s stiffness decreases. A model based on the Rayleigh-Ritz method is established to demonstrate the principle of the strain-smoothing effect. The voltage and power outputs of the generators are measured. Finite element method simulations are also presented, and the result fits the experiments well.

  11. Bending and Shear Stresses Developed by the Instantaneous Arrest of the Root of a Moving Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Stowell, Elbridge, Z; Schwartz, Edward B; Houbolt, John C

    1945-01-01

    A theoretical and experimental investigation has been made of the behavior of a cantilever beam in transverse motion when its root is suddenly brought to rest. Equations are given for determining the stresses, the deflections, and the accelerations that arise in the beam as a result of the impact. The theoretical equations, which have been confirmed experimentally, reveal that, at a given percentage of the distance from root to tip, the bending stresses for a particular mode are independent of the length of the beam, whereas the shear stresses vary inversely with the length.

  12. Effect of surface stress on stress intensity factors of a nanoscale crack via double cantilever beam model.

    PubMed

    Wang, Hua; Li, Xianfang; Tang, Guojin; Shen, Zhibin

    2013-01-01

    This paper studies the influence of surface elasticity on crack growth for a nanoscale crack advance. A crack is modeled as a double cantilever beam with consideration of surface stress. Using the Euler-Bernoulli beam theory incorporating with surface effects, a governing equation of static bending is derived and bending solution of a cantilever nanowire is obtained for a concentrated force at the free end. Based on the viewpoint of energy balance, the elastic strain energy is given and energy release rate is determined. The influences of the Surface stress and the surface elasticity on crack growth are discussed. Obtained results indicate that consideration of the surface effects decreases stress intensity factors or energy release rates. The residual surface tension impedes propagation of a nanoscale crack and apparent fracture toughness of nanoscale materials is effectively enhanced. PMID:23646757

  13. Numerical Simulation of Output Response of PVDF Sensor Attached on a Cantilever Beam Subjected to Impact Loading.

    PubMed

    Dung, Cao Vu; Sasaki, Eiichi

    2016-04-27

    Polyvinylidene Flouride (PVDF) is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental "stress-averaging" mechanism for dynamic strain sensing in the in-plane mode. A numerical simulation was conducted to simulate the "stress-averaging" mechanism of a PVDF sensor attached on a cantilever beam subjected to an impact loading, taking into account the contribution of piezoelectricity, the cantilever beam's modal properties, and electronic signal conditioning. Impact tests and FEM analysis were also carried out to verify the numerical simulation results. The results of impact tests indicate the excellent capability of the attached PVDF sensor in capturing the fundamental natural frequencies of the cantilever beam. There is a good agreement between the PVDF sensor's output voltage predicted by the numerical simulation and that obtained in the impact tests. Parametric studies were conducted to investigate the effects of sensor size and sensor position and it is shown that a larger sensor tends to generate higher output voltage than a smaller one at the same location. However, the effect of sensor location seems to be more significant for larger sensors due to the cancelling problem. Overall, PVDF sensors exhibit excellent sensing capability for in-plane dynamic strain induced by impact loading.

  14. Numerical Simulation of Output Response of PVDF Sensor Attached on a Cantilever Beam Subjected to Impact Loading.

    PubMed

    Dung, Cao Vu; Sasaki, Eiichi

    2016-01-01

    Polyvinylidene Flouride (PVDF) is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental "stress-averaging" mechanism for dynamic strain sensing in the in-plane mode. A numerical simulation was conducted to simulate the "stress-averaging" mechanism of a PVDF sensor attached on a cantilever beam subjected to an impact loading, taking into account the contribution of piezoelectricity, the cantilever beam's modal properties, and electronic signal conditioning. Impact tests and FEM analysis were also carried out to verify the numerical simulation results. The results of impact tests indicate the excellent capability of the attached PVDF sensor in capturing the fundamental natural frequencies of the cantilever beam. There is a good agreement between the PVDF sensor's output voltage predicted by the numerical simulation and that obtained in the impact tests. Parametric studies were conducted to investigate the effects of sensor size and sensor position and it is shown that a larger sensor tends to generate higher output voltage than a smaller one at the same location. However, the effect of sensor location seems to be more significant for larger sensors due to the cancelling problem. Overall, PVDF sensors exhibit excellent sensing capability for in-plane dynamic strain induced by impact loading. PMID:27128919

  15. The TriBeam system: Femtosecond laser ablation in situ SEM

    SciTech Connect

    Echlin, McLean P.; Straw, Marcus; Randolph, Steven; Filevich, Jorge; Pollock, Tresa M.

    2015-02-15

    Femtosecond laser ablation offers the unique ability to remove material at rates that are orders of magnitude faster than existing ion beam technologies with little or no associated damage. By combining ultrafast lasers with state-of-the-art electron microscopy equipment, we have developed a TriBeam system capable of targeted, in-situ tomography providing chemical, structural, and topographical information in three dimensions of near mm{sup 3} sized volumes. The origins, development, physics, current uses, and future potential for the TriBeam system are described in this tutorial review. - Graphical abstract: Display Omitted - Highlights: • An emerging tool, the TriBeam, for in situ femtosecond (fs) laser ablation is presented. • Fs laser ablation aided tomography at the mm{sup 3}-scale is demonstrated. • Fs laser induced deposition of Pt is demonstrated at sub-diffraction limit resolution. • Fs laser surface structuring is reviewed as well as micromachining applications.

  16. Sizing Single Cantilever Beam Specimens for Characterizing Facesheet/Core Peel Debonding in Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.

    2010-01-01

    This technical publication details part of an effort focused on the development of a standardized facesheet/core peel debonding test procedure. The purpose of the test is to characterize facesheet/core peel in sandwich structure, accomplished through the measurement of the critical strain energy release rate associated with the debonding process. Following an examination of previously developed tests and a recent evaluation of a selection of these methods, a single cantilever beam (SCB) specimen was identified as being a promising candidate for establishing such a standardized test procedure. The objective of the work described here was to begin development of a protocol for conducting a SCB test that will render the procedure suitable for standardization. To this end, a sizing methodology was developed to ensure appropriate SCB specimen dimensions are selected for a given sandwich system. Application of this method to actual sandwich systems yielded SCB specimen dimensions that would be practical for use. This study resulted in the development of a practical SCB specimen sizing method, which should be well-suited for incorporation into a standardized testing protocol.

  17. Effects of T-tabs and large deflections in double cantilever beam specimen tests

    NASA Technical Reports Server (NTRS)

    Naik, Rajiv A.; Crews, John H., Jr.; Shivakumar, Kunigal N.

    1991-01-01

    A simple strength of materials analysis was developed for a double-cantilever beam (DCB) specimen to account for geometric nonlinearity effects due to large deflections and T-tabs. A new DCB data analysis procedure was developed to include the effects of these nonlinearities. The results of the analysis were evaluated by DCB tests performed for materials having a wide range of toughnesses. The materials used in the present study were T300/5208, IM7/8551-7, and AS4/PEEK. Based on the present analysis, for a typical deflection/crack length ratio of 0.3 (for AS4/PEEK), T-tabs and large deflections cause a 15 and 3 percent error, respectively, in the computer Mode I strain energy release rate. Design guidelines for DCB specimen thickness and T-tab height were also developed in order to keep errors due to these nonlinearities within 2 percent. Based on the test results, for both hinged and tabbed specimens, the effects of large deflection on the Mode I fracture toughness (G sub Ic) were almost negligible (less than 1 percent) in the case of T300/5208 and IM7/8551-7; however, AS4/PEEK showed a 2 to 3 percent effect. The effects of T-tabs G sub Ic were more significant for all the materials with T300/5208 showing a 5 percent error, IM7/8551-7 a 15 percent error, and, AS4/PEEK a 20 percent error.

  18. A Mode-Shape-Based Fault Detection Methodology for Cantilever Beams

    NASA Technical Reports Server (NTRS)

    Tejada, Arturo

    2009-01-01

    An important goal of NASA's Internal Vehicle Health Management program (IVHM) is to develop and verify methods and technologies for fault detection in critical airframe structures. A particularly promising new technology under development at NASA Langley Research Center is distributed Bragg fiber optic strain sensors. These sensors can be embedded in, for instance, aircraft wings to continuously monitor surface strain during flight. Strain information can then be used in conjunction with well-known vibrational techniques to detect faults due to changes in the wing's physical parameters or to the presence of incipient cracks. To verify the benefits of this technology, the Formal Methods Group at NASA LaRC has proposed the use of formal verification tools such as PVS. The verification process, however, requires knowledge of the physics and mathematics of the vibrational techniques and a clear understanding of the particular fault detection methodology. This report presents a succinct review of the physical principles behind the modeling of vibrating structures such as cantilever beams (the natural model of a wing). It also reviews two different classes of fault detection techniques and proposes a particular detection method for cracks in wings, which is amenable to formal verification. A prototype implementation of these methods using Matlab scripts is also described and is related to the fundamental theoretical concepts.

  19. Effects of T-tabs and large deflections in double cantilever beam specimen tests

    NASA Astrophysics Data System (ADS)

    Naik, Rajiv A.; Crews, John H., Jr.; Shivakumar, Kunigal N.

    A simple strength of materials analysis was developed for a double-cantilever beam (DCB) specimen to account for geometric nonlinearity effects due to large deflections and T-tabs. A new DCB data analysis procedure was developed to include the effects of these nonlinearities. The results of the analysis were evaluated by DCB tests performed for materials having a wide range of toughnesses. The materials used in the present study were T300/5208, IM7/8551-7, and AS4/PEEK. Based on the present analysis, for a typical deflection/crack length ratio of 0.3 (for AS4/PEEK), T-tabs and large deflections cause a 15 and 3 percent error, respectively, in the computer Mode I strain energy release rate. Design guidelines for DCB specimen thickness and T-tab height were also developed in order to keep errors due to these nonlinearities within 2 percent. Based on the test results, for both hinged and tabbed specimens, the effects of large deflection on the Mode I fracture toughness (G sub Ic) were almost negligible (less than 1 percent) in the case of T300/5208 and IM7/8551-7; however, AS4/PEEK showed a 2 to 3 percent effect. The effects of T-tabs G sub Ic were more significant for all the materials with T300/5208 showing a 5 percent error, IM7/8551-7 a 15 percent error, and, AS4/PEEK a 20 percent error.

  20. Analysis of the dynamic characteristics of a slant-cracked cantilever beam

    NASA Astrophysics Data System (ADS)

    Ma, Hui; Zeng, Jin; Lang, Ziqiang; Zhang, Long; Guo, Yuzhu; Wen, Bangchun

    2016-06-01

    In this study, the dynamic characteristics of a slant-cracked cantilever beam are studied based on a new finite element (FE) model where both plane and beam elements are used to reduce the computational costs. Simulation studies show that the proposed model has the same system natural frequencies and vibration responses as those in the pure plane element model but is computationally more efficient. Based on the new model, the effects of loads such as gravity Fg, excitation force amplitude F0 and direction angles of excitation force φ, and crack parameters including slant crack angle θ, dimensionless crack depth s and dimensionless crack location p, on system dynamics have been analyzed. The results indicate that (1) the gravity has a more significant effect on the sub-harmonic resonance responses than on the super-harmonic resonance and resonance responses; (2) The amplitudes of the system responses at both excitation force frequencies fe and its harmonics such as 2fe and 3fe increase almost linearly with the increase of the excitation force amplitude F0; (3) Under the constant excitation force in the flexural direction, the tensile and compressive forces along the longitudinal direction can lead to opposite breathing behaviors of the crack within the super-harmonic and sub-harmonic resonance frequency regions; (4) Vibration is most severe under the straight crack angle (θ=90°) and near the straight crack angle such as θ=100° and 110°, and the vibration responses under smaller or larger crack angles such as θ=30° and θ=150° become weaker; (5) The resonance at 2fe is sensitive to the faint crack signals when s is small and p is large. In addition, the significant vibration responses at the multiple frequency of 3fe and the fractional frequency of 0.5fe can be regarded as a distinguishable feature of the serious crack with large s and small p.

  1. Numerical Simulation of Output Response of PVDF Sensor Attached on a Cantilever Beam Subjected to Impact Loading

    PubMed Central

    Dung, Cao Vu; Sasaki, Eiichi

    2016-01-01

    Polyvinylidene Flouride (PVDF) is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental “stress-averaging” mechanism for dynamic strain sensing in the in-plane mode. A numerical simulation was conducted to simulate the “stress-averaging” mechanism of a PVDF sensor attached on a cantilever beam subjected to an impact loading, taking into account the contribution of piezoelectricity, the cantilever beam’s modal properties, and electronic signal conditioning. Impact tests and FEM analysis were also carried out to verify the numerical simulation results. The results of impact tests indicate the excellent capability of the attached PVDF sensor in capturing the fundamental natural frequencies of the cantilever beam. There is a good agreement between the PVDF sensor’s output voltage predicted by the numerical simulation and that obtained in the impact tests. Parametric studies were conducted to investigate the effects of sensor size and sensor position and it is shown that a larger sensor tends to generate higher output voltage than a smaller one at the same location. However, the effect of sensor location seems to be more significant for larger sensors due to the cancelling problem. Overall, PVDF sensors exhibit excellent sensing capability for in-plane dynamic strain induced by impact loading. PMID:27128919

  2. Beam-assisted large elongation of in situ formed Li2O nanowires

    PubMed Central

    Zheng, He; Liu, Yang; Mao, Scott X.; Wang, Jianbo; Huang, Jian Yu

    2012-01-01

    As an important component of the solid electrolyte interface in lithium ion batteries and an effective blanket breeding material in fusion reactor, the mechanical property of Li2O is of great interest but is not well understood. Here we show that the polycrystalline Li2O nanowires were formed in situ by touching and pulling lithium hydroxide under electron beam (e-beam) illumination. The Li2O nanowires sustained an enhanced elongation (from 80% to 176%) under low dose e-beam irradiation near room temperature as compared with that (from 51% to 57%) without e-beam irradiation. The extremely high deformability could be understood by the fast Li2O diffusion under e-beam irradiation and tensile stress condition. The large elongation without e-beam irradiation implies that nano-structured Li2O is ductile near room temperature. PMID:22848788

  3. In-Situ atomic force microscopic observation of ion beam bombarded plant cell envelopes

    NASA Astrophysics Data System (ADS)

    Sangyuenyongpipat, S.; Yu, L. D.; Brown, I. G.; Seprom, C.; Vilaithong, T.

    2007-04-01

    A program in ion beam bioengineering has been established at Chiang Mai University (CMU), Thailand, and ion beam induced transfer of plasmid DNA molecules into bacterial cells (Escherichia coli) has been demonstrated. However, a good understanding of the fundamental physical processes involved is lacking. In parallel work, onion skin cells have been bombarded with Ar+ ions at energy 25 keV and fluence1-2 × 1015 ions/cm2, revealing the formation of microcrater-like structures on the cell wall that could serve as channels for the transfer of large macromolecules into the cell interior. An in-situ atomic force microscope (AFM) system has been designed and installed in the CMU bio-implantation facility as a tool for the observation of these microcraters during ion beam bombardment. Here we describe some of the features of the in-situ AFM and outline some of the related work.

  4. Focussed ion beam machined cantilever aperture probes for near-field optical imaging.

    PubMed

    Jin, E X; Xu, X

    2008-03-01

    Near-field optical probe is the key element of a near-field scanning optical microscopy (NSOM) system. The key innovation in the first two NSOM experiments (Pohl et al., 1984; Lewis et al., 1984) is the fabrications of a sub-wavelength optical aperture at the apex of a sharply pointed transparent probe tip with a thin metal coating. This paper discusses the routine use of focussed ion beam (FIB) to micro-machine NSOM aperture probes from the commercial silicon nitride cantilevered atomic force microscopy probes. Two FIB micro-machining approaches are used to form a nanoaperture of controllable size and shape at the apex of the tip. The FIB side slicing produces a silicon nitride aperture on the flat-end tips with controllable sizes varying from 120 nm to 30 nm. The FIB head-on drilling creates holes on the aluminium-coated tips with sizes down to 50 nm. Nanoapertures in C and bow tie shapes can also be patterned using the FIB head-on milling method to possibly enhance the optical transmission. A transmission-collection NSOM system is constructed from a commercial atomic force microscopy to characterize the optical resolution of FIB-micro-machined aperture tips. The optical resolution of 78 nm is demonstrated by an aperture probe fabricated by FIB head-on drilling. Simultaneous topography imaging can also be realized using the same probe. By mapping the optical near-field from a bow-tie aperture, optical resolution as small as 59 nm is achieved by an aperture probe fabricated by the FIB side slicing method. Overall, high resolution and reliable optical imaging of routinely FIB-micro-machined aperture probes are demonstrated.

  5. Application of J-Integral in the Case of a Single Crack in Cantilever Beam

    NASA Astrophysics Data System (ADS)

    Mladensky, Angel S.; Rizov, Victor I.

    2012-12-01

    Mixed mode II/III crack investigation in cantilever bilayered unidirectional fiber reinforced composite beam is reported. The crack is situated between the layers. The two crack arms have different widths. Formula for the strain energy release rate is obtained by the linear elastic fracture mechanics methods using the magnitude of the applied forces, geometrical characteristics of the cross-section, and the elastic moduli of the layers. An equivalent shear modulus of the un-cracked beam portion is used. Several diagrams illustrating the results of parametrical analysis of the strain energy release rate are presented. The paper is a part of a research in the field of fracture behaviour of composite beams.

  6. Decreasing Beam Auto Tuning Interruption Events with In-Situ Chemical Cleaning on Axcelis GSD

    NASA Astrophysics Data System (ADS)

    Fuchs, Dieter; Spreitzer, Stefan; Vogl, Josef; Bishop, Steve; Eldridge, David; Kaim, Robert

    2008-11-01

    Ion beam auto tuning time and success rate are often major factors in the utilization and productivity of ion implanters. Tuning software frequently fails to meet specified setup times or recipe parameters, causing production stoppages and requiring manual intervention. Build-up of conductive deposits in the arc chamber and extraction gap can be one of the main causes of auto tuning problems. The deposits cause glitching and ion beam instabilities, which lead to errors in the software optimization routines. Infineon Regensburg has been testing use of XeF2, an in-situ chemical cleaning reagent, with positive results in reducing auto tuning interruption events.

  7. Decreasing Beam Auto Tuning Interruption Events with In-Situ Chemical Cleaning on Axcelis GSD

    SciTech Connect

    Fuchs, Dieter; Spreitzer, Stefan; Vogl, Josef; Bishop, Steve; Eldridge, David; Kaim, Robert

    2008-11-03

    Ion beam auto tuning time and success rate are often major factors in the utilization and productivity of ion implanters. Tuning software frequently fails to meet specified setup times or recipe parameters, causing production stoppages and requiring manual intervention. Build-up of conductive deposits in the arc chamber and extraction gap can be one of the main causes of auto tuning problems. The deposits cause glitching and ion beam instabilities, which lead to errors in the software optimization routines. Infineon Regensburg has been testing use of XeF{sub 2}, an in-situ chemical cleaning reagent, with positive results in reducing auto tuning interruption events.

  8. In situ nanomechanical testing in focused ion beam and scanning electron microscopes.

    PubMed

    Gianola, D S; Sedlmayr, A; Mönig, R; Volkert, C A; Major, R C; Cyrankowski, E; Asif, S A S; Warren, O L; Kraft, O

    2011-06-01

    The recent interest in size-dependent deformation of micro- and nanoscale materials has paralleled both technological miniaturization and advancements in imaging and small-scale mechanical testing methods. Here we describe a quantitative in situ nanomechanical testing approach adapted to a dual-beam focused ion beam and scanning electron microscope. A transducer based on a three-plate capacitor system is used for high-fidelity force and displacement measurements. Specimen manipulation, transfer, and alignment are performed using a manipulator, independently controlled positioners, and the focused ion beam. Gripping of specimens is achieved using electron-beam assisted Pt-organic deposition. Local strain measurements are obtained using digital image correlation of electron images taken during testing. Examples showing results for tensile testing of single-crystalline metallic nanowires and compression of nanoporous Au pillars will be presented in the context of size effects on mechanical behavior and highlight some of the challenges of conducting nanomechanical testing in vacuum environments.

  9. A short pulse (7 μs FWHM) and high repetition rate (dc-5kHz) cantilever piezovalve for pulsed atomic and molecular beams

    NASA Astrophysics Data System (ADS)

    Irimia, Daniel; Dobrikov, Dimitar; Kortekaas, Rob; Voet, Han; van den Ende, Daan A.; Groen, Wilhelm A.; Janssen, Maurice H. M.

    2009-11-01

    In this paper we report on the design and operation of a novel piezovalve for the production of short pulsed atomic or molecular beams. The high speed valve operates on the principle of a cantilever piezo. The only moving part, besides the cantilever piezo itself, is a very small O-ring that forms the vacuum seal. The valve can operate continuous (dc) and in pulsed mode with the same drive electronics. Pulsed operation has been tested at repetition frequencies up to 5 kHz. The static deflection of the cantilever, as mounted in the valve body, was measured as a function of driving field strength with a confocal microscope. The deflection and high speed dynamical response of the cantilever can be easily changed and optimized for a particular nozzle diameter or repetition rate by a simple adjustment of the free cantilever length. Pulsed molecular beams with a full width at half maximum pulse width as low as 7 μs have been measured at a position 10 cm downstream of the nozzle exit. This represents a gas pulse with a length of only 10 mm making it well matched to for instance experiments using laser beams. Such a short pulse with 6 bar backing pressure behind a 150 μm nozzle releases about 1016 particles/pulse and the beam brightness was estimated to be 4×1022 particles/(s str). The short pulses of the cantilever piezovalve result in a much reduced gas load in the vacuum system. We demonstrate operation of the pulsed valve with skimmer in a single vacuum chamber pumped by a 520 l/s turbomolecular pump maintaining a pressure of 5×10-6 Torr, which is an excellent vacuum to have the strong and cold skimmed molecular beam interact with laser beams only 10 cm downstream of the nozzle to do velocity map slice imaging with a microchannel-plate imaging detector in a single chamber. The piezovalve produces cold and narrow (Δv /v=2%-3%) velocity distributions of molecules seeded in helium or neon at modest backing pressures of only 6 bar. The low gas load of the cantilever

  10. A short pulse (7 {mu}s FWHM) and high repetition rate (dc-5kHz) cantilever piezovalve for pulsed atomic and molecular beams

    SciTech Connect

    Irimia, Daniel; Dobrikov, Dimitar; Kortekaas, Rob; Voet, Han; Janssen, Maurice H. M.; Ende, Daan A. van den; Groen, Wilhelm A.

    2009-11-15

    In this paper we report on the design and operation of a novel piezovalve for the production of short pulsed atomic or molecular beams. The high speed valve operates on the principle of a cantilever piezo. The only moving part, besides the cantilever piezo itself, is a very small O-ring that forms the vacuum seal. The valve can operate continuous (dc) and in pulsed mode with the same drive electronics. Pulsed operation has been tested at repetition frequencies up to 5 kHz. The static deflection of the cantilever, as mounted in the valve body, was measured as a function of driving field strength with a confocal microscope. The deflection and high speed dynamical response of the cantilever can be easily changed and optimized for a particular nozzle diameter or repetition rate by a simple adjustment of the free cantilever length. Pulsed molecular beams with a full width at half maximum pulse width as low as 7 {mu}s have been measured at a position 10 cm downstream of the nozzle exit. This represents a gas pulse with a length of only 10 mm making it well matched to for instance experiments using laser beams. Such a short pulse with 6 bar backing pressure behind a 150 {mu}m nozzle releases about 10{sup 16} particles/pulse and the beam brightness was estimated to be 4x10{sup 22} particles/(s str). The short pulses of the cantilever piezovalve result in a much reduced gas load in the vacuum system. We demonstrate operation of the pulsed valve with skimmer in a single vacuum chamber pumped by a 520 l/s turbomolecular pump maintaining a pressure of 5x10{sup -6} Torr, which is an excellent vacuum to have the strong and cold skimmed molecular beam interact with laser beams only 10 cm downstream of the nozzle to do velocity map slice imaging with a microchannel-plate imaging detector in a single chamber. The piezovalve produces cold and narrow ({Delta}v/v=2%-3%) velocity distributions of molecules seeded in helium or neon at modest backing pressures of only 6 bar. The low gas

  11. A short pulse (7 micros FWHM) and high repetition rate (dc-5 kHz) cantilever piezovalve for pulsed atomic and molecular beams.

    PubMed

    Irimia, Daniel; Dobrikov, Dimitar; Kortekaas, Rob; Voet, Han; van den Ende, Daan A; Groen, Wilhelm A; Janssen, Maurice H M

    2009-11-01

    In this paper we report on the design and operation of a novel piezovalve for the production of short pulsed atomic or molecular beams. The high speed valve operates on the principle of a cantilever piezo. The only moving part, besides the cantilever piezo itself, is a very small O-ring that forms the vacuum seal. The valve can operate continuous (dc) and in pulsed mode with the same drive electronics. Pulsed operation has been tested at repetition frequencies up to 5 kHz. The static deflection of the cantilever, as mounted in the valve body, was measured as a function of driving field strength with a confocal microscope. The deflection and high speed dynamical response of the cantilever can be easily changed and optimized for a particular nozzle diameter or repetition rate by a simple adjustment of the free cantilever length. Pulsed molecular beams with a full width at half maximum pulse width as low as 7 micros have been measured at a position 10 cm downstream of the nozzle exit. This represents a gas pulse with a length of only 10 mm making it well matched to for instance experiments using laser beams. Such a short pulse with 6 bar backing pressure behind a 150 microm nozzle releases about 10(16) particles/pulse and the beam brightness was estimated to be 4x10(22) particles/(s str). The short pulses of the cantilever piezovalve result in a much reduced gas load in the vacuum system. We demonstrate operation of the pulsed valve with skimmer in a single vacuum chamber pumped by a 520 l/s turbomolecular pump maintaining a pressure of 5x10(-6) Torr, which is an excellent vacuum to have the strong and cold skimmed molecular beam interact with laser beams only 10 cm downstream of the nozzle to do velocity map slice imaging with a microchannel-plate imaging detector in a single chamber. The piezovalve produces cold and narrow (Delta v/v=2%-3%) velocity distributions of molecules seeded in helium or neon at modest backing pressures of only 6 bar. The low gas load of the

  12. In situ ion beam research in Argonne`s intermediate voltage electron microscope

    SciTech Connect

    Allen, C.W.; Ryan, E.A.

    1996-11-01

    Since Fall 1995, a state-of-the-art intermediate voltage electron microscope (IVEM) has been operational in the HVEM-Tandem Facility with in situ ion irradiation capabilities similar to those of the HVEM of the Facility. A 300 kV Hitachi H-9000NAR is interfaced to the two ion accelerators of the Facility, with a demonstrated point-to-point spatial resolution for imaging of 0.25 nm with the ion beamline attached to the microscope. The IVEM incorporates a Faraday cup system for ion dosimetry with measurement aperture 6.5 cm from the TEM specimen, which was described in Symposium A of the 1995 MRS Fall Meeting. The IVEM is now employed for a variety of in situ ion beam studies ranging from low dose ion damage experiments with GaAs, in which damage zones individual displacement cascades are observed, to implantation studies in metals, in which irradiation-induced noble gas precipitate mobility is studied in real time. In this presentation, the new instrumentation and its specifications will be described briefly, several basic concepts relating to in situ experiments in transmission electron microscopes will be summarized and examples of in situ experiments will be presented which exploit the experimental capabilities of this new user facility instrumentation.

  13. Electron Beam Induced Artifacts During in situ TEM Deformation of Nanostructured Metals

    PubMed Central

    Sarkar, Rohit; Rentenberger, Christian; Rajagopalan, Jagannathan

    2015-01-01

    A critical assumption underlying in situ transmission electron microscopy studies is that the electron beam (e-beam) exposure does not fundamentally alter the intrinsic deformation behavior of the materials being probed. Here, we show that e-beam exposure causes increased dislocation activation and marked stress relaxation in aluminum and gold films spanning a range of thicknesses (80–400 nanometers) and grain sizes (50–220 nanometers). Furthermore, the e-beam induces anomalous sample necking, which unusually depends more on the e-beam diameter than intensity. Notably, the stress relaxation in both aluminum and gold occurs at beam energies well below their damage thresholds. More remarkably, the stress relaxation and/or sample necking is significantly more pronounced at lower accelerating voltages (120 kV versus 200 kV) in both the metals. These observations in aluminum and gold, two metals with highly dissimilar atomic weights and properties, indicate that e-beam exposure can cause anomalous behavior in a broad spectrum of nanostructured materials, and simultaneously suggest a strategy to minimize such artifacts. PMID:26552934

  14. Electron Beam Induced Artifacts During in situ TEM Deformation of Nanostructured Metals

    NASA Astrophysics Data System (ADS)

    Sarkar, Rohit; Rentenberger, Christian; Rajagopalan, Jagannathan

    2015-11-01

    A critical assumption underlying in situ transmission electron microscopy studies is that the electron beam (e-beam) exposure does not fundamentally alter the intrinsic deformation behavior of the materials being probed. Here, we show that e-beam exposure causes increased dislocation activation and marked stress relaxation in aluminum and gold films spanning a range of thicknesses (80-400 nanometers) and grain sizes (50-220 nanometers). Furthermore, the e-beam induces anomalous sample necking, which unusually depends more on the e-beam diameter than intensity. Notably, the stress relaxation in both aluminum and gold occurs at beam energies well below their damage thresholds. More remarkably, the stress relaxation and/or sample necking is significantly more pronounced at lower accelerating voltages (120 kV versus 200 kV) in both the metals. These observations in aluminum and gold, two metals with highly dissimilar atomic weights and properties, indicate that e-beam exposure can cause anomalous behavior in a broad spectrum of nanostructured materials, and simultaneously suggest a strategy to minimize such artifacts.

  15. Electron Beam Induced Artifacts During in situ TEM Deformation of Nanostructured Metals.

    PubMed

    Sarkar, Rohit; Rentenberger, Christian; Rajagopalan, Jagannathan

    2015-01-01

    A critical assumption underlying in situ transmission electron microscopy studies is that the electron beam (e-beam) exposure does not fundamentally alter the intrinsic deformation behavior of the materials being probed. Here, we show that e-beam exposure causes increased dislocation activation and marked stress relaxation in aluminum and gold films spanning a range of thicknesses (80-400 nanometers) and grain sizes (50-220 nanometers). Furthermore, the e-beam induces anomalous sample necking, which unusually depends more on the e-beam diameter than intensity. Notably, the stress relaxation in both aluminum and gold occurs at beam energies well below their damage thresholds. More remarkably, the stress relaxation and/or sample necking is significantly more pronounced at lower accelerating voltages (120 kV versus 200 kV) in both the metals. These observations in aluminum and gold, two metals with highly dissimilar atomic weights and properties, indicate that e-beam exposure can cause anomalous behavior in a broad spectrum of nanostructured materials, and simultaneously suggest a strategy to minimize such artifacts. PMID:26552934

  16. Advanced in situ metrology for x-ray beam shaping with super precision.

    PubMed

    Wang, Hongchang; Sutter, John; Sawhney, Kawal

    2015-01-26

    We report a novel method for in situ metrology of an X-ray bimorph mirror by using the speckle scanning technique. Both the focusing beam and the "tophat" defocussed beam have been generated by optimizing the bimorph mirror in a single iteration. Importantly, we have demonstrated that the angular sensitivity for measuring the slope error of an optical surface can reach accuracy in the range of two nanoradians. When compared with conventional ex-situ metrology techniques, the method enables a substantial increase of around two orders of magnitude in the angular sensitivity and opens the way to a previously inaccessible region of slope error measurement. Such a super precision metrology technique will be beneficial for both the manufacture of polished mirrors and the optimization of beam shaping.

  17. IN SITU PRECISE ANGLE MONITORING ON SYNCHROTRON RADIATION MONOCHROMATOR BY USE OF PENCIL BEAM INTERFEROMETER.

    SciTech Connect

    QIAN,S.TAKACS,P.DONG,Q.HULBERT,S.

    2003-08-25

    Monochromator is a very important and precise instrument used in beam lines at synchrotron radiation facilities. We need to know if there is actual thermal distortion on gratings resulting in the degradation of the monochromator resolution. We need to know the characteristics of the grating rotation. It is possible to make a simple but precise in-situ distortion monitoring and rotation angle test of the grating by use of a precise pencil beam angle monitor. We have made preliminary measurements on a monochrometer grating of an undulator beam line X1B at Brookhaven National Laboratory. We monitored a small amount of angle variation on the grating. We detected 1.7 {micro}rad backlash (P-V) of the grating controlling system.

  18. Experimental procedures to mitigate electron beam induced artifacts during in situ fluid imaging of nanomaterials.

    PubMed

    Woehl, Taylor J; Jungjohann, Katherine L; Evans, James E; Arslan, Ilke; Ristenpart, William D; Browning, Nigel D

    2013-04-01

    Scanning transmission electron microscopy of various fluid and hydrated nanomaterial samples has revealed multiple imaging artifacts and electron beam-fluid interactions. These phenomena include growth of crystals on the fluid stage windows, repulsion of particles from the irradiated area, bubble formation, and the loss of atomic information during prolonged imaging of individual nanoparticles. Here we provide a comprehensive review of these fluid stage artifacts, and we present new experimental evidence that sheds light on their origins in terms of experimental apparatus issues and indirect electron beam sample interactions with the fluid layer. A key finding is that many artifacts are a result of indirect electron beam interactions, such as production of reactive radicals in the water by radiolysis, and the associated crystal growth. The results presented here will provide a methodology for minimizing fluid stage imaging artifacts and acquiring quantitative in situ observations of nanomaterial behavior in a liquid environment.

  19. "Metallic burn paper" used for in situ characterization of laser beam properties.

    PubMed

    Bass, Isaac L; Negres, Raluca A; Stanion, Ken; Guss, Gabe; Bude, Jeff

    2016-04-20

    In situ ablation of thin metal films on fused silica substrates by picosecond class lasers was investigated as a method of characterizing the beam at the sample plane. The technique involved plotting the areas enclosed by constant fluence contours identified in optical microscope images of the ablation sites versus the logs of the pulse energies. Inconel films on commercially available neutral density filters as well as magnetron sputtered gold films were used. It was also shown that this technique could be used to calibrate real-time beam profile diagnostics against the beam at the sample plane. The contours were shown to correspond to the boundary where part or all of the film was ablated.

  20. Novel in situ method for locating virtual source in high-rate electron-beam evaporation

    NASA Astrophysics Data System (ADS)

    Bhatia, M. S.

    1994-07-01

    The concept of virtual source simplifies calculation of thickness distribution on extended substrates in high rate vacuum coating employing electron-beam heating. The height of the point (virtual source), from which vapor can be assumed to emanate in accordance with Knudsen's cosine law, to yield the experimentally obtained thickness distribution, is calculated and this establishes the position of virtual source. Such as post facto determination is cumbersome as it is valid for the prescribed material evaporating at a certain rate in a specified geometry. A change in any of these entails a fresh measurement. Experimenters who use a large number of materials and deposit at different rates therefore have to carry out a number of trials before they can locate the virtual source at the desired deposition parameters. An in situ method for obtaining virtual source position can go a long way in reducing the labor of these experiments. A novel in situ method is described to locate the virtual source.

  1. In situ mitigation of subsurface and peripheral focused ion beam damage via simultaneous pulsed laser heating

    DOE PAGES

    Stanford, Michael G.; Lewis, Brett B.; Iberi, Vighter O.; Fowlkes, Jason Davidson; Tan, Shida; Livengood, Rick; Rack, Philip D.

    2016-02-16

    Focused helium and neon ion (He(+)/Ne(+) ) beam processing has recently been used to push resolution limits of direct-write nanoscale synthesis. The ubiquitous insertion of focused He(+) /Ne(+) beams as the next-generation nanofabrication tool-of-choice is currently limited by deleterious subsurface and peripheral damage induced by the energetic ions in the underlying substrate. The in situ mitigation of subsurface damage induced by He(+)/Ne(+) ion exposures in silicon via a synchronized infrared pulsed laser-assisted process is demonstrated. The pulsed laser assist provides highly localized in situ photothermal energy which reduces the implantation and defect concentration by greater than 90%. The laser-assisted exposuremore » process is also shown to reduce peripheral defects in He(+) patterned graphene, which makes this process an attractive candidate for direct-write patterning of 2D materials. In conclusion, these results offer a necessary solution for the applicability of high-resolution direct-write nanoscale material processing via focused ion beams.« less

  2. In Situ Mitigation of Subsurface and Peripheral Focused Ion Beam Damage via Simultaneous Pulsed Laser Heating.

    PubMed

    Stanford, Michael G; Lewis, Brett B; Iberi, Vighter; Fowlkes, Jason D; Tan, Shida; Livengood, Rick; Rack, Philip D

    2016-04-01

    Focused helium and neon ion (He(+)/Ne(+)) beam processing has recently been used to push resolution limits of direct-write nanoscale synthesis. The ubiquitous insertion of focused He(+)/Ne(+) beams as the next-generation nanofabrication tool-of-choice is currently limited by deleterious subsurface and peripheral damage induced by the energetic ions in the underlying substrate. The in situ mitigation of subsurface damage induced by He(+)/Ne(+) ion exposures in silicon via a synchronized infrared pulsed laser-assisted process is demonstrated. The pulsed laser assist provides highly localized in situ photothermal energy which reduces the implantation and defect concentration by greater than 90%. The laser-assisted exposure process is also shown to reduce peripheral defects in He(+) patterned graphene, which makes this process an attractive candidate for direct-write patterning of 2D materials. These results offer a necessary solution for the applicability of high-resolution direct-write nanoscale material processing via focused ion beams. PMID:26864147

  3. In Situ Mitigation of Subsurface and Peripheral Focused Ion Beam Damage via Simultaneous Pulsed Laser Heating.

    PubMed

    Stanford, Michael G; Lewis, Brett B; Iberi, Vighter; Fowlkes, Jason D; Tan, Shida; Livengood, Rick; Rack, Philip D

    2016-04-01

    Focused helium and neon ion (He(+)/Ne(+)) beam processing has recently been used to push resolution limits of direct-write nanoscale synthesis. The ubiquitous insertion of focused He(+)/Ne(+) beams as the next-generation nanofabrication tool-of-choice is currently limited by deleterious subsurface and peripheral damage induced by the energetic ions in the underlying substrate. The in situ mitigation of subsurface damage induced by He(+)/Ne(+) ion exposures in silicon via a synchronized infrared pulsed laser-assisted process is demonstrated. The pulsed laser assist provides highly localized in situ photothermal energy which reduces the implantation and defect concentration by greater than 90%. The laser-assisted exposure process is also shown to reduce peripheral defects in He(+) patterned graphene, which makes this process an attractive candidate for direct-write patterning of 2D materials. These results offer a necessary solution for the applicability of high-resolution direct-write nanoscale material processing via focused ion beams.

  4. In situ surface/interface x-ray diffractometer for oxide molecular beam epitaxy

    SciTech Connect

    Lee, J. H.; Tung, I. C.; Chang, S. -H.; Bhattacharya, A.; Fong, D. D.; Freeland, J. W.; Hong, Hawoong

    2016-01-01

    In situ studies of oxide molecular beam epitaxy by synchrotron x-ray scattering has been made possible by upgrading an existing UHV/molecular beam epitaxy (MBE) six-circle diffractometer system. For oxide MBE growth, pure ozone delivery to the chamber has been made available, and several new deposition sources have been made available on a new 12 in. CF (ConFlat, a registered trademark of Varian, Inc.) flange. X-ray diffraction has been used as a major probe for film growth and structures for the system. In the original design, electron diffraction was intended for the secondary diagnostics available without the necessity of the x-ray and located at separate positions. Deposition of films was made possible at the two diagnostic positions. And, the aiming of the evaporation sources is fixed to the point between two locations. Ozone can be supplied through two separate nozzles for each location. Also two separate thickness monitors are installed. Additional features of the equipment are also presented together with the data taken during typical oxide film growth to illustrate the depth of information available via in situ x-ray techniques.

  5. In situ surface/interface x-ray diffractometer for oxide molecular beam epitaxy.

    PubMed

    Lee, J H; Tung, I C; Chang, S-H; Bhattacharya, A; Fong, D D; Freeland, J W; Hong, Hawoong

    2016-01-01

    In situ studies of oxide molecular beam epitaxy by synchrotron x-ray scattering has been made possible by upgrading an existing UHV/molecular beam epitaxy (MBE) six-circle diffractometer system. For oxide MBE growth, pure ozone delivery to the chamber has been made available, and several new deposition sources have been made available on a new 12 in. CF (ConFlat, a registered trademark of Varian, Inc.) flange. X-ray diffraction has been used as a major probe for film growth and structures for the system. In the original design, electron diffraction was intended for the secondary diagnostics available without the necessity of the x-ray and located at separate positions. Deposition of films was made possible at the two diagnostic positions. And, the aiming of the evaporation sources is fixed to the point between two locations. Ozone can be supplied through two separate nozzles for each location. Also two separate thickness monitors are installed. Additional features of the equipment are also presented together with the data taken during typical oxide film growth to illustrate the depth of information available via in situ x-ray techniques.

  6. Effects of initial delamination on CIc and GIth values from glass/epoxy double cantilever beam tests

    NASA Technical Reports Server (NTRS)

    Martin, Roderick H.

    1988-01-01

    The effect of insert thickness and method of precracking on mode I interlaminar fracture toughness, GIc, and delamination fatigue threshold, GIth, values were determined for a glass/epoxy double cantilever beam specimen. The results of the static tests showed that precracking in tension would cause fiber bridging and thus may yield unconservative values of GIc and GIth. Precracking in shear yields suitable values of GIc but overly conservative values of GIth. For the glass/epoxy composite used, an insert thickness of 0.5 mil was most suitable for determining GIc and GIth values, although an insert thickness up to 3 mil was acceptable. Inserts thicker than 3 mil were not acceptable for determining GIc and GIth values.

  7. Fluid-structure interaction of quasi-one-dimensional potential flow along channel bounded by symmetric cantilever beams

    NASA Astrophysics Data System (ADS)

    Jang, Gang-Won; Chang, Se-Myong; Gim, Gyun-Ho

    2013-07-01

    An analysis of fluid-structure interaction is presented for incompressible and inviscid flow in a channel bounded by symmetric cantilever beams. Small deflections of the beams and no flows normal to the beams are assumed, thus allowing the governing equations to be defined using quasi-one-dimensional pressure and flow velocity distribution; pressure and velocity are assumed to be uniform across the cross section of the channel. The steady-state solution of the present problem is analytically derived by the linearization of the governing equations. The solution is shown to consist of infinite modes, which is verified by comparing with numerical solutions obtained by the finite element method. The nonlinear effect in the steady-state solution is modeled by numerical method to estimate the error due to linearization. However, only a few leading modes are physically significant owing to the effects of flow compressibility and viscosity. The analytic solutions of the fluid-structure interaction are also presented for dynamic problems assuming harmonic vibration. The steady-state and stationary initial conditions are used, and the equilibrium frequency is determined to minimize the residual error of Euler equation. The fluid-structure interaction is characterized by a phase difference and distortion of waveform shape in the time history of the boundary velocity.

  8. Robust energy harvesting from walking vibrations by means of nonlinear cantilever beams

    NASA Astrophysics Data System (ADS)

    Kluger, Jocelyn M.; Sapsis, Themistoklis P.; Slocum, Alexander H.

    2015-04-01

    In the present work we examine how mechanical nonlinearity can be appropriately utilized to achieve strong robustness of performance in an energy harvesting setting. More specifically, for energy harvesting applications, a great challenge is the uncertain character of the excitation. The combination of this uncertainty with the narrow range of good performance for linear oscillators creates the need for more robust designs that adapt to a wider range of excitation signals. A typical application of this kind is energy harvesting from walking vibrations. Depending on the particular characteristics of the person that walks as well as on the pace of walking, the excitation signal obtains completely different forms. In the present work we study a nonlinear spring mechanism that is composed of a cantilever wrapping around a curved surface as it deflects. While for the free cantilever, the force acting on the free tip depends linearly on the tip displacement, the utilization of a contact surface with the appropriate distribution of curvature leads to essentially nonlinear dependence between the tip displacement and the acting force. The studied nonlinear mechanism has favorable mechanical properties such as low frictional losses, minimal moving parts, and a rugged design that can withstand excessive loads. Through numerical simulations we illustrate that by utilizing this essentially nonlinear element in a 2 degrees-of-freedom (DOF) system, we obtain strongly nonlinear energy transfers between the modes of the system. We illustrate that this nonlinear behavior is associated with strong robustness over three radically different excitation signals that correspond to different walking paces. To validate the strong robustness properties of the 2DOF nonlinear system, we perform a direct parameter optimization for 1DOF and 2DOF linear systems as well as for a class of 1DOF and 2DOF systems with nonlinear springs similar to that of the cubic spring that are physically realized

  9. Thermographic In-Situ Process Monitoring of the Electron Beam Melting Technology used in Additive Manufacturing

    SciTech Connect

    Dinwiddie, Ralph Barton; Dehoff, Ryan R; Lloyd, Peter D; Lowe, Larry E; Ulrich, Joseph B

    2013-01-01

    Oak Ridge National Laboratory (ORNL) has been utilizing the ARCAM electron beam melting technology to additively manufacture complex geometric structures directly from powder. Although the technology has demonstrated the ability to decrease costs, decrease manufacturing lead-time and fabricate complex structures that are impossible to fabricate through conventional processing techniques, certification of the component quality can be challenging. Because the process involves the continuous deposition of successive layers of material, each layer can be examined without destructively testing the component. However, in-situ process monitoring is difficult due to metallization on inside surfaces caused by evaporation and condensation of metal from the melt pool. This work describes a solution to one of the challenges to continuously imaging inside of the chamber during the EBM process. Here, the utilization of a continuously moving Mylar film canister is described. Results will be presented related to in-situ process monitoring and how this technique results in improved mechanical properties and reliability of the process.

  10. In-situ Study of Nanostructure and Electrical Resistance of Nanocluster Films Irradiated with Ion Beams

    SciTech Connect

    Jiang, Weilin; Sundararajan, Jennifer A.; Varga, Tamas; Bowden, Mark E.; Qiang, You; McCloy, John S.; Henager, Charles H.; Montgomery, Robert O.

    2014-08-11

    An in-situ study is reported on the structural evolution in nanocluster films under He+ ion irradiation using an advanced helium ion microscope. The films consist of loosely interconnected nanoclusters of magnetite or iron-magnetite (Fe-Fe3O4) core-shells. The nanostructure is observed to undergo dramatic changes under ion-beam irradiation, featuring grain growth, phase transition, particle aggregation, and formation of nanowire-like network and nano-pores. Studies based on ion irradiation, thermal annealing and election irradiation have indicated that the major structural evolution is activated by elastic nuclear collisions, while both electronic and thermal processes can play a significant role once the evolution starts. The electrical resistance of the Fe-Fe3O4 films measured in situ exhibits a super-exponential decay with dose. The behavior suggests that the nanocluster films possess an intrinsic merit for development of an advanced online monitor for neutron radiation with both high detection sensitivity and long-term applicability, which can enhance safety measures in many nuclear operations.

  11. Mechanical test in-situ fracture device for Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Moorhead, R. D.

    1975-01-01

    An in-situ fracture device for Auger spectroscopy was described. The device is designed to handle small tensile specimens or small double cantilever beam specimens and is fully instrumented with load and displacement transducers so that quantitative stress-strain measurements can be made directly. Some initial test results for specimens made from 4130 and 1020 steel were presented.

  12. In situ formation of bismuth nanoparticles through electron-beam irradiation in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Sepulveda-Guzman, S.; Elizondo-Villarreal, N.; Ferrer, D.; Torres-Castro, A.; Gao, X.; Zhou, J. P.; Jose-Yacaman, M.

    2007-08-01

    In this work, bismuth nanoparticles were synthesized when a precursor, sodium bismuthate, was exposed to an electron beam at room temperature in a transmission electron microscope (TEM). The irradiation effects were investigated in situ using selected-area electron diffraction, high-resolution transmission electron microscopy and x-ray energy dispersive spectroscopy. After the electron irradiation, bismuth nanoparticles with a rhombohedral structure and diameter of 6 nm were observed. The average particle size increased with the irradiation time. The electron-induced reduction is attributed to the desorption of oxygen ions. This method offers a one-step route to synthesize bismuth nanoparticles using electron irradiation, and the particle size can be controlled by the irradiation time.

  13. Non-uniform shrinkage of multiple-walled carbon nanotubes under in situ electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Li, Lunxiong; Su, Jiangbin; Zhu, Xianfang

    2016-10-01

    Instability of multiple-walled carbon nanotubes (MWCNTs) was investigated by in situ transmission electron microscopy at room temperature. Specially, the non-uniform shrinkage of tubes was found: The pristine MWCNT shrank preferentially in its axial direction from the most curved free cap end of the tube, but the shrinkage of the tube diameter was offset by the axial shrinkage: For the complex MWCNT, the two inner MWCNTs also preferentially axially shrank from their most curved cap ends and separated from each other. However, for the effect of the radial pressure from the out walls which enveloped the two inner tubes and the tube amorphization, the two inner tubes were extruded to come close to each other and finally touched again. The new "evaporation" and "diffusion" mechanisms of carbon atoms as driven by the nano-curvature of CNT and the electron beam-induced athermal activation were suggested to explain the above phenomena.

  14. Micro-/nanosized cantilever beams and mass sensors under applied axial tensile/compressive force vibrating in vacuum and viscous fluid

    SciTech Connect

    Stachiv, Ivo; Fang, Te-Hua; Chen, Tao-Hsing

    2015-11-15

    Vibrating micro-/nanosized cantilever beams under an applied axial force are the key components of various devices used in nanotechnology. In this study, we perform a complete theoretical investigation of the cantilever beams under an arbitrary value of the axial force vibrating in a specific environment such as vacuum, air or viscous fluid. Based on the results easy accessible expressions enabling one the fast and highly accurate estimations of changes in the Q-factor and resonant frequencies of beam oscillating in viscous fluid caused by the applied axial force are derived and analyzed. It has been also shown that for beam-to-string and string vibrational regimes the mode shape starts to significantly deviate from the one known for a beam without axial force. Moreover, a linear dependency of the vibrational amplitude in resonance on the dimensionless tension parameter has been found. We revealed that only a large axial force, i.e. the string vibrational regime, significantly improves the Q-factor of beams submerged in fluid, while an increase of the axial force in beam and beam-to-string transition regimes has a negligibly small impact on the Q-factor enhancement. Experiments carried out on the carbon nanotubes and nanowires are in a good agreement with present theoretical predictions.

  15. Micro-/nanosized cantilever beams and mass sensors under applied axial tensile/compressive force vibrating in vacuum and viscous fluid

    NASA Astrophysics Data System (ADS)

    Stachiv, Ivo; Fang, Te-Hua; Chen, Tao-Hsing

    2015-11-01

    Vibrating micro-/nanosized cantilever beams under an applied axial force are the key components of various devices used in nanotechnology. In this study, we perform a complete theoretical investigation of the cantilever beams under an arbitrary value of the axial force vibrating in a specific environment such as vacuum, air or viscous fluid. Based on the results easy accessible expressions enabling one the fast and highly accurate estimations of changes in the Q-factor and resonant frequencies of beam oscillating in viscous fluid caused by the applied axial force are derived and analyzed. It has been also shown that for beam-to-string and string vibrational regimes the mode shape starts to significantly deviate from the one known for a beam without axial force. Moreover, a linear dependency of the vibrational amplitude in resonance on the dimensionless tension parameter has been found. We revealed that only a large axial force, i.e. the string vibrational regime, significantly improves the Q-factor of beams submerged in fluid, while an increase of the axial force in beam and beam-to-string transition regimes has a negligibly small impact on the Q-factor enhancement. Experiments carried out on the carbon nanotubes and nanowires are in a good agreement with present theoretical predictions.

  16. Advanced in-situ electron-beam lithography for deterministic nanophotonic device processing.

    PubMed

    Kaganskiy, Arsenty; Gschrey, Manuel; Schlehahn, Alexander; Schmidt, Ronny; Schulze, Jan-Hindrik; Heindel, Tobias; Strittmatter, André; Rodt, Sven; Reitzenstein, Stephan

    2015-07-01

    We report on an advanced in-situ electron-beam lithography technique based on high-resolution cathodoluminescence (CL) spectroscopy at low temperatures. The technique has been developed for the deterministic fabrication and quantitative evaluation of nanophotonic structures. It is of particular interest for the realization and optimization of non-classical light sources which require the pre-selection of single quantum dots (QDs) with very specific emission features. The two-step electron-beam lithography process comprises (a) the detailed optical study and selection of target QDs by means of CL-spectroscopy and (b) the precise retrieval of the locations and integration of target QDs into lithographically defined nanostructures. Our technology platform allows for a detailed pre-process determination of important optical and quantum optical properties of the QDs, such as the emission energies of excitonic complexes, the excitonic fine-structure splitting, the carrier dynamics, and the quantum nature of emission. In addition, it enables a direct and precise comparison of the optical properties of a single QD before and after integration which is very beneficial for the quantitative evaluation of cavity-enhanced quantum devices. PMID:26233395

  17. Enhancing RHIC luminosity capabilities with in-situ beam piple coating

    SciTech Connect

    Herschcovitch,A.; Blaskiewicz, M.; Fischer, W.; Poole, H. J.

    2009-05-04

    Electron clouds have been observed in many accelerators, including the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory (BNL). They can limit the machine performance through pressure degradation, beam instabilities or incoherent emittance growth. The formation of electron clouds can be suppressed with beam pipe surfaces that have low secondary electron yield. At the same time, high wall resistivity in accelerators can result in levels of ohmic heating unacceptably high for superconducting magnets. This is a concern for the RHIC machine, as its vacuum chamber in the superconducting dipoles is made from relatively high resistivity 316LN stainless steel. The high resistivity can be addressed with a copper (Cu) coating; a reduction in the secondary electron yield can be achieved with a titanium nitride (TiN) or amorphous carbon (a-C) coating. Applying such coatings in an already constructed machine is rather challenging. We started developing a robotic plasma deposition technique for in-situ coating of long, small diameter tubes. The technique entails fabricating a device comprised of staged magnetrons and/or cathodic arcs mounted on a mobile mole for deposition of about 5 {micro}m (a few skin depths) of Cu followed by about 0.1 {micro}m of TiN (or a-C).

  18. Advanced in-situ electron-beam lithography for deterministic nanophotonic device processing

    SciTech Connect

    Kaganskiy, Arsenty; Gschrey, Manuel; Schlehahn, Alexander; Schmidt, Ronny; Schulze, Jan-Hindrik; Heindel, Tobias; Rodt, Sven Reitzenstein, Stephan; Strittmatter, André

    2015-07-15

    We report on an advanced in-situ electron-beam lithography technique based on high-resolution cathodoluminescence (CL) spectroscopy at low temperatures. The technique has been developed for the deterministic fabrication and quantitative evaluation of nanophotonic structures. It is of particular interest for the realization and optimization of non-classical light sources which require the pre-selection of single quantum dots (QDs) with very specific emission features. The two-step electron-beam lithography process comprises (a) the detailed optical study and selection of target QDs by means of CL-spectroscopy and (b) the precise retrieval of the locations and integration of target QDs into lithographically defined nanostructures. Our technology platform allows for a detailed pre-process determination of important optical and quantum optical properties of the QDs, such as the emission energies of excitonic complexes, the excitonic fine-structure splitting, the carrier dynamics, and the quantum nature of emission. In addition, it enables a direct and precise comparison of the optical properties of a single QD before and after integration which is very beneficial for the quantitative evaluation of cavity-enhanced quantum devices.

  19. Advanced in-situ electron-beam lithography for deterministic nanophotonic device processing

    NASA Astrophysics Data System (ADS)

    Kaganskiy, Arsenty; Gschrey, Manuel; Schlehahn, Alexander; Schmidt, Ronny; Schulze, Jan-Hindrik; Heindel, Tobias; Strittmatter, André; Rodt, Sven; Reitzenstein, Stephan

    2015-07-01

    We report on an advanced in-situ electron-beam lithography technique based on high-resolution cathodoluminescence (CL) spectroscopy at low temperatures. The technique has been developed for the deterministic fabrication and quantitative evaluation of nanophotonic structures. It is of particular interest for the realization and optimization of non-classical light sources which require the pre-selection of single quantum dots (QDs) with very specific emission features. The two-step electron-beam lithography process comprises (a) the detailed optical study and selection of target QDs by means of CL-spectroscopy and (b) the precise retrieval of the locations and integration of target QDs into lithographically defined nanostructures. Our technology platform allows for a detailed pre-process determination of important optical and quantum optical properties of the QDs, such as the emission energies of excitonic complexes, the excitonic fine-structure splitting, the carrier dynamics, and the quantum nature of emission. In addition, it enables a direct and precise comparison of the optical properties of a single QD before and after integration which is very beneficial for the quantitative evaluation of cavity-enhanced quantum devices.

  20. Optimum structural sizing of conventional cantilever and joined wing configurations using equivalent beam models

    NASA Technical Reports Server (NTRS)

    Hajela, P.; Chen, J. L.

    1986-01-01

    The present paper describes an approach for the optimum sizing of single and joined wing structures that is based on representing the built-up finite element model of the structure by an equivalent beam model. The low order beam model is computationally more efficient in an environment that requires repetitive analysis of several trial designs. The design procedure is implemented in a computer program that requires geometry and loading data typically available from an aerodynamic synthesis program, to create the finite element model of the lifting surface and an equivalent beam model. A fully stressed design procedure is used to obtain rapid estimates of the optimum structural weight for the beam model for a given geometry, and a qualitative description of the material distribution over the wing structure. The synthesis procedure is demonstrated for representative single wing and joined wing structures.

  1. Nonlinear targeted energy transfer of two coupled cantilever beams coupled to a bistable light attachment

    NASA Astrophysics Data System (ADS)

    Mattei, P.-O.; Ponçot, R.; Pachebat, M.; Côte, R.

    2016-07-01

    In order to control the sound radiation by a structure, one aims to control vibration of radiating modes of vibration using "Energy Pumping" also named "Targeted Energy Transfer". This principle is here applied to a simplified model of a double leaf panel. This model is made of two beams coupled by a spring. One of the beams is connected to a nonlinear absorber. This nonlinear absorber is made of a 3D-printed support on which is clamped a buckled thin small beam with a small mass fixed at its centre having two equilibrium positions. The experiments showed that, once attached onto a vibrating system to be controlled, under forced excitation of the primary system, the light bistable oscillator allows a reduction of structural vibration up to 10 dB for significant amplitude and frequency range around the first two vibration modes of the system.

  2. A Novel Method for Characterizing Fatigue Delamination Growth Under Mode I Using the Double Cantilever Beam Specimen

    NASA Technical Reports Server (NTRS)

    Carvalho, Nelson; Murri, G.

    2014-01-01

    A novel method is proposed to obtain Mode I delamination growth rate from a Double Cantilever Beam (DCB) specimen. In the proposed method, Unidirectional (UD) DCB specimens are tested in fatigue at different initial maximum energy release rates levels. The growth rate data obtained in the first increments of crack growth at each maximum energy release rate level are used to generate a Paris Law equation, which characterizes delamination growth rate without fiber-bridging, and can also be used to determine a delamination onset curve. The remaining delamination growth rate data from each test are used to determine a modified Paris law, which characterizes the delamination growth rate in a DCB specimen, explicitly accounting for fiber-bridging. The proposed expression captures well the scatter in experimental data obtained using the DCB specimens, suggesting its adequacy. The Paris Law characterizing delamination growth rate without fiber-bridging predicts higher delamination growth rates for the same maximum energy release rate applied, leading to a conservative estimate for delamination growth. This is particularly relevant, since in generic ply interfaces, fiber-bridging is less predominant than in UD DCB specimens. Failing to account for fiber-bridging in UD DCB specimens may underestimate the delamination growth rate, yielding non-conservative predictions.

  3. Modeling energy transport in a cantilevered Euler-Bernoulli beam actively vibrating in Newtonian fluid

    NASA Astrophysics Data System (ADS)

    Faria, Cassio T.; Inman, Daniel J.

    2014-04-01

    When a mechanical and/or structural component is immersed in a fluid and it vibrates, the reasonable assumption is that part of the energy is transmitted to the adjacent media. For some engineering applications the energy transport between these two domains, i.e., structure and fluid, plays a central role. The work presented in this paper is focused on discussing the energy transport in beam-like structures as they can be used to represent flexible swimmers (fish-like pulsating mechanisms) in their simplest form. In order to expose the role of each of the fluid and beam properties effecting the energy transfer process, a simplified analytical fluid-structure interaction (FSI) model is derived. After analysis of the resulting coupled-systems' damping coefficient, a new energy transport component is added to the initial Euler-Bernoulli beam equation; a term associated with diffusion (fluid viscosity). In addition our modeling results in an added mass term, a characteristic consistent with previous literature. While deriving the model, an important assumption is made: beam mode shapes are not significantly affected by the domains' interaction. This hypothesis is experimentally tested in two different fluid media and confirmed to be reasonable for the first three vibration mode shapes.

  4. Precise voltage contrast image assisted positioning for in situ electron beam nanolithography for nanodevice fabrication with suspended nanowire structures

    NASA Astrophysics Data System (ADS)

    Long, Renhai; Chen, Jiajun; Lim, Jin-Hee; Wiley, John B.; Zhou, Weilie

    2009-07-01

    In this paper, we demonstrate precise voltage contrast image positioning for in situ electron beam (e-beam) nanolithography to integrate nanowires into suspended structures for nanoswitch fabrication. The positioning of the deflection electrodes on the nanowires can be well controlled using a precise voltage contrast image positioning technique, where the error can be minimized to about 10 nm. Using such a method, dispersed nanowires can be sandwiched between two layers of resist and suspended by one e-beam nanolithography process without any etching. The in situ e-beam nanolithography eliminates the stage movement error by preventing any movements of the stage during the nanolithography process; hence, a high precision laser stage and alignment marks on the substrate are not needed, which simplifies the traditional e-beam nanolithography process. The nanoswitches fabricated using this method show ON and OFF states with the changes of applied voltages. This simplified process provides an easy, low cost and less time-consuming route to integrating suspended nanowire based structures using a converted field emission scanning electron microscope e-beam system, which can also be customized to fabricate multi-layer structures and a site-specific nanodevice fabrication.

  5. In situ stress monitoring of the concrete beam under static loading with cement-based piezoelectric sensors

    NASA Astrophysics Data System (ADS)

    Dong, Biqin; Liu, Yuqing; Qin, Lei; Wang, Yaocheng; Fang, Yuan; Xing, Feng; Chen, Xianchuan

    2015-10-01

    In this paper, the application of a novel cement-based piezoelectric ceramic sensor is stated for the in situ stress monitoring of the reinforced concrete beam under static loading. Smart beam composite structures were designed and characterised by a range of experimental methods. Finite element analysis is used to analyse the mechanical response of the concrete beam under static loading. The results show that the mechanical-electrical response of sensors embedded in reinforced concrete beams follows a linear relationship under various loading conditions. The sensors are able to record the stress history of the beam under static loads. Moreover, the measured stress data agree well with the simulated results and the smart structures are found to be capable of reliably monitoring the response of a beam during stress testing for static loading modes to real concrete structures. The study indicates that such cement-based piezoelectric composites have a high feasibility and applicability to the in situ stress monitoring of reinforced concrete structures.

  6. Uncertain boundary condition Bayesian identification from experimental data: A case study on a cantilever beam

    NASA Astrophysics Data System (ADS)

    Ritto, T. G.; Sampaio, R.; Aguiar, R. R.

    2016-02-01

    In many mechanical applications (wind turbine tower, substructure joints, etc.), the stiffness of the boundary conditions is uncertain and might decrease with time, due to wear and/or looseness. In this paper, a torsional stiffness parameter is used to model the clamped side of a Timoshenko beam. The goal is to perform the identification with experimental data. To represent the decreasing stiffness of the clamped side, an experimental test rig is constructed, where several rubber layers are added to the clamped side, making it softer. Increasing the number of layers decreases the stiffness, thus representing a loss in the stiffness. The Bayesian approach is applied to update the probabilistic model related to the boundary condition (torsional stiffness parameter). The proposed Bayesian strategy worked well for the problem analyzed, where the experimental natural frequencies were within the 95% confidence limits of the computed natural frequencies probability density functions.

  7. Bending and shear stresses developed by the instantaneous arrest of the root of a cantilever beam rotating with constant angular velocity about a transverse axis through the root

    NASA Technical Reports Server (NTRS)

    Stowell, Elbridge Z; Schwartz, Edward B; Houbolt, John C

    1945-01-01

    A theoretical investigation was made of the behavior of a cantilever beam in rotational motion about a transverse axis through the root determining the stresses, the deflections, and the accelerations that occur in the beam as a result of the arrest of motion. The equations for bending and shear stress reveal that, at a given percentage of the distance from root to tip and at a given trip velocity, the bending stresses for a particular mode are independent of the length of the beam and the shear stresses vary inversely with the length. When examined with respect to a given angular velocity instead of a given tip velocity, the equations reveal that the bending stress is proportional to the length of the beam whereas the shear stress is independent of the length. Sufficient experimental verification of the theory has previously been given in connection with another problem of the same type.

  8. In-situ characterization of nanoparticle beams focused with an aerodynamic lens by Laser-Induced Breakdown Detection.

    PubMed

    Barreda, F-A; Nicolas, C; Sirven, J-B; Ouf, F-X; Lacour, J-L; Robert, E; Benkoula, S; Yon, J; Miron, C; Sublemontier, O

    2015-01-01

    The Laser-Induced Breakdown Detection technique (LIBD) was adapted to achieve fast in-situ characterization of nanoparticle beams focused under vacuum by an aerodynamic lens. The method employs a tightly focused, 21 μm, scanning laser microprobe which generates a local plasma induced by the laser interaction with a single particle. A counting mode optical detection allows the achievement of 2D mappings of the nanoparticle beams with a reduced analysis time thanks to the use of a high repetition rate infrared pulsed laser. As an example, the results obtained with Tryptophan nanoparticles are presented and the advantages of this method over existing ones are discussed. PMID:26498694

  9. Note: An advanced in situ diagnostic system for characterization of electric propulsion thrusters and ion beam sources

    NASA Astrophysics Data System (ADS)

    Bundesmann, C.; Tartz, M.; Scholze, F.; Leiter, H. J.; Scortecci, F.; Gnizdor, R. Y.; Neumann, H.

    2010-04-01

    We present an advanced diagnostic system for in situ characterization of electric propulsion thrusters and ion beam sources. The system uses a high-precision five-axis positioning system with a modular setup and the following diagnostic tools: a telemicroscopy head for optical imaging, a triangular laser head for surface profile scanning, a pyrometer for temperature scanning, a Faraday probe for current density mapping, and an energy-selective mass spectrometer for beam characterization (energy and mass distribution, composition). The capabilities of our diagnostic system are demonstrated with a Hall effect thruster SPT-100D EM1.

  10. In-situ characterization of nanoparticle beams focused with an aerodynamic lens by Laser-Induced Breakdown Detection

    PubMed Central

    Barreda, F.-A.; Nicolas, C.; Sirven, J.-B.; Ouf, F.-X.; Lacour, J.-L.; Robert, E.; Benkoula, S.; Yon, J.; Miron, C.; Sublemontier, O.

    2015-01-01

    The Laser-Induced Breakdown Detection technique (LIBD) was adapted to achieve fast in-situ characterization of nanoparticle beams focused under vacuum by an aerodynamic lens. The method employs a tightly focused, 21 μm, scanning laser microprobe which generates a local plasma induced by the laser interaction with a single particle. A counting mode optical detection allows the achievement of 2D mappings of the nanoparticle beams with a reduced analysis time thanks to the use of a high repetition rate infrared pulsed laser. As an example, the results obtained with Tryptophan nanoparticles are presented and the advantages of this method over existing ones are discussed. PMID:26498694

  11. In-situ characterization of nanoparticle beams focused with an aerodynamic lens by Laser-Induced Breakdown Detection.

    PubMed

    Barreda, F-A; Nicolas, C; Sirven, J-B; Ouf, F-X; Lacour, J-L; Robert, E; Benkoula, S; Yon, J; Miron, C; Sublemontier, O

    2015-10-26

    The Laser-Induced Breakdown Detection technique (LIBD) was adapted to achieve fast in-situ characterization of nanoparticle beams focused under vacuum by an aerodynamic lens. The method employs a tightly focused, 21 μm, scanning laser microprobe which generates a local plasma induced by the laser interaction with a single particle. A counting mode optical detection allows the achievement of 2D mappings of the nanoparticle beams with a reduced analysis time thanks to the use of a high repetition rate infrared pulsed laser. As an example, the results obtained with Tryptophan nanoparticles are presented and the advantages of this method over existing ones are discussed.

  12. Note: An advanced in situ diagnostic system for characterization of electric propulsion thrusters and ion beam sources.

    PubMed

    Bundesmann, C; Tartz, M; Scholze, F; Leiter, H J; Scortecci, F; Gnizdor, R Y; Neumann, H

    2010-04-01

    We present an advanced diagnostic system for in situ characterization of electric propulsion thrusters and ion beam sources. The system uses a high-precision five-axis positioning system with a modular setup and the following diagnostic tools: a telemicroscopy head for optical imaging, a triangular laser head for surface profile scanning, a pyrometer for temperature scanning, a Faraday probe for current density mapping, and an energy-selective mass spectrometer for beam characterization (energy and mass distribution, composition). The capabilities of our diagnostic system are demonstrated with a Hall effect thruster SPT-100D EM1. PMID:20441379

  13. Tensile, Compression, Open-Hole Compression and Double Cantilever Beam Fracture Toughness Testing of Multiple NASA Langley Research Center Composite Materials

    NASA Technical Reports Server (NTRS)

    Adams, Donald F.

    1999-01-01

    The attached data summarizes the work performed by the Composite Materials Research Group at the University of Wyoming funded by the NASA LaRC Research Grant NAG-1-1294. The work consisted primarily of tension, compression, open-hole compression and double cantilever beam fracture toughness testing performed an a variety of NASA LaRC composite materials. Tests were performed at various environmental conditions and pre-conditioning requirements. The primary purpose of this work was to support the LaRC material development efforts. The data summaries are arranged in chronological order from oldest to newest.

  14. In situ patterning of organic molecules in aqueous solutions using an inverted electron-beam lithography system

    NASA Astrophysics Data System (ADS)

    Miyazako, Hiroki; Ishihara, Kazuhiko; Mabuchi, Kunihiko; Hoshino, Takayuki

    2016-06-01

    A method for in situ controlling the detachment and deposition of organic molecules such as sugars and biocompatible polymers in aqueous solutions by electron-beam (EB) scan is proposed and evaluated. It was demonstrated that EB irradiation could detach 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers from a silicon nitride membrane. Moreover, organic molecules such as cationic polymers and sugars could be deposited on the membrane by EB irradiation. Spatial distributions of scattered electrons were numerically simulated, and acceleration voltage dependences of the detachment and deposition phenomena were experimentally measured. The simulations and experimental results suggest that the detachment of MPC polymers is mainly due to electrical effects of primary electrons, and that the deposition of organic molecules is mainly due to chemical reactions induced by primary electrons. In view of these findings, the proposed method can be applied to in situ and nanoscale patterning such as the fabrication of cell scaffolds.

  15. In situ magnetic compensation for potassium spin-exchange relaxation-free magnetometer considering probe beam pumping effect

    SciTech Connect

    Fang, Jiancheng; Wang, Tao Quan, Wei; Yuan, Heng; Li, Yang; Zhang, Hong; Zou, Sheng

    2014-06-15

    A novel method to compensate the residual magnetic field for an atomic magnetometer consisting of two perpendicular beams of polarizations was demonstrated in this paper. The method can realize magnetic compensation in the case where the pumping rate of the probe beam cannot be ignored. In the experiment, the probe beam is always linearly polarized, whereas, the probe beam contains a residual circular component due to the imperfection of the polarizer, which leads to the pumping effect of the probe beam. A simulation of the probe beam's optical rotation and pumping rate was demonstrated. At the optimized points, the wavelength of the probe beam was optimized to achieve the largest optical rotation. Although, there is a small circular component in the linearly polarized probe beam, the pumping rate of the probe beam was non-negligible at the optimized wavelength which if ignored would lead to inaccuracies in the magnetic field compensation. Therefore, the dynamic equation of spin evolution was solved by considering the pumping effect of the probe beam. Based on the quasi-static solution, a novel magnetic compensation method was proposed, which contains two main steps: (1) the non-pumping compensation and (2) the sequence compensation with a very specific sequence. After these two main steps, a three-axis in situ magnetic compensation was achieved. The compensation method was suitable to design closed-loop spin-exchange relaxation-free magnetometer. By a combination of the magnetic compensation and the optimization, the magnetic field sensitivity was approximately 4 fT/Hz{sup 1/2}, which was mainly dominated by the noise of the magnetic shield.

  16. In situ magnetic compensation for potassium spin-exchange relaxation-free magnetometer considering probe beam pumping effect.

    PubMed

    Fang, Jiancheng; Wang, Tao; Quan, Wei; Yuan, Heng; Zhang, Hong; Li, Yang; Zou, Sheng

    2014-06-01

    A novel method to compensate the residual magnetic field for an atomic magnetometer consisting of two perpendicular beams of polarizations was demonstrated in this paper. The method can realize magnetic compensation in the case where the pumping rate of the probe beam cannot be ignored. In the experiment, the probe beam is always linearly polarized, whereas, the probe beam contains a residual circular component due to the imperfection of the polarizer, which leads to the pumping effect of the probe beam. A simulation of the probe beam's optical rotation and pumping rate was demonstrated. At the optimized points, the wavelength of the probe beam was optimized to achieve the largest optical rotation. Although, there is a small circular component in the linearly polarized probe beam, the pumping rate of the probe beam was non-negligible at the optimized wavelength which if ignored would lead to inaccuracies in the magnetic field compensation. Therefore, the dynamic equation of spin evolution was solved by considering the pumping effect of the probe beam. Based on the quasi-static solution, a novel magnetic compensation method was proposed, which contains two main steps: (1) the non-pumping compensation and (2) the sequence compensation with a very specific sequence. After these two main steps, a three-axis in situ magnetic compensation was achieved. The compensation method was suitable to design closed-loop spin-exchange relaxation-free magnetometer. By a combination of the magnetic compensation and the optimization, the magnetic field sensitivity was approximately 4 fT/Hz(1/2), which was mainly dominated by the noise of the magnetic shield.

  17. Effect of the location and size of a single crack on first fundamental frequency of a cantilever beam using fiber optic polarimetric sensors and characterisation of FBG sensors

    NASA Astrophysics Data System (ADS)

    Maheshwari, Muneesh; Asundi, A. K.; Tjin, Swee C.

    2013-08-01

    Fiber Optics Polarimetric Sensors (FOPS), utilizing first fundamental frequency mode and its harmonics, have already been used as damage detection tool. The FOPS technology is attractive in damage detection as it facilitates us with real time non-destructive health monitoring of different mechanical and civil structures. In this paper, the effects of the size and the location of a single crack on the frequency of first fundamental mode of a cantilever beam have been studied. A relation between the relative size of a crack and relative change in the first fundamental frequency has been established theoretically and then verified experimentally. Further, it has been shown that the cracks, close to the fixed end of the cantilever beam, have significant effect on the frequency of first fundamental mode and as the crack moves away from the fixed end, the effect on the frequency starts becoming diminished. Also the sensitivity of Fiber Bragg Grating (FBG) sensor against a single crack has been studied along both the directions; parallel to the axis of FBG sensor and perpendicular to the axis of FBG sensor. Experimental results show that the range of sensitivity in both the directions is almost the same bur FBG is more efficient along its axis.

  18. Compliant cantilevered micromold

    DOEpatents

    Morales, Alfredo Martin; Domeier, Linda A.; Gonzales, Marcela G.; Keifer, Patrick N.; Garino, Terry Joseph

    2006-08-15

    A compliant cantilevered three-dimensional micromold is provided. The compliant cantilevered micromold is suitable for use in the replication of cantilevered microparts and greatly simplifies the replication of such cantilevered parts. The compliant cantilevered micromold may be used to fabricate microparts using casting or electroforming techniques. When the compliant micromold is used to fabricate electroformed cantilevered parts, the micromold will also comprise an electrically conducting base formed by a porous metal substrate that is embedded within the compliant cantilevered micromold. Methods for fabricating the compliant cantilevered micromold as well as methods of replicating cantilevered microparts using the compliant cantilevered micromold are also provided.

  19. In-situ epitaxial growth of graphene/h-BN van der Waals heterostructures by molecular beam epitaxy.

    PubMed

    Zuo, Zheng; Xu, Zhongguang; Zheng, Renjing; Khanaki, Alireza; Zheng, Jian-Guo; Liu, Jianlin

    2015-01-01

    Van der Waals materials have received a great deal of attention for their exceptional layered structures and exotic properties, which can open up various device applications in nanoelectronics. However, in situ epitaxial growth of dissimilar van der Waals materials remains challenging. Here we demonstrate a solution for fabricating van der Waals heterostructures. Graphene/hexagonal boron nitride (h-BN) heterostructures were synthesized on cobalt substrates by using molecular beam epitaxy. Various characterizations were carried out to evaluate the heterostructures. Wafer-scale heterostructures consisting of single-layer/bilayer graphene and multilayer h-BN were achieved. The mismatch angle between graphene and h-BN is below 1°.

  20. Short-wavelength light beam in situ monitoring growth of InGaN/GaN green LEDs by MOCVD.

    PubMed

    Sun, Xiaojuan; Li, Dabing; Song, Hang; Chen, Yiren; Jiang, Hong; Miao, Guoqing; Li, Zhiming

    2012-05-31

    In this paper, five-period InGaN/GaN multiple quantum well green light-emitting diodes (LEDs) were grown by metal organic chemical vapor deposition with 405-nm light beam in situ monitoring system. Based on the signal of 405-nm in situ monitoring system, the related information of growth rate, indium composition and interfacial quality of each InGaN/GaN QW were obtained, and thus, the growth conditions and structural parameters were optimized to grow high-quality InGaN/GaN green LED structure. Finally, a green LED with a wavelength of 509 nm was fabricated under the optimal parameters, which was also proved by ex situ characterization such as high-resolution X-ray diffraction, photoluminescence, and electroluminescence. The results demonstrated that short-wavelength in situ monitoring system was a quick and non-destroyed tool to provide the growth information on InGaN/GaN, which would accelerate the research and development of GaN-based green LEDs.

  1. In situ study of e-beam Al and Hf metal deposition on native oxide InP (100)

    SciTech Connect

    Dong, H.; KC, Santosh; Azcatl, A.; Cabrera, W.; Qin, X.; Brennan, B.; Cho, K.; Wallace, R. M.; Zhernokletov, D.

    2013-11-28

    The interfacial chemistry of thin Al (∼3 nm) and Hf (∼2 nm) metal films deposited by electron beam (e-beam) evaporation on native oxide InP (100) samples at room temperature and after annealing has been studied by in situ angle resolved X-ray photoelectron spectroscopy and low energy ion scattering spectroscopy. The In-oxides are completely scavenged forming In-In/In-(Al/Hf) bonding after Al and Hf metal deposition. The P-oxide concentration is significantly decreased, and the P-oxide chemical states have been changed to more P-rich oxides upon metal deposition. Indium diffusion through these metals before and after annealing at 250 °C has also been characterized. First principles calculation shows that In has lower surface formation energy compared with Al and Hf metals, which is consistent with the observed indium diffusion behavior.

  2. In situ study of erosion and deposition of amorphous hydrogenated carbon films by exposure to a hydrogen atom beam

    SciTech Connect

    Markelj, Sabina; Pelicon, Primoz; Cadez, Iztok; Schwarz-Selinger, Thomas; Jacob, Wolfgang

    2012-07-15

    This paper reports on the first dual-beam experiment employing a hydrogen atom beam for sample exposure and an ion beam for analysis, enabling in situ and real-time studies of hydrogen atom interaction with materials. The erosion of an amorphous hydrogenated carbon (a-C:H) layer by deuterium atoms at 580 K sample temperature was studied and the uptake of deuterium during the erosion process was measured in real time. The deuterium areal density increased at the beginning to 7.3 Multiplication-Sign 10{sup 15} D cm{sup -2}, but then stabilized at a constant value of 5.5 Multiplication-Sign 10{sup 15} D cm{sup -2}. Formation of a polymer-like deposit on an a-C:H layer held at room temperature and subjected to the deuterium atom beam was observed and also studied in situ. For both erosion and deposition studies an a-{sup 13}C:H layer on top of an Si substrate was used as a sample, making the experiments isotopically fully specified and thereby differentiating the deposited from the original layer and the interacting D atoms from H atoms present in the layer and in the residual vacuum. From the deposition study it was shown that carbon in the deposited layer originates from carbon-carrying species in the background vacuum that interact with hydrogen atoms. The areal density of the carbon at the surface was determined from the energy shift of the Si edge in the Rutherford backscattering spectrum. The cross section for {sup 7}Li on D at 4.3 MeV Li ion energy and at a recoil angle of 30 Degree-Sign was also determined to be (236 {+-} 16) Multiplication-Sign 10{sup -27} cm{sup 2}/sr. This is a factor of 3 {+-} 0.2 times higher than the Rutherford elastic cross section.

  3. In situ conversion of nanostructures from solid to hollow in transmission electron microscopes using electron beam.

    PubMed

    El Mel, Abdel-Aziz; Bittencourt, Carla

    2016-06-01

    With the current development of electron beam sources, the use of transmission electron microscopes is no more limited to imaging or chemical analysis but has rather been extended to nanoengineering. This includes the e-beam induced growth, etching and structural transformation of nanomaterials. In this review we summarize recent progress on the e-beam induced morphological transformation of nanostructures from solid to hollow. We provide a detailed account of the processes reported so far in the literature with a special emphasis on the mechanistic understanding of the e-beam induced hollowing of nanomaterials. Through an important number of examples, we discuss how one can achieve a precise control of such hollowing processes by understanding the fundamental mechanisms occurring at the atomic scale during the irradiation of solid nanostructures. Finally, we conclude with remarks and our own view on the prospective future directions of this research field.

  4. In situ conversion of nanostructures from solid to hollow in transmission electron microscopes using electron beam.

    PubMed

    El Mel, Abdel-Aziz; Bittencourt, Carla

    2016-06-01

    With the current development of electron beam sources, the use of transmission electron microscopes is no more limited to imaging or chemical analysis but has rather been extended to nanoengineering. This includes the e-beam induced growth, etching and structural transformation of nanomaterials. In this review we summarize recent progress on the e-beam induced morphological transformation of nanostructures from solid to hollow. We provide a detailed account of the processes reported so far in the literature with a special emphasis on the mechanistic understanding of the e-beam induced hollowing of nanomaterials. Through an important number of examples, we discuss how one can achieve a precise control of such hollowing processes by understanding the fundamental mechanisms occurring at the atomic scale during the irradiation of solid nanostructures. Finally, we conclude with remarks and our own view on the prospective future directions of this research field. PMID:27172892

  5. Calibrating IR cameras for in-situ temperature measurement during the electron beam melt processing of Inconel 718 and Ti-Al6-V4

    NASA Astrophysics Data System (ADS)

    Dinwiddie, R. B.; Kirka, M. M.; Lloyd, P. D.; Dehoff, R. R.; Lowe, L. E.; Marlow, G. S.

    2016-05-01

    High performance mid-wave infrared (IR) cameras are used for in-situ electron beam melt process monitoring and temperature measurements. Since standard factory calibrations are insufficient due to very low transmissions of the leaded glass window required for X-ray absorption, two techniques for temperature calibrations are compared. In-situ measurement of emittance will also be discussed. Ultimately, these imaging systems have the potential for routine use for online quality assurance and feedback control.

  6. A comparison of constant-load and constant-deflection stress-corrosion tests on precracked DCB specimens. [Double Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Dorward, R. C.; Hasse, K. R.

    1978-01-01

    A comparison is made between measurements of stress-corrosion crack propagation made by a constant-load procedure and by a constant-deflection procedure. Precracked double cantilever beam specimens from 7075 aluminum alloy plate were used. The specimens were oriented in such a way that cracking would begin in the short-transverse plane and would propagate in the rolling direction. The specimens were subjected to a buffered salt-chromate solution and a 3.6% synthetic sea salt solution. The measurements were made optically with a binocular microscope. Stress intensities and crack lengths were calculated and crack velocities were obtained. Velocity was plotted against the average calculated stress intensity. Good agreement between the two methods was found for the salt-chromate solution, although some descrepancies were noted for the artificial sea salt solution.

  7. Experimental Investigation of Effects of Random Loading on the Fatigue Life of Notched Cantilever-Beam Specimens of 7075-T6 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Fralich, Robert W.

    1959-01-01

    Results of random-loading fatigue tests on 125 notched cantilever-beam specimens and constant-amplitude fatigue tests on 46 similar specimens are presented in terms of the root-mean-square value of peak stresses. The results from the two sets of tests are compared on the basis of time to failure, where the results from the constant-amplitude tests are expressed in terms of an equivalent time to failure based on the natural period of vibration. Compared on this basis, failure at the lower stress levels occurred in a shorter time for the random loading than for the constant-amplitude loading, whereas at the higher stress levels failure occurred in the reverse order. A theoretical result for random loading is also presented and compared with the experimental results. The theoretical result shows good agreement with experiment for low values of stress but underestimates the time to failure at the higher stresses.

  8. Modeling effects of gas bubbles on the mechanical behaviors of Ag/Bi-2212 round wires using a double cantilever beam bridge model

    NASA Astrophysics Data System (ADS)

    Lu, Yurong; Wang, Zhongtong; Yong, Huadong; Zhou, Youhe

    2016-07-01

    Due to the larger current-carrying property, Bi2Sr2CaCu2Ox (Bi2212) superconductors have a great potential application in high field magnet. Bi2212 superconducting material can be fabricated as an isotropic round wire. However, there is 30% void space in the wire, such as gas bubbles. The void space has a larger influence on the property of the wire. In this paper, we will study the effect of gas bubble on the fracture behavior. Based on the double cantilever beam model and critical state theory, the mechanical behavior of Bi2212 wire is studied for decreasing field. Two different damage mechanisms are discussed using the strain energy release rate and strain of bridge. The results show that the large gas bubble can increase the strain of bridge. The central filaments with gas bubble are easier to be damaged than the edge filaments with gas bubble.

  9. A surface-micromachining-based inertial micro-switch with compliant cantilever beam as movable electrode for enduring high shock and prolonging contact time

    NASA Astrophysics Data System (ADS)

    Xu, Qiu; Yang, Zhuoqing; Fu, Bo; Li, Jianhua; Wu, Hao; Zhang, Qihuan; Sun, Yunna; Ding, Guifu; Zhao, Xiaolin

    2016-11-01

    A novel laterally-driven inertial micro-switch with two L-shaped elastic cantilever beams as the movable electrode, which is attached to the proof mass, is proposed in this paper. The advantage of this design is that the contact time of the inertial micro-switch can be prolonged. Meanwhile, the micro-switch can withstand a higher shock than the traditional designs whose cantilever beams are attached to the fixed electrode. The designed inertial micro-switch was simulated and optimized with ANSYS software and fabricated on a quartz substrate by surface micromachining technology. The simulated result demonstrates that the threshold acceleration (aths) under stable switch-on state is about 288 g and the contact time is about 198 μs when the pulse width of acceleration loads is 1 ms. At the same time, it indicates that the threshold acceleration, the response time and the contact time of designed micro-switch all increase with the pulse width of acceleration loads. The simulation of impact process in non-sensitive direction shows that the introduced constraint sleeve structure in the novel inertial micro-switch can lower the off-axis sensitivity. The fabricated micro-switch prototype has been tested by a standard dropping hammer system under shock accelerations with various amplitudes and pulse widths. The experimental measurements show that the contact time is about 150 μs when the threshold acceleration is about 288 g. It also indicates that the response time and the contact time both increase with the pulse width, which is consistent with the simulation ones.

  10. In-situ determination of energy species yields of intense particle beams

    DOEpatents

    Kugel, H.W.; Kaita, R.

    1983-09-26

    Objects of the present invention are provided for a particle beam having a full energy component at least as great as 25 keV, which is directed onto a beamstop target, such that Rutherford backscattering, preferably near-surface backscattering occurs. The geometry, material composition and impurity concentration of the beam stop are predetermined, using any suitable conventional technique. The energy-yield characteristic response of backscattered particles is measured over a range of angles using a fast ion electrostatic analyzer having a microchannel plate array at its focal plane. The knee of the resulting yield curve, on a plot of yield versus energy, is analyzed to determine the energy species components of various beam particles having the same mass.

  11. In situ radiation test of silicon and diamond detectors operating in superfluid helium and developed for beam loss monitoring

    NASA Astrophysics Data System (ADS)

    Kurfürst, C.; Dehning, B.; Sapinski, M.; Bartosik, M. R.; Eisel, T.; Fabjan, C.; Rementeria, C. A.; Griesmayer, E.; Eremin, V.; Verbitskaya, E.; Zabrodskii, A.; Fadeeva, N.; Tuboltsev, Y.; Eremin, I.; Egorov, N.; Härkönen, J.; Luukka, P.; Tuominen, E.

    2015-05-01

    As a result of the foreseen increase in the luminosity of the Large Hadron Collider, the discrimination between the collision products and possible magnet quench-provoking beam losses of the primary proton beams is becoming more critical for safe accelerator operation. We report the results of ongoing research efforts targeting the upgrading of the monitoring system by exploiting Beam Loss Monitor detectors based on semiconductors located as close as possible to the superconducting coils of the triplet magnets. In practice, this means that the detectors will have to be immersed in superfluid helium inside the cold mass and operate at 1.9 K. Additionally, the monitoring system is expected to survive 20 years of LHC operation, resulting in an estimated radiation fluence of 1×1016 proton/cm2, which corresponds to a dose of about 2 MGy. In this study, we monitored the signal degradation during the in situ irradiation when silicon and single-crystal diamond detectors were situated in the liquid/superfluid helium and the dependences of the collected charge on fluence and bias voltage were obtained. It is shown that diamond and silicon detectors can operate at 1.9 K after 1×1016 p/cm2 irradiation required for application as BLMs, while the rate of the signal degradation was larger in silicon detectors than in the diamond ones. For Si detectors this rate was controlled mainly by the operational mode, being larger at forward bias voltage.

  12. Thermographic in-situ process monitoring of the electron-beam melting technology used in additive manufacturing

    NASA Astrophysics Data System (ADS)

    Dinwiddie, Ralph B.; Dehoff, Ryan R.; Lloyd, Peter D.; Lowe, Larry E.; Ulrich, Joe B.

    2013-05-01

    Oak Ridge National Laboratory (ORNL) has been utilizing the ARCAM electron beam melting technology to additively manufacture complex geometric structures directly from powder. Although the technology has demonstrated the ability to decrease costs, decrease manufacturing lead-time and fabricate complex structures that are impossible to fabricate through conventional processing techniques, certification of the component quality can be challenging. Because the process involves the continuous deposition of successive layers of material, each layer can be examined without destructively testing the component. However, in-situ process monitoring is difficult due to metallization on inside surfaces caused by evaporation and condensation of metal from the melt pool. This work describes a solution to one of the challenges to continuously imaging inside of the chamber during the EBM process. Here, the utilization of a continuously moving Mylar film canister is described. Results will be presented related to in-situ process monitoring and how this technique results in improved mechanical properties and reliability of the process.

  13. Prototype cantilevers for quantitative lateral force microscopy

    SciTech Connect

    Reitsma, Mark G.; Gates, Richard S.; Friedman, Lawrence H.; Cook, Robert F.

    2011-09-15

    Prototype cantilevers are presented that enable quantitative surface force measurements using contact-mode atomic force microscopy (AFM). The ''hammerhead'' cantilevers facilitate precise optical lever system calibrations for cantilever flexure and torsion, enabling quantifiable adhesion measurements and friction measurements by lateral force microscopy (LFM). Critically, a single hammerhead cantilever of known flexural stiffness and probe length dimension can be used to perform both a system calibration as well as surface force measurements in situ, which greatly increases force measurement precision and accuracy. During LFM calibration mode, a hammerhead cantilever allows an optical lever ''torque sensitivity'' to be generated for the quantification of LFM friction forces. Precise calibrations were performed on two different AFM instruments, in which torque sensitivity values were specified with sub-percent relative uncertainty. To examine the potential for accurate lateral force measurements using the prototype cantilevers, finite element analysis predicted measurement errors of a few percent or less, which could be reduced via refinement of calibration methodology or cantilever design. The cantilevers are compatible with commercial AFM instrumentation and can be used for other AFM techniques such as contact imaging and dynamic mode measurements.

  14. In-situ white beam microdiffraction study of the deformation behavior in polycrystalline magnesium alloy during uniaxial loading

    SciTech Connect

    Advanced Light Source; Tamura, Nobumichi; Lynch, P.A.; Stevenson, A.W.; Liang, D.; Parry, D.; Wilkins, S.; Madsen, I.C.; Bettles, C.; Tamura, N.; Geandier, G.

    2007-01-19

    Scanning white beam X-ray microdiffraction has been used to study the heterogeneous grain deformation in a polycrystalline Mg alloy (MgAZ31). The high spatial resolution achieved on beamline 7.3.3 at the Advanced Light Source provides a unique method to measure the elastic strain and orientation of single grains as a function of applied load. To carry out in-situmeasurements a light weight (~;;0.5kg) tensile stage, capable of providing uniaxial loads of up to 600kg, was designed to collect diffraction data on the loading and unloading cycle. In-situ observation of the deformation process provides insight about the crystallographic deformation mode via twinning and dislocation slip.

  15. Highly indistinguishable photons from deterministic quantum-dot microlenses utilizing three-dimensional in situ electron-beam lithography.

    PubMed

    Gschrey, M; Thoma, A; Schnauber, P; Seifried, M; Schmidt, R; Wohlfeil, B; Krüger, L; Schulze, J-H; Heindel, T; Burger, S; Schmidt, F; Strittmatter, A; Rodt, S; Reitzenstein, S

    2015-01-01

    The success of advanced quantum communication relies crucially on non-classical light sources emitting single indistinguishable photons at high flux rates and purity. We report on deterministically fabricated microlenses with single quantum dots inside which fulfil these requirements in a flexible and robust quantum device approach. In our concept we combine cathodoluminescence spectroscopy with advanced in situ three-dimensional electron-beam lithography at cryogenic temperatures to pattern monolithic microlenses precisely aligned to pre-selected single quantum dots above a distributed Bragg reflector. We demonstrate that the resulting deterministic quantum-dot microlenses enhance the photon-extraction efficiency to (23±3)%. Furthermore we prove that such microlenses assure close to pure emission of triggered single photons with a high degree of photon indistinguishability up to (80±7)% at saturation. As a unique feature, both single-photon purity and photon indistinguishability are preserved at high excitation power and pulsed excitation, even above saturation of the quantum emitter.

  16. Direct growth of graphene on in situ epitaxial hexagonal boron nitride flakes by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Xu, Zhongguang; Zheng, Renjing; Khanaki, Alireza; Zuo, Zheng; Liu, Jianlin

    2015-11-23

    Hexagonal boron nitride (h-BN) single-crystal domains were grown on cobalt (Co) substrates at a substrate temperature of 850–900 °C using plasma-assisted molecular beam epitaxy. Three-point star shape h-BN domains were observed by scanning electron microscopy, and confirmed by Raman and X-ray photoelectron spectroscopy. The h-BN on Co template was used for in situ growth of multilayer graphene, leading to an h-BN/graphene heterostructure. Carbon atoms preferentially nucleate on Co substrate and edges of h-BN and then grow laterally to form continuous graphene. Further introduction of carbon atoms results in layer-by-layer growth of graphene on graphene and lateral growth of graphene on h-BN until it may cover entire h-BN flakes.

  17. Phase Transformations During Solidification of a Laser-Beam-Welded TiAl Alloy—An In Situ Synchrotron Study

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Staron, Peter; Riekehr, Stefan; Stark, Andreas; Schell, Norbert; Huber, Norbert; Schreyer, Andreas; Müller, Martin; Kashaev, Nikolai

    2016-09-01

    An in situ highly time-resolved, high-energy X-ray diffraction investigation was carried out to observe the phase transformations of a TiAl alloy during laser beam welding. The diffraction patterns are recorded every 0.1 seconds by a fast area two-dimensional detector and plotted according to time, yielding the solidification pathway, the solid phase volume fraction, and the lattice parameter variation of different phases during the solidification and cooling process. Moreover, it is the first study that can demonstrate that the α phase without any Burgers orientation relationship, the so-called non-Burgers α, precipitates appear earlier than the Burgers α. The non-Burgers α grains are found to nucleate on the primary borides.

  18. Toward Higher-Order Mass Detection: Influence of an Adsorbate's Rotational Inertia and Eccentricity on the Resonant Response of a Bernoulli-Euler Cantilever Beam.

    PubMed

    Heinrich, Stephen M; Dufour, Isabelle

    2015-11-19

    In this paper a new theoretical model is derived, the results of which permit a detailed examination of how the resonant characteristics of a cantilever are influenced by a particle (adsorbate) attached at an arbitrary position along the beam's length. Unlike most previous work, the particle need not be small in mass or dimension relative to the beam, and the adsorbate's geometric characteristics are incorporated into the model via its rotational inertia and eccentricity relative to the beam axis. For the special case in which the adsorbate's (translational) mass is indeed small, an analytical solution is obtained for the particle-induced resonant frequency shift of an arbitrary flexural mode, including the effects of rotational inertia and eccentricity. This solution is shown to possess the exact first-order behavior in the normalized particle mass and represents a generalization of analytical solutions derived by others in earlier studies. The results suggest the potential for "higher-order" nanobeam-based mass detection methods by which the multi-mode frequency response reflects not only the adsorbate's mass but also important geometric data related to its size, shape, or orientation (i.e., the mass distribution), thus resulting in more highly discriminatory techniques for discrete-mass sensing.

  19. In-situ Quasi-Instantaneous e-beam Driven Catalyst-Free Formation Of Crystalline Aluminum Borate Nanowires

    PubMed Central

    Gonzalez-Martinez, Ignacio G.; Gemming, Thomas; Mendes, Rafael; Bachmatiuk, Alicja; Bezugly, Viktor; Kunstmann, Jens; Eckert, Jürgen; Cuniberti, Gianaurelio; Rümmeli, Mark H.

    2016-01-01

    The catalyst-assisted nucleation and growth mechanisms for many kinds of nanowires and nanotubes are pretty well understood. At times, though, 1D nanostructures form without a catalyst and the argued growth modes have inconsistencies. One such example is the catalyst-free growth of aluminium borate nanowires. Here we develop an in-situ catalyst-free room temperature growth route for aluminium nanowires using the electron beam in a transmission electron microscope. We provide strong experimental evidence that supports a formation process that can be viewed as a phase transition in which the generation of free-volume induced by the electron beam irradiation enhances the atomic mobility within the precursor material. The enhanced atomic mobility and specific features of the crystal structure of Al5BO9 drive the atomic rearrangement that results in the large scale formation of highly crystalline aluminium borate nanowires. The whole formation process can be completed within fractions of a second. Our developed growth mechanism might also be extended to describe the catalyst-free formation of other nanowires. PMID:26934833

  20. In-situ Quasi-Instantaneous e-beam Driven Catalyst-Free Formation Of Crystalline Aluminum Borate Nanowires.

    PubMed

    Gonzalez-Martinez, Ignacio G; Gemming, Thomas; Mendes, Rafael; Bachmatiuk, Alicja; Bezugly, Viktor; Kunstmann, Jens; Eckert, Jürgen; Cuniberti, Gianaurelio; Rümmeli, Mark H

    2016-01-01

    The catalyst-assisted nucleation and growth mechanisms for many kinds of nanowires and nanotubes are pretty well understood. At times, though, 1D nanostructures form without a catalyst and the argued growth modes have inconsistencies. One such example is the catalyst-free growth of aluminium borate nanowires. Here we develop an in-situ catalyst-free room temperature growth route for aluminium nanowires using the electron beam in a transmission electron microscope. We provide strong experimental evidence that supports a formation process that can be viewed as a phase transition in which the generation of free-volume induced by the electron beam irradiation enhances the atomic mobility within the precursor material. The enhanced atomic mobility and specific features of the crystal structure of Al5BO9 drive the atomic rearrangement that results in the large scale formation of highly crystalline aluminium borate nanowires. The whole formation process can be completed within fractions of a second. Our developed growth mechanism might also be extended to describe the catalyst-free formation of other nanowires. PMID:26934833

  1. Toward Higher-Order Mass Detection: Influence of an Adsorbate’s Rotational Inertia and Eccentricity on the Resonant Response of a Bernoulli-Euler Cantilever Beam

    PubMed Central

    Heinrich, Stephen M.; Dufour, Isabelle

    2015-01-01

    In this paper a new theoretical model is derived, the results of which permit a detailed examination of how the resonant characteristics of a cantilever are influenced by a particle (adsorbate) attached at an arbitrary position along the beam’s length. Unlike most previous work, the particle need not be small in mass or dimension relative to the beam, and the adsorbate’s geometric characteristics are incorporated into the model via its rotational inertia and eccentricity relative to the beam axis. For the special case in which the adsorbate’s (translational) mass is indeed small, an analytical solution is obtained for the particle-induced resonant frequency shift of an arbitrary flexural mode, including the effects of rotational inertia and eccentricity. This solution is shown to possess the exact first-order behavior in the normalized particle mass and represents a generalization of analytical solutions derived by others in earlier studies. The results suggest the potential for “higher-order” nanobeam-based mass detection methods by which the multi-mode frequency response reflects not only the adsorbate’s mass but also important geometric data related to its size, shape, or orientation (i.e., the mass distribution), thus resulting in more highly discriminatory techniques for discrete-mass sensing. PMID:26610493

  2. Electron beam exposure mechanisms in hydrogen silsesquioxane investigated by vibrational spectroscopy and in-situ electron beam induced desorption

    SciTech Connect

    Olynick, D.L.; Cord, B.; Schipotinin, A.; Ogletree, D.F.; Schuck, P.J.

    2009-11-13

    Hydrogen Silsesquioxane (HSQ) is used as a high-resolution resist with resolution down below 10nm half-pitch. This material or materials with related functionalities could have widespread impact in nanolithography and nanoscience applications if the exposure mechanism was understood and instabilities controlled. Here we have directly investigated the exposure mechanism using vibrational spectroscopy (both Raman and Fourier transform Infrared) and electron beam desorption spectrocscopy (EBDS). In the non-networked HSQ system, silicon atoms sit at the corners of a cubic structure. Each silicon is bonded to a hydrogen atom and bridges 3 oxygen atoms (formula: HSiO3/2). For the first time, we have shown, via changes in the Si-H2 peak at ~;;2200 cm -1 in the Raman spectra and the release of SiHx products in EBID, that electron-bam exposed materials crosslinks via a redistribution reaction. In addition, we observe the release of significantly more H2 than SiH2 during EBID, which is indicative of additional reaction mechanisms. Additionally, we compare the behavior of HSQ in response to both thermal and electron-beam induced reactions.

  3. Molecular beam mass spectrometer equipped with a catalytic wall reactor for in situ studies in high temperature catalysis research

    SciTech Connect

    Horn, R.; Ihmann, K.; Ihmann, J.; Jentoft, F.C.; Geske, M.; Taha, A.; Pelzer, K.; Schloegl, R.

    2006-05-15

    A newly developed apparatus combining a molecular beam mass spectrometer and a catalytic wall reactor is described. The setup has been developed for in situ studies of high temperature catalytic reactions (>1000 deg. C), which involve besides surface reactions also gas phase reactions in their mechanism. The goal is to identify gas phase radicals by threshold ionization. A tubular reactor, made from the catalytic material, is positioned in a vacuum chamber. Expansion of the gas through a 100 {mu}m sampling orifice in the reactor wall into differentially pumped nozzle, skimmer, and collimator chambers leads to the formation of a molecular beam. A quadrupole mass spectrometer with electron impact ion source designed for molecular beam inlet and threshold ionization measurements is used as the analyzer. The sampling time from nozzle to detector is estimated to be less than 10 ms. A detection time resolution of up to 20 ms can be reached. The temperature of the reactor is measured by pyrometry. Besides a detailed description of the setup components and the physical background of the method, this article presents measurements showing the performance of the apparatus. After deriving the shape and width of the energy spread of the ionizing electrons from measurements on N{sub 2} and He we estimated the detection limit in threshold ionization measurements using binary mixtures of CO in N{sub 2} to be in the range of several hundreds of ppm. Mass spectra and threshold ionization measurements recorded during catalytic partial oxidation of methane at 1250 deg. C on a Pt catalyst are presented. The detection of CH{sub 3}{center_dot} radicals is successfully demonstrated.

  4. Optimization and Analysis of Laser Beam Machining Parameters for Al7075-TiB2 In-situ Composite

    NASA Astrophysics Data System (ADS)

    Manjoth, S.; Keshavamurthy, R.; Pradeep Kumar, G. S.

    2016-09-01

    The paper focuses on laser beam machining (LBM) of In-situ synthesized Al7075-TiB2 metal matrix composite. Optimization and influence of laser machining process parameters on surface roughness, volumetric material removal rate (VMRR) and dimensional accuracy of composites were studied. Al7075-TiB2 metal matrix composite was synthesized by in-situ reaction technique using stir casting process. Taguchi's L9 orthogonal array was used to design experimental trials. Standoff distance (SOD) (0.3 - 0.5mm), Cutting Speed (1000 - 1200 m/hr) and Gas pressure (0.5 - 0.7 bar) were considered as variable input parameters at three different levels, while power and nozzle diameter were maintained constant with air as assisting gas. Optimized process parameters for surface roughness, volumetric material removal rate (VMRR) and dimensional accuracy were calculated by generating the main effects plot for signal noise ratio (S/N ratio) for surface roughness, VMRR and dimensional error using Minitab software (version 16). The Significant of standoff distance (SOD), cutting speed and gas pressure on surface roughness, volumetric material removal rate (VMRR) and dimensional error were calculated using analysis of variance (ANOVA) method. Results indicate that, for surface roughness, cutting speed (56.38%) is most significant parameter followed by standoff distance (41.03%) and gas pressure (2.6%). For volumetric material removal (VMRR), gas pressure (42.32%) is most significant parameter followed by cutting speed (33.60%) and standoff distance (24.06%). For dimensional error, Standoff distance (53.34%) is most significant parameter followed by cutting speed (34.12%) and gas pressure (12.53%). Further, verification experiments were carried out to confirm performance of optimized process parameters.

  5. Deposition and characterization of Pb(Zr,Ti)O3 sol gel thin films for piezoelectric cantilever beams

    NASA Astrophysics Data System (ADS)

    Liu, Mengwei; Wang, Jing; Wang, Liding; Cui, Tianhong

    2007-02-01

    PZT thin films of various thickness were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by the sol-gel method. A new method to control the crystallographic orientation of the PZT thin films by modifying the coating layers in one annealing cycle is presented in this paper. PZT films with (111) and (100) preferred orientation were obtained using the multi-coating-layer-annealed and the one-coating-layer-annealed sol-gel methods, respectively. The optimized baking and annealing temperatures at 200 and 600 °C were obtained by analyzing the phase transformation of the PZT precursor solution. The effect of film thickness on the microstructures, crystalline phases, and electrical properties of the PZT films was investigated. Compared to the multi-coating-layer-annealed method, the one-coating-layer-annealed method decreases the residual stress of the PZT films. The remanent polarization increases with the thickness of the PZT films. The remanent polarization (Pr) and coercive fields (Ec) of the one-coating-layer-annealed PZT films with 1.6 µm thickness are 25.7 µC cm-2 and 59.2 kV cm-1, respectively. New microcantilevers with two PZT piezoelectric elements and three electric electrodes were designed. These structures can be applied to microsensors, microactuators, or versatile devices having both sensing and actuating functions. The cantilevers were successfully fabricated with wet and dry combined bulk micromachining technique.

  6. Quantitative measurements of electromechanical response with a combined optical beam and interferometric atomic force microscope

    SciTech Connect

    Labuda, Aleksander; Proksch, Roger

    2015-06-22

    An ongoing challenge in atomic force microscope (AFM) experiments is the quantitative measurement of cantilever motion. The vast majority of AFMs use the optical beam deflection (OBD) method to infer the deflection of the cantilever. The OBD method is easy to implement, has impressive noise performance, and tends to be mechanically robust. However, it represents an indirect measurement of the cantilever displacement, since it is fundamentally an angular rather than a displacement measurement. Here, we demonstrate a metrological AFM that combines an OBD sensor with a laser Doppler vibrometer (LDV) to enable accurate measurements of the cantilever velocity and displacement. The OBD/LDV AFM allows a host of quantitative measurements to be performed, including in-situ measurements of cantilever oscillation modes in piezoresponse force microscopy. As an example application, we demonstrate how this instrument can be used for accurate quantification of piezoelectric sensitivity—a longstanding goal in the electromechanical community.

  7. Quantitative measurements of electromechanical response with a combined optical beam and interferometric atomic force microscope

    NASA Astrophysics Data System (ADS)

    Labuda, Aleksander; Proksch, Roger

    2015-06-01

    An ongoing challenge in atomic force microscope (AFM) experiments is the quantitative measurement of cantilever motion. The vast majority of AFMs use the optical beam deflection (OBD) method to infer the deflection of the cantilever. The OBD method is easy to implement, has impressive noise performance, and tends to be mechanically robust. However, it represents an indirect measurement of the cantilever displacement, since it is fundamentally an angular rather than a displacement measurement. Here, we demonstrate a metrological AFM that combines an OBD sensor with a laser Doppler vibrometer (LDV) to enable accurate measurements of the cantilever velocity and displacement. The OBD/LDV AFM allows a host of quantitative measurements to be performed, including in-situ measurements of cantilever oscillation modes in piezoresponse force microscopy. As an example application, we demonstrate how this instrument can be used for accurate quantification of piezoelectric sensitivity—a longstanding goal in the electromechanical community.

  8. In-situ weak-beam and polarization control of multidimensional laser sidebands for ultrafast optical switching

    SciTech Connect

    Liu, Weimin; Wang, Liang; Fang, Chong

    2014-03-17

    All-optical switching has myriad applications in optoelectronics, optical communications, and quantum information technology. To achieve ultrafast optical switching in a compact yet versatile setup, we demonstrate distinct sets of two-dimensional (2D) broadband up-converted multicolor arrays (BUMAs) in a thin type-I β-barium-borate crystal with two noncollinear near-IR femtosecond pulses at various phase-matching conditions. The unique interaction mechanism is revealed as quadratic spatial solitons (QSSs)-coupled cascaded four-wave mixing (CFWM), corroborated by numerical calculations of the governing phase-matching conditions. Broad and continuous spectral-spatial tunability of the 2D BUMAs are achieved by varying the time delay between the two incident pulses that undergo CFWM interaction, rooted in the chirped nature of the weak white light and the QSSs generation of the intense fundamental beam. The control of 2D BUMAs is accomplished via seeding a weak second-harmonic pulse in situ to suppress the 2D arrays with polarization dependence on the femtosecond timescale that matches the control pulse duration of ∼35 fs. A potential application is proposed on femtosecond all-optical switching in an integrated wavelength-time division multiplexing device.

  9. Highly indistinguishable photons from deterministic quantum-dot microlenses utilizing three-dimensional in situ electron-beam lithography

    PubMed Central

    Gschrey, M.; Thoma, A.; Schnauber, P.; Seifried, M.; Schmidt, R.; Wohlfeil, B.; Krüger, L.; Schulze, J. -H.; Heindel, T.; Burger, S.; Schmidt, F.; Strittmatter, A.; Rodt, S.; Reitzenstein, S.

    2015-01-01

    The success of advanced quantum communication relies crucially on non-classical light sources emitting single indistinguishable photons at high flux rates and purity. We report on deterministically fabricated microlenses with single quantum dots inside which fulfil these requirements in a flexible and robust quantum device approach. In our concept we combine cathodoluminescence spectroscopy with advanced in situ three-dimensional electron-beam lithography at cryogenic temperatures to pattern monolithic microlenses precisely aligned to pre-selected single quantum dots above a distributed Bragg reflector. We demonstrate that the resulting deterministic quantum-dot microlenses enhance the photon-extraction efficiency to (23±3)%. Furthermore we prove that such microlenses assure close to pure emission of triggered single photons with a high degree of photon indistinguishability up to (80±7)% at saturation. As a unique feature, both single-photon purity and photon indistinguishability are preserved at high excitation power and pulsed excitation, even above saturation of the quantum emitter. PMID:26179766

  10. High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry

    SciTech Connect

    Duden, Thomas; Radmilovic, Velimir

    2009-03-04

    We describe a setup for the resonance frequency measurement of individual microcantilevers. The setup displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The high sensitivity to specimen vibrations is achieved by the combination of optical Fabry-Perot interferometry and narrow band RF detection. Wave fronts reflected on the specimen and on the fiber tip end face interfere, thus no reference plane on the specimen is needed, as demonstrated with the example of freestanding silicon nitride micro-cantilevers. The resulting system is integrated in a DB-235 dual beam FIB system, thereby allowing the measurement of micro-cantilever responses during observation in SEM mode. The FIB was used to modify the optical fiber tip. At this point of our RF system development, the microcantilevers used to characterize the detector were not modified in situ.

  11. Mode 1 and Mode 2 Analysis of Graphite/Epoxy Composites Using Double Cantilever Beam and End-Notched Flexure Tests

    NASA Technical Reports Server (NTRS)

    Hufnagel, Kathleen P.

    1995-01-01

    The critical strain energy release rates associated with debonding of the adhesive bondlines in graphite/epoxy IM6/3501-6 interlaminar fracture specimens were investigated. Two panels were manufactured for this investigation; however, panel two was layed-up incorrectly. As a result, data collected from Panel Two serves no real purpose in this investigation. Double Cantilever Beam (DCB) specimens were used to determine the opening Mode I interlaminar fracture toughness, G1(sub c), of uni-directional fiber re-inforced composites. The five specimens tested from Panel One had an average value of 946.42J/sq m for G1(sub c) with an acceptable coefficient of variation. The critical strain energy release rate, G2(sub c), for initiation of delamination under inplane shear loading was investigated using the End-Notched Flexure (ENF) Test. Four specimens were tested from Panel One and an average value of 584.98J/sq m for G2(sub c) was calculated. Calculations from the DCB and ENF test results for Panel One represent typical values of G1(sub c) and G2(sub c) for the adhesive debonding in the material studied in this investigation.

  12. Electron beam collimation with a 40 000 tip metallic double-gate field emitter array and in-situ control of nanotip sharpness distribution

    SciTech Connect

    Helfenstein, P.; Guzenko, V. A.; Tsujino, S.; Fink, H.-W.

    2013-01-28

    The generation of highly collimated electron beams from a double-gate field emitter array with 40000 metallic tips and large collimation gate apertures is reported. Field emission beam measurements demonstrated the reduction of the beam envelope down to the array size by applying a negative potential to the on-chip gate electrode for the collimation of individual field emission beamlets. Owing to the optimized gate structure, the concomitant decrease of the emission current was minimal, leading to a net enhancement of the current density. Furthermore, a noble gas conditioning process was successfully applied to the double-gate device to improve the beam uniformity in-situ with orders of magnitude increase of the active emission area. The results show that the proposed double-gate field emission cathodes are promising for high current and high brightness electron beam applications such as free-electron lasers and THz power devices.

  13. Pulsed ion beam surface analysis (PIBSA) as a means of in-situ real-time analysis of thin films during growth

    SciTech Connect

    Krauss, A.R; Lamich, G.J.; Gruen, D.M.; Lin, Y. |; Chang, R.P.H.; Auciello, O.; Schultz, J.A.

    1993-10-01

    Low energy (5-15 keV) pulsed ion beam surface analysis (PIBSA) comprises several different surface spectroscopies which provide a wide range of information relevant to growth of single and multi-component semiconductor, metal and metal oxide thin f@ and layered structures. Ion beam methods have not been widely used as an in-situ monitor of thin film growth. PIBSA has been developed as a non-destructive, in-situ, real-time probe of thin film composition and structure which does not physically interfere with deposition. Several PIBSA versions are exceptionally surface-specific, yet can yield high resolution data at ambient pressures in excess of 1 m Torr (4-5 orders of magnitude higher than conventional surface analytic methods). Therefore, PIBSA is ideal for studying ultra-thin layers and atomically abrupt interfaces. PIBSA instrumentation designed for use as an in-situ, real-time monitor of growth processes for single and multi-component thin films and layered structures is described. Representative data are shown for in-situ analysis of Pb and Zr layers at room temperature and high vacuum, as well as under conditions for growth of PZT perovskite films on MgO and RuO{sub 2} substrates.

  14. Piezoelectric cantilever sensors

    NASA Technical Reports Server (NTRS)

    Shih, Wan Y. (Inventor); Shih, Wei-Heng (Inventor); Shen, Zuyan (Inventor)

    2008-01-01

    A piezoelectric cantilever with a non-piezoelectric, or piezoelectric tip useful as mass and viscosity sensors. The change in the cantilever mass can be accurately quantified by monitoring a resonance frequency shift of the cantilever. For bio-detection, antibodies or other specific receptors of target antigens may be immobilized on the cantilever surface, preferably on the non-piezoelectric tip. For chemical detection, high surface-area selective absorbent materials are coated on the cantilever tip. Binding of the target antigens or analytes to the cantilever surface increases the cantilever mass. Detection of target antigens or analytes is achieved by monitoring the cantilever's resonance frequency and determining the resonance frequency shift that is due to the mass of the adsorbed target antigens on the cantilever surface. The use of a piezoelectric unimorph cantilever allows both electrical actuation and electrical sensing. Incorporating a non-piezoelectric tip (14) enhances the sensitivity of the sensor. In addition, the piezoelectric cantilever can withstand damping in highly viscous liquids and can be used as a viscosity sensor in wide viscosity range.

  15. Tunnel junctions, cantilevers, and potentials

    NASA Astrophysics Data System (ADS)

    Tanner, Shawn

    We have developed a process for making sub-micrometer dimensional cantilevers, clamped beams, and more complicate electro-mechanical structures that carry integrated electrical leads. Such objects are perhaps useful as test structures for connecting to and measuring the electrical properties of molecular sized objects, as high frequency electromechanical components for radio and microwave frequency applications, and as sensor components for studying the fluctuation physics of small machines. Our process uses two realigned electron-beam lithography steps, a thin film angled deposition system, and differential removal of sacrificial aluminum layers to produce freely suspended sub-micron electromechanical components. We have produced cantilevers and beams on a variety of substrates (silica, silicon, and poly-imide) and have produced insulating, conductive, and multi-layer mechanical structures. We have measured mechanical resonances in the 10 MHz range by electrostatically actuating the cantilevers while in a magnetic field (3500 gauss) and measuring the voltage that results across the front edge of the cantilever. Two structures are fabricated sharing a common ground so that a balanced detection technique can be used to eliminate background signals. Due to the square dependence of the electrostatic force on the voltage, they can be resonated by a drive voltage of 1/2 the natural frequency or at the natural frequency. Two separate attempts have been made to apply these resonators. First, a process was developed to integrate a tunnel junction with the cantilever. These devices can possibly be used for probing small-scale systems such as molecules. We have verified the exponential variation of the tunneling resistance with both substrate flex and electrostatic gating. Second, a novel gate structure was developed to create a double potential well for resonator motion. This is accomplished by placing a multilayer structure in front of the hairpin cantilever consisting two

  16. Cantilevered carbon nanotube hygrometer

    NASA Astrophysics Data System (ADS)

    Kuroyanagi, Toshinori; Terada, Yuki; Takei, Kuniharu; Akita, Seiji; Arie, Takayuki

    2014-05-01

    We investigate the effects of humidity on the vibrations of carbon nanotubes (CNTs) using two types of CNT cantilevers: open-ended and close-ended CNT cantilevers. As the humidity increases, the resonant frequency of the open-ended CNT cantilever decreases due to the adsorption of water molecules onto the CNT tip, whereas that of the close-ended CNT cantilever increases probably due to the change in the viscosity of the air surrounding the CNT cantilever, which is negatively correlated with the humidity of air. Our findings suggest that a close-ended CNT cantilever is more suitable for a quick-response and ultrasensitive hygrometer because it continuously reads the viscosity change of moist air in the vicinity of the CNT.

  17. Development of double-cantilever infrared detectors

    NASA Astrophysics Data System (ADS)

    Huang, Shusen

    Detection and imaging of infrared (IR) radiation are of great importance to a variety of military and civilian applications. Recent advances in microelectromechanical systems (MEMS) have led to the development of uncooled cantilever IR focal plane arrays (FPAs), which function based on the bending of bimaterial cantilevers upon the absorption of IR energy. In this dissertation, capacitive-based double-cantilever IR FPAs, which have a potential of reaching a noise-equivalent temperature difference (NETD) approaching the theoretical limit, i.e., <10 mK, are developed. Each pixel in the proposed double-cantilever IR FPAs consists of two facing bimaterial cantilevers: one bends upward and the other downward upon IR radiation, resulting in an extremely high sensitivity of the device. It is predicted that the NETD of the double-cantilever IR FPAs is about 60% of the current single-cantilever IR FPAs, which is a significant improvement of device performance. A surface micromachining module with polyimide as a sacrificial material is developed for the fabrication of both simplified single- and double-cantilever FPAs. It is found the as-fabricated FPAs are curved because of the imbalanced residual stresses (strains) in thin films developed in the fabrication processes. In this dissertation, therefore, the general relationship between the residual strain and the resultant elastic bending deformation is modeled. A thorough investigation of residual stresses in cantilever IR materials and structures is then conducted using the theory developed in this dissertation. Furthermore, thermal-cycling experiments reveal that the residual stresses in IR materials, i.e., plasma-enhanced chemical vapor deposited (PECVD) SiNx and electron beam (Ebeam) AI, can be significantly modified by thermal annealing. Therefore, an engineering approach to flattening IR FPAs is developed by using rapid thermal annealing (RTA). Finally, this dissertation demonstrates the thermal detection of cantilever

  18. Development of a dual-ion beam accelerator connected with a TEM for in situ observation of radiation-induced defects

    NASA Astrophysics Data System (ADS)

    Suzuki, Kazumichi; Shigenaka, Naoto; Hashimoto, Tsuneyuki; Nishimura, Eiichi

    1987-04-01

    A dual-ion beam accelerator connected with a TEM has been developed for in situ observation of radiation-induced defects. The system consists of a 400-kV Cockcroft-Walton accelerator, which can accelerate two different kinds of ions alternatively, and a 200-kV TEM equipped with a high-sensitivity TV camera. The ion beam from the accelerator is fed into the TEM by an electrostatic beam transport system which consists of three deflectors, two quadrupole lenses and a 57° static prism. A copper specimen is bombarded with 150-keV Ar ions. A small cascade of < 5 nm in diameter is observed for an Ar-ion current of about 85 nA/cm 2. At a higher current of 1 μA/cm 2, recombination, growth, overlap, and collective motions of cascades are observed during irradiation. In situ observation of argon bubbles at a grain boundary of copper gives a diameter growth rate of 2.8 × 10 -2 nm/s at a dose rate of 5.3 × 10 14 Ar +/cm 2 s and a temperature of about 500 K.

  19. Cantilever piezoelectric energy harvester with multiple cavities

    NASA Astrophysics Data System (ADS)

    Srinivasulu Raju, S.; Umapathy, M.; Uma, G.

    2015-11-01

    Energy harvesting employing piezoelectric materials in mechanical structures such as cantilever beams, plates, diaphragms, etc, has been an emerging area of research in recent years. The research in this area is also focused on structural tailoring to improve the harvested power from the energy harvesters. Towards this aim, this paper presents a method for improving the harvested power from a cantilever piezoelectric energy harvester by introducing multiple rectangular cavities. A generalized model for a piezoelectric energy harvester with multiple rectangular cavities at a single section and two sections is developed. A method is suggested to optimize the thickness of the cavities and the number of cavities required to generate a higher output voltage for a given cantilever beam structure. The performance of the optimized energy harvesters is evaluated analytically and through experimentation. The simulation and experimental results show that the performance of the energy harvester can be increased with multiple cavities compared to the harvester with a single cavity.

  20. On the resolution and linearity of lensless in situ X-ray beam diagnostics using pixelated sensors.

    PubMed

    Kachatkou, Anton; van Silfhout, Roelof

    2013-02-25

    We present a theoretical model that describes the resolution and linearity of a novel transparent X-ray beam imaging and position measurement method. Using a pinhole or coded aperture camera with pixelated area sensors to image a small fraction of radiation scattered by a thin foil placed at oblique angles with respect to the beam, a very precise measurement of the beam position is made. We show that the resolution of the method is determined by incident beam intensity, beam size, camera parameters, sensor pixel size and noise. The model is verified experimentally showing a sub-micrometer resolution over a large linear range.

  1. In situ micro-focused X-ray beam characterization with a lensless camera using a hybrid pixel detector.

    PubMed

    Kachatkou, Anton; Marchal, Julien; van Silfhout, Roelof

    2014-03-01

    Results of studies on micro-focused X-ray beam diagnostics using an X-ray beam imaging (XBI) instrument based on the idea of recording radiation scattered from a thin foil of a low-Z material with a lensless camera are reported. The XBI instrument captures magnified images of the scattering region within the foil as illuminated by the incident beam. These images contain information about beam size, beam position and beam intensity that is extracted during dedicated signal processing steps. In this work the use of the device with beams for which the beam size is significantly smaller than that of a single detector pixel is explored. The performance of the XBI device equipped with a state-of-the-art hybrid pixel X-ray imaging sensor is analysed. Compared with traditional methods such as slit edge or wire scanners, the XBI micro-focused beam characterization is significantly faster and does not interfere with on-going experiments. The challenges associated with measuring micrometre-sized beams are described and ways of optimizing the resolution of beam position and size measurements of the XBI instrument are discussed.

  2. Calibrating IR Cameras for In-Situ Temperature Measurement During the Electron Beam Melting Process using Inconel 718 and Ti-Al6-V4

    SciTech Connect

    Dinwiddie, Ralph Barton; Lloyd, Peter D; Dehoff, Ryan R; Lowe, Larry E

    2016-01-01

    The Department of Energy s (DOE) Manufacturing Demonstration Facility (MDF) at Oak Ridge National Laboratory (ORNL) provides world-leading capabilities in advanced manufacturing (AM) facilities which leverage previous, on-going government investments in materials science research and characterization. MDF contains systems for fabricating components with complex geometries using AM techniques (i.e. 3D-Printing). Various metal alloy printers, for example, use electron beam melting (EBM) systems for creating these components which are otherwise extremely difficult- if not impossible- to machine. ORNL has partnered with manufacturers on improving the final part quality of components and developing new materials for further advancing these devices. One method being used to study (AM) processes in more depth relies on the advanced imaging capabilities at ORNL. High performance mid-wave infrared (IR) cameras are used for in-situ process monitoring and temperature measurements. However, standard factory calibrations are insufficient due to very low transmissions of the leaded glass window required for X-ray absorption. Two techniques for temperature calibrations will be presented and compared. In-situ measurement of emittance will also be discussed. Ample information can be learned from in-situ IR process monitoring of the EBM process. Ultimately, these imaging systems have the potential for routine use for online quality assurance and feedback control.

  3. Nanograting-based compact VUV spectrometer and beam profiler for in-situ characterization of high-order harmonic generation light sources

    SciTech Connect

    Kornilov, Oleg; Wilcox, Russell; Gessner, Oliver

    2010-07-09

    A compact, versatile device for VUV beam characterization is presented. It combines the functionalities of a VUV spectrometer and a VUV beam profiler in one unit and is entirely supported by a standard DN200 CF flange. The spectrometer employs a silicon nitride transmission nanograting in combination with a micro-channel plate based imaging detector. This enables the simultaneous recording of wavelengths ranging from 10 nm to 80 nm with a resolution of 0.25 nm to 0.13 nm. Spatial beam profiles with diameters up to 10 mm are imaged with 0.1 mm resolution. The setup is equipped with an in-vacuum translation stage that allows for in situ switching between the spectrometer and beam profiler modes and for moving the setup out of the beam. The simple, robust design of the device is well suited for non-intrusive routine characterization of emerging laboratory- and accelerator-based VUV light sources. Operation of the device is demonstrated by characterizing the output of a femtosecond high-order harmonic generation light source.

  4. A Weed Cantilever

    ERIC Educational Resources Information Center

    Keller, Elhannan L.; Padalino, John

    1977-01-01

    Describes the Environmental Action Task activity, which may be used as a recreational game or an environmental perception experience, may be conducted indoors or out-of-doors, using weed stems (or spaghetti) and masking tape to construct a cantilever. Small groups of children work together to make the cantilever with the longest arm. Further…

  5. Epoxy and acrylate sterolithography resins: in-situ property measurements

    SciTech Connect

    Guess, T.R.; Chambers, R.S.; Hinnerichs, T.D.

    1996-01-01

    Stereolithography is a rapid prototyping method that is becoming an important product realization and concurrent engineering tool, with applications in advanced and agile manufacturing. During the build process, material behavior plays a significant role in the mechanics leading to internal stresses and, potentially, to distortion (curling) of parts. The goal of the ``Stereolithography Manufacturing Process Modeling and Optimization`` LDRD program was to develop engineering tools for improving overall part accuracy during the stereolithography build process. These tools include phenomenological material models of solidifying stereolithography photocurable resins and a 3D finite element architecture that incorporates time varying material behavior, laser path dependence, and structural linkage. This SAND report discusses the in situ measurement of shrinkage and force relaxation behavior of two photocurable resins, and the measurement of curl in simple cantilever beams. These studies directly supported the development of phenomenological material models for solidifying resins and provided experimental curl data to compare to model predictions.

  6. Cantilever mounted resilient pad gas bearing

    NASA Technical Reports Server (NTRS)

    Etsion, I. (Inventor)

    1978-01-01

    A gas-lubricated bearing is described, employing at least one pad mounted on a rectangular cantilever beam to produce a lubricating wedge between the face of the pad and a moving surface. The load-carrying and stiffness characteristics of the pad are related to the dimensions and modulus of elasticity of the beam. The bearing is applicable to a wide variety of types of hydrodynamic bearings.

  7. Accurate spring constant calibration for very stiff atomic force microscopy cantilevers.

    PubMed

    Grutzik, Scott J; Gates, Richard S; Gerbig, Yvonne B; Smith, Douglas T; Cook, Robert F; Zehnder, Alan T

    2013-11-01

    There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is required. In most cases, the forces of interest are very small, thus compliant cantilevers are used. A number of methods have been developed that are well suited to measuring low stiffness values. However, in some cases a cantilever with much greater stiffness is required. Thus, a direct, traceable method for calibrating very stiff (approximately 200 N/m) cantilevers is presented here. The method uses an instrumented and calibrated nanoindenter to determine the stiffness of a reference cantilever. This reference cantilever is then used to measure the stiffness of a number of AFM test cantilevers. This method is shown to have much smaller uncertainty than previously proposed methods. An example application to fracture testing of nanoscale silicon beam specimens is included.

  8. Accurate spring constant calibration for very stiff atomic force microscopy cantilevers

    SciTech Connect

    Grutzik, Scott J.; Zehnder, Alan T.; Gates, Richard S.; Gerbig, Yvonne B.; Smith, Douglas T.; Cook, Robert F.

    2013-11-15

    There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is required. In most cases, the forces of interest are very small, thus compliant cantilevers are used. A number of methods have been developed that are well suited to measuring low stiffness values. However, in some cases a cantilever with much greater stiffness is required. Thus, a direct, traceable method for calibrating very stiff (approximately 200 N/m) cantilevers is presented here. The method uses an instrumented and calibrated nanoindenter to determine the stiffness of a reference cantilever. This reference cantilever is then used to measure the stiffness of a number of AFM test cantilevers. This method is shown to have much smaller uncertainty than previously proposed methods. An example application to fracture testing of nanoscale silicon beam specimens is included.

  9. In situ X-ray beam imaging using an off-axis magnifying coded aperture camera system.

    PubMed

    Kachatkou, Anton; Kyele, Nicholas; Scott, Peter; van Silfhout, Roelof

    2013-07-01

    An imaging model and an image reconstruction algorithm for a transparent X-ray beam imaging and position measuring instrument are presented. The instrument relies on a coded aperture camera to record magnified images of the footprint of the incident beam on a thin foil placed in the beam at an oblique angle. The imaging model represents the instrument as a linear system whose impulse response takes into account the image blur owing to the finite thickness of the foil, the shape and size of camera's aperture and detector's point-spread function. The image reconstruction algorithm first removes the image blur using the modelled impulse response function and then corrects for geometrical distortions caused by the foil tilt. The performance of the image reconstruction algorithm was tested in experiments at synchrotron radiation beamlines. The results show that the proposed imaging system produces images of the X-ray beam cross section with a quality comparable with images obtained using X-ray cameras that are exposed to the direct beam.

  10. Facility for low-temperature spin-polarized-scanning tunneling microscopy studies of magnetic/spintronic materials prepared in situ by nitride molecular beam epitaxy.

    PubMed

    Lin, Wenzhi; Foley, Andrew; Alam, Khan; Wang, Kangkang; Liu, Yinghao; Chen, Tianjiao; Pak, Jeongihm; Smith, Arthur R

    2014-04-01

    Based on the interest in, as well as exciting outlook for, nitride semiconductor based structures with regard to electronic, optoelectronic, and spintronic applications, it is compelling to investigate these systems using the powerful technique of spin-polarized scanning tunneling microscopy (STM), a technique capable of achieving magnetic resolution down to the atomic scale. However, the delicate surfaces of these materials are easily corrupted by in-air transfers, making it unfeasible to study them in stand-alone ultra-high vacuum STM facilities. Therefore, we have carried out the development of a hybrid system including a nitrogen plasma assisted molecular beam epitaxy/pulsed laser epitaxy facility for sample growth combined with a low-temperature, spin-polarized scanning tunneling microscope system. The custom-designed molecular beam epitaxy growth system supports up to eight sources, including up to seven effusion cells plus a radio frequency nitrogen plasma source, for epitaxially growing a variety of materials, such as nitride semiconductors, magnetic materials, and their hetero-structures, and also incorporating in situ reflection high energy electron diffraction. The growth system also enables integration of pulsed laser epitaxy. The STM unit has a modular design, consisting of an upper body and a lower body. The upper body contains the coarse approach mechanism and the scanner unit, while the lower body accepts molecular beam epitaxy grown samples using compression springs and sample skis. The design of the system employs two stages of vibration isolation as well as a layer of acoustic noise isolation in order to reduce noise during STM measurements. This isolation allows the system to effectively acquire STM data in a typical lab space, which during its construction had no special and highly costly elements included, (such as isolated slabs) which would lower the environmental noise. The design further enables tip exchange and tip coating without

  11. Facility for low-temperature spin-polarized-scanning tunneling microscopy studies of magnetic/spintronic materials prepared in situ by nitride molecular beam epitaxy

    SciTech Connect

    Lin, Wenzhi; Foley, Andrew; Alam, Khan; Wang, Kangkang; Liu, Yinghao; Chen, Tianjiao; Pak, Jeongihm; Smith, Arthur R.

    2014-04-15

    Based on the interest in, as well as exciting outlook for, nitride semiconductor based structures with regard to electronic, optoelectronic, and spintronic applications, it is compelling to investigate these systems using the powerful technique of spin-polarized scanning tunneling microscopy (STM), a technique capable of achieving magnetic resolution down to the atomic scale. However, the delicate surfaces of these materials are easily corrupted by in-air transfers, making it unfeasible to study them in stand-alone ultra-high vacuum STM facilities. Therefore, we have carried out the development of a hybrid system including a nitrogen plasma assisted molecular beam epitaxy/pulsed laser epitaxy facility for sample growth combined with a low-temperature, spin-polarized scanning tunneling microscope system. The custom-designed molecular beam epitaxy growth system supports up to eight sources, including up to seven effusion cells plus a radio frequency nitrogen plasma source, for epitaxially growing a variety of materials, such as nitride semiconductors, magnetic materials, and their hetero-structures, and also incorporating in situ reflection high energy electron diffraction. The growth system also enables integration of pulsed laser epitaxy. The STM unit has a modular design, consisting of an upper body and a lower body. The upper body contains the coarse approach mechanism and the scanner unit, while the lower body accepts molecular beam epitaxy grown samples using compression springs and sample skis. The design of the system employs two stages of vibration isolation as well as a layer of acoustic noise isolation in order to reduce noise during STM measurements. This isolation allows the system to effectively acquire STM data in a typical lab space, which during its construction had no special and highly costly elements included, (such as isolated slabs) which would lower the environmental noise. The design further enables tip exchange and tip coating without

  12. Facility for low-temperature spin-polarized-scanning tunneling microscopy studies of magnetic/spintronic materials prepared in situ by nitride molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Lin, Wenzhi; Foley, Andrew; Alam, Khan; Wang, Kangkang; Liu, Yinghao; Chen, Tianjiao; Pak, Jeongihm; Smith, Arthur R.

    2014-04-01

    Based on the interest in, as well as exciting outlook for, nitride semiconductor based structures with regard to electronic, optoelectronic, and spintronic applications, it is compelling to investigate these systems using the powerful technique of spin-polarized scanning tunneling microscopy (STM), a technique capable of achieving magnetic resolution down to the atomic scale. However, the delicate surfaces of these materials are easily corrupted by in-air transfers, making it unfeasible to study them in stand-alone ultra-high vacuum STM facilities. Therefore, we have carried out the development of a hybrid system including a nitrogen plasma assisted molecular beam epitaxy/pulsed laser epitaxy facility for sample growth combined with a low-temperature, spin-polarized scanning tunneling microscope system. The custom-designed molecular beam epitaxy growth system supports up to eight sources, including up to seven effusion cells plus a radio frequency nitrogen plasma source, for epitaxially growing a variety of materials, such as nitride semiconductors, magnetic materials, and their hetero-structures, and also incorporating in situ reflection high energy electron diffraction. The growth system also enables integration of pulsed laser epitaxy. The STM unit has a modular design, consisting of an upper body and a lower body. The upper body contains the coarse approach mechanism and the scanner unit, while the lower body accepts molecular beam epitaxy grown samples using compression springs and sample skis. The design of the system employs two stages of vibration isolation as well as a layer of acoustic noise isolation in order to reduce noise during STM measurements. This isolation allows the system to effectively acquire STM data in a typical lab space, which during its construction had no special and highly costly elements included, (such as isolated slabs) which would lower the environmental noise. The design further enables tip exchange and tip coating without

  13. Kinetic mechanisms of the in situ electron beam-induced self-organization of gold nanoclusters in SiO2

    NASA Astrophysics Data System (ADS)

    Ruffino, F.; Grimaldi, M. G.; Giannazzo, F.; Roccaforte, F.; Raineri, V.; Bongiorno, C.; Spinella, C.

    2009-04-01

    Gold nanoclusters (NCs) were produced in thin SiO2 film by a sequential sputtering deposition procedure. In situ time-lapse studies of the NCs size distribution and morphology under 200 keV electron-beam irradiation have been performed using a transmission electron microscopy. Such a study has revealed the microscopic kinetic mechanisms of the NCs growth. In the 0-1620 s irradiation time range, the NCs growth process was found to be formed by two stages: in the 0-720 s time range, the main growth mechanism is demonstrated to be an electron beam-induced ripening of three-dimensional particles controlled by the Au diffusion in the SiO2 matrix. The application of the classical ripening theoretical model allowed us to derive the room-temperature Au diffusion coefficient in SiO2 under the electron-beam irradiation. In the 900-1620 s time range, the main growth mechanism is found to be a particle sintering in which neighbouring NCs form necks, by a partial deformation of their surfaces, through which the Au atomic diffusion occurs from the smaller NCs to the larger one. About the NCs morphology, three main classes of NCs were identified on the basis of their internal atomic structure, as a function of the irradiation time: FCC crystal structure, icosahedral-defect free structure and decahedral multi-twinned structure.

  14. Experimental observation of contact mode cantilever dynamics with nanosecond resolution

    NASA Astrophysics Data System (ADS)

    Payton, O. D.; Picco, L.; Champneys, A. R.; Homer, M. E.; Miles, M. J.; Raman, A.

    2011-04-01

    We report the use of a laser Doppler vibrometer to measure the motion of an atomic force microscope contact mode cantilever during continuous line scans of a mica surface. With a sufficiently high density of measurement points the dynamics of the entire cantilever beam, from the apex to the base, can be reconstructed. We demonstrate nanosecond resolution of both rectangular and triangular cantilevers. This technique permits visualization and quantitative measurements of both the normal and lateral tip sample interactions for the first and higher order eigenmodes. The ability to derive quantitative lateral force measurements is of interest to the field of microtribology/nanotribology while the comprehensive understanding of the cantilever's dynamics also aids new cantilever designs and simulations.

  15. In situ mask designed for selective growth of InAs quantum dots in narrow regions developed for molecular beam epitaxy system

    SciTech Connect

    Ohkouchi, Shunsuke; Nakamura, Yusui; Ikeda, Naoki; Sugimoto, Yoshimasa; Asakawa, Kiyoshi

    2007-07-15

    We have developed an in situ mask that enables the selective formation of molecular beam epitaxially grown layers in narrow regions. This mask can be fitted to a sample holder and removed in an ultrahigh-vacuum environment; thus, device structures can be fabricated without exposing the sample surfaces to air. Moreover, this mask enables the observation of reflection high-energy electron diffraction during growth with the mask positioned on the sample holder and provides for the formation of marker layers for ensuring alignment in the processes following the selective growth. To explore the effectiveness of the proposed in situ mask, we used it to grow quantum dot (QD) structures in narrow regions and verified the perfect selectivity of the QD growth. The grown QDs exhibited high optical quality with a photoluminescence peak at approximately 1.30 {mu}m and a linewidth of 30 meV at room temperature. The proposed technique can be applied for the integration of microstructures into optoelectronic functional devices.

  16. Direct observation of strain in InAs quantum dots and cap layer during molecular beam epitaxial growth using in situ X-ray diffraction

    SciTech Connect

    Shimomura, Kenichi; Ohshita, Yoshio; Kamiya, Itaru; Suzuki, Hidetoshi; Sasaki, Takuo; Takahasi, Masamitu

    2015-11-14

    Direct measurements on the growth of InAs quantum dots (QDs) and various cap layers during molecular beam epitaxy are performed by in situ X-ray diffraction (XRD). The evolution of strain induced both in the QDs and cap layers during capping is discussed based on the XRD intensity transients obtained at various lattice constants. Transients with different features are observed from those obtained during InGaAs and GaAs capping. The difference observed is attributed to In-Ga intermixing between the QDs and the cap layer under limited supply of In. Photoluminescence (PL) wavelength can be tuned by controlling the intermixing, which affects both the strain induced in the QDs and the barrier heights. The PL wavelength also varies with the cap layer thickness. A large redshift occurs by reducing the cap thickness. The in situ XRD observation reveals that this is a result of reduced strain. We demonstrate how such information about strain can be applied for designing and preparing novel device structures.

  17. X-ray photoelectron spectroscopic study of the oxide removal mechanism of GaAs /100/ molecular beam epitaxial substrates in in situ heating

    NASA Technical Reports Server (NTRS)

    Vasquez, R. P.; Lewis, B. F.; Grunthaner, F. J.

    1983-01-01

    A standard cleaning procedure for GaAs (100) molecular beam epitaxial (MBE) substrates is a chemical treatment with a solution of H2SO4/H2O2/H2O, followed by in situ heating prior to MBE growth. X-ray photoelectron spectroscopic (XPS) studies of the surface following the chemical treatment show that the oxidized As is primarily As(+ 5). Upon heating to low temperatures (less than (350 C) the As(+ 5) oxidizes the substrate to form Ga2O3 and elemental As, and the As(+ 5) is reduced to As(+ 3) in the process. At higher temperatures (500 C), the As(+ 3) and elemental As desorb, while the Ga(+ 3) begins desorbing at about 600 C.

  18. Influence of in-situ annealing ambient on p-type conduction in dual ion beam sputtered Sb-doped ZnO thin films

    SciTech Connect

    Pandey, Sushil Kumar; Kumar Pandey, Saurabh; Awasthi, Vishnu; Mukherjee, Shaibal; Gupta, M.; Deshpande, U. P.

    2013-08-12

    Sb-doped ZnO (SZO) films were deposited on c-plane sapphire substrates by dual ion beam sputtering deposition system and subsequently annealed in-situ in vacuum and in various proportions of O{sub 2}/(O{sub 2} + N{sub 2})% from 0% (N{sub 2}) to 100% (O{sub 2}). Hall measurements established all SZO films were p-type, as was also confirmed by typical diode-like rectifying current-voltage characteristics from p-ZnO/n-ZnO homojunction. SZO films annealed in O{sub 2} ambient exhibited higher hole concentration as compared with films annealed in vacuum or N{sub 2} ambient. X-ray photoelectron spectroscopic analysis confirmed that Sb{sup 5+} states were more preferable in comparison to Sb{sup 3+} states for acceptor-like Sb{sub Zn}-2V{sub Zn} complex formation in SZO films.

  19. Note: A resonating reflector-based optical system for motion measurement in micro-cantilever arrays

    SciTech Connect

    Sathishkumar, P.; Punyabrahma, P.; Sri Muthu Mrinalini, R.; Jayanth, G. R.

    2015-09-15

    A robust, compact optical measurement unit for motion measurement in micro-cantilever arrays enables development of portable micro-cantilever sensors. This paper reports on an optical beam deflection-based system to measure the deflection of micro-cantilevers in an array that employs a single laser source, a single detector, and a resonating reflector to scan the measurement laser across the array. A strategy is also proposed to extract the deflection of individual cantilevers from the acquired data. The proposed system and measurement strategy are experimentally evaluated and demonstrated to measure motion of multiple cantilevers in an array.

  20. Optically controlled bimorph cantilever by Poly(vinylidene difluoride) and its application of optical actuator

    NASA Astrophysics Data System (ADS)

    Mizutani, Yasuhiro; Otani, Yukitoshi

    2008-11-01

    An optically driven actuator is a non-contact method for the remote application of light energy. A new method for optically driving actuators which uses a polyvinylidine difluoride (PVDF) cantilever is proposed. The PVDF cantilever is coated with silver on one surface. The PVDF is a ferroelectric polymer that has both pyroelectric and piezoelectric properties. When one side of the cantilever is irradiated by a laser beam, an electric field is produced along cross-section of the cantilever and mechanical displacement occurs by the piezoelectric effect. The response of the PVDF cantilever is analyzed mathematically.

  1. Active retroreflector with in situ beam analysis to measure the rotational orientation in conjunction with a laser tracker

    NASA Astrophysics Data System (ADS)

    Hofherr, O.; Wachten, C.; Müller, C.; Reinecke, H.

    2013-04-01

    High precision optical non-contact position measurement is a key technology in modern engineering. Laser trackers (LT) can determine accurately x-y-z coordinates of passive retroreflectors. Next-generation systems answer the additional need to measure an object`s rotational orientation (pitch, yaw, roll). These devices are based either on photogrammetry or on enhanced retroreflectors. However, photogrammetry relies on costly camera systems and time-consuming image processing. Enhanced retroreflectors analyze the LT`s beam but are restricted in roll angle measurements. In the past we have presented a new method [1][2] to measure all six degrees of freedom in conjunction with a LT. Now we dramatically optimized the method and designed a new prototype, e.g. taking into consideration optical alignment, reduced power loss, highly optimized measuring signals and higher resolution. A method is described that allows compensating the influence of the LT's beam offset during tracking the active retroreflector. We prove the functionality of the active retroreflector with the LT and, furthermore, demonstrate the capability of the system to characterize the tracking behavior of a LT. The measurement range for the incident laser beam is +/-12° with a resolution of 0.6".

  2. VIEW OF BRIDGE CANTILEVER THROUGH TRUSS CANTILEVER PORTAL ON WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BRIDGE CANTILEVER THROUGH TRUSS CANTILEVER PORTAL ON WEST BANK SIDE LOOKING NORTHWEST. - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  3. VIEW OF BRIDGE CANTILEVER THROUGH TRUSS CANTILEVER SECTION, LOOKING WEST. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BRIDGE CANTILEVER THROUGH TRUSS CANTILEVER SECTION, LOOKING WEST. - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  4. Piezoelectric cantilevers energy harvesting in MEMS technique

    NASA Astrophysics Data System (ADS)

    Shang, Yingqi; Qiu, Chengjun; Liu, Hongmei; Chen, Xiaojie; Qu, Wei; Dou, Yanwei

    2011-11-01

    Piezoelectric cantilevers energy harvesting made by micro-electromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed cantilevers energy harvesting are featured with resonate frequency and power output in microwatt level, which is sufficient to the self-supportive sensors for in-service integrity monitoring of large social and environmental infrastructures at remote locations. In this paper, piezoelectric energy harvesting based on thick-film piezoelectric cantilevers is investigated to resonate at specific frequencies of an external vibration energy source, which creating electrical energy via the piezoelectric effect. Our cantilever device has a multiple structure with a proof mass added to the end. The thick film lead zirconate titanate Pb(Zr,Ti)O3 (PZT) coated on the top of Au/Cr/SiO2/Si substrates by sol-gel-spin method. The thickness of the PZT membrane was up to 2μm and the cantilevers substrates thickness 50μm, wideness 1.5mm, length 4mm. The Au/Ti top electrode is patterned on top of the sol-gel-spin coated PZT thick film in order to employ the d31 mode. The prototype energy generator has a measured performance of 0.74μW effective electrical power, and 4.93 DC output voltages to resistance load. The effect of proof mass, beam shape and damping on the power generating performance are modeled to provide a design guideline for maximum power harvesting from environmentally available low frequency vibrations. A multiple structure cantilever is designed to achieve compactness, low resonant frequency and minimum damping coefficient, simultaneously. This device is promising to support networks of ultra-low-power sensor.

  5. Piezoelectric cantilevers energy harvesting in MEMS technique

    NASA Astrophysics Data System (ADS)

    Shang, Yingqi; Qiu, Chengjun; Liu, Hongmei; Chen, Xiaojie; Qu, Wei; Dou, Yanwei

    2012-04-01

    Piezoelectric cantilevers energy harvesting made by micro-electromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed cantilevers energy harvesting are featured with resonate frequency and power output in microwatt level, which is sufficient to the self-supportive sensors for in-service integrity monitoring of large social and environmental infrastructures at remote locations. In this paper, piezoelectric energy harvesting based on thick-film piezoelectric cantilevers is investigated to resonate at specific frequencies of an external vibration energy source, which creating electrical energy via the piezoelectric effect. Our cantilever device has a multiple structure with a proof mass added to the end. The thick film lead zirconate titanate Pb(Zr,Ti)O3 (PZT) coated on the top of Au/Cr/SiO2/Si substrates by sol-gel-spin method. The thickness of the PZT membrane was up to 2μm and the cantilevers substrates thickness 50μm, wideness 1.5mm, length 4mm. The Au/Ti top electrode is patterned on top of the sol-gel-spin coated PZT thick film in order to employ the d31 mode. The prototype energy generator has a measured performance of 0.74μW effective electrical power, and 4.93 DC output voltages to resistance load. The effect of proof mass, beam shape and damping on the power generating performance are modeled to provide a design guideline for maximum power harvesting from environmentally available low frequency vibrations. A multiple structure cantilever is designed to achieve compactness, low resonant frequency and minimum damping coefficient, simultaneously. This device is promising to support networks of ultra-low-power sensor.

  6. In situ synchrotron radiation photoelectron spectroscopy study of the oxidation of the Ge(100)-2 × 1 surface by supersonic molecular oxygen beams

    SciTech Connect

    Yoshigoe, Akitaka; Teraoka, Yuden; Okada, Ryuta; Yamada, Yoichi; Sasaki, Masahiro

    2014-11-07

    In situ synchrotron radiation photoelectron spectroscopy was performed during the oxidation of the Ge(100)-2 × 1 surface induced by a molecular oxygen beam with various incident energies up to 2.2 eV from the initial to saturation coverage of surface oxides. The saturation coverage of oxygen on the clean Ge(100) surface was much lower than one monolayer and the oxidation state of Ge was +2 at most. This indicates that the Ge(100) surface is so inert toward oxidation that complete oxidation cannot be achieved with only pure oxygen (O{sub 2}) gas, which is in strong contrast to Si surfaces. Two types of dissociative adsorption, trapping-mediated and direct dissociation, were confirmed by oxygen uptake measurements depending on the incident energy of O{sub 2}. The direct adsorption process can be activated by increasing the translational energy, resulting in an increased population of Ge{sup 2+} and a higher final oxygen coverage. We demonstrated that hyperthermal O{sub 2} beams remarkably promote the room-temperature oxidation with novel atomic configurations of oxides at the Ge(100) surface. Our findings will contribute to the fundamental understanding of oxygen adsorption processes at 300 K from the initial stages to saturated oxidation.

  7. In situ ion-beam-induced luminescence analysis for evaluating a micrometer-scale radio-photoluminescence glass dosimeter

    NASA Astrophysics Data System (ADS)

    Kawabata, Shunsuke; Kada, Wataru; Parajuli, Raj Kumar; Matsubara, Yoshinori; Sakai, Makoto; Miura, Kenta; Satoh, Takahiro; Koka, Masashi; Yamada, Naoto; Kamiya, Tomihiro; Hanaizumi, Osamu

    2016-06-01

    Micrometer-scale responses of radio-photoluminescence (RPL) glass dosimeters to focused ionized particle radiation were evaluated by combining ion-beam-induced luminescence (IBIL) and proton beam writing (PBW) using a 3 MeV focused proton microbeam. RPL phosphate glass dosimeters doped with ionic Ag or Cu activators at concentrations of 0.2 and 0.1% were fabricated, and their scintillation intensities were evaluated by IBIL spectroscopy under a PBW micropatterning condition. Compared with the Ag-doped dosimeter, the Cu-doped dosimeter was more tolerant of the radiation, while the peak intensity of its luminescence was lower, under the precise dose control of the proton microprobe. Proton-irradiated areas were successfully recorded using these dosimeters and their RPL centers were visualized under 375 nm ultraviolet light. The reproduction of the irradiated region by post-RPL imaging suggests that precise estimation of irradiation dose using microdosimeters can be accomplished by optimizing RPL glass dosimeters for various proton microprobe applications in organic material analysis and in micrometer-scale material modifications.

  8. Fundamental Investigations of Nanoscale Phenomena in Beam-Assisted Nucleation, Growth and Surface Smoothing, Using in situ LEEM

    SciTech Connect

    Flynn, Colin P

    2008-11-05

    The purposes for which this grant was provided were specifically (1) to construct a tandem instrument that combined a low energy electron microscope (LEEM) with an ion beam source capably of irradiating a sample during observation of the surface using LEEM; and (2) to employ the new machine to whatever degree possible to observe the evolution of clean crystal surfaces during ion beam irradiation. A principal motivation was to investigate the fundamental behavior of radiation damage under circumstances for which the damage can be observed directly in real time as it occurs. A second main motivation was to create tunable perturbations of the defect (adatom and advacancy) equilibrium on clean crystal planes and in this way explore the fundamental kinetics of surface behavior that enters into numerous phenomena of interest to DOE including surface erosion, catalysis, and the damage to crystals caused by impacts of energetic particles. The funding has been employed to successfully pursue all the original goals, and additional opportunities that developed as a result of discoveries made in this research.

  9. In situ investigation of growth modes during plasma-assisted molecular beam epitaxy of (0001) GaN

    SciTech Connect

    Koblmueller, G.; Fernandez-Garrido, S.; Calleja, E.; Speck, J. S.

    2007-10-15

    Real-time analysis of the growth modes during homoepitaxial (0001) GaN growth by plasma-assisted molecular beam epitaxy was performed using reflection high energy electron diffraction. A growth mode map was established as a function of Ga/N flux ratio and growth temperature, exhibiting distinct transitions between three-dimensional (3D), layer-by-layer, and step-flow growth modes. The layer-by-layer to step-flow growth transition under Ga-rich growth was surfactant mediated and related to a Ga adlayer coverage of one monolayer. Under N-rich conditions the transition from 3D to layer-by-layer growth was predominantly thermally activated, facilitating two-dimensional growth at temperatures of thermal decomposition.

  10. Ion-beam assisted deposition of MgO with in situ RHEED monitoring to control Bi-axial texture

    SciTech Connect

    Arendt, P. N.; Foltyn, S. R.; Jia, Quanxi; DePaula, R. F.; Dowden, P. C.; Kung, H.; Holesinger, T. G.; Stan, L.; Emmert, L. A.; Peterson, E. J.; Groves, J. R.

    2001-01-01

    We have studied the growth of magnesium oxide using ion-beam assisted deposition (IBAD) to achieve (100) oriented, bi-axially textured films with low mosaic spread, for film thicknesses of 10 nm on silicon substrates. We have refined the process by using reflected high-energy electron diffraction (RHEED) to monitor the growth of IBAD MgO films and found that the diffracted intensity can be used to determine (and ultimately control) final in-plane texture of the film. Here we present results on our work to develop the use of real-time RHEED monitoring to deposit well-oriented IBAD MgO films. The results have been corroborated with extensive grazing-incidence X-ray diffraction (GID). Results of these analyses have allowed us to deposit films on metallic substrates with in-plane mosaic spread less than 7{sup o}.

  11. Radioluminescence characterization of in situ x-ray nanodosimeters: Potential real-time monitors and modulators of external beam radiation therapy

    SciTech Connect

    Souris, Jeffrey S.; La Riviere, Patrick; Chen, Chin-Tu; Cheng, Shih-Hsun; Chen, Nai-Tzu; Lo, Leu-Wei; Pelizzari, Charles

    2014-11-17

    Europium-doped yttrium oxide (Y{sub 2}O{sub 3}:Eu) has garnered considerable interest recently for its use as a highly efficient, red phosphor in a variety of lighting applications that include fluorescent lamps, plasma, and field emission display panels, light emitting diodes (LEDs), and lasers. In the present work, we describe the development of Y{sub 2}O{sub 3}:Eu nanoparticles for a very different application: in situ, in vivo x-ray dosimetry. Spectroscopic analyses of these nanoparticles during x-ray irradiation reveal surprisingly bright and stable radioluminescence at near-infrared wavelengths, with markedly linear response to changes in x-ray flux and energy. Monte Carlo modeling of incident flux and broadband, wide-field imaging of mouse phantoms bearing both Y{sub 2}O{sub 3}:Eu nanoparticles and calibrated LEDs of similar spectral emission demonstrated significant transmission of radioluminescence, in agreement with spectroscopic studies; with approximately 15 visible photons being generated for every x-ray photon incident. Unlike the dosimeters currently employed in clinical practice, these nanodosimeters can sample both dose and dose rate rapidly enough as to provide real-time feedback for x-ray based external beam radiotherapy (EBRT). The technique's use of remote sensing and absence of supporting structures enable perturbation-free dosing of the targeted region and complete sampling from any direction. With the conjugation of pathology-targeting ligands onto their surfaces, these nanodosimeters offer a potential paradigm shift in the real-time monitoring and modulation of delivered dose in the EBRT of cancer in situ.

  12. Radioluminescence characterization of in situ x-ray nanodosimeters: Potential real-time monitors and modulators of external beam radiation therapy

    NASA Astrophysics Data System (ADS)

    Souris, Jeffrey S.; Cheng, Shih-Hsun; Pelizzari, Charles; Chen, Nai-Tzu; La Riviere, Patrick; Chen, Chin-Tu; Lo, Leu-Wei

    2014-11-01

    Europium-doped yttrium oxide (Y2O3:Eu) has garnered considerable interest recently for its use as a highly efficient, red phosphor in a variety of lighting applications that include fluorescent lamps, plasma, and field emission display panels, light emitting diodes (LEDs), and lasers. In the present work, we describe the development of Y2O3:Eu nanoparticles for a very different application: in situ, in vivo x-ray dosimetry. Spectroscopic analyses of these nanoparticles during x-ray irradiation reveal surprisingly bright and stable radioluminescence at near-infrared wavelengths, with markedly linear response to changes in x-ray flux and energy. Monte Carlo modeling of incident flux and broadband, wide-field imaging of mouse phantoms bearing both Y2O3:Eu nanoparticles and calibrated LEDs of similar spectral emission demonstrated significant transmission of radioluminescence, in agreement with spectroscopic studies; with approximately 15 visible photons being generated for every x-ray photon incident. Unlike the dosimeters currently employed in clinical practice, these nanodosimeters can sample both dose and dose rate rapidly enough as to provide real-time feedback for x-ray based external beam radiotherapy (EBRT). The technique's use of remote sensing and absence of supporting structures enable perturbation-free dosing of the targeted region and complete sampling from any direction. With the conjugation of pathology-targeting ligands onto their surfaces, these nanodosimeters offer a potential paradigm shift in the real-time monitoring and modulation of delivered dose in the EBRT of cancer in situ.

  13. Improved Sensitivity MEMS Cantilever Sensor for Terahertz Photoacoustic Spectroscopy.

    PubMed

    Coutu, Ronald A; Medvedev, Ivan R; Petkie, Douglas T

    2016-01-01

    In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever's anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom built, low-volume, vacuum chamber. The resulting cantilever sensors exhibited improved signal to noise ratios, sensitivities and normalized noise equivalent absorption (NNEA) coefficients of approximately 4.28 × 10(-10) cm(-1)·WHz(-1/2). This reported NNEA represents approximately a 70% improvement over previously fabricated and tested SOI cantilever sensors for THz PA spectroscopy.

  14. Improved Sensitivity MEMS Cantilever Sensor for Terahertz Photoacoustic Spectroscopy.

    PubMed

    Coutu, Ronald A; Medvedev, Ivan R; Petkie, Douglas T

    2016-01-01

    In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever's anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom built, low-volume, vacuum chamber. The resulting cantilever sensors exhibited improved signal to noise ratios, sensitivities and normalized noise equivalent absorption (NNEA) coefficients of approximately 4.28 × 10(-10) cm(-1)·WHz(-1/2). This reported NNEA represents approximately a 70% improvement over previously fabricated and tested SOI cantilever sensors for THz PA spectroscopy. PMID:26907280

  15. In-situ microscopic observation of GaAs surfaces during molecular beam epitaxy and metalorganic molecular beam epitaxy by scanning microprobe reflection high energy electron diffraction

    NASA Astrophysics Data System (ADS)

    Isu, Toshiro; Watanabe, Akiyoshi; Hata, Masayuki; Katayama, Yoshifumi

    1990-03-01

    Microscopic observations of epitaxial growth layers of GaAs were made with a scanning microprobe reflection high energy electron diffraction (RHEED). A scanning microprobe electron gun has been combined with a specially designed molecular beam epitaxy (MBE) system with both solid sources and gas sources. Scanning reflection electron microscope (SREM) images using the specular beam spot revealed granular features over the entire surfaces of MBE-grown GaAs layers, which were thought to come from undulation of the surface. Similar features of the surface were observed on the layers grown by gas-source MBE using trimethylgallium and arsine. A microscopic surface morphology was found to be fairly rough and the features depended on the species of the sources and growth conditions.

  16. Method for providing a compliant cantilevered micromold

    DOEpatents

    Morales, Alfredo M.; Domeier, Linda A.; Gonzales, Marcela G.; Keifer, Patrick N.; Garino, Terry J.

    2008-12-16

    A compliant cantilevered three-dimensional micromold is provided. The compliant cantilevered micromold is suitable for use in the replication of cantilevered microparts and greatly simplifies the replication of such cantilevered parts. The compliant cantilevered micromold may be used to fabricate microparts using casting or electroforming techniques. When the compliant micromold is used to fabricate electroformed cantilevered parts, the micromold will also comprise an electrically conducting base formed by a porous metal substrate that is embedded within the compliant cantilevered micromold. Methods for fabricating the compliant cantilevered micromold as well as methods of replicating cantilevered microparts using the compliant cantilevered micromold are also provided.

  17. Nondestructive experimental determination of bimaterial rectangular cantilever spring constants in water

    SciTech Connect

    Snow, David E.; Kim, Dae Jung; Hope-Weeks, Louisa J.; Weeks, Brandon L.; Pitchimani, Rajasekar

    2008-08-15

    In order to address the issue of spring constant calibration in viscous fluids such as water, a new method is presented that allows for the experimental calibration of bimaterial cantilever spring constants. This method is based on modeling rectangular cantilever beam bending as a function of changing temperature. The temperature change is accomplished by heating water as it flows around the cantilever beams in an enclosed compartment. The optical static method of detection is used to measure the deflection of cantilever at the free end. Experimentally determined results are compared to Sader's method and to the Thermotune method most commonly used in cantilever calibrations. Results indicate that the new bimaterial thermal expansion method is accurate within 15%-20% of the actual cantilever spring constant, which is comparable to other nondestructive calibration techniques.

  18. Dislocation generation related to micro-cracks in Si wafers: High temperature in situ study with white beam X-ray topography

    NASA Astrophysics Data System (ADS)

    Danilewsky, A.; Wittge, J.; Hess, A.; Cröll, A.; Allen, D.; McNally, P.; Vagovič, P.; Cecilia, A.; Li, Z.; Baumbach, T.; Gorostegui-Colinas, E.; Elizalde, M. R.

    2010-02-01

    The generation and propagation of dislocations in Si at high temperature is observed in situ with white beam X-ray topography. For the heating experiments a double ellipsoidal mirror furnace was installed at the Topo-Tomo beamline of the ANKA synchrotron light source, Research Centre Karlsruhe, Germany. Details of the experimental set-up and the first results on the occurrence of dislocations are presented. Artificial damage was generated in commercial (1 0 0) Si wafers using a nanoindenter with various loads. The applied forces for each set of indents were varied from 100 to 500 mN, respectively. After heating to approx. 790 °C large area transmission topographs were taken every 30 min which were then compared to room temperature topographs before and after heating. At the outset straight 60°-dislocations with b = a/2<1 1 0> originate from the 500 mN indents into the direction of the strongest temperature gradient. After 60 min at constant temperature an increase in the length and number of the dislocations in other directions is also observed. As a result of the continual thermal stressing dislocations develop from the 100 mN indents too.

  19. Thermal and mechanical properties of palm oil-based polyurethane acrylate/clay nanocomposites prepared by in-situ intercalative method and electron beam radiation

    SciTech Connect

    Salih, A. M.; Ahmad, Mansor Bin; Ibrahim, Nor Azowa; Dahlan, Khairul Zaman Hj Mohd; Tajau, Rida; Mahmood, Mohd Hilmi; Yunus, Wan Md. Zin Wan

    2014-02-12

    Palm oil based-polyurethane acrylate (POBUA)/clay nanocomposites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5%wt), and then subjected to polycondensation reaction with MDI. Nanocomposites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nanoclay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Å, while the structure morphology of the nanocomposites was investigated by TEM and SEM. The nanocomposites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nanocomposites was significantly increased by incorporation of nanoclay into the polymer matrix. DSC results reveal that the Tg was shifted to higher values, gradually with increasing the amount of filler in the nanocomposites. Tensile strength and Young's modulus of the nanocomposites showed remarkable improvement compared to the neat POBUA.

  20. In situ strain relaxation comparison between GaAsBi and GaInAs grown by molecular-beam epitaxy

    NASA Astrophysics Data System (ADS)

    France, R.; Jiang, C.-S.; Ptak, A. J.

    2011-03-01

    The strain relaxation of GaAsBi is studied in order to determine both the maximum thickness before dislocations form for various misfits and the potential of GaAsBi for usage in the compositionally graded buffer of lattice-mismatched devices. Low-misfit GaAsBi epilayers are grown and compared with GaInAs, a well-studied material currently used in compositional grades. Relaxation behavior and dislocation energetics are compared using in situ wafer curvature. Samples are grown using molecular-beam epitaxy under similar conditions with misfit up to -0.81%. GaAsBi begins to relax at a lower thickness than GaInAs of the same mismatch. This leads to the majority of GaAsBi strain relaxation occurring with less material growth than comparable GaInAs. However, GaAsBi has greater residual strain than GaInAs after 2 μm of growth. These results indicate that GaAsBi requires less elastic energy to form dislocations and more elastic energy to either encourage glide or multiply dislocations than GaInAs. GaAsBi shows less surface roughness than GaInAs for all samples, ruling out roughness as a source of dislocations and hindered glide in these alloys.

  1. Thermal and mechanical properties of palm oil-based polyurethane acrylate/clay nanocomposites prepared by in-situ intercalative method and electron beam radiation

    NASA Astrophysics Data System (ADS)

    Salih, A. M.; Ahmad, Mansor Bin; Ibrahim, Nor Azowa; Dahlan, Khairul Zaman Hj Mohd; Tajau, Rida; Mahmood, Mohd Hilmi; Yunus, Wan Md. Zin Wan

    2014-02-01

    Palm oil based-polyurethane acrylate (POBUA)/clay nanocomposites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5%wt), and then subjected to polycondensation reaction with MDI. Nanocomposites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nanoclay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Å, while the structure morphology of the nanocomposites was investigated by TEM and SEM. The nanocomposites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nanocomposites was significantly increased by incorporation of nanoclay into the polymer matrix. DSC results reveal that the Tg was shifted to higher values, gradually with increasing the amount of filler in the nanocomposites. Tensile strength and Young's modulus of the nanocomposites showed remarkable improvement compared to the neat POBUA.

  2. Material Transport and Synthesis by Cantilever-free Scanning Probe Lithography

    NASA Astrophysics Data System (ADS)

    Liao, Xing

    Reliably synthesizing and transporting materials in nanoscale is the key question in many fields of nanotechnology. Cantilever-free scanning probe lithography, by replacing fragile and costly cantilevers with a robust and low cost elastomeric structure, fundamentally solved the low-throughput nature of scanning probe lithography, which has great potential to be a powerful and point-of-use tool for high throughput synthesis of various kinds of nanomaterials. Two nanolithographic methods, polymer pen lithography (PPL) and beam pen lithography (BPL), have been developed based on the cantilever-free architecture to directly deliver materials and transfer energy to substrates, respectively. The first portion of my thesis, including chapter two and chapter three, addresses major challenges remaining in the cantilever-free scanning probe lithographic techniques. Chapter two details the role of contact force in polymer pen lithography. A geometric model was developed to quantitatively explain the relationship between the z-piezo extension, the contact force and the resulted feature size. With such a model, force can be used as the in-situ feedback during the patterning and a new method for leveling the pen arrays was developed, which utilizes the total force between the pen arrays and the surface to achieve leveling with a tilt of less than 0.004°. In chapter three, massively multiplexed near-field photolithography has been demonstrated by combining BPL with a batch method to fabricate nanometer scale apertures in parallel fashion and a strategy to individually actuation of each pen in the pen array are discussed. This transformative combination enables one to writing arbitrary patterns composed of diffraction-unlimited features over square centimeter areas that are in registry with existing patterns and nanostructures, creating a unified tool for constructing and studying nanomaterials. The second portion of this thesis focuses on applications of cantilever-free scanning

  3. A cantilever based optical fiber acoustic sensor fabricated by femtosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Yuan, Lei; Huang, Jie; Xiao, Hai

    2016-04-01

    In this paper, we present a pure silica micro-cantilever based optical fiber sensor for acoustic wave detection. The cantilever is directly fabricated by fs laser micromachining on an optical fiber tip functioning as an inline Fabry-Perot interferometer (FPI). The applied acoustic wave pressurizes the micro-cantilever beam and the corresponding dynamic signals can be probed by the FPI. The thickness, length, and width of the micro-cantilever beam can be flexibly designed and fabricated so that the sensitivity, frequency response, and the total measurement range can be varied to fit many practical applications. Experimental results will be presented and analyzed. Due to the assembly free fabrication of the fs-laser, multiple micro-cantilever beams could be potentially fabricated in/on a single optical fiber for quasi-distributed acoustic mapping with high spatial resolution.

  4. Controlling the opto-mechanics of a cantilever in an interferometer via cavity loss

    SciTech Connect

    Schmidsfeld, A. von Reichling, M.

    2015-09-21

    In a non-contact atomic force microscope, based on interferometric cantilever displacement detection, the optical return loss of the system is tunable via the distance between the fiber end and the cantilever. We utilize this for tuning the interferometer from a predominant Michelson to a predominant Fabry-Pérot characteristics and introduce the Fabry-Pérot enhancement factor as a quantitative measure for multibeam interference in the cavity. This experimentally easily accessible and adjustable parameter provides a control of the opto-mechanical interaction between the cavity light field and the cantilever. The quantitative assessment of the light pressure acting on the cantilever oscillating in the cavity via the frequency shift allows an in-situ measurement of the cantilever stiffness with remarkable precision.

  5. [Physiological behavior of Cantilever].

    PubMed

    Feeldman, I; Frugone, R; Vládilo, N T

    1990-11-01

    The prosthetic rehabilitation is common of the integral treatment of patients that integral treatment of patients that have lost one or several dental pieces as a consequence of periodontal diseases. It has been demonstrated that plural fixed prothesis to extention, plovide a distribution pattern and magnitude of favourable forces to the periodontal during the different functions of the stomathologic apparatus, that justify rehabilitation based to it patients periodontically affected. The physiological behaviour of cantilever was basically analized on report on different investigation studies performed on patients periodontically diminis hed treated with plural fixed prothesis of crossed are with two unit or bilateral vear cantilever units, dento supported or fixed in place on implants. It is important to emphasize that favourable results previously analized in base to this type of rehabilitation in its different varieties have been obtained through record done on patients in which considerations of indications, design and occlusion stability have been optimized. PMID:2075270

  6. Spatial spectrograms of vibrating atomic force microscopy cantilevers coupled to sample surfaces

    SciTech Connect

    Wagner, Ryan; Raman, Arvind; Proksch, Roger

    2013-12-23

    Many advanced dynamic Atomic Force Microscopy (AFM) techniques such as contact resonance, force modulation, piezoresponse force microscopy, electrochemical strain microscopy, and AFM infrared spectroscopy exploit the dynamic response of a cantilever in contact with a sample to extract local material properties. Achieving quantitative results in these techniques usually requires the assumption of a certain shape of cantilever vibration. We present a technique that allows in-situ measurements of the vibrational shape of AFM cantilevers coupled to surfaces. This technique opens up unique approaches to nanoscale material property mapping, which are not possible with single point measurements alone.

  7. Multi-directional energy harvesting by piezoelectric cantilever-pendulum with internal resonance

    SciTech Connect

    Xu, J.; Tang, J.

    2015-11-23

    This letter reports a piezoelectric cantilever-pendulum design for multi-directional energy harvesting. A pendulum is attached to the tip of a piezoelectric cantilever-type energy harvester. This design aims at taking advantage of the nonlinear coupling between the pendulum motion in 3-dimensional space and the beam bending vibration at resonances. Experimental studies indicate that, under properly chosen parameters, 1:2 internal resonance can be induced, which enables the multi-directional energy harvesting with a single cantilever. The advantages of the design with respect to traditional piezoelectric cantilever are examined.

  8. Improved Sensitivity MEMS Cantilever Sensor for Terahertz Photoacoustic Spectroscopy

    PubMed Central

    Coutu, Ronald A.; Medvedev, Ivan R.; Petkie, Douglas T.

    2016-01-01

    In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever’s anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom built, low-volume, vacuum chamber. The resulting cantilever sensors exhibited improved signal to noise ratios, sensitivities and normalized noise equivalent absorption (NNEA) coefficients of approximately 4.28 × 10−10 cm−1·WHz−1/2. This reported NNEA represents approximately a 70% improvement over previously fabricated and tested SOI cantilever sensors for THz PA spectroscopy. PMID:26907280

  9. An approach towards 3D sensitive AFM cantilevers

    NASA Astrophysics Data System (ADS)

    Koops, Richard; Fokkema, Vincent

    2014-04-01

    scheme where both the position of the spot to excite the cantilever and the spot position of the read-out beam provide additional parameters to fully control and optimize the multi-mode structure required for 3D AFM measurements.

  10. A new cantilever system for gas and liquid sensing.

    PubMed

    Vidic, A; Then, D; Ziegler, Ch

    2003-01-01

    A novel setup for gas and liquid sensing was developed and tested. It is based on both detection of frequency shift and of bending of micro-cantilevers to measure mass changes as well as viscosity changes. To drive the cantilevers new electrostatic and magnetic actuations were invented with a closed feed-back loop which forces the cantilever to oscillate always at its resonance frequency. The oscillation is detected via the beam-deflection technique. By measuring the DC signal of the photodiode the static bending of the cantilever can be monitored simultaneously. The closed feed-back loop propagates a very stable oscillation at the resonance frequency and gives a strong increase in the quality factor compared to a system without such feed-back loop. Furthermore, it is possible to operate this cantilever transducer system in liquids. These cantilever sensors hence, show the potential for use in easy-to-use and highly sensitive sensor systems for gas and liquid phase chemical and biochemical sensing. PMID:12801696

  11. Gland With Cantilever Seal

    NASA Technical Reports Server (NTRS)

    Melton, Patrick B.

    1989-01-01

    Single-piece gland forms tight seal on probe or tube containing liquid or gas at high pressure. Gland and probe align as assembled by simple torquing procedure. Disconnected easily and reused at same site. Made from any of wide variety of materials so compatible with application. Cantilever ring at top of gland bites into wall of tube or probe, sealing it. Wall of tube or probe must be thick enough to accommodate deformation without rupturing. Maximum deformation designed in coordination with seating and deformation of boss or conical seal.

  12. In Situ Frequency Measurement of Inidividual Nanostructures Using Fiber Optical Interferometry

    SciTech Connect

    Duden, Thomas; Duden, Thomas; Radmilovic, Velimir

    2008-07-01

    In this paper we describe a setup for the resonance frequency measurement of nanocantilevers, which displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The spatial selectivity is determined by the tip geometry, the high sensitivity to vibrations stems from interference of wave fronts reflected on the specimen and on the fiber tip itself. No reference plane on the specimen is needed, as demonstrated with the example of a freestanding silicon nitride cantilever. The resulting system is integrated in the DB-235 dual beam FIB system, thus allowing the measurement of sample responses in-situ, during observation in SEM mode. By combining optical interferometry and narrow band RF amplification and detection, we demonstrate an exceptional vibrational sensitivity at high spatial resolution.

  13. In-situ property measurements on laser-drawn strands of SL 5170 epoxy and SL 5149 acrylate

    SciTech Connect

    Guess, T.R.; Chambers, R.S.

    1995-08-01

    Material behavior plays a significant role in the mechanics leading to internal stresses and, potentially, to distortion (curling) of parts as they are built by stereolithography processes that utilize photocuring resins. A study is underway to generate material properties that can be used to develop phenomenological material models of epoxy and acrylate resins. Strand tests are performed in situ in a 3D System`s SLA-250 machine; strands are drawn by either single or multiple exposures of the resin to a laser beam. Linear shrinkage, cross-sectional areas, cure shrinkage forces and stress-strain data are presented. Also, the curl in cantilever beam specimens, built with different draw patterns, are compared.

  14. Cantilever clamp fitting

    NASA Technical Reports Server (NTRS)

    Melton, Patrick B. (Inventor)

    1989-01-01

    A device is disclosed for sealing and clamping a cylindrical element which is to be attached to an object such as a wall, a pressurized vessel or another cylindrical element. The device includes a gland having an inner cylindrical wall, which is threaded at one end and is attached at a bendable end to a deformable portion, which in turn is attached to one end of a conical cantilever structure. The other end of the cantilever structure connects at a bendable area to one end of an outer cylindrical wall. The opposite end of cylindrical wall terminates in a thickened portion, the radially outer surface of which is adapted to accommodate a tool for rotating the gland. The terminal end of cylindrical wall also includes an abutment surface, which is adapted to engage a seal, which in turn engages a surface of a receiver. The receiver further includes a threaded portion for engagement with the threaded portion of gland whereby a tightening rotation of gland relative to receiver will cause relative movement between cylindrical walls and of gland. This movement causes a rotation of the conical structure and thus a bending action at bending area and at the bending end of the upper end of inner cylindrical wall. These rotational and bending actions result in a forcing of the deformable portion radially inwardly so as to contact and deform a pipe. This forcible contact creates a seal between gland and pipe, and simultaneously clamps the pipe in position.

  15. Vibration analysis of magnetostrictive thin-film composite cantilever actuator

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Shang, Xinchun

    2016-09-01

    The transverse vibration of a composed cantilever beam with magnetostrictive layer is analyzed, which is employed to simulate dynamic response of an actuator. The high-order shear deformation theory of beam and the coupling magnetoelastic constitutive relationship are introduced to construct the governing equations, all interface conditions between magnetostrictive film and elastic substrate as well as the free stress condition on the top and bottom surfaces of the beam can be satisfied. In order to demonstrate validity of the presented mathematical modeling, the verification examples are also given. Furthermore, the effect of geometry and material parameters on dynamic characteristics of magnetostrictive cantilever beam, such as the nature frequency and amplitude, is discussed. Moreover, through computing the magneto-mechanical coupling factor of the beam structure, the variation tendency curves of the factor along with different parameters and frequencies of magnetostrictive cantilever beam actuator have been presented. These numerical results should be useful for the design of beam-type with magnetostrictive thin-film actuators.

  16. Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy.

    PubMed

    Loganathan, Muthukumaran; Bristow, Douglas A

    2014-04-01

    This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields.

  17. Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy

    SciTech Connect

    Loganathan, Muthukumaran; Bristow, Douglas A.

    2014-04-15

    This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields.

  18. Cantilever epitaxial process

    DOEpatents

    Ashby, Carol I.; Follstaedt, David M.; Mitchell, Christine C.; Han, Jung

    2003-07-29

    A process of growing a material on a substrate, particularly growing a Group II-VI or Group III-V material, by a vapor-phase growth technique where the growth process eliminates the need for utilization of a mask or removal of the substrate from the reactor at any time during the processing. A nucleation layer is first grown upon which a middle layer is grown to provide surfaces for subsequent lateral cantilever growth. The lateral growth rate is controlled by altering the reactor temperature, pressure, reactant concentrations or reactant flow rates. Semiconductor materials, such as GaN, can be produced with dislocation densities less than 10.sup.7 /cm.sup.2.

  19. Viscous drag measurements utilizing microfabricated cantilevers

    SciTech Connect

    Oden, P.I.; Chen, G.Y.; Steele, R.A.; Warmack, R.J.; Thundat, T.

    1996-06-01

    The influence of viscous drag forces on cantilevers is investigated using standard atomic force microscope (AFM) cantilevers. Viscosity effects on several geometrically different cantilevers manifest themselves as variations in resonance frequencies, quality factors, and cantilever response amplitudes. With this novel measurement, a single cantilever can be used to measure viscosities ranging from {eta}=10{sup {minus}2} to 10{sup 2} g/cms. {copyright} {ital 1996 American Institute of Physics.}

  20. Label-free protein assay based on a nanomechanical cantilever array

    NASA Astrophysics Data System (ADS)

    Arntz, Y.; Seelig, J. D.; Lang, H. P.; Zhang, J.; Hunziker, P.; Ramseyer, J. P.; Meyer, E.; Hegner, M.; Gerber, Ch

    2003-01-01

    We demonstrate continuous label-free detection of two cardiac biomarker proteins (creatin kinase and myoglobin) using an array of microfabricated cantilevers functionalized with covalently anchored anti-creatin kinase and anti-myoglobin antibodies. This method allows biomarker proteins to be detected via measurement of surface stress generated by antigen-antibody molecular recognition. Reference cantilevers are used to eliminate thermal drifts, undesired chemical reactions and turbulences from injections of liquids by calculating differential deflection signals with respect to sensor cantilevers. The sensitivity achieved for myoglobin detection is below 20 µg ml-1. Both myoglobin and creatin kinase could be detected independently using cantilevers functionalized with the corresponding antibodies, in unspecific protein background. This approach permits the use of up to seven different antigen-antibody reactions simultaneously, including an additional thermomechanical and chemical in situ reference. Applications lie in the field of early and rapid diagnosis of acute myocardial infarction.

  1. Nondestructive testing and hardness measurement based on contact resonance of piezoelectric cantilevers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Li, Faxin; Fu, Ji

    2016-04-01

    A suitable defect identification parameter is very important in the field of nondestructive testing (NDT). In this work, we proposed a NDT method which detects the sample's local contact stiffness (LCS) based on the contact resonance of a piezoelectric cantilever. Firstly, through finite element analysis we showed that LCS is quite sensitive to typical defects including debonding, voids, cracks and inclusions, making it a good identification parameter. Secondly, a homemade NDT system containing a piezoelectric unimorph cantilever was assembled to detect the sample's LCS by tracking the contact resonance frequency (CRF) of the cantilever-sample system based on strain signals. Testing results indicated that this NDT system could detect the above mentioned defects efficiently. The cantilever-stiffness dependent detection sensitivity was specially investigated and the stiffer cantilevers were found to be more sensitive to small defects. Then, a piezoelectric bimorph cantilever was fabricated and the electromechanical impedance, other than the strain signals, was measured to track the CRF of the cantilever-system. The LCS is then derived by using the equivalent-circuit model. The electromechanical impedance based NDT system is more compact and can be further developed to be a portable device. Finally, a Vicker indenter is fabricated onto the bimorph tip and the contact area is derived from the measured LCS. Thus the NDT system turns to be a hardness tester without any optical devices. It is very useful for in-situ testing or testing on inner surfaces where conventional hardness tester is not applicable.

  2. Efficiency enhancement of a cantilever-based vibration energy harvester.

    PubMed

    Kubba, Ali E; Jiang, Kyle

    2013-01-01

    Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (V(ave)), and average normal strain in the piezoelectric transducer (ε(ave)) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle). PMID:24366177

  3. SU-8 hollow cantilevers for AFM cell adhesion studies

    NASA Astrophysics Data System (ADS)

    Martinez, Vincent; Behr, Pascal; Drechsler, Ute; Polesel-Maris, Jérôme; Potthoff, Eva; Vörös, Janos; Zambelli, Tomaso

    2016-05-01

    A novel fabrication method was established to produce flexible, transparent, and robust tipless hollow atomic force microscopy (AFM) cantilevers made entirely from SU-8. Channels of 3 μm thickness and several millimeters length were integrated into 12 μm thick and 40 μm wide cantilevers. Connected to a pressure controller, the devices showed high sealing performance with no leakage up to 6 bars. Changing the cantilever lengths from 100 μm to 500 μm among the same wafer allowed the targeting of various spring constants ranging from 0.5 to 80 N m-1 within a single fabrication run. These hollow polymeric AFM cantilevers were operated in the optical beam deflection configuration. To demonstrate the performance of the device, single-cell force spectroscopy experiments were performed with a single probe detaching in a serial protocol more than 100 Saccharomyces cerevisiae yeast cells from plain glass and glass coated with polydopamine while measuring adhesion forces in the sub-nanoNewton range. SU-8 now offers a new alternative to conventional silicon-based hollow cantilevers with more flexibility in terms of complex geometric design and surface chemistry modification.

  4. SU-8 hollow cantilevers for AFM cell adhesion studies

    NASA Astrophysics Data System (ADS)

    Martinez, Vincent; Behr, Pascal; Drechsler, Ute; Polesel-Maris, Jérôme; Potthoff, Eva; Vörös, Janos; Zambelli, Tomaso

    2016-05-01

    A novel fabrication method was established to produce flexible, transparent, and robust tipless hollow atomic force microscopy (AFM) cantilevers made entirely from SU-8. Channels of 3 μm thickness and several millimeters length were integrated into 12 μm thick and 40 μm wide cantilevers. Connected to a pressure controller, the devices showed high sealing performance with no leakage up to 6 bars. Changing the cantilever lengths from 100 μm to 500 μm among the same wafer allowed the targeting of various spring constants ranging from 0.5 to 80 N m‑1 within a single fabrication run. These hollow polymeric AFM cantilevers were operated in the optical beam deflection configuration. To demonstrate the performance of the device, single-cell force spectroscopy experiments were performed with a single probe detaching in a serial protocol more than 100 Saccharomyces cerevisiae yeast cells from plain glass and glass coated with polydopamine while measuring adhesion forces in the sub-nanoNewton range. SU-8 now offers a new alternative to conventional silicon-based hollow cantilevers with more flexibility in terms of complex geometric design and surface chemistry modification.

  5. Efficiency Enhancement of a Cantilever-Based Vibration Energy Harvester

    PubMed Central

    Kubba, Ali E.; Jiang, Kyle

    2014-01-01

    Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (Vave), and average normal strain in the piezoelectric transducer (εave) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle). PMID:24366177

  6. Efficiency enhancement of a cantilever-based vibration energy harvester.

    PubMed

    Kubba, Ali E; Jiang, Kyle

    2013-12-23

    Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (V(ave)), and average normal strain in the piezoelectric transducer (ε(ave)) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle).

  7. High throughput reproducible cantilever functionalization

    SciTech Connect

    Evans, Barbara R; Lee, Ida

    2014-01-21

    A method for functionalizing cantilevers is provided that includes providing a holder having a plurality of channels each having a width for accepting a cantilever probe and a plurality of probes. A plurality of cantilever probes are fastened to the plurality of channels of the holder by the spring clips. The wells of a well plate are filled with a functionalization solution, wherein adjacent wells in the well plate are separated by a dimension that is substantially equal to a dimension separating adjacent channels of the plurality of channels. Each cantilever probe that is fastened within the plurality of channels of the holder is applied to the functionalization solution that is contained in the wells of the well plate.

  8. High throughout reproducible cantilever functionalization

    SciTech Connect

    Evans, Barbara R; Lee, Ida

    2014-11-25

    A method for functionalizing cantilevers is provided that includes providing a holder having a plurality of channels each having a width for accepting a cantilever probe and a plurality of probes. A plurality of cantilever probes are fastened to the plurality of channels of the holder by the spring clips. The wells of a well plate are filled with a functionalization solution, wherein adjacent wells in the well plate are separated by a dimension that is substantially equal to a dimension separating adjacent channels of the plurality of channels. Each cantilever probe that is fastened within the plurality of channels of the holder is applied to the functionalization solution that is contained in the wells of the well plate.

  9. 17. LOWER CHORD CONNECTION, FLOOR BEAM & STRINGER SYSTEMS, WALKWAY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. LOWER CHORD CONNECTION, FLOOR BEAM & STRINGER SYSTEMS, WALKWAY CANTILEVER SUPPORTS; WALKWAY CANTILEVER SUPPORTS; LOOKING N - Traer Street Bridge, Spanning Shell Rock River at Traer Street, Greene, Butler County, IA

  10. Effect of tip mass on frequency response and sensitivity of AFM cantilever in liquid.

    PubMed

    Farokh Payam, Amir; Fathipour, Morteza

    2015-03-01

    The effect of tip mass on the frequency response and sensitivity of atomic force microscope (AFM) cantilever in the liquid environment is investigated. For this purpose, using Euler-Bernoulli beam theory and considering tip mass and hydrodynamic functions in a liquid environment, an expression for the resonance frequencies of AFM cantilever in liquid is derived. Then, based on this expression, the effect of the surface contact stiffness on the flexural mode of a rectangular AFM cantilever in fluid is investigated and compared with the case where the AFM cantilever operates in the air. The results show that in contrast with an air environment, the tip mass has no significant impact on the resonance frequency and sensitivity of the AFM cantilever in the liquid. Hence, analysis of AFM behaviour in liquid environment by neglecting the tip mass is logical. PMID:25562584

  11. Fabrication of nanoscale magnet-tipped cantilevers for magnetic resonance force microscopy

    NASA Astrophysics Data System (ADS)

    Hickman, Steven A.; Garner, Sean R.; Harrell, Lee E.; Kuehn, Seppe; Marohn, John A.

    2006-03-01

    Magnetic resonance force microscopy(MRFM) is a promising new technique for acquiring magnetic resonance images of a single molecule; to date we have demonstrated a sensitivity of approximately 10,000 proton spins. In MRFM the force exerted on the cantilever, per spin, is proportional to the field gradient from the cantilever's magnetic tip. To increase the force requires shrinking the magnet size. Achieving the attonewton force sensitivity necessary to image single spins requires mitigating surface induced dissipation. We choose to meet both of these conditions by creating nanoscale magnets extending from the tips of silicon cantilevers. We will present a 50-nm wide overhanging cobalt magnet fabricated by a process involving electron beam lithography and anisotropic KOH etching. This process can be integrated into a fabrication protocol for ultrasensitive silicon cantilevers. With these cantilevers we expect a sensitivity of better than 1000 protons.

  12. In situ Stiffness Adjustment of AFM Probes by Two Orders of Magnitude

    PubMed Central

    de Laat, Marcel Lambertus Cornelis; Pérez Garza, Héctor Hugo; Ghatkesar, Murali Krishna

    2016-01-01

    The choice on which type of cantilever to use for Atomic Force Microscopy (AFM) depends on the type of the experiment being done. Typically, the cantilever has to be exchanged when a different stiffness is required and the entire alignment has to be repeated. In the present work, a method to adjust the stiffness in situ of a commercial AFM cantilever is developed. The adjustment is achieved by changing the effective length of the cantilever by electrostatic pull-in. By applying a voltage between the cantilever and an electrode (with an insulating layer at the point of contact), the cantilever snaps to the electrode, reducing the cantilever’s effective length. An analytical model was developed to find the pull-in voltage of the system. Subsequently, a finite element model was developed to study the pull-in behavior. The working principle of this concept is demonstrated with a proof-of-concept experiment. The electrode was positioned close to the cantilever by using a robotic nanomanipulator. To confirm the change in stiffness, the fundamental resonance frequency of the cantilever was measured for varying electrode positions. The results match with the theoretical expectations. The stiffness was adjusted in situ in the range of 0.2 N/m to 27 N/m, covering two orders of magnitude in one single cantilever. This proof-of-concept is the first step towards a micro fabricated prototype, that integrates the electrode positioning system and cantilever that can be used for actual AFM experiments. PMID:27077863

  13. Multidomain piezo-ceramic cantilever

    NASA Astrophysics Data System (ADS)

    Sedorook, David P.

    PZT-5H is a ferroelectric and piezoelectric material that has many applications that are the subjects of current research. As a ferroelectric, PZT-5H has a permanent electrical polarization that arises from ferroelectric domains. In this thesis, numerical simulations were conducted via the well know Finite Element Method of several types of piezoelectric cantilevers that were made of PIC-181, a high quality PZT-5H made in Germany. Single crystal cantilever models with multiple polarization vectors were investigated with Q factors ranging from Q = 50 to Q = 1200, where the acoustical displacements were calculated. Further, the displacements were calculated for a multidomain cantilever model with inversely poled domains and uniform electrode configuration as well as a single crystal cantilever model with uniformly poled crystal and bipolar electrode configuration. It was shown that cantilevers that are less oblong in shape could benefit from the bipolar electrode configuration in applications where size may be an important parameter, for instance in small flying robotic insects. From the experimental measurements of the resonance and anti-resonance frequencies in various PIC-181 samples, the radial and longitudinal components of speed of sound in material were calculated. Experimental results of longitudinal speed of sound differed from the accepted value of 4.6 km/s by 1.6 % error.

  14. Precise atomic force microscope cantilever spring constant calibration using a reference cantilever array.

    PubMed

    Gates, Richard S; Reitsma, Mark G

    2007-08-01

    A method for calibrating the stiffness of atomic force microscope (AFM) cantilevers is demonstrated using an array of uniform microfabricated reference cantilevers. A series of force-displacement curves was obtained using a commercial AFM test cantilever on the reference cantilever array, and the data were analyzed using an implied Euler-Bernoulli model to extract the test cantilever spring constant from linear regression fitting. The method offers a factor of 5 improvement over the precision of the usual reference cantilever calibration method and, when combined with the Systeme International traceability potential of the cantilever array, can provide very accurate spring constant calibrations.

  15. Precise atomic force microscope cantilever spring constant calibration using a reference cantilever array

    SciTech Connect

    Gates, Richard S.; Reitsma, Mark G.

    2007-08-15

    A method for calibrating the stiffness of atomic force microscope (AFM) cantilevers is demonstrated using an array of uniform microfabricated reference cantilevers. A series of force-displacement curves was obtained using a commercial AFM test cantilever on the reference cantilever array, and the data were analyzed using an implied Euler-Bernoulli model to extract the test cantilever spring constant from linear regression fitting. The method offers a factor of 5 improvement over the precision of the usual reference cantilever calibration method and, when combined with the Systeme International traceability potential of the cantilever array, can provide very accurate spring constant calibrations.

  16. Use of Ion Beam Analysis to Study in Situ the Oxygen Diffusion and Interfacial Transfer Coefficients in Y1Ba2Cu 3O7-x Thin Films

    NASA Astrophysics Data System (ADS)

    García López, J.; Siejka, J.; Lemaitre, Y.; Mage, J. C.; Marcilhac, B.

    An experimental chamber was connected to the 2.5 MV Van de Graaff accelerator allowing in situ sample annealing at T ≤ 700°C and under pO2 ranging from 10-8 to 1 bar. For the first time to our knowledge the 16O(3He,α)15O nuclear reaction has been employed to monitor in situ the oxygen loss and uptake in Y1Ba2Cu3 O7-x (YBCO) thin films as a function of oxygen pressure and temperature (T ≤ 500°C). The role played by the presence of carbon contamination on YBCO surface was elucidated. Using the 12C(d,p)13C nuclear reaction the carbon loss was observed for T ≥ 250°C and it was associated with the oxygen loss enhancement in YBCO. It is found that in absence of carbon contamination, oxygen in-diffusion rate in YBCO is much faster than the out-diffusion rate, the later being surface reaction limited. The oxygen diffusion coefficients and the surface exchange coefficients of YBCO films have been evaluated. These results will be discussed in relation with the mechanism of high temperature YBCO thin film growth by cathodic sputtering and with the mechanism of the oxygen loss and/or uptake during the sample cooling.

  17. Torsion/cantilever-based MEMS bistable mechanisms with different support configurations: structure design and comparison

    NASA Astrophysics Data System (ADS)

    Wu, Yibo; Zhang, Congchun; Wang, Hong; Ding, Guifu

    2011-04-01

    Three types of torsion/cantilever-based MEMS bistable mechanisms (BMs) with different support configurations have been constructed, modeled and experimented. For the support configuration, there is a crisscross-shaped, a ring-shaped and a diamond-shaped support beam, respectively. The proposed MEMS BMs consist of a free-free torsion-based cantilever which forms a symmetrical rocker lever. The free-free cantilever is suspended by a support skeleton which in turn is attached to a torsion cantilever. A permanent magnet is attached beside for holding the closed state with a permalloy soft magnetic circuit. The different special support configurations account for a low torsional compliance with the overhanging beams. In order to deduce the equivalent stiffness coefficient of BM systems, mechanical modeling of three types of torsion/cantilever-based MEMS BMs was performed by the classical beam theorem. Meanwhile, the magnetostatic latching force was also deduced by the Maxwell electromagnetism theory. The performances of these MEMS BMs have been compared by the evaluation of static deformation variations, equivalent stiffness coefficients and dynamical switching characterizations. Finally, mechanical performance was characterized by atomic force microscopy, combined with a Nanoindentation Tester. In addition, bistabilities of the MEMS BMs were proved by theoretical analysis as well as experimental results. Among these BMs, the ring-shaped MEMS BM is extremely prone to deflect due to relatively low stiffness compared with other types. The torsion/cantilever-based MEMS BMs have potential application in the field of latching relays with low power consumption.

  18. Direct comparative study on the energy level alignments in unoccupied/occupied states of organic semiconductor/electrode interface by constructing in-situ photoemission spectroscopy and Ar gas cluster ion beam sputtering integrated analysis system

    SciTech Connect

    Yun, Dong-Jin Chung, JaeGwan; Kim, Yongsu; Park, Sung-Hoon; Kim, Seong-Heon; Heo, Sung

    2014-10-21

    Through the installation of electron gun and photon detector, an in-situ photoemission and damage-free sputtering integrated analysis system is completely constructed. Therefore, this system enables to accurately characterize the energy level alignments including unoccupied/occupied molecular orbital (LUMO/HOMO) levels at interface region of organic semiconductor/electrode according to depth position. Based on Ultraviolet Photoemission Spectroscopy (UPS), Inverse Photoemission Spectroscopy (IPES), and reflective electron energy loss spectroscopy, the occupied/unoccupied state of in-situ deposited Tris[4-(carbazol-9-yl)phenyl]amine (TCTA) organic semiconductors on Au (E{sub LUMO}: 2.51 eV and E{sub HOMO}: 1.35 eV) and Ti (E{sub LUMO}: 2.19 eV and E{sub HOMO}: 1.69 eV) electrodes are investigated, and the variation of energy level alignments according to work function of electrode (Au: 4.81 eV and Ti: 4.19 eV) is clearly verified. Subsequently, under the same analysis condition, the unoccupied/occupied states at bulk region of TCTA/Au structures are characterized using different Ar gas cluster ion beam (Ar GCIB) and Ar ion sputtering processes, respectively. While the Ar ion sputtering process critically distorts both occupied and unoccupied states in UPS/IPES spectra, the Ar GCIB sputtering process does not give rise to damage on them. Therefore, we clearly confirm that the in-situ photoemission spectroscopy in combination with Ar GCIB sputtering allows of investigating accurate energy level alignments at bulk/interface region as well as surface region of organic semiconductor/electrode structure.

  19. Calibration of the effective spring constant of ultra-short cantilevers for a high-speed atomic force microscope

    NASA Astrophysics Data System (ADS)

    Song, Yun-Peng; Wu, Sen; Xu, Lin-Yan; Zhang, Jun-Ming; Dorantes-Gonzalez, Dante J.; Fu, Xing; Hu, Xiao-Dong

    2015-06-01

    Ultra-short cantilevers are a new type of cantilever designed for the next generation of high-speed atomic force microscope (HS-AFM). Ultra-short cantilevers have smaller dimensions and higher resonant frequency than conventional AFM cantilevers. Moreover, their geometry may also be different from the conventional beam-shape or V-shape. These changes increase the difficulty of determining the spring constant for ultra-short cantilevers, and hence limit the accuracy and precision of force measurement based on a HS-AFM. This paper presents an experimental method to calibrate the effective spring constant of ultra-short cantilevers. By using a home-made AFM head, the cantilever is bent against an electromagnetic compensation balance under servo control. Meanwhile the bending force and the cantilever deflection are synchronously measured by the balance and the optical lever in the AFM head, respectively. Then the effective spring constant is simply determined as the ratio of the force to the corresponding deflection. Four ultra-short trapezoid shape cantilevers were calibrated using this method. A quantitative uncertainty analysis showed that the combined relative standard uncertainty of the calibration result is less than 2%, which is better than the uncertainty of any previously reported techniques.

  20. Cantilevered probe detector with piezoelectric element

    SciTech Connect

    Adams, Jesse D; Sulchek, Todd A; Feigin, Stuart C

    2014-04-29

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  1. Cantilevered probe detector with piezoelectric element

    SciTech Connect

    Adams, Jesse D; Sulchek, Todd A; Feigin, Stuart C

    2013-04-30

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  2. Cantilevered probe detector with piezoelectric element

    DOEpatents

    Adams, Jesse D.; Sulchek, Todd A.; Feigin, Stuart C.

    2010-04-06

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  3. Cantilevered probe detector with piezoelectric element

    DOEpatents

    Adams, Jesse D.; Sulchek, Todd A.; Feigin, Stuart C.

    2012-07-10

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  4. Lateral force microscope calibration using a modified atomic force microscope cantilever

    SciTech Connect

    Reitsma, M. G.

    2007-10-15

    A proof-of-concept study is presented for a prototype atomic force microscope (AFM) cantilever and associated calibration procedure that provide a path for quantitative friction measurement using a lateral force microscope (LFM). The calibration procedure is based on the method proposed by Feiler et al. [Rev. Sci. Instrum. 71, 2746 (2000)] but allows for calibration and friction measurements to be carried out in situ and with greater precision. The modified AFM cantilever is equipped with lateral lever arms that facilitate the application of normal and lateral forces, comparable to those acting in a typical LFM friction experiment. The technique allows the user to select acceptable precision via a potentially unlimited number of calibration measurements across the full working range of the LFM photodetector. A microfabricated version of the cantilever would be compatible with typical commercial AFM instrumentation and allow for common AFM techniques such as topography imaging and other surface force measurements to be performed.

  5. Experimental study of aerodynamic damping in arrays of vibrating cantilevers

    NASA Astrophysics Data System (ADS)

    Kimber, M.; Lonergan, R.; Garimella, S. V.

    2009-11-01

    Cantilever structures vibrating in a fluid are encountered in numerous engineering applications. The aerodynamic loading from a fluid can have a large effect on both the resonance frequency and damping, and has been the subject of numerous studies. The aerodynamic loading on a single beam is altered when multiple beams are configured in an array. In such situations, neighboring beams interact through the fluid and their dynamic behavior is modified. In this work, aerodynamic interactions between neighboring cantilever beams operating near their first resonance mode and vibrating at amplitudes comparable to their widths are experimentally explored. The degree to which two beams become coupled through the fluid is found to be sensitive to vibration amplitude and proximity of neighboring components in the array. The cantilever beams considered are slender piezoelectric fans (approximately 6 cm in length), and are caused to vibrate in-phase and out-of-phase at frequencies near their fundamental resonance values. Aerodynamic damping is expressed in terms of the quality factor for two different array configurations and estimated for both in-phase and out-of-phase conditions. The two array configurations considered are for neighboring fans placed face-to-face and edge-to-edge. It is found that the damping is greatly influenced by proximity of neighboring fans and phase difference. For the face-to-face configuration, a reduction in damping is observed for in-phase vibration, while it is greatly increased for out-of-phase vibration; the opposite effect is seen for the edge-to-edge configuration. The resonance frequencies also show a dependence on the phase difference, but these changes are small compared to those observed for damping. Correlations are developed based on the experimental data which can be used to predict the aerodynamic damping in arrays of vibrating cantilevers. The distance at which the beams no longer interact is quantified for both array configurations

  6. Piezoelectric cantilever-pendulum for multi-directional energy harvesting with internal resonance

    NASA Astrophysics Data System (ADS)

    Xu, J.; Tang, J.

    2015-04-01

    Piezoelectric transducers are widely employed in vibration-based energy harvesting schemes. Simple piezoelectric cantilever for energy harvesting is uni-directional and has bandwidth limitation. In this research we explore utilizing internal resonances to harvest vibratory energy due to excitations from an arbitrary direction with the usage of a single piezoelectric cantilever. Specifically, it is identified that by attaching a pendulum to the piezoelectric cantilever, 1:2 internal resonances can be induced based on the nonlinear coupling. The nonlinear effect induces modal energy exchange between beam bending motion and pendulum motions in 3-dimensional space, which ultimately yield multidirectional energy harvesting by a single cantilever. Systematic analysis and experimental investigation are carried out to demonstrate this new concept.

  7. Laser Actuation of Cantilevers for Picometre Amplitude Dynamic Force Microscopy

    PubMed Central

    Evans, Drew R.; Tayati, Ponlawat; An, Hongjie; Lam, Ping Koy; Craig, Vincent S. J.; Senden, Tim J.

    2014-01-01

    As nanoscale and molecular devices become reality, the ability to probe materials on these scales is increasing in importance. To address this, we have developed a dynamic force microscopy technique where the flexure of the microcantilever is excited using an intensity modulated laser beam to achieve modulation on the picoscale. The flexure arises from thermally induced bending through differential expansion and the conservation of momentum when the photons are reflected and absorbed by the cantilever. In this study, we investigated the photothermal and photon pressure responses of monolithic and layered cantilevers using a modulated laser in air and immersed in water. The developed photon actuation technique is applied to the stretching of single polymer chains. PMID:24993548

  8. Optical fibre cantilever sensor for biological application

    NASA Astrophysics Data System (ADS)

    Li, J.; Zhou, Y. X.; Patterson, G.; Shu, W. M.; Maier, R. R. J.; Fowler, R.; Hand, D. P.; MacPherson, W. N.

    2014-05-01

    Micro-cantilever sensors have shown great promise in a wide range of application are as including chemical and biological sensing. However, many of these devices are based upon a sensor `chip' that requires careful alignment between the cantilever and the read-out system, which can be challenging. Furthermore, optical interrogation typically involves a bulky free-space system. Optical fibre addressed cantilevers have been reported previously in the literature and in this paper we propose techniques to design and fabricate polymer micro-cantilevers for attachment onto the end of standard single mode fibres using laser machining. Low-cost optical sources and a fibre coupled spectrometer are employed to monitor the cantilever deflection and therefore observe biological binding between a species of interest and an activated cantilever. Proof-of-concept experiments show that the sensor is capable of detecting pathogen concentration with down to a level of 105cfu/ml.

  9. Microstructural improvements of InP on GaAs (001) grown by molecular beam epitaxy by in situ hydrogenation and postgrowth annealing

    SciTech Connect

    Morales, F. M.; Garcia, R.; Molina, S. I.; Aouni, A.; Postigo, P. A.; Fonstad, C. G.

    2009-01-26

    The characterization of high quality InP on GaAs (001) fabricated by molecular beam epitaxy using a two-step growth method involving hydrogenation during growth is reported. Electron diffraction and high-resolution transmission electron microscopy confirm that {approx}2 {mu}m thick InP epilayers on GaAs are heteroepitaxial and strain relaxed. Stacking faults and threading dislocations are mostly confined near the InP/GaAs interface and their densities decrease monotonically toward the InP surface. Additionally, rapid-thermal annealing following growth is found to result in a marked reduction in the number of dislocations and the disappearance of planar defects.

  10. Defect-free zinc-blende structured InAs nanowires realized by in situ two V/III ratio growth in molecular beam epitaxy.

    PubMed

    Zhang, Zhi; Lu, Zhen-Yu; Chen, Ping-Ping; Lu, Wei; Zou, Jin

    2015-08-01

    In this study, we devised a two-V/III-ratio procedure to control the Au-assisted growth of defect-free InAs nanowires in molecular beam epitaxy. The demonstrated two V/III ratio procedure consists of a first high V/III ratio growth step to prepare the nanowire foundation on the substrate surface, followed by a low V/III ratio step to induce the nanowire growth. By manipulating the V/III ratios in different steps, we have achieved the controlled growth of pure defect-free zinc-blende structured InAs nanowires on the GaAs {1̄1̄1̄} substrates. This study provides an approach to control not only the crystal structure of semiconductor nanowires, but also their structural qualities.

  11. Colloid probes with increased tip height for higher sensitivity in friction force microscopy and less cantilever damping in dynamic force microscopy.

    PubMed

    Schmutz, Jan-Erik; Schäfer, Marcus M; Hölscher, Hendrik

    2008-02-01

    We present a method how to glue small spheres to atomic force microscope cantilevers. In difference to an often used approach where the sphere is glued to a tipless cantilever, we suggest to mount small spheres to a conventional cantilever with integrated tips modified by a focused ion beam. In this way it is possible to manufacture a spherical probe with increased tip height which enhances the sensitivity in friction force microscopy and reduces the cantilever damping in dynamic force microscopy. By milling cavities for the spheres at the tip apex the colloid particles can be attached at defined positions and contamination with glue can be prevented. PMID:18315335

  12. Study on the design method of the jack-up's x-type cantilever allowable load nephogram

    NASA Astrophysics Data System (ADS)

    Zhu, Yazhou; Sun, Chengmeng; Qin, Hongde; Jiang, Bin; Fan, Yansong

    2014-09-01

    The extending of a cantilever and transverse moving of a drilling floor enable the jack-up to operate in several well positions after the Jack-up has pitched. The cantilever allowable load nephogram is the critical reference which can evaluate the jack-up's drilling ability, design the cantilever structure and instruct a jack-up manager to make the operations safe. The intent of this paper is to explore the interrelationships between the cantilever position, drilling floor and the loads including wind force, the stand set-back weight etc., through analyzing the structure and load characteristics of the x-type cantilever and the simplified mechanics model with the restriction of the maximum moment capacity of the cantilever single side beam. Referring to several typical position designs load values, the cantilever allowable load nephogram is obtained by using the suitable interpolation method. The paper gives a method for cantilever allowable load design, which is proved reliable and effective by the calculation example.

  13. Ion beam analysis of C-13 and deuterium deposition in DIII-D and their removal by in-situ oxygen baking

    SciTech Connect

    Wampler, W. R.; Allen, S. L.; Brooks, N. H.; Chrobak, C P; Davis, J W; Ellis, R; McLean, A. G.

    2011-01-01

    An experiment was conducted in DIII-D to examine carbon deposition when a secondary separatrix is near the wall. The magnetic configuration for this experiment was a biased double-null, similar to that foreseen for ITER. C-13 methane was injected toroidally symmetrically near the secondary separatrix into ELMy H-mode deuterium plasmas. The resulting deposition of C-13 was determined by nuclear reaction analysis. These results show that very little of the injected C-13 was deposited at the primary separatrix, whereas a large fraction of injected C-13 was deposited close to the point of injection near the secondary separatrix. Six of the tiles were put back into DIII-D, where they were baked at 350-360 degrees C for 2 h at similar to 1 kPa in a 20% O-2/80% He gas mixture. Subsequent ion beam analysis of these tiles showed that about 21% of the C-13 and 54% of the deuterium were removed by the bake.

  14. Derivation of the surface free energy of ZnO and GaN using in situ electron beam hole drilling.

    PubMed

    Ghatak, Jay; Huang, Jun-Han; Liu, Chuan-Pu

    2016-01-01

    Surface free energy, as an intrinsic property, is essential in determining the morphology of materials, but it is extremely difficult to determine experimentally. We report on the derivation of the SE of different facets of ZnO and GaN experimentally from the holes developed using electron beam drilling with transmission electron microscopy. Inverse Wullf's construction is employed to obtain polar maps of the SE of different facets to study different nanomaterials (ZnO and GaN) in different morphologies (nanorod, nanobelt and thin film) to prove its versatility and capability. The results show that the SE of ZnO{10-13} is derived to be 0.99 J m(-2), and the SE of ZnO{10-10} is found to be less than {0002} and {11-20}. A GaN thin film also exhibits a similar trend in the SE of different facets as ZnO and the SE of GaN{10-13} is determined to be 1.36 J m(-2).

  15. Derivation of the surface free energy of ZnO and GaN using in situ electron beam hole drilling.

    PubMed

    Ghatak, Jay; Huang, Jun-Han; Liu, Chuan-Pu

    2016-01-01

    Surface free energy, as an intrinsic property, is essential in determining the morphology of materials, but it is extremely difficult to determine experimentally. We report on the derivation of the SE of different facets of ZnO and GaN experimentally from the holes developed using electron beam drilling with transmission electron microscopy. Inverse Wullf's construction is employed to obtain polar maps of the SE of different facets to study different nanomaterials (ZnO and GaN) in different morphologies (nanorod, nanobelt and thin film) to prove its versatility and capability. The results show that the SE of ZnO{10-13} is derived to be 0.99 J m(-2), and the SE of ZnO{10-10} is found to be less than {0002} and {11-20}. A GaN thin film also exhibits a similar trend in the SE of different facets as ZnO and the SE of GaN{10-13} is determined to be 1.36 J m(-2). PMID:26646378

  16. High-speed imaging upgrade for a standard sample scanning atomic force microscope using small cantilevers

    SciTech Connect

    Adams, Jonathan D.; Nievergelt, Adrian; Erickson, Blake W.; Yang, Chen; Dukic, Maja; Fantner, Georg E.

    2014-09-15

    We present an atomic force microscope (AFM) head for optical beam deflection on small cantilevers. Our AFM head is designed to be small in size, easily integrated into a commercial AFM system, and has a modular architecture facilitating exchange of the optical and electronic assemblies. We present two different designs for both the optical beam deflection and the electronic readout systems, and evaluate their performance. Using small cantilevers with our AFM head on an otherwise unmodified commercial AFM system, we are able to take tapping mode images approximately 5–10 times faster compared to the same AFM system using large cantilevers. By using additional scanner turnaround resonance compensation and a controller designed for high-speed AFM imaging, we show tapping mode imaging of lipid bilayers at line scan rates of 100–500 Hz for scan areas of several micrometers in size.

  17. Study of node and mass sensitivity of resonant mode based cantilevers with concentrated mass loading

    NASA Astrophysics Data System (ADS)

    Zhang, Kewei; Chai, Yuesheng; Fu, Jiahui

    2015-12-01

    Resonant-mode based cantilevers are an important type of acoustic wave based mass-sensing devices. In this work, the governing vibration equation of a bi-layer resonant-mode based cantilever attached with concentrated mass is established by using a modal analysis method. The effects of resonance modes and mass loading conditions on nodes and mass sensitivity of the cantilever were theoretically studied. The results suggested that the node did not shift when concentrated mass was loaded on a specific position. Mass sensitivity of the cantilever was linearly proportional to the square of the point displacement at the mass loading position for all the resonance modes. For the first resonance mode, when mass loading position xc satisfied 0 < xc < ˜ 0.3l (l is the cantilever beam length and 0 represents the rigid end), mass sensitivity decreased as the mass increasing while the opposite trend was obtained when mass loading satisfied ˜0.3l ≤ xc ≤ l. Mass sensitivity did not change when concentrated mass was loaded at the rigid end. This work can provide scientific guidance to optimize the mass sensitivity of a resonant-mode based cantilever.

  18. Study of node and mass sensitivity of resonant mode based cantilevers with concentrated mass loading

    SciTech Connect

    Zhang, Kewei Chai, Yuesheng; Fu, Jiahui

    2015-12-15

    Resonant-mode based cantilevers are an important type of acoustic wave based mass-sensing devices. In this work, the governing vibration equation of a bi-layer resonant-mode based cantilever attached with concentrated mass is established by using a modal analysis method. The effects of resonance modes and mass loading conditions on nodes and mass sensitivity of the cantilever were theoretically studied. The results suggested that the node did not shift when concentrated mass was loaded on a specific position. Mass sensitivity of the cantilever was linearly proportional to the square of the point displacement at the mass loading position for all the resonance modes. For the first resonance mode, when mass loading position x{sub c} satisfied 0 < x{sub c} < ∼ 0.3l (l is the cantilever beam length and 0 represents the rigid end), mass sensitivity decreased as the mass increasing while the opposite trend was obtained when mass loading satisfied ∼0.3l ≤ x{sub c} ≤ l. Mass sensitivity did not change when concentrated mass was loaded at the rigid end. This work can provide scientific guidance to optimize the mass sensitivity of a resonant-mode based cantilever.

  19. Development of Multi-Degree-Of-Freedom Piezoelectric Energy Harvester Using Interdigital Shaped Cantilevers.

    PubMed

    Cho, Hyunok; Park, Jongcheol; Park, Jae Yeong

    2016-05-01

    A piezoelectric vibration energy harvester with interdigital shaped cantilever was developed by using silicon bulk micromachining technology. The proposed energy harvester was designed to obtain multi degree-of-freedom (m-DOF). Most of the piezoelectric vibration energy harvesters are comprised of mass-loaded cantilever beams having several resonant frequencies. The second resonant frequency of such a device has lower amplitude compared to its first resonant frequency (fundamental frequency). Therefore, the interdigital shaped cantilever has been proposed for multiple fundamental resonant frequencies. The fabricated piezoelectric vibration energy harvester is composed of main cantilever (MC), sub-main cantilever (SMC), and secondary cantilevers (SC). MC surrounds SMC and SC which have same dimension of 5600 x 800 x 10 μm3. The fabricated piezoelectric energy harvester can generate 51.4 mV(p-p) and 11 mV(p-p) of output voltages at 24.2 Hz and 33 Hz of its resonant frequencies by MC. Moreover, it can generate 8 mV(p-p) and 6.6 mV(p-p) of output voltages at 24.2 Hz and 33.2 Hz of its resonant frequencies by SMC; and 364 mV(p-p) of output voltage at 33.6 Hz of its resonant frequency by SC. PMID:27483909

  20. Micro electro-mechanical system piezoelectric cantilever array for a broadband vibration energy harvester.

    PubMed

    Chun, Inwoo; Lee, Hyun-Woo; Kwon, Kwang-Ho

    2014-12-01

    Limited energy sources of ubiquitous sensor networks (USNs) such as fuel cells and batteries have grave drawbacks such as the need for replacements and re-charging owing to their short durability and environmental pollution. Energy harvesting which is converting environmental mechanical vibration into electrical energy has been researched with some piezoelectric materials and various cantilever designs to increase the efficiency of energy-harvesting devices. In this study, we focused on an energy-harvesting cantilever with a broadband vibration frequency. We fabricated a lead zirconate titanate (PZT) cantilever array with various Si proof masses on small beams (5.5 mm x 0.5 mm x 0.5 mm). We obtained broadband resonant frequencies ranging between 127 Hz and 136 Hz using a micro electro-mechanical system (MEMS) process. In order to obtain broadband resonant characteristics, the cantilever array was comprised of six cantilevers with different resonant frequencies. We obtained an output power of about 2.461 μW at an acceleration of 0.23 g and a resistance of 4 kΩ. The measured bandwidth of the resonant frequency was approximately 9 Hz (127-136 Hz), which is about six times wider than the bandwidth of a single cantilever. PMID:25971046

  1. Micro electro-mechanical system piezoelectric cantilever array for a broadband vibration energy harvester.

    PubMed

    Chun, Inwoo; Lee, Hyun-Woo; Kwon, Kwang-Ho

    2014-12-01

    Limited energy sources of ubiquitous sensor networks (USNs) such as fuel cells and batteries have grave drawbacks such as the need for replacements and re-charging owing to their short durability and environmental pollution. Energy harvesting which is converting environmental mechanical vibration into electrical energy has been researched with some piezoelectric materials and various cantilever designs to increase the efficiency of energy-harvesting devices. In this study, we focused on an energy-harvesting cantilever with a broadband vibration frequency. We fabricated a lead zirconate titanate (PZT) cantilever array with various Si proof masses on small beams (5.5 mm x 0.5 mm x 0.5 mm). We obtained broadband resonant frequencies ranging between 127 Hz and 136 Hz using a micro electro-mechanical system (MEMS) process. In order to obtain broadband resonant characteristics, the cantilever array was comprised of six cantilevers with different resonant frequencies. We obtained an output power of about 2.461 μW at an acceleration of 0.23 g and a resistance of 4 kΩ. The measured bandwidth of the resonant frequency was approximately 9 Hz (127-136 Hz), which is about six times wider than the bandwidth of a single cantilever.

  2. Development of Multi-Degree-Of-Freedom Piezoelectric Energy Harvester Using Interdigital Shaped Cantilevers.

    PubMed

    Cho, Hyunok; Park, Jongcheol; Park, Jae Yeong

    2016-05-01

    A piezoelectric vibration energy harvester with interdigital shaped cantilever was developed by using silicon bulk micromachining technology. The proposed energy harvester was designed to obtain multi degree-of-freedom (m-DOF). Most of the piezoelectric vibration energy harvesters are comprised of mass-loaded cantilever beams having several resonant frequencies. The second resonant frequency of such a device has lower amplitude compared to its first resonant frequency (fundamental frequency). Therefore, the interdigital shaped cantilever has been proposed for multiple fundamental resonant frequencies. The fabricated piezoelectric vibration energy harvester is composed of main cantilever (MC), sub-main cantilever (SMC), and secondary cantilevers (SC). MC surrounds SMC and SC which have same dimension of 5600 x 800 x 10 μm3. The fabricated piezoelectric energy harvester can generate 51.4 mV(p-p) and 11 mV(p-p) of output voltages at 24.2 Hz and 33 Hz of its resonant frequencies by MC. Moreover, it can generate 8 mV(p-p) and 6.6 mV(p-p) of output voltages at 24.2 Hz and 33.2 Hz of its resonant frequencies by SMC; and 364 mV(p-p) of output voltage at 33.6 Hz of its resonant frequency by SC.

  3. MEMS cantilever sensor for THz photoacoustic chemical sensing and pectroscopy

    NASA Astrophysics Data System (ADS)

    Glauvitz, Nathan E.

    Sensitive Microelectromechanical System (MEMS) cantilever designs were modeled, fabricated, and tested to measure the photoacoustic (PA) response of gasses to terahertz (THz) radiation. Surface and bulk micromachining technologies were employed to create the extremely sensitive devices that could detect very small changes in pressure. Fabricated devices were then tested in a custom made THz PA vacuum test chamber where the cantilever deflections caused by the photoacoustic effect were measured with a laser interferometer and iris beam clipped methods. The sensitive cantilever designs achieved a normalized noise equivalent absorption coefficient of 2.83x10-10 cm-1 W Hz-½ using a 25 microW radiation source power and a 1 s sampling time. Traditional gas phase molecular spectroscopy absorption cells are large and bulky. The outcome of this research resulted was a photoacoustic detection method that was virtually independent of the absorption path-length, which allowed the chamber dimensions to be greatly reduced, leading to the possibility of a compact, portable chemical detection and spectroscopy system

  4. Analysis of AFM cantilever dynamics close to sample surface

    NASA Astrophysics Data System (ADS)

    Habibnejad Korayem, A.; Habibnejad Korayem, Moharam; Ghaderi, Reza

    2013-07-01

    For imaging and manipulation of biological specimens application of atomic force microscopy (AFM) in liquid is necessary. In this paper, tapping-mode AFM cantilever dynamics in liquid close to sample surface is modeled and simulated by well defining the contact forces. The effect of cantilever tilting angle has been accounted carefully. Contact forces have some differences in liquid in comparison to air or vacuum in magnitude or formulation. Hydrodynamic forces are also applied on the cantilever due to the motion in liquid. A continuous beam model is used with its first mode and forward-time simulation method for simulation of its hybrid dynamics and the frequency response and amplitude versus separation diagrams are extracted. The simulation results show a good agreement with experimental results. The resonance frequency in liquid is so small in comparison to air due to additional mass and also additional damping due to the viscosity of the liquid around. The results show that the effect of separation on free vibration amplitude is great. Its effect on resonance frequency is considerable too.

  5. In-situ ellipsometry studies of adsorption of Hg on CdTe(211)B/Si(211) and molecular beam epitaxy growth of HgCdTe(211)B

    NASA Astrophysics Data System (ADS)

    Badano, G.; Chang, Y.; Garland, J. W.; Sivananthan, S.

    2004-06-01

    We study the adsorption of Hg on CdTe(211)B using an 88-wavelength spectroscopic ellipsometer mounted on a commercial, molecular beam epitaxy (MBE) chamber. A detailed analysis of the pseudo-dielectric function shows that Hg is present at the surface both in chemisorbed and physisorbed form. Effective medium models for a mixture of chemisorbed and physisorbed Hg on the microscopically rough CdTe surface could not fit our data. However, a proposed model in which a partial layer of physisorbed Hg sits on top of a partial layer of chemisorbed Hg fits the measured pseudo-dielectric function well and yields precise values for the thicknesses of the chemisorbed and the physisorbed Hg layers. These values change in the expected manner as a function of Hg flux, temperature, and Te coverage. An analysis of the uncertainty in the measured thicknesses is carried out in detail, and a study of the limitations of the ellipsometer used for this study is presented. The effects of these limitations on the precision and accuracy of in-situ data are enumerated.

  6. Cantilevers orthodontics forces measured by fiber sensors

    NASA Astrophysics Data System (ADS)

    Schneider, Neblyssa; Milczewski, Maura S.; de Oliveira, Valmir; Guariza Filho, Odilon; Lopes, Stephani C. P. S.; Kalinowski, Hypolito J.

    2015-09-01

    Fibers Bragg Gratings were used to evaluate the transmission of the forces generates by orthodontic mechanic based one and two cantilevers used to move molars to the upright position. The results showed levels forces of approximately 0,14N near to the root of the molar with one and two cantilevers.

  7. Resonance response of scanning force microscopy cantilevers

    SciTech Connect

    Chen, G.Y.; Warmack, R.J.; Thundat, T.; Allison, D.P. ); Huang, A. )

    1994-08-01

    A variational method is used to calculate the deflection and the fundamental and harmonic resonance frequencies of commercial V-shaped and rectangular atomic force microscopy cantilevers. The effective mass of V-shaped cantilevers is roughly half that calculated for the equivalent rectangular cantilevers. Damping by environmental gases, including air, nitrogen, argon, and helium, affects the frequency of maximum response and to a much greater degree the quality factor [ital Q]. Helium has the lowest viscosity, resulting in the highest [ital Q], and thus provides the best sensitivity in noncontact force microscopy. Damping in liquids is dominated by an increase in effective mass of the cantilever due to an added mass of the liquid being dragged with that cantilever.

  8. Influence of rotation and pretwist on cantilever fan blade flutter

    NASA Technical Reports Server (NTRS)

    Sisto, F.; Chang, A. T.

    1985-01-01

    The fundamental and lowest frequency natural modes in a cantilever fan blade exhibit significant amounts of flexure and torsion coupled by pretwist and operation in a rotational force field. Consequently the flutter estimation of such blades requires an accurate structural description that incorporates these two effects, amongst others. A beam-type finite element model is used in this study with up to six spanwise elements, each element being pretwisted. Coalescence-type flutter is found with subsonic aerodynamics. Evidence of the aerodynamic resonance phenomenon is exhibited and the importance of including radially varying aerodynamic forces is brought out.

  9. Vibrations of twisted cantilever plates - A comparison of theoretical results

    NASA Technical Reports Server (NTRS)

    Kielb, R. E.; Leissa, A. W.; Macbain, J. C.

    1985-01-01

    As a result of significant differences in the published results for various methods of analysis involving the use of finite element techniques, there are now some questions regarding the adequacy of these methods to predict accurately the vibratory characteristics of highly twisted cantilever plates. In an attempt to help in a resolution of the arising problems, a joint government/industry/university research effort was initiated. The primary objective of the present paper is to summarize the theoretical methods used in the study and show samples of the obtained results. The study provided 19 sets of theoretical results which are derived from beam theory, shell theory, and finite element methods.

  10. Nonlinear finite amplitude torsional vibrations of cantilevers in viscous fluids

    NASA Astrophysics Data System (ADS)

    Aureli, Matteo; Pagano, Christopher; Porfiri, Maurizio

    2012-06-01

    In this paper, we study torsional vibrations of cantilever beams undergoing moderately large oscillations within a quiescent viscous fluid. The structure is modeled as an Euler-Bernoulli beam, with thin rectangular cross section, under base excitation. The distributed hydrodynamic loading experienced by the vibrating structure is described through a complex-valued hydrodynamic function which incorporates added mass and fluid damping elicited by moderately large rotations. We conduct a parametric study on the two dimensional computational fluid dynamics of a pitching rigid lamina, representative of a generic beam cross section, to investigate the dependence of the hydrodynamic function on the governing flow parameters. As the frequency and amplitude of the oscillation increase, vortex shedding and convection phenomena increase, thus resulting into nonlinear hydrodynamic damping. We derive a handleable nonlinear correction to the classical hydrodynamic function developed for small amplitude torsional vibrations for use in a reduced order nonlinear modal model and we validate theoretical results against experimental findings.

  11. In situ groundwater bioremediation

    SciTech Connect

    Hazen, Terry C.

    2009-02-01

    In situ groundwater bioremediation of hydrocarbons has been used for more than 40 years. Most strategies involve biostimulation; however, recently bioaugmentation have been used for dehalorespiration. Aquifer and contaminant profiles are critical to determining the feasibility and strategy for in situ groundwater bioremediation. Hydraulic conductivity and redox conditions, including concentrations of terminal electron acceptors are critical to determine the feasibility and strategy for potential bioremediation applications. Conceptual models followed by characterization and subsequent numerical models are critical for efficient and cost effective bioremediation. Critical research needs in this area include better modeling and integration of remediation strategies with natural attenuation.

  12. In situ macromolecular crystallography using microbeams

    PubMed Central

    Axford, Danny; Owen, Robin L.; Aishima, Jun; Foadi, James; Morgan, Ann W.; Robinson, James I.; Nettleship, Joanne E.; Owens, Raymond J.; Moraes, Isabel; Fry, Elizabeth E.; Grimes, Jonathan M.; Harlos, Karl; Kotecha, Abhay; Ren, Jingshan; Sutton, Geoff; Walter, Thomas S.; Stuart, David I.; Evans, Gwyndaf

    2012-01-01

    Despite significant progress in high-throughput methods in macromolecular crystallography, the production of diffraction-quality crystals remains a major bottleneck. By recording diffraction in situ from crystals in their crystallization plates at room temperature, a number of problems associated with crystal handling and cryoprotection can be side-stepped. Using a dedicated goniometer installed on the microfocus macromolecular crystallography beamline I24 at Diamond Light Source, crystals have been studied in situ with an intense and flexible microfocus beam, allowing weakly diffracting samples to be assessed without a manual crystal-handling step but with good signal to noise, despite the background scatter from the plate. A number of case studies are reported: the structure solution of bovine enterovirus 2, crystallization screening of membrane proteins and complexes, and structure solution from crystallization hits produced via a high-throughput pipeline. These demonstrate the potential for in situ data collection and structure solution with microbeams. PMID:22525757

  13. In situ investigation of the surface silvering of late Roman coins by combined use of high energy broad-beam and low energy micro-beam X-ray fluorescence techniques

    NASA Astrophysics Data System (ADS)

    Romano, F. P.; Garraffo, S.; Pappalardo, L.; Rizzo, F.

    2012-07-01

    The compositional analysis of archeological metals performed with the X-ray Fluorescence technique (XRF) provides information on the ancient technology. One of the most interesting case-study concerns the techniques used by Romans for silvering the surface of coins. Different metallurgical processes have been suggested in previous studies. Recently the investigation has been addressed to the mercury-silvering and to its possible use in the mass-production of coins minted during the late period (after 294 AD). In the present paper the non-destructive investigation of the silvering process used for manufacturing the Roman nummi - the important typology of coin introduced by Diocletian in his monetary reform - is approached by the combined use of the standard X-Ray Fluorescence (XRF) and the low energy micro-X-Ray Fluorescence (LE-μXRF) portable methods. The research was focused on the systematic determination of the mercury presence in a large number of samples and on its correlation with silver in the surface of the coins. 1041 Roman nummi belonging to the Misurata Treasure were analyzed in situ, at the Leptis Magna Museum (Al Khums, Libya). The treasure, composed of about 108 thousand silvered coins, gives the unique opportunity to study the Roman coinage in a wide interval of time (about 40 years in the period 294-333 AD) and in almost all the imperial mints operating in the Roman world.

  14. Nonlinear output properties of cantilever driving low frequency piezoelectric energy harvester

    NASA Astrophysics Data System (ADS)

    Xu, Chundong; Ren, Bo; Liang, Zhu; Chen, Jianwei; Zhang, Haiwu; Yue, Qingwen; Xu, Qing; Zhao, Xiangyong; Luo, Haosu

    2012-11-01

    Cantilever driving low frequency piezoelectric energy harvester (CANDLE) has been found as a promising structure for vibration energy harvesting. This paper presents the nonlinear output properties of the CANDLE to optimize the performance of the device. Simulation results of the finite element method illustrate that nonlinear contacts between the cymbal transducers and the cantilever beam are main reasons of the nonlinear output. However, high excitation acceleration of the nonlinear leap point limits the application of the device. Based on the simulation results and theory analysis, the excitation acceleration is reduced to 30 m/s2 by increasing the proof mass.

  15. In Situ Cometary Cosmochemistry

    NASA Astrophysics Data System (ADS)

    Wright, I. P.; Andrews, D. J.; Barber, S. J.; Sheridan, S.; Morgan, G. H.; Morse, A. D.

    2013-09-01

    In 2014 the Rosetta space mission arrives at comet 67P. Herein we describe the ambitions of one of the instruments, Ptolemy, included on the lander. Our aim is to make in situ measurements of isotopic compositions of elements such as H, C, N and O.

  16. In Situ Processing.

    ERIC Educational Resources Information Center

    Edgar, T. F.; Schechter, R. S.

    1980-01-01

    Describes research on in situ processing to develop necessary theory and understanding of the underground process to facilitate commercialization of a wide range of mineral deposits. Goal is to produce laboratory and computer-based tools to allow site evaluation based on field and laboratory measurements of mineral and associated overburdens.…

  17. Droplet Impacting a Cantilever: A Leaf-Raindrop System

    NASA Astrophysics Data System (ADS)

    Gart, Sean; Mates, Joseph E.; Megaridis, Constantine M.; Jung, Sunghwan

    2015-04-01

    Previous studies show that air pollution and wind erosion, which damage a leaf's epicuticular wax layer, can change leaf surface properties from hydrophobic to hydrophilic. However, the dynamic response of a damaged leaf to a raindrop impact has not been investigated and could clarify the direct influence of changes in wettability on early leaf abscission. In this article, we investigate how leaves with different surface properties respond to falling raindrops, viewing this as a unique system of coupled elasticity and drop dynamics. An elastic beam with tunable surface wettability properties is used as a simple leaf model. We find that wettable beams experience much higher torque and bending energy than nonwettable beams. This is because a drop sticks to a wettable beam, while a drop falls off a nonwettable beam. An analytical model using momentum balance and simple cantilever beam theory quantifies the bending energy and torque experienced by wettable and nonwettable beams. The results elucidate the potential damage caused by raindrops impacting a leaf as a function of its surface wettability and are correlated with environmental factors contributing to premature changes of leaf surface properties.

  18. Improved cantilever profiles for sensor elements

    NASA Astrophysics Data System (ADS)

    Fernando, Sanchitha; Austin, Michael; Chaffey, Jason

    2007-12-01

    The problem of simultaneously enhancing sensitivity and noise immunity of microcantilevers is investigated. The dependence of deflection and resonant frequency of a microcantilever on its dimensions is studied. A principle to increase deflection and resonant frequency simultaneously is established. Several cantilevers agreeing with this principle are investigated using analytical models and are compared with FEM simulations. Using these results, a cantilever profile that achieves a larger deflection and a larger resonant frequency compared with uniform cantilevers is proposed to be used in sensor elements.

  19. Self-reciprocating radioisotope-powered cantilever

    NASA Astrophysics Data System (ADS)

    Li, Hui; Lal, Amit; Blanchard, James; Henderson, Douglass

    2002-07-01

    A reciprocating cantilever utilizing emitted charges from a millicurie radioisotope thin film is presented. The actuator realizes a direct collected-charge-to-motion conversion. The reciprocation is obtained by self-timed contact between the cantilever and the radioisotope source. A static model balancing the electrostatic and mechanical forces from an equivalent circuit leads to an analytical solution useful for device characterization. Measured reciprocating periods agree with predicted values from the analytical model. A scaling analysis shows that microscale arrays of such cantilevers provide an integrated sensor and actuator platform.

  20. High-Gradient Nanomagnets on Cantilevers for Sensitive Detection of Nuclear Magnetic Resonance

    PubMed Central

    Longenecker, Jonilyn G.; Mamin, H. J.; Senko, Alexander W.; Chen, Lei; Rettner, Charles T.; Rugar, Daniel; Marohn, John A.

    2012-01-01

    Detection of magnetic resonance as a force between a magnetic tip and nuclear spins has previously been shown to enable sub-10 nm resolution 1H imaging. Maximizing the spin force in such a magnetic resonance force microscopy (MRFM) experiment demands a high field gradient. In order to study a wide range of samples, it is equally desirable to locate the magnetic tip on the force sensor. Here we report the development of attonewton-sensitivity cantilevers with high gradient cobalt nanomagnet tips. The damage layer thickness and saturation magnetization of the magnetic material were characterized by X-ray photoelectron spectroscopy and superconducting quantum interference device magnetometry. The coercive field and saturation magnetization of an individual tip were quantified in situ using frequency-shift cantilever magnetometry. Measurements of cantilever dissipation versus magnetic field and tip-sample separation were conducted. MRFM signals from protons in a polystyrene film were studied versus rf irradiation frequency and tip-sample separation, and from this data the tip field and tip-field gradient were evaluated. Magnetic tip performance was assessed by numerically modeling the frequency dependence of the magnetic resonance signal. We observed a tip-field gradient ∂Bztip∕∂z estimated to be between 4.4 and 5.4 MT m−1, which is comparable to the gradient used in recent 4 nm resolution 1H imaging experiments and larger by nearly an order of magnitude than the gradient achieved in prior magnet-on-cantilever MRFM experiments. PMID:23033869

  1. Investigation of static and dynamic behavior of functionally graded piezoelectric actuated Poly-Si micro cantilever probe

    NASA Astrophysics Data System (ADS)

    Pandey, Vibhuti Bhushan; Parashar, Sandeep Kumar

    2016-04-01

    In the present paper a novel functionally graded piezoelectric (FGP) actuated Poly-Si micro cantilever probe is proposed for atomic force microscope. The shear piezoelectric coefficient d15 has much higher value than coupling coefficients d31 and d33, hence in the present work the micro cantilever beam actuated by d15 effect is utilized. The material properties are graded in the thickness direction of actuator by a simple power law. A three dimensional finite element analysis has been performed using COMSOL Multiphysics® (version 4.2) software. Tip deflection and free vibration analysis for the micro cantilever probe has been done. The results presented in the paper shall be useful in the design of micro cantilever probe and their subsequent utilization in atomic force microscopes.

  2. Measurement and reliability issues in resonant mode cantilever for bio-sensing application in fluid medium

    NASA Astrophysics Data System (ADS)

    Kathel, G.; Shajahan, M. S.; Bhadra, P.; Prabhakar, A.; Chadha, A.; Bhattacharya, E.

    2016-09-01

    Cantilevers immersed in liquid experience viscous damping and hydrodynamic loading. We report on the use of such cantilevers, operating in the dynamic mode with, (i) frequency sweeping and (ii) phase locked loop methods. The solution to reliability issues such as random drift in the resonant peak values, and interference of spurious modes in the resonance frequency spectrum, are explained based on the actuation signal provided and laser spot size. The laser beam spot size and its position on the cantilever were found to have an important role, on the output signal and resonance frequency. We describe a method to distinguish the normal modes from the spurious modes for a cantilever. Uncertainties in the measurements define the lower limit of mass detection (m min). The minimum detection limits of the two measurement methods are investigated by measuring salt adsorption from phosphate buffer solution, as an example, a mass of 14 pg was measured using the 14th transverse mode of a 500~μ m  ×  100 μm  ×  1 μm silicon cantilever. The optimized measurement was used to study the interaction between antibody and antigen.

  3. Numerical investigation of band gaps in 3D printed cantilever-in-mass metamaterials

    PubMed Central

    Qureshi, Awais; Li, Bing; Tan, K. T.

    2016-01-01

    In this research, the negative effective mass behavior of elastic/mechanical metamaterials is exhibited by a cantilever-in-mass structure as a proposed design for creating frequency stopping band gaps, based on local resonance of the internal structure. The mass-in-mass unit cell model is transformed into a cantilever-in-mass model using the Bernoulli-Euler beam theory. An analytical model of the cantilever-in-mass structure is derived and the effects of geometrical dimensions and material parameters to create frequency band gaps are examined. A two-dimensional finite element model is created to validate the analytical results, and excellent agreement is achieved. The analytical model establishes an easily tunable metamaterial design to realize wave attenuation based on locally resonant frequency. To demonstrate feasibility for 3D printing, the analytical model is employed to design and fabricate 3D printable mechanical metamaterial. A three-dimensional numerical experiment is performed using COMSOL Multiphysics to validate the wave attenuation performance. Results show that the cantilever-in-mass metamaterial is capable of mitigating stress waves at the desired resonance frequency. Our study successfully presents the use of one constituent material to create a 3D printed cantilever-in-mass metamaterial with negative effective mass density for stress wave mitigation purposes. PMID:27329828

  4. Numerical investigation of band gaps in 3D printed cantilever-in-mass metamaterials

    NASA Astrophysics Data System (ADS)

    Qureshi, Awais; Li, Bing; Tan, K. T.

    2016-06-01

    In this research, the negative effective mass behavior of elastic/mechanical metamaterials is exhibited by a cantilever-in-mass structure as a proposed design for creating frequency stopping band gaps, based on local resonance of the internal structure. The mass-in-mass unit cell model is transformed into a cantilever-in-mass model using the Bernoulli-Euler beam theory. An analytical model of the cantilever-in-mass structure is derived and the effects of geometrical dimensions and material parameters to create frequency band gaps are examined. A two-dimensional finite element model is created to validate the analytical results, and excellent agreement is achieved. The analytical model establishes an easily tunable metamaterial design to realize wave attenuation based on locally resonant frequency. To demonstrate feasibility for 3D printing, the analytical model is employed to design and fabricate 3D printable mechanical metamaterial. A three-dimensional numerical experiment is performed using COMSOL Multiphysics to validate the wave attenuation performance. Results show that the cantilever-in-mass metamaterial is capable of mitigating stress waves at the desired resonance frequency. Our study successfully presents the use of one constituent material to create a 3D printed cantilever-in-mass metamaterial with negative effective mass density for stress wave mitigation purposes.

  5. Design of piezoelectric MEMS cantilever for low-frequency vibration energy harvester

    NASA Astrophysics Data System (ADS)

    Takei, Ryohei; Makimoto, Natsumi; Okada, Hironao; Itoh, Toshihiro; Kobayashi, Takeshi

    2016-06-01

    We report the design of piezoelectric MEMS cantilevers formed on a silicon-on-insulator wafer to efficiently harvest electrical power from harmonic vibration with a frequency of approximately 30 Hz. Numerical simulation indicates that a >4-µm-thick top silicon layer and >3-µm-thick piezoelectric film are preferable to maximize the output electrical power. An in-plane structure of the cantilever is also designed retaining the footprint of the cantilever. The simulation results indicate that the output power is maximized when the length ratio of the proof mass to the cantilever beam is 1.5. To ensure the accuracy of the simulation, we fabricated and characterized cantilevers with a 10-µm-thick top silicon layer and a 1.8-µm-thick piezoelectric film, resulting in 0.21 µW at a vibration of 0.5 m/s2 and 25.1 Hz. The measured output power is in agreement with the simulated value, meaning that the design is significantly reliable for low-frequency vibration energy harvesters.

  6. Numerical investigation of band gaps in 3D printed cantilever-in-mass metamaterials.

    PubMed

    Qureshi, Awais; Li, Bing; Tan, K T

    2016-01-01

    In this research, the negative effective mass behavior of elastic/mechanical metamaterials is exhibited by a cantilever-in-mass structure as a proposed design for creating frequency stopping band gaps, based on local resonance of the internal structure. The mass-in-mass unit cell model is transformed into a cantilever-in-mass model using the Bernoulli-Euler beam theory. An analytical model of the cantilever-in-mass structure is derived and the effects of geometrical dimensions and material parameters to create frequency band gaps are examined. A two-dimensional finite element model is created to validate the analytical results, and excellent agreement is achieved. The analytical model establishes an easily tunable metamaterial design to realize wave attenuation based on locally resonant frequency. To demonstrate feasibility for 3D printing, the analytical model is employed to design and fabricate 3D printable mechanical metamaterial. A three-dimensional numerical experiment is performed using COMSOL Multiphysics to validate the wave attenuation performance. Results show that the cantilever-in-mass metamaterial is capable of mitigating stress waves at the desired resonance frequency. Our study successfully presents the use of one constituent material to create a 3D printed cantilever-in-mass metamaterial with negative effective mass density for stress wave mitigation purposes. PMID:27329828

  7. Fabrication and characterization of large arrays of mesoscopic gold rings on large-aspect-ratio cantilevers

    NASA Astrophysics Data System (ADS)

    Ngo, D. Q.; Petković, I.; Lollo, A.; Castellanos-Beltran, M. A.; Harris, J. G. E.

    2014-10-01

    We have fabricated large arrays of mesoscopic metal rings on ultrasensitive cantilevers. The arrays are defined by electron beam lithography and contain up to 105 rings. The rings have a circumference of 1 μm, and are made of ultrapure (6N) Au that is deposited onto a silicon-on-insulator wafer without an adhesion layer. Subsequent processing of the SOI wafer results in each array being supported at the end of a free-standing cantilever. To accommodate the large arrays while maintaining a low spring constant, the cantilevers are nearly 1 mm in both lateral dimensions and 100 nm thick. The extreme aspect ratio of the cantilevers, the large array size, and the absence of a sticking layer are intended to enable measurements of the rings' average persistent current ⟨I⟩ in the presence of relatively small magnetic fields. We describe the motivation for these measurements, the fabrication of the devices, and the characterization of the cantilevers' mechanical properties. We also discuss the devices' expected performance in measurements of ⟨I⟩.

  8. Fabrication and characterization of large arrays of mesoscopic gold rings on large-aspect-ratio cantilevers

    SciTech Connect

    Ngo, D. Q.; Petković, I. Lollo, A.; Castellanos-Beltran, M. A.; Harris, J. G. E.

    2014-10-15

    We have fabricated large arrays of mesoscopic metal rings on ultrasensitive cantilevers. The arrays are defined by electron beam lithography and contain up to 10{sup 5} rings. The rings have a circumference of 1 μm, and are made of ultrapure (6N) Au that is deposited onto a silicon-on-insulator wafer without an adhesion layer. Subsequent processing of the SOI wafer results in each array being supported at the end of a free-standing cantilever. To accommodate the large arrays while maintaining a low spring constant, the cantilevers are nearly 1 mm in both lateral dimensions and 100 nm thick. The extreme aspect ratio of the cantilevers, the large array size, and the absence of a sticking layer are intended to enable measurements of the rings' average persistent current in the presence of relatively small magnetic fields. We describe the motivation for these measurements, the fabrication of the devices, and the characterization of the cantilevers' mechanical properties. We also discuss the devices' expected performance in measurements of .

  9. Calibration of the torsional and lateral spring constants of cantilever sensors.

    PubMed

    Parkin, John D; Hähner, Georg

    2014-06-01

    A method suitable for the calibration of the spring constants of all torsional and lateral eigenmodes of micro- and nanocantilever sensors is described. Such sensors enable nanomechanical measurements and the characterization of nanomaterials, for example with atomic force microscopy. The method presented involves the interaction of a flow of fluid from a microchannel with the cantilever beam. Forces imparted by the flow cause the cantilever to bend and induce a measurable change of the torsional and lateral resonance frequencies. From the frequency shifts the cantilever spring constants can be determined. The method does not involve physical contact between the cantilever or its tip and a hard surface. As such it is non-invasive and does not risk damage to the cantilever. Experimental data is presented for two rectangular microcantilevers with fundamental flexural spring constants of 0.046 and 0.154 N m(-1). The experimentally determined torsional stiffness values are compared with those obtained by the Sader method. We demonstrate that the torsional spring constants can be readily calibrated using the method with an accuracy of around 15%.

  10. Double sided surface stress cantilever sensor

    NASA Astrophysics Data System (ADS)

    Rasmussen, P. A.; Grigorov, A. V.; Boisen, A.

    2005-05-01

    Micromachined cantilevers, originally developed for use in atomic force microscopy, are gaining more and more interest as biochemical sensors, where the way in which the binding of chemical species changes the mechanical properties of the cantilever is utilized. Mass and stiffness changes are measured on resonating structures (Cherian and Thundat 2002 Appl. Phys. Lett. 80 2219-21 Gupta et al 2004 Appl. Phys. Lett. 84 1976-8), whereas changes in surface energy from the binding event are measured as static deflections of cantilevers (Savran et al 2004 Anal. Chem. 76 3194-8). The latter measurement type is referred to as a surface stress sensor and it is the description of a new and more sensitive cantilever surface stress measurement technique that is the topic of this paper.

  11. Generation of squeezing: magnetic dipoles on cantilevers

    NASA Astrophysics Data System (ADS)

    Seok, Hyojun; Singh, Swati; Steinke, Steven; Meystre, Pierre

    2011-05-01

    We investigate the generation of motional squeezed states in a nano-mechanical cantilever. Our model system consists of a nanoscale cantilever - whose center-of-mass motion is initially cooled to its quantum mechanical ground state - magnetically coupled a classically driven mechanical tuning fork. We show that the magnetic dipole-dipole interaction can produce significant phonon squeezing of the center-of-mass motion of the cantilever, and evaluate the effect of various dissipation channels, including the coupling of the cantilever to a heat bath and phase and amplitude fluctuations in the oscillating field driving the tuning fork. US National Science Foundation, the US Army Research Office, DARPA ORCHID program through a grant from AFOSR.

  12. In situ reactor

    DOEpatents

    Radtke, Corey William; Blackwelder, David Bradley

    2004-01-27

    An in situ reactor for use in a geological strata, is described and which includes a liner defining a centrally disposed passageway and which is placed in a borehole formed in the geological strata; and a sampling conduit is received within the passageway defined by the liner and which receives a geological specimen which is derived from the geological strata, and wherein the sampling conduit is in fluid communication with the passageway defined by the liner.

  13. Multi-resonant wideband energy harvester based on a folded asymmetric M-shaped cantilever

    SciTech Connect

    Wu, Meng; Mao, Haiyang; Li, Zhigang; Liu, Ruiwen; Ming, Anjie; Ou, Yi; Ou, Wen

    2015-07-15

    This article reports a compact wideband piezoelectric vibration energy harvester consisting of three proof masses and an asymmetric M-shaped cantilever. The M-shaped beam comprises a main beam and two folded and dimension varied auxiliary beams interconnected through the proof mass at the end of the main cantilever. Such an arrangement constitutes a three degree-of-freedom vibrating body, which can tune the resonant frequencies of its first three orders close enough to obtain a utility wide bandwidth. The finite element simulation results and the experimental results are well matched. The operation bandwidth comprises three adjacent voltage peaks on account of the frequency interval shortening mechanism. The result shows that the proposed piezoelectric energy harvester could be efficient and adaptive in practical vibration circumstance based on multiple resonant modes.

  14. Multi-resonant wideband energy harvester based on a folded asymmetric M-shaped cantilever

    NASA Astrophysics Data System (ADS)

    Wu, Meng; Ou, Yi; Mao, Haiyang; Li, Zhigang; Liu, Ruiwen; Ming, Anjie; Ou, Wen

    2015-07-01

    This article reports a compact wideband piezoelectric vibration energy harvester consisting of three proof masses and an asymmetric M-shaped cantilever. The M-shaped beam comprises a main beam and two folded and dimension varied auxiliary beams interconnected through the proof mass at the end of the main cantilever. Such an arrangement constitutes a three degree-of-freedom vibrating body, which can tune the resonant frequencies of its first three orders close enough to obtain a utility wide bandwidth. The finite element simulation results and the experimental results are well matched. The operation bandwidth comprises three adjacent voltage peaks on account of the frequency interval shortening mechanism. The result shows that the proposed piezoelectric energy harvester could be efficient and adaptive in practical vibration circumstance based on multiple resonant modes.

  15. Study of sensitivity and noise in the piezoelectric self-sensing and self-actuating cantilever with an integrated Wheatstone bridge circuit.

    PubMed

    Shin, ChaeHo; Jeon, InSu; Khim, Zheong G; Hong, J W; Nam, HyoJin

    2010-03-01

    A detection method using a self-sensing cantilever is more desirable than other detection methods (optical fiber and laser beam bounce detection) that are bulky and require alignment. The advantage of the self-sensing cantilever is its simplicity, particularly its simple structure. It can be used for the construction of an atomic force microscopy system with a vacuum, fluids, and a low temperature chamber. Additionally, the self-actuating cantilever can be used for a high speed scanning system because the bandwidth is larger than the bulk scanner. Frequently, ZnO film has been used as an actuator in a self-actuating cantilever. In this paper, we studied the characteristics of the self-sensing and self-actuating cantilever with an integrated Wheatstone bridge circuit substituting the ZnO film with a lead zirconate titanate (PZT) film as the actuator. We can reduce the leakage current (to less than 10(-4) A/cm(2)) in the PZT cantilever and improve sensor sensitivity through a reduction of noise level from the external sensor circuit using the Wheatstone bridge circuit embedded into the cantilever. The self-sensing and actuating cantilever with an integrated Wheatstone bridge circuit was compared with a commercial self-sensing cantilever or self-sensing and actuating cantilever without an integrated Wheatstone bridge circuit. The measurement results have shown that sensing the signal to noise level and the minimum detectable deflection improved to 4.78 mV and 1.18 nm, respectively. We believe that this cantilever allows for easier system integration and miniaturization, provides better controllability and higher scan speeds, and offers the potential for full automation.

  16. Theoretical Study on the Dynamic Behavior of a Plate-Like Micro-Cantilever with Multiple Particles Attached.

    PubMed

    Zhao, Liang; Wang, Fei; Zhang, YanLing; Zhao, Xuezeng

    2016-01-01

    In this study, the dynamic characteristics of a plate-like micro-cantilever beam attached with multiple concentrated masses are studied. The vibration modes of the cantilever plate are represented by combinations of beam functions. Using classical mechanics (the effect of size is not considered) and the corrected Cosserat's theorem (the effect of size is considered), we employ the Lagrange equations to establish a dynamic model of the plate-like micro-cantilever beam attached with multiple concentrated masses. The accuracy of the model proposed in this paper is verified by comparing with the results of published literature. Then, the natural frequencies of the cantilever plates are calculated with self-compiled algorithms, and the results of the plates with 1-5 masses are displayed. The results are in high accordance with the exact solution, and all errors are within 0.5%. The analysis shows that the proposed model and analysis method converges quickly and is highly efficient. In addition, the effects of characteristic lengths, Poisson's ratios and plate thickness on the micro-cantilever plate's resonant frequency for the first five modes are analyzed. PMID:27023056

  17. Theoretical Study on the Dynamic Behavior of a Plate-Like Micro-Cantilever with Multiple Particles Attached

    PubMed Central

    Zhao, Liang; Wang, Fei; Zhang, YanLing; Zhao, Xuezeng

    2016-01-01

    In this study, the dynamic characteristics of a plate-like micro-cantilever beam attached with multiple concentrated masses are studied. The vibration modes of the cantilever plate are represented by combinations of beam functions. Using classical mechanics (the effect of size is not considered) and the corrected Cosserat’s theorem (the effect of size is considered), we employ the Lagrange equations to establish a dynamic model of the plate-like micro-cantilever beam attached with multiple concentrated masses. The accuracy of the model proposed in this paper is verified by comparing with the results of published literature. Then, the natural frequencies of the cantilever plates are calculated with self-compiled algorithms, and the results of the plates with 1–5 masses are displayed. The results are in high accordance with the exact solution, and all errors are within 0.5%. The analysis shows that the proposed model and analysis method converges quickly and is highly efficient. In addition, the effects of characteristic lengths, Poisson's ratios and plate thickness on the micro-cantilever plate’s resonant frequency for the first five modes are analyzed. PMID:27023056

  18. Cantilever noise in off-cantilever-resonance force-detected nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Harrell, Lee E.; Thurber, Kent R.; Smith, Doran D.

    2004-03-01

    Early work in force-detected nuclear magnetic resonance (FD-NMR) and magnetic resonance force microscopy was restricted to nuclei with a relatively large gyromagnetic ratio γ. Increasingly, as researchers look to apply FD-NMR to practical problems, observing isotopes with a small γ is becoming necessary. The small γ of these isotopes places severe restrictions on the radio frequency field strength necessary to flip the sample spins at practical cantilever frequencies by adiabatic rapid passage. These restrictions led us to investigate the feasibility of observing FD-NMR by flipping sample spins at a rate well below the cantilever frequency. In this article we show that there is no increase in thermomechanical force noise in off-cantilever-resonance FD-NMR relative to on-cantilever-resonance work. Further, we show that working off-cantilever resonance can reduce artifacts and decrease data acquisition time. The major disadvantage to working off-cantilever resonance—reduced cantilever response—increases the importance of low noise detection of cantilever oscillation.

  19. Characterizing the free and surface-coupled vibrations of heated-tip atomic force microscope cantilevers

    NASA Astrophysics Data System (ADS)

    Killgore, Jason P.; Tung, Ryan C.; Hurley, Donna C.

    2014-08-01

    Combining heated-tip atomic force microscopy (HT-AFM) with quantitative methods for determining surface mechanical properties, such as contact resonance force microscopy, creates an avenue for nanoscale thermomechanical property characterization. For nanomechanical methods that employ an atomic force microscope cantilever’s vibrational modes, it is essential to understand how the vibrations of the U-shaped HT-AFM cantilever differ from those of a more traditional rectangular lever, for which analytical techniques are better developed. Here we show, with a combination of finite element analysis (FEA) and experiments, that the HT-AFM cantilever exhibits many more readily-excited vibrational modes over typical AFM frequencies compared to a rectangular cantilever. The arms of U-shaped HT-AFM cantilevers exhibit two distinct forms of flexural vibrations that differ depending on whether the two arms are vibrating in-phase or out-of-phase with one another. The in-phase vibrations are qualitatively similar to flexural vibrations in rectangular cantilevers and generally show larger sensitivity to surface stiffness changes than the out-of-phase vibrations. Vibration types can be identified from their frequency and by considering vibration amplitudes in the horizontal and vertical channels of the AFM at different laser spot positions on the cantilever. For identifying contact resonance vibrational modes, we also consider the sensitivity of the resonant frequencies to a change in applied force and hence to tip-sample contact stiffness. Finally, we assess how existing analytical models can be used to accurately predict contact stiffness from contact-resonance HT-AFM results. A simple two-parameter Euler-Bernoulli beam model provided good agreement with FEA for in-phase modes up to a contact stiffness 500 times the cantilever spring constant. By providing insight into cantilever vibrations and exploring the potential of current analysis techniques, our results lay the

  20. In Situ Fabrication Technologies

    NASA Technical Reports Server (NTRS)

    Rolin, Terry D.; Hammond, Monica

    2005-01-01

    A manufacturing system is described that is internal to controlled cabin environments which will produce functional parts to net shape with sufficient tolerance, strength and integrity to meet application specific needs such as CEV ECLS components, robotic arm or rover components, EVA suit items, unforeseen tools, conformal repair patches, and habitat fittings among others. Except for start-up and shut-down, fabrication will be automatic without crew intervention under nominal scenarios. Off-nominal scenarios may require crew and/or Earth control intervention. System will have the ability to fabricate using both provisioned feedstock materials and feedstock refined from in situ regolith.

  1. Fabrication Capabilities Utilizing In Situ Materials

    NASA Technical Reports Server (NTRS)

    McLemore, Carole A.; Fikes, John C.; Darby, Charles A.; Good, James E.; Gilley, Scott D.

    2008-01-01

    The National Aeronautics and Space Administration (NASA) has a Space Exploration Policy that lays out a plan that far exceeds the earlier Apollo goals where landing on the moon and taking those first historic steps fulfilled the mission. The policy states that we will set roots on the moon by establishing an outpost. This outpost will be used as a test bed for residing in more distant locales, such as Mars. In order to become self-sufficient, the occupants must have the capability to fabricate component parts in situ. Additionally, in situ materials must be used to minimize valuable mission upmass and to be as efficient as possible. In situ materials can be found from various sources such as raw lunar regolith whereby specific constituents can be extracted from the regolith (such as aluminum, titanium, or iron), and existing hardware already residing on the moon from past Apollo missions. The Electron Beam Melting (EBM) process lends itself well to fabricating parts, tools, and other necessary items using in situ materials and will be discussed further in this paper.

  2. Dosimetry of in situ activated dysprosium microspheres.

    PubMed

    Adnani, N

    2004-03-01

    This paper presents the results of a study aimed at investigating the dosimetry of stable dysprosium microspheres activated, in situ, by a linac generated photon beam. In phantom measurements of the neutron flux within an 18 MV photon beam were performed using CR-39 detectors and gold activation. The results were used in conjunction with a Monte Carlo computer simulation to investigate the dose distribution resulting from the activation of dysprosium (Dy) microspheres using an 18 MV photon beam. Different depths, lesion volumes and volume concentrations of microspheres are investigated. The linac lower collimator jaws are assumed completely closed to shield the tumour volume from the photon dose. Using a single AP field with 0 x 0 cm2 field size (closed jaws), a photon dose rate of 600 MU min(-1) and 80 cm SSD for 10 min, an average dose exceeding 1 Gy can be delivered to spherical lesions of 0.5 cm and higher diameter. The variation of the average dose with the size of the lesion reaches saturation for tumour volumes exceeding 1 cm in diameter. This report shows that the photon beam of a high-energy linac can be used to activate Dy microspheres in situ and, as a result, deliver a significant dose of beta radiation. Non-radioactive Dy microspheres do not have the toxicity and imaging problems associated with commercially available yttrium-90 based products. PMID:15070199

  3. A theoretical study of a nano-opto-mechanical sensor using a photonic crystal-cantilever cavity

    NASA Astrophysics Data System (ADS)

    Mao, Depeng; Liu, Peng; Ho, Kai-Ming; Dong, Liang

    2012-07-01

    In this simulation study, integration of a nanocantilever inside a two-dimensional (2D) photonic crystal (PC) cavity resulted in a unique photonic crystal-cantilever cavity (PC3), where the cantilever served as a tunable mechanical defect of the PC slab. Strong nano-opto-mechanical interactions between the cantilever and the defect-mode field inside the PC3 gave rise to a high sensitivity of the resonance wavelength to surface stress-induced cantilever deflection. Mechanical and optical responses of the PC3 to surface stress changes on the cantilever surface were studied by using a finite-element method (FEM) and a finite-difference time-domain (FDTD) method, respectively. Theoretical analysis revealed that the devised PC3 sensor could resolve a conservative minimum surface stress at the level of ˜0.8 mN m-1, representing state-of-the-art cantilever sensor performance. Also, the PC3 sensor design used an ultracompact structure with an on-chip optical length of only several microns, while a conventional reflected laser beam detection scheme requires a ˜1 m long free-space optical path.

  4. A theoretical study of a nano-opto-mechanical sensor using a photonic crystal-cantilever cavity

    SciTech Connect

    Mao, Depeng; Liu, Peng; Ho, Kai-Ming; Dong, Liang

    2012-07-09

    In this simulation study, integration of a nanocantilever inside a two-dimensional (2D) photonic crystal (PC) cavity resulted in a unique photonic crystal-cantilever cavity (PC3), where the cantilever served as a tunable mechanical defect of the PC slab. Strong nano-opto-mechanical interactions between the cantilever and the defect-mode field inside the PC3 gave rise to a high sensitivity of the resonance wavelength to surface stress-induced cantilever deflection. Mechanical and optical responses of the PC3 to surface stress changes on the cantilever surface were studied by using a finite-element method (FEM) and a finite-difference time-domain (FDTD) method, respectively. Theoretical analysis revealed that the devised PC3 sensor could resolve a conservative minimum surface stress at the level of ~0.8 mN m−1, representing state-of-the-art cantilever sensor performance. Also, the PC3 sensor design used an ultracompact structure with an on-chip optical length of only several microns, while a conventional reflected laser beam detection scheme requires a ~1 m long free-space optical path.

  5. In Situ Surface Characterization

    NASA Technical Reports Server (NTRS)

    Deen, Robert G.; Leger, Patrick C.; Yanovsky, Igor

    2011-01-01

    Operation of in situ space assets, such as rovers and landers, requires operators to acquire a thorough understanding of the environment surrounding the spacecraft. The following programs help with that understanding by providing higher-level information characterizing the surface, which is not immediately obvious by just looking at the XYZ terrain data. This software suite covers three primary programs: marsuvw, marsrough, and marsslope, and two secondary programs, which together use XYZ data derived from in situ stereo imagery to characterize the surface by determining surface normal, surface roughness, and various aspects of local slope, respectively. These programs all use the Planetary Image Geometry (PIG) library to read mission-specific data files. The programs themselves are completely multimission; all mission dependencies are handled by PIG. The input data consists of images containing XYZ locations as derived by, e.g., marsxyz. The marsuvw program determines surface normals from XYZ data by gathering XYZ points from an area around each pixel and fitting a plane to those points. Outliers are rejected, and various consistency checks are applied. The result shows the orientation of the local surface at each point as a unit vector. The program can be run in two modes: standard, which is typically used for in situ arm work, and slope, which is typically used for rover mobility. The difference is primarily due to optimizations necessary for the larger patch sizes in the slope case. The marsrough program determines surface roughness in a small area around each pixel, which is defined as the maximum peak-to-peak deviation from the plane perpendicular to the surface normal at that pixel. The marsslope program takes a surface normal file as input and derives one of several slope-like outputs from it. The outputs include slope, slope rover direction (a measure of slope radially away from the rover), slope heading, slope magnitude, northerly tilt, and solar energy

  6. Fatigue strength of cantilevered metal frameworks for tissue-integrated prostheses.

    PubMed

    Stewart, R B; Desjardins, R P; Laney, W R; Chao, E Y

    1992-07-01

    The design of the metal alloy framework in cantilevered sections of fixed tissue-integrated prostheses, is critical. Several cross-sectional designs have been advocated, including the popular L-shaped beam, which permits the economical use of space for tooth placement. The fatigue strengths of 15 L-shaped cantilevered framework sections of the same metal alloy were tested. The castings were divided into three groups of five according to vertical wall heights of 4, 5, and 6 mm. Fatigue durability of each sample was determined by counting the number of cycles of vertical forces required to induce catastrophic failure. Statistical analysis revealed significant differences between all three groups in the cycles counted at failure (p less than 0.0019). Fatigue strengths improved significantly with increasing vertical wall height of the L-shaped cantilevered frameworks. In addition, beam flexure was shown to be indirectly proportional to fatigue strength. Theoretical beam deflection was calculated and shown to correlate with the actual beam deflection during the testing. Theoretical calculations in static bending specific for a cross-sectional design may aid in the predictability of fatigue strength.

  7. High-aspect ratio metal tips attached to atomic force microscopy cantilevers with controlled angle, length, and radius for electrostatic force microscopy.

    PubMed

    Cockins, Lynda; Miyahara, Yoichi; Stomp, Romain; Grutter, Peter

    2007-11-01

    We demonstrate a method to fabricate a high-aspect ratio metal tip attached to microfabricated cantilevers with controlled angle, length, and radius, for use in electrostatic force microscopy. A metal wire, after gluing it into a guiding slot that is cut into the cantilever, is shaped into a long, thin tip using a focused ion beam. The high-aspect ratio results in considerable reduction of the capacitive force between tip body and sample when compared to a metal coated pyramidal tip.

  8. 2. DETAIL OF STRUCTURAL SYSTEM FOR CANTILEVERED HOG RUN; BUILDING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. DETAIL OF STRUCTURAL SYSTEM FOR CANTILEVERED HOG RUN; BUILDING 168 (1960 HOG KILL) IS BENEATH HOG RUN - Rath Packing Company, Cantilevered Hog Run, Sycamore Street between Elm & Eighteenth Streets, Waterloo, Black Hawk County, IA

  9. In situ TEM of radiation effects in complex ceramics.

    PubMed

    Lian, Jie; Wang, L M; Sun, Kai; Ewing, Rodney C

    2009-03-01

    In situ transmission electron microscopy (TEM) has been extensively applied to study radiation effects in a wide variety of materials, such as metals, ceramics and semiconductors and is an indispensable tool in obtaining a fundamental understanding of energetic beam-matter interactions, damage events, and materials' behavior under intense radiation environments. In this article, in situ TEM observations of radiation effects in complex ceramics (e.g., oxides, silicates, and phosphates) subjected to energetic ion and electron irradiations have been summarized with a focus on irradiation-induced microstructural evolution, changes in microchemistry, and the formation of nanostructures. New results for in situ TEM observation of radiation effects in pyrochlore, A(2)B(2)O(7), and zircon, ZrSiO(4), subjected to multiple beam irradiations are presented, and the effects of simultaneous irradiations of alpha-decay and beta-decay on the microstructural evolution of potential nuclear waste forms are discussed. Furthermore, in situ TEM results of radiation effects in a sodium borosilicate glass subjected to electron-beam exposure are introduced to highlight the important applications of advanced analytical TEM techniques, including Z-contrast imaging, energy filtered TEM (EFTEM), and electron energy loss spectroscopy (EELS), in studying radiation effects in materials microstructural evolution and microchemical changes. By combining ex situ TEM and advanced analytical TEM techniques with in situ TEM observations under energetic beam irradiations, one can obtain invaluable information on the phase stability and response behaviors of materials under a wide range of irradiation conditions.

  10. In situ measurement system

    DOEpatents

    Lord, D.E.

    1980-11-24

    A multipurpose in situ underground measurement system comprising a plurality of long electrical resistance elements in the form of rigid reinforcing bars, each having an open loop hairpin configuration of shorter length than the other resistance elements. The resistance elements are arranged in pairs in a unitized structure, and grouted in place in the underground volume. Measurement means are provided for obtaining for each pair the electrical resistance of each element and the difference in electrical resistance of the paired elements, which difference values may be used in analytical methods involving resistance as a function of temperature. A scanner means sequentially connects the resistance-measuring apparatus to each individual pair of elements. A source of heating current is also selectively connectable for heating the elements to an initial predetermined temperature prior to electrical resistance measurements when used as an anemometer.

  11. Physics-based signal processing algorithms for micromachined cantilever arrays

    DOEpatents

    Candy, James V; Clague, David S; Lee, Christopher L; Rudd, Robert E; Burnham, Alan K; Tringe, Joseph W

    2013-11-19

    A method of using physics-based signal processing algorithms for micromachined cantilever arrays. The methods utilize deflection of a micromachined cantilever that represents the chemical, biological, or physical element being detected. One embodiment of the method comprises the steps of modeling the deflection of the micromachined cantilever producing a deflection model, sensing the deflection of the micromachined cantilever and producing a signal representing the deflection, and comparing the signal representing the deflection with the deflection model.

  12. Characterization of piesoelectric ZnO thin films and the fabrication of piezoelectric micro-cantilevers

    SciTech Connect

    Johnson, Raegan Lynn

    2005-01-01

    In Atomic Force Microscopy (AFM), a microcantilever is raster scanned across the surface of a sample in order to obtain a topographical image of the sample's surface. In a traditional, optical AFM, the sample rests on a bulk piezoelectric tube and a control loop is used to control the tip-sample separation by actuating the piezo-tube. This method has several disadvantages--the most noticeable one being that response time of the piezo-tube is rather long which leads to slow imaging speeds. One possible solution aimed at improving the speed of imaging is to incorporate a thin piezoelectric film on top of the cantilever beam. This design not only improves the speed of imaging because the piezoelectric film replaces the piezo-tube as an actuator, but the film can also act as a sensor. In addition, the piezoelectric film can excite the cantilever beam near its resonance frequency. This project aims to fabricate piezoelectric microcantilevers for use in the AFM. Prior to fabricating the cantilevers and also part of this project, a systematic study was performed to examine the effects of deposition conditions on the quality of piezoelectric ZnO thin films deposited by RF sputtering. These results will be presented. The deposition parameters that produced the highest quality ZnO film were used in the fabrication of the piezoelectric cantilevers. Unfortunately, the fabricated cantilevers warped due to the intrinsic stress of the ZnO film and were therefore not usable in the AFM. The complete fabrication process will be detailed, the results will be discussed and reasons for the warping will be examined.

  13. Self-heating in piezoresistive cantilevers

    PubMed Central

    Doll, Joseph C.; Corbin, Elise A.; King, William P.; Pruitt, Beth L.

    2011-01-01

    We report experiments and models of self-heating in piezoresistive microcantilevers that show how cantilever measurement resolution depends on the thermal properties of the surrounding fluid. The predicted cantilever temperature rise from a finite difference model is compared with detailed temperature measurements on fabricated devices. Increasing the fluid thermal conductivity allows for lower temperature operation for a given power dissipation, leading to lower force and displacement noise. The force noise in air is 76% greater than in water for the same increase in piezoresistor temperature. PMID:21731884

  14. Operating characteristics of a cantilever-mounted resilient-pad gas-lubricated thrust bearing

    NASA Technical Reports Server (NTRS)

    Nemeth, Z. N.

    1979-01-01

    A resilient-pad gas thrust bearing consisting of pads mounted on cantilever beams was tested to determine its operating characteristic. The bearing was run at a thrust load of 74 newtons to a speed of 17000 rpm. The pad film thickness and bearing friction torque were measured and compared with theory. The measured film thickness was less than that predicted by theory. The bearing friction torque was greater than that predicted by theory.

  15. Analysis and design of a cantilever-mounted resilient-pad gas-lubricated thrust bearing

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1976-01-01

    A thrust bearing consisting of pads mounted on resilient, metallic, cantilever beams is described and analyzed. Compliance and stiffness of the bearing assembly are discussed, and the effects of bearing design parameters on performance are shown. After the general analysis, a design example is presented for a flat sector-shaped gas bearing. A special case where zero axial movement of the runner can be obtained is pointed out.

  16. Interdisciplinary cantilever physics: Elasticity of carrot, celery, and plasticware

    NASA Astrophysics Data System (ADS)

    Pestka, Kenneth A.

    2014-05-01

    This article presents several simple cantilever-based experiments using common household items (celery, carrot, and a plastic spoon) that are appropriate for introductory undergraduate laboratories or independent student projects. By applying Hooke's law and Euler beam theory, students are able to determine Young's modulus, fracture stress, yield stress, strain energy, and sound speed of these apparently disparate materials. In addition, a cellular foam elastic model is introduced—applicable to biologic materials as well as an essential component in the development of advanced engineering composites—that provides a mechanism to determine Young's modulus of the cell wall material found in celery and carrot. These experiments are designed to promote exploration of the similarities and differences between common inorganic and organic materials, fill a void in the typical undergraduate curriculum, and provide a foundation for more advanced material science pursuits within biology, botany, and food science as well as physics and engineering.

  17. Three-dimensional vibrations of cantilevered right triangular plates

    NASA Astrophysics Data System (ADS)

    McGee, O. G.; Giaimo, G. T.

    1992-12-01

    The first known three-dimensional continuum vibration solutions for cantilevered right triangular plates with variable thickness are obtained using the Ritz method. Assumed displacement functions are in the form of algebraic polynomials, which satisfy the fixed face conditions exactly, and which are mathematically complete. Reasonably accurate natural frequencies are calculated for low aspect ratio, right triangular thin plates having arbitrary values of thickness taper ratios in the spanwise direction. Detailed numerical studies show that a three-dimensional analysis is essential to monitoring coupled-mode sensitivities in the variation of non-dimensional natural frequencies with increasing thickness taper ratio. Upper bound results, obtained using the present method, are compared with those obtained by other investigators using ordinary beam theories, two-dimensional finite element and finite difference procedures, and experimental methods. This unified comparison of upper and lower bound solutions is presented here with the aim of 'bracketing' the exact analytical solution of the subject problem.

  18. Peculiarities of the third natural frequency vibrations of a cantilever for the improvement of energy harvesting.

    PubMed

    Ostasevicius, Vytautas; Janusas, Giedrius; Milasauskaite, Ieva; Zilys, Mindaugas; Kizauskiene, Laura

    2015-01-01

    This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH) prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4-4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation. PMID:26029948

  19. Peculiarities of the third natural frequency vibrations of a cantilever for the improvement of energy harvesting.

    PubMed

    Ostasevicius, Vytautas; Janusas, Giedrius; Milasauskaite, Ieva; Zilys, Mindaugas; Kizauskiene, Laura

    2015-05-28

    This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH) prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4-4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation.

  20. Peculiarities of the Third Natural Frequency Vibrations of a Cantilever for the Improvement of Energy Harvesting

    PubMed Central

    Ostasevicius, Vytautas; Janusas, Giedrius; Milasauskaite, Ieva; Zilys, Mindaugas; Kizauskiene, Laura

    2015-01-01

    This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH) prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4–4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation. PMID:26029948

  1. Microfluidic cantilever detects bacteria and measures their susceptibility to antibiotics in small confined volumes

    PubMed Central

    Etayash, Hashem; Khan, M. F.; Kaur, Kamaljit; Thundat, Thomas

    2016-01-01

    In the fight against drug-resistant bacteria, accurate and high-throughput detection is essential. Here, a bimaterial microcantilever with an embedded microfluidic channel with internal surfaces chemically or physically functionalized with receptors selectively captures the bacteria passing through the channel. Bacterial adsorption inside the cantilever results in changes in the resonance frequency (mass) and cantilever deflection (adsorption stress). The excitation of trapped bacteria using infrared radiation (IR) causes the cantilever to deflect in proportion to the infrared absorption of the bacteria, providing a nanomechanical infrared spectrum for selective identification. We demonstrate the in situ detection and discrimination of Listeria monocytogenes at a concentration of single cell per μl. Trapped Escherichia coli in the microchannel shows a distinct nanomechanical response when exposed to antibiotics. This approach, which combines enrichment with three different modes of detection, can serve as a platform for the development of a portable, high-throughput device for use in the real-time detection of bacteria and their response to antibiotics. PMID:27698375

  2. Microfluidic cantilever detects bacteria and measures their susceptibility to antibiotics in small confined volumes

    NASA Astrophysics Data System (ADS)

    Etayash, Hashem; Khan, M. F.; Kaur, Kamaljit; Thundat, Thomas

    2016-10-01

    In the fight against drug-resistant bacteria, accurate and high-throughput detection is essential. Here, a bimaterial microcantilever with an embedded microfluidic channel with internal surfaces chemically or physically functionalized with receptors selectively captures the bacteria passing through the channel. Bacterial adsorption inside the cantilever results in changes in the resonance frequency (mass) and cantilever deflection (adsorption stress). The excitation of trapped bacteria using infrared radiation (IR) causes the cantilever to deflect in proportion to the infrared absorption of the bacteria, providing a nanomechanical infrared spectrum for selective identification. We demonstrate the in situ detection and discrimination of Listeria monocytogenes at a concentration of single cell per μl. Trapped Escherichia coli in the microchannel shows a distinct nanomechanical response when exposed to antibiotics. This approach, which combines enrichment with three different modes of detection, can serve as a platform for the development of a portable, high-throughput device for use in the real-time detection of bacteria and their response to antibiotics.

  3. Maximizing Output Power in a Cantilevered Piezoelectric Vibration Energy Harvester by Electrode Design

    NASA Astrophysics Data System (ADS)

    Du, Sijun; Jia, Yu; Seshia, Ashwin

    2015-12-01

    A resonant vibration energy harvester typically comprises of a clamped anchor and a vibrating shuttle with a proof mass. Piezoelectric materials are embedded in locations of high strain in order to transduce mechanical deformation into electric charge. Conventional design for piezoelectric vibration energy harvesters (PVEH) usually utilizes piezoelectric material and metal electrode layers covering the entire surface area of the cantilever with no consideration provided to examining the trade-off involved with respect to maximizing output power. This paper reports on the theory and experimental verification underpinning optimization of the active electrode area of a cantilevered PVEH in order to maximize output power. The analytical formulation utilizes Euler-Bernoulli beam theory to model the mechanical response of the cantilever. The expression for output power is reduced to a fifth order polynomial expression as a function of the electrode area. The maximum output power corresponds to the case when 44% area of the cantilever is covered by electrode metal. Experimental results are also provided to verify the theory.

  4. An analytic model for accurate spring constant calibration of rectangular atomic force microscope cantilevers.

    PubMed

    Li, Rui; Ye, Hongfei; Zhang, Weisheng; Ma, Guojun; Su, Yewang

    2015-10-29

    Spring constant calibration of the atomic force microscope (AFM) cantilever is of fundamental importance for quantifying the force between the AFM cantilever tip and the sample. The calibration within the framework of thin plate theory undoubtedly has a higher accuracy and broader scope than that within the well-established beam theory. However, thin plate theory-based accurate analytic determination of the constant has been perceived as an extremely difficult issue. In this paper, we implement the thin plate theory-based analytic modeling for the static behavior of rectangular AFM cantilevers, which reveals that the three-dimensional effect and Poisson effect play important roles in accurate determination of the spring constants. A quantitative scaling law is found that the normalized spring constant depends only on the Poisson's ratio, normalized dimension and normalized load coordinate. Both the literature and our refined finite element model validate the present results. The developed model is expected to serve as the benchmark for accurate calibration of rectangular AFM cantilevers.

  5. Fabrication Challenges in Producing Magnet-tipped Cantilevers for Magnetic Resonance Force Microscopy

    NASA Astrophysics Data System (ADS)

    Hickman, Steven A.; Garner, Sean R.; Harrell, Lee E.; Ong, Jeremy C.; Kuehn, Seppe; Marohn, John A.

    2008-03-01

    Magnetic resonance force microscopy (MRFM) is a technique that may allow MR imaging of single molecules -- an extremely exciting prospect. To date we have demonstrated MRFM sensitivity of ˜10^5 proton spins. By making improved magnetic tips and increasing force sensitivity, it may be possible to achieve single-proton sensitivity necessary for molecular imaging. In MRFM the force exerted on the cantilever, per spin, is proportional to the field gradient from the cantilever's magnetic tip. Achieving single proton sensitivity thus requires dramatically reducing magnet size. We have developed an e-beam lithography process for batch fabricating nanoscale magnets on silicon cantilevers. With these sized magnets we will still require attonewton force sensitivity. Research by our group has shown that surface induced dissipation is a major noise source. We believe this can be minimized by producing magnets overhanging the cantilever end. As proof of concept, we will show a 50-nm overhanging cobalt magnet made by a process involving KOH etching, as well as preliminary work on making overhanging magnets by dry fabrication methods. Our current challenge appears to be preventing the formation of metal silicides.

  6. An analytic model for accurate spring constant calibration of rectangular atomic force microscope cantilevers

    PubMed Central

    Li, Rui; Ye, Hongfei; Zhang, Weisheng; Ma, Guojun; Su, Yewang

    2015-01-01

    Spring constant calibration of the atomic force microscope (AFM) cantilever is of fundamental importance for quantifying the force between the AFM cantilever tip and the sample. The calibration within the framework of thin plate theory undoubtedly has a higher accuracy and broader scope than that within the well-established beam theory. However, thin plate theory-based accurate analytic determination of the constant has been perceived as an extremely difficult issue. In this paper, we implement the thin plate theory-based analytic modeling for the static behavior of rectangular AFM cantilevers, which reveals that the three-dimensional effect and Poisson effect play important roles in accurate determination of the spring constants. A quantitative scaling law is found that the normalized spring constant depends only on the Poisson’s ratio, normalized dimension and normalized load coordinate. Both the literature and our refined finite element model validate the present results. The developed model is expected to serve as the benchmark for accurate calibration of rectangular AFM cantilevers. PMID:26510769

  7. Note: Improved calibration of atomic force microscope cantilevers using multiple reference cantilevers

    SciTech Connect

    Sader, John E.; Friend, James R.

    2015-05-15

    Overall precision of the simplified calibration method in J. E. Sader et al., Rev. Sci. Instrum. 83, 103705 (2012), Sec. III D, is dominated by the spring constant of the reference cantilever. The question arises: How does one take measurements from multiple reference cantilevers, and combine these results, to improve uncertainty of the reference cantilever’s spring constant and hence the overall precision of the method? This question is addressed in this note. Its answer enables manufacturers to specify of a single set of data for the spring constant, resonant frequency, and quality factor, from measurements on multiple reference cantilevers. With this data set, users can trivially calibrate cantilevers of the same type.

  8. Nanoelectrodes integrated in atomic force microscopy cantilevers for imaging of in situ enzyme activity.

    PubMed

    Kueng, Angelika; Kranz, Christine; Lugstein, Alois; Bertagnolli, Emmerich; Mizaikoff, Boris

    2005-01-01

    For investigation of laterally resolved information on biological activity, techniques for simultaneously obtaining complementary information correlated in time and space are required. In this context, recent developments in scanning probe microscopy are aimed at information on the sample topography and simultaneously on the physical and chemical properties at the nanometer scale. With the integration of submicro- and nanoelectrodes into atomic force microscopy (AFM) probes using microfabrication techniques, an elegant approach combining scanning electrochemical microscopy with AFM is demonstrated. This instrumentation enables simultaneous imaging of topography and obtainment of laterally resolved electrochemical information in AFM tapping mode. Hence, topographical and electrochemical information on soft surfaces (e.g., biological species) and polymers can be obtained. The functionality of tip-integrated electrodes is demonstrated by simultaneous electrochemical and topographical studies of an enzyme-modified micropattern.

  9. A method to provide rapid in situ determination of tip radius in dynamic atomic force microscopy.

    PubMed

    Santos, Sergio; Guang, Li; Souier, Tewfik; Gadelrab, Karim; Chiesa, Matteo; Thomson, Neil H

    2012-04-01

    We provide a method to characterize the tip radius of an atomic force microscopy in situ by monitoring the dynamics of the cantilever in ambient conditions. The key concept is that the value of free amplitude for which transitions from the attractive to repulsive force regimes are observed, strongly depends on the curvature of the tip. In practice, the smaller the value of free amplitude required to observe a transition, the sharper the tip. This general behavior is remarkably independent of the properties of the sample and cantilever characteristics and shows the strong dependence of the transitions on the tip radius. The main advantage of this method is rapid in situ characterization. Rapid in situ characterization enables one to continuously monitor the tip size during experiments. Further, we show how to reproducibly shape the tip from a given initial size to any chosen larger size. This approach combined with the in situ tip size monitoring enables quantitative comparison of materials measurements between samples. These methods are set to allow quantitative data acquisition and make direct data comparison readily available in the community.

  10. Biomechanical load analysis of cantilevered implant systems.

    PubMed

    Osier, J F

    1991-01-01

    Historically, dental implants have been placed in areas where quality bone exists. The maxillary sinus areas and mandibular canal proximities have been avoided. From these placements, various cantilevered prosthetic applications have emerged. This analysis uses static engineering principles to define the loads (i.e., forces) placed upon the implants. These principles make use of Newton's first and third laws of mechanics by summing the forces and moments to zero. These summations then generate mathematical equations and their algebraic solutions. Three implant systems are analyzed. The first is a two-implant system. The second is a three-implant cross-arch stabilized system usually found in mandibular replacements of lower full dentures. The third is a five-implant system which is identical to the three-implant cantilevered system but which uses implants in the first molar area, thereby negating the cantilevered load magnification of the three-implant design. These analyses demonstrate that, in a cantilevered application, the implant closest to the point of load application (usually the most posterior implant) takes the largest compressive load. Implants opposite the load application (generally the anterior implant) are in tension. These loads on the implants are normally magnified over the biting force and can easily reach 2 1/2 to five times the biting load.

  11. Calibration of higher eigenmodes of cantilevers.

    PubMed

    Labuda, Aleksander; Kocun, Marta; Lysy, Martin; Walsh, Tim; Meinhold, Jieh; Proksch, Tania; Meinhold, Waiman; Anderson, Caleb; Proksch, Roger

    2016-07-01

    A method is presented for calibrating the higher eigenmodes (resonant modes) of atomic force microscopy cantilevers that can be performed prior to any tip-sample interaction. The method leverages recent efforts in accurately calibrating the first eigenmode by providing the higher-mode stiffness as a ratio to the first mode stiffness. A one-time calibration routine must be performed for every cantilever type to determine a power-law relationship between stiffness and frequency, which is then stored for future use on similar cantilevers. Then, future calibrations only require a measurement of the ratio of resonant frequencies and the stiffness of the first mode. This method is verified through stiffness measurements using three independent approaches: interferometric measurement, AC approach-curve calibration, and finite element analysis simulation. Power-law values for calibrating higher-mode stiffnesses are reported for several cantilever models. Once the higher-mode stiffnesses are known, the amplitude of each mode can also be calibrated from the thermal spectrum by application of the equipartition theorem. PMID:27475563

  12. Calibration of higher eigenmodes of cantilevers

    NASA Astrophysics Data System (ADS)

    Labuda, Aleksander; Kocun, Marta; Lysy, Martin; Walsh, Tim; Meinhold, Jieh; Proksch, Tania; Meinhold, Waiman; Anderson, Caleb; Proksch, Roger

    2016-07-01

    A method is presented for calibrating the higher eigenmodes (resonant modes) of atomic force microscopy cantilevers that can be performed prior to any tip-sample interaction. The method leverages recent efforts in accurately calibrating the first eigenmode by providing the higher-mode stiffness as a ratio to the first mode stiffness. A one-time calibration routine must be performed for every cantilever type to determine a power-law relationship between stiffness and frequency, which is then stored for future use on similar cantilevers. Then, future calibrations only require a measurement of the ratio of resonant frequencies and the stiffness of the first mode. This method is verified through stiffness measurements using three independent approaches: interferometric measurement, AC approach-curve calibration, and finite element analysis simulation. Power-law values for calibrating higher-mode stiffnesses are reported for several cantilever models. Once the higher-mode stiffnesses are known, the amplitude of each mode can also be calibrated from the thermal spectrum by application of the equipartition theorem.

  13. Direct and alignment-insensitive measurement of cantilever curvature

    SciTech Connect

    Hermans, Rodolfo I.; Aeppli, Gabriel; Bailey, Joe M.

    2013-07-15

    We analytically derive and experimentally demonstrate a method for the simultaneous measurement of deflection for large arrays of cantilevers. The Fresnel diffraction patterns of a cantilever independently reveal tilt, curvature, cubic, and higher order bending of the cantilever. It provides a calibrated absolute measurement of the polynomial coefficients describing the cantilever shape, without careful alignment and could be applied to several cantilevers simultaneously with no added complexity. We show that the method is easily implemented, works in both liquid media and in air, for a broad range of displacements and is especially suited to the requirements for multi-marker biosensors.

  14. In Situ Nuclear Characterization Infrastructure

    SciTech Connect

    James A. Smith; J. Rory Kennedy

    2011-11-01

    To be able to evolve microstructure with a prescribed in situ process, an effective measurement infrastructure must exist. This interdisciplinary infrastructure needs to be developed in parallel with in situ sensor technology. This paper discusses the essential elements in an effective infrastructure.

  15. Expanded beam deflection method for simultaneous measurement of displacement and vibrations of multiple microcantilevers

    SciTech Connect

    Nieradka, K.; MaloziePc, G.; Kopiec, D.; Gotszalk, T.

    2011-10-15

    Here we present an extension of optical beam deflection (OBD) method for measuring displacement and vibrations of an array of microcantilevers. Instead of focusing on the cantilever, the optical beam is either focused above or below the cantilever array, or focused only in the axis parallel to the cantilevers length, allowing a wide optical line to span multiple cantilevers in the array. Each cantilever reflects a part of the incident beam, which is then directed onto a photodiode array detector in a manner allowing distinguishing between individual beams. Each part of reflected beam behaves like a single beam of roughly the same divergence angle in the bending sensing axis as the incident beam. Since sensitivity of the OBD method depends on the divergence angle of deflected beam, high sensitivity is preserved in proposed expanded beam deflection (EBD) method. At the detector, each spot's position is measured at the same time, without time multiplexing of light sources. This provides real simultaneous readout of entire array, unavailable in most of competitive methods, and thus increases time resolution of the measurement. Expanded beam can also span another line of cantilevers allowing monitoring of specially designed two-dimensional arrays. In this paper, we present first results of application of EBD method to cantilever sensors. We show how thermal noise resolution can be easily achieved and combined with thermal noise based resonance frequency measurement.

  16. In situ mercury stabilization

    SciTech Connect

    Fuhrmann, M.; Kalb, P.; Adams, J.

    2004-09-01

    BNL Royalty Project Internal Status Report. The funds from the allotment of royalty income were used to experimentally explore feasibility of related, potential new techniques based on the Environmental Sciences Department successful technology licensed for the ex situ treatment of mercury. Specifically, this work is exploring the concept of using Sulfur Polymer Cement (SPC) in an in situ application to stabilize and/or remove mercury (Hg) from surficial soil. Patent disclosure forms have been filed for this process. Soil was artificially spiked with 500 ppm Hg and a series of experiments were set up in which SPC rods were placed in the center of a mass of this soil. Some experiments were conducted at 20 C and others at 50 C. After times ranging from 11 to 24 days, these experiments were opened, photographed and the soil was sampled from discrete locations in the containers. The soil and SPC samples were analyzed for Fe and Hg by x-ray fluorescence. The Hg profile in the soil was significantly altered, with concentrations along the outer edge of the soil reduced by as much as 80% from the starting concentration. Conversely, closer to the treatment rod containing SPC, concentrations of Hg were significantly increased over the original concentration. Preliminary results for elevated temperature sample are shown graphically in Figure 2. Apparently the Hg had migrated toward the SPC and reacted with sulfur to form Hg S. This appears to be a reaction between gaseous phases of both S and Hg, with Hg having a greater vapor pressure. The concentration of low solubility HgS (i.e., low leaching properties) developed within 11 days at 50 C and 21 days at 20 C, confirming the potential of this concept.

  17. In-Situ Electrochemical Transmission Electron Microscopy for Battery Research

    SciTech Connect

    Mehdi, Beata L; Gu, Meng; Parent, Lucas; Xu, WU; Nasybulin, Eduard; Chen, Xilin; Unocic, Raymond R; Xu, Pinghong; Welch, David; Abellan, Patricia; Zhang, Ji-Guang; Liu, Jun; Wang, Chongmin; Arslan, Ilke; Evans, James E; Browning, Nigel

    2014-01-01

    The recent development of in-situ liquid stages for (scanning) transmission electron microscopes now makes it possible for us to study the details of electrochemical processes under operando conditions. As electrochemical processes are complex, care must be taken to calibrate the system before any in-situ/operando observations. In addition, as the electron beam can cause effects that look similar to electrochemical processes at the electrolyte/electrode interface, an understanding of the role of the electron beam in modifying the operando observations must also be understood. In this paper we describe the design, assembly, and operation of an in-situ electrochemical cell, paying particular attention to the method for controlling and quantifying the experimental parameters. The use of this system is then demonstrated for the lithiation/delithiation of silicon nanowires.

  18. In Situ Electrochemical Transmission Electron Microscopy for Battery Research

    SciTech Connect

    Mehdi, Beata L.; Gu, Meng; Parent, Lucas R.; Xu, Wu; Nasybulin, Eduard N.; Chen, Xilin; Unocic, Raymond R.; Xu, Pinghong; Welch, David A.; Abellan, Patricia; Zhang, Jiguang; Liu, Jun; Wang, Chong M.; Arslan, Ilke; Evans, James E.; Browning, Nigel D.

    2014-04-01

    The recent development of in situ liquid stages for (scanning) transmission electron microscopes now makes it possible for us to study the details of electrochemical processes under operando conditions. As electrochemical processes are complex, care must be taken to calibrate the system before any in situ/operando observations. In addition, as the electron beam can cause effects that look similar to electrochemical processes at the electrolyte/electrode interface, an understanding of the role of the electron beam in modifying the operando observations must also be understood. In this paper we describe the design, assembly, and operation of an in situ electrochemical cell, paying particular attention to the method for controlling and quantifying the experimental parameters. The use of this system is then demonstrated for the lithiation/delithiation of silicon nanowires.

  19. 3D finite element analysis of electrostatic deflection of commercial and FIB-modified cantilevers for electric and Kelvin force microscopy: I. Triangular shaped cantilevers with symmetric pyramidal tips.

    PubMed

    Valdrè, Giovanni; Moro, Daniele

    2008-10-01

    The investigation of the nanoscale distribution of electrostatic forces on material surfaces is of paramount importance for the development of nanotechnology, since these confined forces govern many physical processes on which a large number of technological applications are based. For instance, electric force microscopy (EFM) and micro-electro-mechanical-systems (MEMS) are technologies based on an electrostatic interaction between a cantilever and a specimen. In the present work we report on a 3D finite element analysis of the electrostatic deflection of cantilevers for electric and Kelvin force microscopy. A commercial triangular shaped cantilever with a symmetric pyramidal tip was modelled. In addition, the cantilever was modified by a focused ion beam (FIB) in order to reduce its parasitic electrostatic force, and its behaviour was studied by computation analysis. 3D modelling of the electrostatic deflection was realized by using a multiphysics finite element analysis software and it was applied to the real geometry of the cantilevers and probes obtained by using basic CAD tools. The results of the modelling are in good agreement with experimental data.

  20. Sensitivity of flexural vibration mode of the rectangular atomic force microscope micro cantilevers in liquid to the surface stiffness variations.

    PubMed

    Farokh Payam, Amir

    2013-12-01

    In this paper, the resonance frequencies and modal sensitivity of flexural vibration modes of a rectangular atomic force microscope (AFM) cantilever immersed in a liquid to surface stiffness variations have been analyzed and a closed-form expression is derived. For this purpose, the Euler-Bernoulli beam theory is used to develop the AFM cantilever model in liquid. Then, an expression for the resonance frequencies of AFM cantilever in liquid is derived and the results of the derived expression are compared with the experimental measurements. Based on this expression, the effect of the surface contact stiffness on flexural mode of a rectangular AFM cantilever in a fluid is investigated and compared with the case that AFM cantilever operates in the air. The results show that in the low surface stiffness, the first mode is the most sensitive mode and the best image contrast is obtained by excitation this mode, but by increasing the sample surface stiffness the higher modes have better image contrast. In addition, comparison between modal sensitivities in air and liquid shows that the resonance frequency shifts in the air are greater than the shifts in the fluid, which means that for the similar surface stiffness the image contrast in air, is better than liquid. PMID:23942312

  1. Cantilever RF-MEMS for monolithic integration with phased array antennas on a PCB

    NASA Astrophysics Data System (ADS)

    Aguilar-Armenta, C. J.; Porter, S. J.

    2015-12-01

    This article presents the development and operation of a novel electrostatic metal-to-metal contact cantilever radio-frequency microelectromechanical system (RF-MEMS) switch for monolithic integration with microstrip phased array antennas (PAAs) on a printed circuit board. The switch is fabricated using simple photolithography techniques on a Rogers 4003c substrate, with a footprint of 200 µm × 100 µm, based on a 1 µm-thick copper cantilever. An alternative wet-etching technique for effectively releasing the cantilever is described. Electrostatic and electromagnetic measurements show that the RF-MEMS presents an actuation voltage of 90 V for metal-to-metal contact, an isolation of -8.7 dB, insertion loss of -2.5 dB and a return loss of -15 dB on a 50 Ω microstrip line at 12.5 GHz. For proof-of-concept, a beam-steering 2 × 2 microstrip PAA, based on two 1-bit phase shifters suitable for the monolithic integration of the RF-MEMS, has been designed and measured at 12.5 GHz. Measurements show that the beam-steering system presents effective radiation characteristics with scanning capabilities from broadside towards 29° in the H-plane.

  2. Dynamic analysis of a vertically deploying/retracting cantilevered pipe conveying fluid

    NASA Astrophysics Data System (ADS)

    Huo, Yinlei; Wang, Zhongmin

    2016-01-01

    Based on Euler-Bernoulli beam theory and Hamilton's principle, the differential equation of a vertical cantilevered pipe conveying fluid is derived when the pipe has deploying or retracting motion. The resulting equation is discretized via the Galerkin method in which the eigenfunctions of a clamped-free Euler-Bernoulli beam are utilized. Then, the dynamic responses and stability are discussed with regard to the deploying or retracting speed, mass ratio, and fluid velocity. Numerical results reveal that the dynamical behavior of the system is mainly affected by the flow velocity, instantaneous length of pipe, gravity, and mass ratio. For the small flow velocity, the fluid and higher mass ratio helps to stabilize the transverse vibration of the cantilevered pipe conveying fluid in both deployment and retraction modes, and the system will lose stability with the further increase of flow velocity. The critical flow velocity is mainly influenced by the instantaneous length of pipe. The additional restoring force due to gravity causes critical flow velocity to be higher for the vertically cantilevered pipe conveying fluid. Therefore, gravity is conducive to the stability the transverse vibration of the system in both deployment and retraction modes.

  3. IN SITU ENHANCED SOURCE REMOVAL

    EPA Science Inventory

    This html report describes and compares the performance of in situ technologies designed to accelerate the removal of organic contaminants from unconsolidated soils and aquifers. The research was conducted through the Enhanced Source Removal (ESR) Program within the Subsurface Pr...

  4. Nonlinear Vibrations of Ferroelectric Bimorph Cantilever

    NASA Astrophysics Data System (ADS)

    Ostrovskii, Igor; Nadtochiy, Andriy

    2008-06-01

    Nonlinear vibrations of a bimorph LiNbO3 microcantilever are investigated. A periodically poled LiNbO3 wafer is used as an initial chip. The cantilever is micro-machined near an interdomain wall between two inversely poled domains. The vibrations are excited by an applied rf-voltage, and motion of a cantilever tip is detected optically. Nonlinearity is revealed by measuring the changes in the dependencies of vibration amplitude versus frequency when amplitude increases, and by reading of sub-harmonic oscillations. A surface of the microcantilever may be modified with a silane, which is sensitive to certain biomolecules. This composite nonlinear micro-vibrator may be used for developing a smart biosensor operating in ambient atmosphere in a real time mode.

  5. Calibration of optical cantilever deflection readers

    NASA Astrophysics Data System (ADS)

    Hu, Zhiyu; Seeley, Tim; Kossek, Sebastian; Thundat, Thomas

    2004-02-01

    Because of its ultrahigh sensitivity, the optical lever detection method similar to that used in the atomic force microscope (AFM) has been widely employed as a standard technique for measuring microcantilever deflection. Along with the increasing interest in using the microcantilever as a sensing platform, there is also a requirement for a reliable calibration technique. Many researchers have used the concept of optical lever detection to construct microcantilever deflection readout instruments for chemical, physical, and biological detection. However, without an AFM piezo z scanner, it is very difficult to precisely calibrate these instruments. Here, we present a step-by-step method to conveniently calibrate an instrument using commercially available piezoresistive cantilevers. The experimental results closely match the theoretical calculation. Following this procedure, one can easily calibrate any optical cantilever deflection detection system with high reproducibility, precision, and reliability. A detailed discussion of the optical lever readout system design has been addressed in this article.

  6. Intrinsic dissipation in atomic force microscopy cantilevers.

    PubMed

    Zypman, Fredy

    2011-07-01

    In this paper we build a practical modification to the standard Euler-Bernoulli equation for flexural modes of cantilever vibrations most relevant for operation of AFM in high vacuum conditions. This is done by the study of a new internal dissipation term into the Euler-Bernoulli equation. This term remains valid in ultra-high vacuum, and becomes particularly relevant when viscous dissipation with the fluid environment becomes negligible. We derive a compact explicit equation for the quality factor versus pressure for all the flexural modes. This expression is used to compare with corresponding extant high vacuum experiments. We demonstrate that a single internal dissipation parameter and a single viscosity parameter provide enough information to reproduce the first three experimental flexural resonances at all pressures. The new term introduced here has a mesoscopic origin in the relative motion between adjacent layers in the cantilever. PMID:21741914

  7. Nonlinear hydrodynamic damping of sharp-edged cantilevers in viscous fluids undergoing multi-harmonic base excitation

    NASA Astrophysics Data System (ADS)

    Facci, Andrea L.; Porfiri, Maurizio

    2012-12-01

    In this paper, we investigate finite amplitude polychromatic flexural vibration of a thin beam oscillating in a quiescent viscous fluid. We consider a cantilever beam with rectangular cross section undergoing periodic base excitation in the form of a triangular wave. Experiments are performed on centimeter-size beams in water to elucidate the effect of the amplitude and the frequency of the base excitation on the fluid structure interaction. The fundamental frequency of the excitation is selected to induce structural resonance and the shape of the cantilevers is parametrically varied to explore different flow regimes. Experimental results demonstrate the presence of a frequency-dependent nonlinear hydrodynamic damping which tends to enhance higher frequency harmonics as compared to the fundamental harmonic. Such filtering effect produced by the encompassing fluid increases with both the frequency and amplitude of the base excitation. Experimental results are interpreted through available theoretical models, based on the notion of the complex hydrodynamic function, and pertinent computational fluid dynamics findings.

  8. Experimental characterization of cantilever-type piezoelectric generator operating at resonance for vibration energy harvesting

    NASA Astrophysics Data System (ADS)

    Montanini, Roberto; Quattrocchi, Antonino

    2016-06-01

    A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d31 mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequency highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.

  9. Recording oscillations of sub-micron size cantilevers by extreme ultraviolet Fourier transform holography.

    PubMed

    Monserud, Nils C; Malm, Erik B; Wachulak, Przemyslaw W; Putkaradze, Vakhtang; Balakrishnan, Ganesh; Chao, Weilun; Anderson, Erik; Carlton, David; Marconi, Mario C

    2014-02-24

    We recorded the fast oscillation of sub-micron cantilevers using time-resolved extreme ultraviolet (EUV) Fourier transform holography. A tabletop capillary discharge EUV laser with a wavelength of 46.9 nm provided a large flux of coherent illumination that was split using a Fresnel zone plate to generate the object and the reference beams. The reference wave was produced by the first order focus while a central opening in the zone plate provided a direct illumination of the cantilevers. Single-shot holograms allowed for the composition of a movie featuring the fast oscillation. Three-dimensional displacements of the object were determined as well by numerical back-propagation, or "refocusing" of the electromagnetic fields during the reconstruction of a single hologram. PMID:24663740

  10. Development of low noise cantilever deflection sensor for multienvironment frequency-modulation atomic force microscopy

    SciTech Connect

    Fukuma, Takeshi; Kimura, Masayuki; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

    2005-05-15

    We have developed a low noise cantilever deflection sensor with a deflection noise density of 17 fm/{radical}(Hz) by optimizing the parameters used in optical beam deflection (OBD) method. Using this sensor, we have developed a multienvironment frequency-modulation atomic force microscope (FM-AFM) that can achieve true molecular resolution in various environments such as in moderate vacuum, air, and liquid. The low noise characteristic of the deflection sensor makes it possible to obtain a maximum frequency sensitivity limited by the thermal Brownian motion of the cantilever in every environment. In this paper, the major noise sources in OBD method are discussed in both theoretical and experimental aspects. The excellent noise performance of the deflection sensor is demonstrated in deflection and frequency measurements. True molecular-resolution FM-AFM images of a polydiacetylene single crystal taken in vacuum, air, and water are presented.

  11. Simultaneous Scanning Ion Conductance Microscopy and Atomic Force Microscopy with Microchanneled Cantilevers

    NASA Astrophysics Data System (ADS)

    Ossola, Dario; Dorwling-Carter, Livie; Dermutz, Harald; Behr, Pascal; Vörös, János; Zambelli, Tomaso

    2015-12-01

    We combined scanning ion conductance microscopy (SICM) and atomic force microscopy (AFM) into a single tool using AFM cantilevers with an embedded microchannel flowing into the nanosized aperture at the apex of the hollow pyramid. An electrode was positioned in the AFM fluidic circuit connected to a second electrode in the bath. We could thus simultaneously measure the ionic current and the cantilever bending (in optical beam deflection mode). First, we quantitatively compared the SICM and AFM contact points on the approach curves. Second, we estimated where the probe in SICM mode touches the sample during scanning on a calibration grid and applied the finding to image a network of neurites on a Petri dish. Finally, we assessed the feasibility of a double controller using both the ionic current and the deflection as input signals of the piezofeedback. The experimental data were rationalized in the framework of finite elements simulations.

  12. Readout of micromechanical cantilever sensor arrays by Fabry-Perot interferometry

    SciTech Connect

    Wehrmeister, Jana; Fuss, Achim; Saurenbach, Frank; Berger, Ruediger; Helm, Mark

    2007-10-15

    The increasing use of micromechanical cantilevers in sensing applications causes a need for reliable readout techniques of micromechanical cantilever sensor (MCS) bending. Current optical beam deflection techniques suffer from drawbacks such as artifacts due to changes in the refraction index upon exchange of media. Here, an adaptation of the Fabry-Perot interferometer is presented that allows simultaneous determination of MCS bending and changes in the refraction index of media. Calibration of the instrument with liquids of known refraction index provides an avenue to direct measurement of bending with nanometer precision. Versatile construction of flow cells in combination with alignment features for substrate chips allows simultaneous measurement of two MCS situated either on the same, or on two different support chips. The performance of the instrument is demonstrate in several sensing applications, including adsorption experiments of alkanethioles on MCS gold surfaces, and measurement of humidity changes in air.

  13. Simultaneous Scanning Ion Conductance Microscopy and Atomic Force Microscopy with Microchanneled Cantilevers.

    PubMed

    Ossola, Dario; Dorwling-Carter, Livie; Dermutz, Harald; Behr, Pascal; Vörös, János; Zambelli, Tomaso

    2015-12-01

    We combined scanning ion conductance microscopy (SICM) and atomic force microscopy (AFM) into a single tool using AFM cantilevers with an embedded microchannel flowing into the nanosized aperture at the apex of the hollow pyramid. An electrode was positioned in the AFM fluidic circuit connected to a second electrode in the bath. We could thus simultaneously measure the ionic current and the cantilever bending (in optical beam deflection mode). First, we quantitatively compared the SICM and AFM contact points on the approach curves. Second, we estimated where the probe in SICM mode touches the sample during scanning on a calibration grid and applied the finding to image a network of neurites on a Petri dish. Finally, we assessed the feasibility of a double controller using both the ionic current and the deflection as input signals of the piezofeedback. The experimental data were rationalized in the framework of finite elements simulations. PMID:26684144

  14. In Situ Activation of Microcapsules

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

    2000-01-01

    Disclosed are microcapsules comprising a polymer shell enclosing two or more immiscible liquid phases in which a drug, or a prodrug and a drug activator are partitioned into separate phases. or prevented from diffusing out of the microcapsule by a liquid phase in which the drug is poorly soluble. Also disclosed are methods of using the microcapsules for in situ activation of drugs where upon exposure to an appropriate energy source the internal phases mix and the drug is activated in situ.

  15. Understanding interferometry for micro-cantilever displacement detection.

    PubMed

    von Schmidsfeld, Alexander; Nörenberg, Tobias; Temmen, Matthias; Reichling, Michael

    2016-01-01

    Interferometric displacement detection in a cantilever-based non-contact atomic force microscope (NC-AFM) operated in ultra-high vacuum is demonstrated for the Michelson and Fabry-Pérot modes of operation. Each mode is addressed by appropriately adjusting the distance between the fiber end delivering and collecting light and a highly reflective micro-cantilever, both together forming the interferometric cavity. For a precise measurement of the cantilever displacement, the relative positioning of fiber and cantilever is of critical importance. We describe a systematic approach for accurate alignment as well as the implications of deficient fiber-cantilever configurations. In the Fabry-Pérot regime, the displacement noise spectral density strongly decreases with decreasing distance between the fiber-end and the cantilever, yielding a noise floor of 24 fm/Hz(0.5) under optimum conditions. PMID:27547601

  16. Understanding interferometry for micro-cantilever displacement detection

    PubMed Central

    Nörenberg, Tobias; Temmen, Matthias; Reichling, Michael

    2016-01-01

    Summary Interferometric displacement detection in a cantilever-based non-contact atomic force microscope (NC-AFM) operated in ultra-high vacuum is demonstrated for the Michelson and Fabry–Pérot modes of operation. Each mode is addressed by appropriately adjusting the distance between the fiber end delivering and collecting light and a highly reflective micro-cantilever, both together forming the interferometric cavity. For a precise measurement of the cantilever displacement, the relative positioning of fiber and cantilever is of critical importance. We describe a systematic approach for accurate alignment as well as the implications of deficient fiber–cantilever configurations. In the Fabry–Pérot regime, the displacement noise spectral density strongly decreases with decreasing distance between the fiber-end and the cantilever, yielding a noise floor of 24 fm/Hz0.5 under optimum conditions. PMID:27547601

  17. Dynamics of a cantilever beam attached to a moving base

    NASA Astrophysics Data System (ADS)

    Liu, Jinyang; Hong, Jiazhen; Cui, Lin

    2007-12-01

    The previous low-order approximate nonlinear formulations succeeded in capturing the stiffening terms, but failed in simulation of mechanical systems with large deformation due to the neglect of the high-order deformation terms. In this paper, a new hybrid-coordinate formulation is proposed, which is suitable for flexible multibody systems with large deformation. On the basis of exact strain displacement relation, equations of motion for flexible multibody system are derived by using virtual work principle. A matrix separation method is put forward to improve the efficiency of the calculation. Agreement of the present results with those obtained by absolute nodal coordinate formulation (ANCF) verifies the correctness of the proposed formulation. Furthermore, the present results are compared with those obtained by use of the linear model and the low-order approximate nonlinear model to show the suitability of the proposed models.

  18. Imaging using lateral bending modes of atomic force microscope cantilevers

    NASA Astrophysics Data System (ADS)

    Caron, A.; Rabe, U.; Reinstädtler, M.; Turner, J. A.; Arnold, W.

    2004-12-01

    Using scanning probe techniques, surface properties such as shear stiffness and friction can be measured with a resolution in the nanometer range. The torsional deflection or buckling of atomic force microscope cantilevers has previously been used in order to measure the lateral forces acting on the tip. This letter shows that the flexural vibration modes of cantilevers oscillating in their width direction parallel to the sample surface can also be used for imaging. These lateral cantilever modes exhibit vertical deflection amplitudes if the cantilever is asymmetric in thickness direction, e.g., by a trapezoidal cross section.

  19. Antibody-based protein detection using piezoresistive cantilever arrays

    NASA Astrophysics Data System (ADS)

    Dauksaite, Vita; Lorentzen, Martin; Besenbacher, Flemming; Kjems, Jørgen

    2007-03-01

    A piezoresistive cantilever array platform with electrical read-out was applied for protein detection using GST (glutathione-S-transferase) and GST antibodies as a model system. Sensing was performed in the static deflection mode under constant flow conditions. The GST antibodies were directly immobilized on the cantilever gold surface by means of free thiol groups. The setup allowed simultaneous deflection measurements with sensor and control-antibody-immobilized reference cantilevers and enabled detection of 1 ng µl-1 (40 nM) of GST protein, which is similar to the sensitivity reported for cantilever sensors using an optical read-out system.

  20. In situ microbial filter used for bioremediation

    DOEpatents

    Carman, M. Leslie; Taylor, Robert T.

    2000-01-01

    An improved method for in situ microbial filter bioremediation having increasingly operational longevity of an in situ microbial filter emplaced into an aquifer. A method for generating a microbial filter of sufficient catalytic density and thickness, which has increased replenishment interval, improved bacteria attachment and detachment characteristics and the endogenous stability under in situ conditions. A system for in situ field water remediation.

  1. Theoretical investigation of nonlinear resonances in a carbon nanotube cantilever with a tip-mass under electrostatic excitation

    NASA Astrophysics Data System (ADS)

    Kim, I. K.; Lee, S. I.

    2013-09-01

    The nonlinear dynamics of a resonating carbon nanotube (CNT) cantilever having an attached mass at the tip ("tip mass") were investigated by incorporating electrostatic forces and intermolecular interactions between the CNT and a conducting plane surface. This work enables applications of CNT resonating sensors for tiny mass detection and provides a better understanding of the dynamics of CNT cantilevers. The effect of tip mass on a resonating CNT cantilever is normally characterized by the fundamental frequency shift in the linear resonance regime. However, there are more complex dynamics in the nonlinear resonance regime, such as secondary resonances with parametric excitation. The latter have been limited to nano-cantilevers without tip mass or to axially excited micro-beams. To analyze the nonlinear dynamics, we developed a differential equation model that includes both geometric and inertial nonlinear terms for the large vibration amplitudes at increasing drive forces. In our approach, we used Galerkin discretization techniques and numerical integration methods. The CNT cantilever exhibited complex nonlinear responses due to the applied AC and DC voltages and various tip masses. The nonlinear model had a softer response for increasing tip mass than those of the linear model with the same driving conditions. At low applied voltages, the cantilever had linear amplitude and phase responses at primary and secondary superharmonic resonance frequencies. The response branches were softened at the primary resonance through saddle-node (SN) bifurcation from harmonic electrostatic excitation at higher applied voltages. After SN bifurcation, the lower branch of the solution near resonance became unstable. In addition, theoretical analyses were performed on more complex nonlinear responses and stability changes with tip mass variations, such as period-doubling (PD) bifurcation at subharmonic resonance frequencies.

  2. Triplex in-situ hybridization

    DOEpatents

    Fresco, Jacques R.; Johnson, Marion D.

    2002-01-01

    Disclosed are methods for detecting in situ the presence of a target sequence in a substantially double-stranded nucleic acid segment, which comprises: a) contacting in situ under conditions suitable for hybridization a substantially double-stranded nucleic acid segment with a detectable third strand, said third strand being capable of hybridizing to at least a portion of the target sequence to form a triple-stranded structure, if said target sequence is present; and b) detecting whether hybridization between the third strand and the target sequence has occured.

  3. In situ secondary ion mass spectrometry analysis

    SciTech Connect

    Groenewold, G.S.; Applehans, A.D.; Ingram, J.C.; Delmore, J.E.; Dahl, D.A.

    1993-01-01

    The direct detection of tributyl phosphate (TBP) on rocks using molecular beam surface analysis [MBSA or in situ secondary ion mass spectrometry (SIMS)] is demonstrated. Quantities as low as 250 ng were detected on basalt and sandstone with little or no sample preparation. Detection of TBP on soil has proven to be more problematic and requires further study. Ethylenediaminetetraacetic acid (EDTA) is more difficult to detect because it is very reactive with surfaces of interest. Nevertheless, it is possible to detect EDTA if the acidity of the surface is controlled. The detection of EDTA-metal complexes is currently an open question, but evidence is presented for the detection of ions arising from a EDTA-lead complex. Carboxylic acids (i.e., citric, ascorbic, malic, succinic, malonic, and oxalic) give characteristic SIM spectra, but their detection on sample surfaces awaits evaluation.

  4. Cantilever rib grafting in salvage rhinoplasty.

    PubMed

    Shubailat, Ghaith F

    2003-01-01

    Loss of nasal skeletal support, whether congenital, following trauma or secondary to multiple failed surgeries, calls for reconstruction aiming at restoring rigid dorsal stability, maintaining tip projection, and restoring respiratory function. Where septal and conchal grafts are inadequate to be used as building blocks, our procedure of choice has been the cantilever osseocartilagenous rib graft with microscrew fixation. In the past 10 years, 48 patients were candidates for this salvage procedure. Long-term functional and cosmetic results have been highly satisfactory. PMID:15058550

  5. Improved assembly processes for the Quartz Digital Accelerometer cantilever

    SciTech Connect

    Romero, A.M.; Gebert, C.T.

    1990-07-01

    This report covers the development of improved assembly processes for the Quartz Digital Accelerometer cantilever. In this report we discuss improved single-assembly tooling, the development of tooling and processes for precision application of polyimide adhesive, the development of the wafer scale assembly procedure, and the application of eutectic bonding to cantilever assembly. 2 refs., 17 figs.

  6. Use of Cantilever Mechanics for Impacted Teeth: Case Series

    PubMed Central

    Paduano, Sergio; Spagnuolo, Gianrico; Franzese, Gerardo; Pellegrino, Gioacchino; Valletta, Rosa; Cioffi, Iacopo

    2013-01-01

    This paper describes the orthodontic treatment, and the biomechanics of cantilevers for the impaction of permanent teeth in youngs, adolescents, and adults. In these case series, multibracket straightwire fixed appliances, together with cantilever mechanics, were used to treat the impaired occlusion. PMID:24511332

  7. CLOSEUP VIEW OF BOTTOM OF MAIN BRIDGE CANTILEVER THROUGH TRUSS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CLOSE-UP VIEW OF BOTTOM OF MAIN BRIDGE CANTILEVER THROUGH TRUSS SPAN SHOWING CANTILEVERED HIGHWAY FLOOR BRACKET LOOKING NORTHWEST AT PIER “II”. - Huey P. Long Bridge, Spanning Mississippi River approximately midway between nine & twelve mile points upstream from & west of New Orleans, Jefferson, Jefferson Parish, LA

  8. Fiber-optic, cantilever-type acoustic motion velocity hydrophone.

    PubMed

    Cranch, G A; Miller, G A; Kirkendall, C K

    2012-07-01

    The interaction between fluid loaded fiber-optic cantilevers and a low frequency acoustic wave is investigated as the basis for an acoustic vector sensor. The displacements of the prototype cantilevers are measured with an integrated fiber laser strain sensor. A theoretical model predicting the frequency dependent shape of acoustically driven planar and cylindrical fiber-optic cantilevers incorporating effects of fluid viscosity is presented. The model demonstrates good agreement with the measured response of two prototype cantilevers, characterized with a vibrating water column, in the regime of Re ≥ 1. The performance of each cantilever geometry is also analyzed. Factors affecting the sensor performance such as fluid viscosity, laser mode profile, and support motion are considered. The planar cantilever is shown to experience the largest acoustically induced force and hence the highest acoustic responsivity. However, the cylindrical cantilever exhibits the smoothest response in water, due to the influence of viscous fluid damping, and is capable of two axis particle velocity measurement. These cantilevers are shown to be capable of achieving acoustic resolutions approaching the lowest sea-state ocean noise. PMID:22779459

  9. 11. VIEW, LOOKING SOUTHEAST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWARD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. VIEW, LOOKING SOUTHEAST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWARD TOWARD NORTH PORTAL. Note vertical displacement in deck caused by partial collapse at point of connection between south cantilever arm and suspended span. - Smith River Bridge, CA State Highway 199 Spanning Smith River, Crescent City, Del Norte County, CA

  10. Hysteresis of the resonance frequency of magnetostrictive bending cantilevers

    NASA Astrophysics Data System (ADS)

    Löffler, Michael; Kremer, Ramona; Sutor, Alexander; Lerch, Reinhard

    2015-05-01

    Magnetostrictive bending cantilevers are applicable for wirelessly measuring physical quantities such as pressure and strain. Exploiting the ΔE-effect, the resonance frequency of the cantilevers is shifted because of a change in the magnetic biasing field. The biasing field, in turn, depends on the applied pressure or strain, respectively. With a view to the application as a reliable sensor, maximum sensitivity but minimum hysteresis in the biasing field/resonance frequency dependence is preferred. In this contribution, monomorph bending cantilevers fabricated using magnetostrictive Fe49Co49V2 and Metglas 2605SA1 are investigated regarding their applicability for future sensors. For this purpose, the biasing field-dependent polarization of the magnetostrictive materials and bending of the cantilevers are determined. Furthermore, a setup to magnetically bias the cantilevers and determine the bending resonance frequency is presented. Here, the resonance frequency is identified by measuring the impulse response employing a laser Doppler vibrometer. The measurement results reveal that cantilevers made of Fe49Co49V2 possess a distinct hysteretic behaviour at low magnetic biasing field magnitudes. This is ascribed to the polarization and bending hysteresis. Cantilevers fabricated using Metglas 2605SA1 feature a lower resonance frequency shift compared to cantilevers with Fe49Co49V2, which would result in a lower sensitivity of the sensor. However, their resonance frequency hysteresis is almost negligible.

  11. Resonating cantilever mass sensor with mechanical on-plane excitation

    NASA Astrophysics Data System (ADS)

    Teva, Jordi; Abadal, Gabriel; Jordà, Xavier; Borrise, Xavier; Davis, Zachary; Barniol, Nuria

    2003-04-01

    The aim of this paper is to report the experimental setup designed, developed and tested in order to achieve the first vibrating mode of a lateral cantilever with mechanical excitation. The on-plane oscillating cantilever is the basis of a proposed mass sensor with an expected resolution in the atto-gram scale. In a first system design, the cantilever is driven electrostatically by an electrode, which is placed parallel to the cantilever. The cantilever is driven to its first resonant mode applying an AC voltage between the cantilever and a driver. Also, a DC voltage is applied to increase the system response. The signal read-out of the transducer is the capacitive current of the cantilever-driver system. The mass sensor proposed, based on this cantilever-driver structure (CDS), is integrated with a CMOS circuitry in order to minimize the parasitic capacitances, that in this case take special relevance because of the low level output current coming from the transducer. Moreover, the electrostatic excitation introduces a parasitic current that overlaps the current due to the resonance. The mechanical excitation is an alternative excitation method which aim is to eliminate the excitation current. Here we describe the experimental facilities developed to achieve mechanical excitation and report preliminary results obtained by this excitation technique. The results are complemented with dynamic simulations of an equivalent system model that are in accordance with the experimental values.

  12. In situ biofilm coupon device

    DOEpatents

    Peyton, Brent M.; Truex, Michael J.

    1997-01-01

    An apparatus for characterization of in-situ microbial biofilm populations in subsurface groundwater. The device permits biofilm-forming microorganisms to adhere to packing material while emplaced in a groundwater strata, so that the packing material can be later analyzed for quantity and type of microorganisms, growth rate, and nutrient requirements.

  13. In situ biofilm coupon device

    DOEpatents

    Peyton, B.M.; Truex, M.J.

    1997-06-24

    An apparatus is disclosed for characterization of in-situ microbial biofilm populations in subsurface groundwater. The device permits biofilm-forming microorganisms to adhere to packing material while emplaced in a groundwater strata, so that the packing material can be later analyzed for quantity and type of microorganisms, growth rate, and nutrient requirements. 3 figs.

  14. Multi-material bio-fabrication of hydrogel cantilevers and actuators with stereolithography.

    PubMed

    Chan, Vincent; Jeong, Jae Hyun; Bajaj, Piyush; Collens, Mitchell; Saif, Taher; Kong, Hyunjoon; Bashir, Rashid

    2012-01-01

    Cell-based biohybrid actuators are integrated systems that use biological components including proteins and cells to power material components by converting chemical energy to mechanical energy. The latest progress in cell-based biohybrid actuators has been limited to rigid materials, such as silicon and PDMS, ranging in elastic moduli on the order of mega (10(6)) to giga (10(9)) Pascals. Recent reports in the literature have established a correlation between substrate rigidity and its influence on the contractile behavior of cardiomyocytes (A. J. Engler, C. Carag-Krieger, C. P. Johnson, M. Raab, H. Y. Tang and D. W. Speicher, et al., J. Cell Sci., 2008, 121(Pt 22), 3794-3802, P. Bajaj, X. Tang, T. A. Saif and R. Bashir, J. Biomed. Mater. Res., Part A, 2010, 95(4), 1261-1269). This study explores the fabrication of a more compliant cantilever, similar to that of the native myocardium, with elasticity on the order of kilo (10(3)) Pascals. 3D stereolithographic technology, a layer-by-layer UV polymerizable rapid prototyping system, was used to rapidly fabricate multi-material cantilevers composed of poly(ethylene glycol) diacrylate (PEGDA) and acrylic-PEG-collagen (PC) mixtures. The incorporation of acrylic-PEG-collagen into PEGDA-based materials enhanced cell adhesion, spreading, and organization without altering the ability to vary the elastic modulus through the molecular weight of PEGDA. Cardiomyocytes derived from neonatal rats were seeded on the cantilevers, and the resulting stresses and contractile forces were calculated using finite element simulations validated with classical beam equations. These cantilevers can be used as a mechanical sensor to measure the contractile forces of cardiomyocyte cell sheets, and as an early prototype for the design of optimal cell-based biohybrid actuators.

  15. A macroscopic non-destructive testing system based on the cantilever-sample contact resonance

    NASA Astrophysics Data System (ADS)

    Fu, Ji; Lin, Lizhi; Zhou, Xilong; Li, Yingwei; Li, Faxin

    2012-12-01

    Detecting the inside or buried defects in materials and structures is always a challenge in the field of nondestructive testing (NDT). In this paper, enlightened by the operation principle of the contact resonance force microscopy or atomic force acoustic microscopy (AFAM), we proposed a macroscopic NDT system based on contact resonance of the cantilever-sample surface to detect the local stiffness variations in materials or structures. We fabricated a piezoelectric unimorph with the dimension typically of 150 mm × 8 mm × 2 mm to act as a macroscopic cantilever, whose flexural mode vibration was driven by a wideband power amplifier together with a signal generator. The vibration signal of the macroscopic cantilever is detected by a high sensitive strain gauge bonded on the cantilever surface which is much more stable than the laser diode sensor in AFAM, thus making it very suitable for outdoor operations. Scanning is realized by a three-dimensional motorized stage with the Z axis for pressing force setting. The whole system is controlled by a LabVIEW-based homemade software. Like the AFAM, this NDT system can also work in two modes, i.e., the single-frequency mode and the resonance-tracking mode. In the latter mode, the contact stiffness at each pixel of the sample can be obtained by using the measured contact resonance frequency and a beam dynamics model. Testing results of this NDT system on a grid structure with an opaque panel show that in both modes the prefabricated defect beneath the panel can be detected and the grid structures can be clearly "seen," which indicates the validity of this NDT system. The sensitivity of this NDT system was also examined.

  16. Calibration of atomic force microscope cantilevers using piezolevers.

    PubMed

    Aksu, Saltuk B; Turner, Joseph A

    2007-04-01

    The atomic force microscope (AFM) can provide qualitative information by numerous imaging modes, but it can also provide quantitative information when calibrated cantilevers are used. In this article a new technique is demonstrated to calibrate AFM cantilevers using a reference piezolever. Experiments are performed on 13 different commercially available cantilevers. The stiff cantilevers, whose stiffness is more than 0.4 N/m, are compared to the stiffness values measured using nanoindentation. The experimental data collected by the piezolever method is in good agreement with the nanoindentation data. Calibration with a piezolever is fast, easy, and nondestructive and a commercially available AFM is enough to perform the experiments. In addition, the AFM laser must not be calibrated. Calibration is reported here for cantilevers whose stiffness lies between 0.08 and 6.02 N/m.

  17. Serial weighting of micro-objects with resonant microchanneled cantilevers.

    PubMed

    Ossola, Dario; Dörig, Pablo; Vörös, János; Zambelli, Tomaso; Vassalli, Massimo

    2016-10-14

    Atomic force microscopy (AFM) cantilevers have proven to be very effective mass sensors. The attachment of a small mass to a vibrating cantilever produces a resonance frequency shift that can be monitored, providing the ability to measure mass changes down to a few molecules resolution. Nevertheless, the lack of a practical method to handle the catch and release process required for dynamic weighting of microobjects strongly hindered the application of the technology beyond proof of concept measurements. Here, a method is proposed in which FluidFM hollow cantilevers are exploited to overcome the standard limitations of AFM-based mass sensors, providing high throughput single object weighting with picogram accuracy. The extension of the dynamic models of AFM cantilevers to hollow cantilevers was discussed and the effectiveness of mass weighting in air was validated on test samples. PMID:27608651

  18. Serial weighting of micro-objects with resonant microchanneled cantilevers

    NASA Astrophysics Data System (ADS)

    Ossola, Dario; Dörig, Pablo; Vörös, János; Zambelli, Tomaso; Vassalli, Massimo

    2016-10-01

    Atomic force microscopy (AFM) cantilevers have proven to be very effective mass sensors. The attachment of a small mass to a vibrating cantilever produces a resonance frequency shift that can be monitored, providing the ability to measure mass changes down to a few molecules resolution. Nevertheless, the lack of a practical method to handle the catch and release process required for dynamic weighting of microobjects strongly hindered the application of the technology beyond proof of concept measurements. Here, a method is proposed in which FluidFM hollow cantilevers are exploited to overcome the standard limitations of AFM-based mass sensors, providing high throughput single object weighting with picogram accuracy. The extension of the dynamic models of AFM cantilevers to hollow cantilevers was discussed and the effectiveness of mass weighting in air was validated on test samples.

  19. Serial weighting of micro-objects with resonant microchanneled cantilevers.

    PubMed

    Ossola, Dario; Dörig, Pablo; Vörös, János; Zambelli, Tomaso; Vassalli, Massimo

    2016-10-14

    Atomic force microscopy (AFM) cantilevers have proven to be very effective mass sensors. The attachment of a small mass to a vibrating cantilever produces a resonance frequency shift that can be monitored, providing the ability to measure mass changes down to a few molecules resolution. Nevertheless, the lack of a practical method to handle the catch and release process required for dynamic weighting of microobjects strongly hindered the application of the technology beyond proof of concept measurements. Here, a method is proposed in which FluidFM hollow cantilevers are exploited to overcome the standard limitations of AFM-based mass sensors, providing high throughput single object weighting with picogram accuracy. The extension of the dynamic models of AFM cantilevers to hollow cantilevers was discussed and the effectiveness of mass weighting in air was validated on test samples.

  20. Orthodontic Traction of Impacted Canine Using Cantilever

    PubMed Central

    Gonçalves, João Roberto; Cassano, Daniel Serra; Bianchi, Jonas

    2016-01-01

    The impaction of the maxillary canines causes relevant aesthetic and functional problems. The multidisciplinary approach to the proper planning and execution of orthodontic traction of the element in question is essential. Many strategies are cited in the literature; among them is the good biomechanical control in order to avoid possible side effects. The aim of this paper is to present a case report in which a superior canine impacted by palatine was pulled out with the aid of the cantilever on the Segmented Arch Technique (SAT) concept. A 14.7-year-old female patient appeared at clinic complaining about the absence of the upper right permanent canine. The proposed treatment prioritized the traction of the upper right canine without changing the occlusion and aesthetics. For this, it only installed the upper fixed appliance (Roth with slot 0.018), opting for SAT in order to minimize unwanted side effects. The use of cantilever to the traction of the upper right canine has enabled an efficient and predictable outcome, because it is of statically determined mechanics. PMID:27800192

  1. Bandwidth increasing mechanism by introducing a curve fixture to the cantilever generator

    NASA Astrophysics Data System (ADS)

    Liu, Weiqun; Liu, Congzhi; Ren, Bingyu; Zhu, Qiao; Hu, Guangdi; Yang, Weiqing

    2016-07-01

    A nonlinear wideband generator architecture by clamping the cantilever beam generator with a curve fixture is proposed. Devices with different nonlinear stiffness can be obtained by properly choosing the fixture curve according to the design requirements. Three available generator types are presented and discussed for polynomial curves. Experimental investigations show that the proposed mechanism effectively extends the operation bandwidth with good power performance. Especially, the simplicity and easy feasibility allow the mechanism to be widely applied for vibration generators in different scales and environments.

  2. A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans.

    PubMed

    Meier, Tobias; Förste, Alexander; Tavassolizadeh, Ali; Rott, Karsten; Meyners, Dirk; Gröger, Roland; Reiss, Günter; Quandt, Eckhard; Schimmel, Thomas; Hölscher, Hendrik

    2015-01-01

    We describe an atomic force microscope (AFM) for the characterization of self-sensing tunneling magnetoresistive (TMR) cantilevers. Furthermore, we achieve a large scan-range with a nested scanner design of two independent piezo scanners: a small high resolution scanner with a scan range of 5 × 5 × 5 μm(3) is mounted on a large-area scanner with a scan range of 800 × 800 × 35 μm(3). In order to characterize TMR sensors on AFM cantilevers as deflection sensors, the AFM is equipped with a laser beam deflection setup to measure the deflection of the cantilevers independently. The instrument is based on a commercial AFM controller and capable to perform large-area scanning directly without stitching of images. Images obtained on different samples such as calibration standard, optical grating, EPROM chip, self-assembled monolayers and atomic step-edges of gold demonstrate the high stability of the nested scanner design and the performance of self-sensing TMR cantilevers.

  3. A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

    PubMed Central

    Förste, Alexander; Tavassolizadeh, Ali; Rott, Karsten; Meyners, Dirk; Gröger, Roland; Reiss, Günter; Quandt, Eckhard; Schimmel, Thomas; Hölscher, Hendrik

    2015-01-01

    Summary We describe an atomic force microscope (AFM) for the characterization of self-sensing tunneling magnetoresistive (TMR) cantilevers. Furthermore, we achieve a large scan-range with a nested scanner design of two independent piezo scanners: a small high resolution scanner with a scan range of 5 × 5 × 5 μm3 is mounted on a large-area scanner with a scan range of 800 × 800 × 35 μm3. In order to characterize TMR sensors on AFM cantilevers as deflection sensors, the AFM is equipped with a laser beam deflection setup to measure the deflection of the cantilevers independently. The instrument is based on a commercial AFM controller and capable to perform large-area scanning directly without stitching of images. Images obtained on different samples such as calibration standard, optical grating, EPROM chip, self-assembled monolayers and atomic step-edges of gold demonstrate the high stability of the nested scanner design and the performance of self-sensing TMR cantilevers. PMID:25821686

  4. Towards microfluidic reactors for in situ synchrotron infrared studies

    NASA Astrophysics Data System (ADS)

    Silverwood, I. P.; Al-Rifai, N.; Cao, E.; Nelson, D. J.; Chutia, A.; Wells, P. P.; Nolan, S. P.; Frogley, M. D.; Cinque, G.; Gavriilidis, A.; Catlow, C. R. A.

    2016-02-01

    Anodically bonded etched silicon microfluidic devices that allow infrared spectroscopic measurement of solutions are reported. These extend spatially well-resolved in situ infrared measurement to higher temperatures and pressures than previously reported, making them useful for effectively time-resolved measurement of realistic catalytic processes. A data processing technique necessary for the mitigation of interference fringes caused by multiple reflections of the probe beam is also described.

  5. In-situ laser retorting of oil shale

    NASA Technical Reports Server (NTRS)

    Bloomfield, H. S. (Inventor)

    1977-01-01

    Oil shale formations are retorted in situ and gaseous hydrocarbon products are recovered by drilling two or more wells into an oil shale formation underneath the surface of the ground. A high energy laser beam is directed into the well and fractures the region of the shale formation. A compressed gas is forced into the well that supports combustion in the flame front ignited by the laser beam, thereby retorting the oil shale. Gaseous hydrocarbon products which permeate through the fractured region are recovered from one of the wells that were not exposed to the laser system.

  6. In situ vadose zone bioremediation.

    PubMed

    Höhener, Patrick; Ponsin, Violaine

    2014-06-01

    Contamination of the vadose zone with various pollutants is a world-wide problem, and often technical or economic constraints impose remediation without excavation. In situ bioremediation in the vadose zone by bioventing has become a standard remediation technology for light spilled petroleum products. In this review, focus is given on new in situ bioremediation strategies in the vadose zone targeting a variety of other pollutants such as perchlorate, nitrate, uranium, chromium, halogenated solvents, explosives and pesticides. The techniques for biostimulation of either oxidative or reductive degradation pathways are presented, and biotransformations to immobile pollutants are discussed in cases of non-degradable pollutants. Furthermore, research on natural attenuation in the vadose zone is presented.

  7. In situ zymography: topographical considerations.

    PubMed

    Mungall, B A; Pollitt, C C

    2001-02-26

    In situ gelatin zymography is a simple technique providing valuable information about the cellular and tissue localization of gelatinases. Until recently, the use of this technique has been confined to soft, relatively homogeneous tissue. In this report in situ zymography has been utilized to assess the sub-lamellar location of gelatinases in the hard, semi-keratinized epidermal layer and the adjacent soft connective tissue matrix of the dermis of the equine hoof. We show that alterations in the orientation at which the tissue is dipped and withdrawn from the emulsion cause profound alterations in emulsion thickness. Microscopic variations in the surface topography of frozen tissue sections also influence emulsion thickness making interpretation of the results difficult. Given these results, researchers must be aware of potential variations in zymographic analysis may be influenced by physical tissue parameters in addition to suspected gelatinase activity.

  8. Integrated in-situ remediation

    SciTech Connect

    Fustos, V.; Lieberman, P.

    1996-01-01

    This article presents an integrated approach to ex-situ and in-situ remediation. A sequence of processes, used successfully in their own right, but used synergistically in this approach, have achieved short-term, economic remediation. In addition the range of contaminants that can be treated is extended. The Process uses ozone, compressed oxygen, water vapor, heat, bioaugmentation and vapor extraction to remediate lower molecular weight hydrocarbons and higher molecular weight hydrocarbons. 3 figs.

  9. Oldest biliary endoprosthesis in situ

    PubMed Central

    Consolo, Pierluigi; Scalisi, Giuseppe; Crinò, Stefano F; Tortora, Andrea; Giacobbe, Giuseppa; Cintolo, Marcello; Familiari, Luigi; Pallio, Socrate

    2013-01-01

    The advantages of endoscopic retrograde cholangiopancreatography over open surgery have made it the predominant method of treating patients with choledocholithiasis. After sphincterotomy, however, 10%-15% of common bile duct stones cannot be removed with a basket or balloon. The methods for managing “irretrievable stones” include surgery, mechanical lithotripsy, intraductal or extracorporeal shock wave lithotripsy and biliary stenting. The case presented was a referred 82-year-old Caucasian woman with a 7-year-old plastic biliary endoprosthesis in situ. To the best of our knowledge the examined endoprosthesis is the oldest endoprosthesis in situ reported in the literature. Endoscopic biliary endoprosthesis placement remains a simple and safe procedure for patients with stones that are difficult to manage by conventional endoscopic methods and for patients who are unfit for surgery or who are high surgical risks. To date no consensus has been reached regarding how long a biliary prosthesis should remain in situ. Long-term biliary stenting may have a role in selected elderly patients if stones extraction has failed because the procedure may prevent stones impaction and cholangitis. PMID:23858381

  10. Improved in situ spring constant calibration for colloidal probe atomic force microscopy.

    PubMed

    McBride, Sean P; Law, Bruce M

    2010-11-01

    In colloidal probe atomic force microscopy (AFM) surface forces cannot be measured without an accurate determination of the cantilever spring constant. The effective spring constant k depends upon the cantilever geometry and therefore should be measured in situ; additionally, k may be coupled to other measurement parameters. For example, colloidal probe AFM is frequently used to measure the slip length b at solid/liquid boundaries by comparing the measured hydrodynamic force with Vinogradova slip theory (V-theory). However, in this measurement k and b are coupled, hence, b cannot be accurately determined without knowing k to high precision. In this paper, a new in situ spring constant calibration method based upon the residuals, namely, the difference between experimental force-distance data and V-theory is presented and contrasted with two other popular spring constant determination methods. In this residuals calibration method, V-theory is fitted to the experimental force-distance data for a range of systematically varied spring constants where the only adjustable parameter in V-theory is the slip length b. The optimal spring constant k is that value where the residuals are symmetrically displaced about zero for all colloidal probe separations. This residual spring constant calibration method is demonstrated by studying three different liquids (n-decanol, n-hexadecane, and n-octane) and two different silane coated colloidal probe-silicon wafer systems (n-hexadecyltrichlorosilane and n-dodecyltrichlorosilane).

  11. Improved in situ spring constant calibration for colloidal probe atomic force microscopy

    SciTech Connect

    McBride, Sean P.; Law, Bruce M.

    2010-11-15

    In colloidal probe atomic force microscopy (AFM) surface forces cannot be measured without an accurate determination of the cantilever spring constant. The effective spring constant k depends upon the cantilever geometry and therefore should be measured in situ; additionally, k may be coupled to other measurement parameters. For example, colloidal probe AFM is frequently used to measure the slip length b at solid/liquid boundaries by comparing the measured hydrodynamic force with Vinogradova slip theory (V-theory). However, in this measurement k and b are coupled, hence, b cannot be accurately determined without knowing k to high precision. In this paper, a new in situ spring constant calibration method based upon the residuals, namely, the difference between experimental force-distance data and V-theory is presented and contrasted with two other popular spring constant determination methods. In this residuals calibration method, V-theory is fitted to the experimental force-distance data for a range of systematically varied spring constants where the only adjustable parameter in V-theory is the slip length b. The optimal spring constant k is that value where the residuals are symmetrically displaced about zero for all colloidal probe separations. This residual spring constant calibration method is demonstrated by studying three different liquids (n-decanol, n-hexadecane, and n-octane) and two different silane coated colloidal probe-silicon wafer systems (n-hexadecyltrichlorosilane and n-dodecyltrichlorosilane).

  12. Cantilevered multilevel LIGA devices and methods

    DOEpatents

    Morales, Alfredo Martin; Domeier, Linda A.

    2002-01-01

    In the formation of multilevel LIGA microstructures, a preformed sheet of photoresist material, such as polymethylmethacrylate (PMMA) is patterned by exposure through a mask to radiation, such as X-rays, and developed using a developer to remove the exposed photoresist material. A first microstructure is then formed by electroplating metal into the areas from which the photoresist has been removed. Additional levels of microstructure are added to the initial microstructure by covering the first microstructure with a conductive polymer, machining the conductive polymer layer to reveal the surface of the first microstructure, sealing the conductive polymer and surface of the first microstructure with a metal layer, and then forming the second level of structure on top of the first level structure. In such a manner, multiple layers of microstructure can be built up to allow complex cantilevered microstructures to be formed.

  13. Piezoresistive cantilever array sensor for consolidated bioprocess monitoring

    SciTech Connect

    Kim, Seonghwan Sam; Rahman, Touhidur; Senesac, Larry R; Davison, Brian H; Thundat, Thomas George

    2009-01-01

    Cellulolytic microbes occur in diverse natural niches and are being screened for industrial modification and utility. A microbe for Consolidated bioprocessing (CBP) development can rapidly degrade pure cellulose and then ferment the resulting sugars into fuels. To identify and screen for novel microbes for CBP, we have developed a piezoresistive cantilever array sensor which is capable of simultaneous monitoring of glucose and ethanol concentration changes in a phosphate buffer solution. 4-mercaptophenylboronic acid (4-MPBA) and polyethyleneglycol (PEG)-thiol are employed to functionalize each piezoresistive cantilever for glucose and ethanol sensing, respectively. Successful concentration measurements of glucose and ethanol with minimal interferences are obtained with our cantilever array sensor.

  14. Voltage generation of piezoelectric cantilevers by laser heating

    PubMed Central

    Hsieh, Chun-Yi; Liu, Wei-Hung; Chen, Yang-Fang; Shih, Wan Y.; Gao, Xiaotong; Shih, Wei-Heng

    2012-01-01

    Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity. PMID:23258941

  15. Thermo-magnetic behaviour of AFM-MFM cantilevers

    NASA Astrophysics Data System (ADS)

    Kumar, M.; Arinero, R.; Bergez, W.; Tordjeman, Ph

    2015-08-01

    Atomic force microscopy (AFM) experiments were performed to study the behaviour of AFM cantilevers under an external magnetic field B and temperature field produced by a coil with an iron core. Four cantilever types were studied. Forces were measured for different B values and at various coil-to-cantilever separation distances. The results were analysed on the basis of a phenomenological model. This model contains the contribution of two terms, one monopole-monopole interaction at short distance, and one apparent paramagnetic interaction in \

  16. Buckled cantilevers for out-of-plane platforms

    NASA Astrophysics Data System (ADS)

    Johnstone, R. W.; Ma, A. H.; Sameoto, D.; Parameswaran, M.; Leung, A. M.

    2008-04-01

    In this paper, we show how surface-micromachined buckled cantilevers can be used to construct out-of-plane structures. We include the relevant theory necessary to predict the height and angle of plates attached to buckled cantilevers, as well as the mechanical stresses involved in assembly. These platforms can be assembled to any angle between 0° and 90° with respect to the substrate by changing the attachment point and the amount of deflection. Example devices were fabricated using PolyMUMPs™ and assembled. Using these devices, the deflection of the buckled cantilevers was verified, as well as the placement for raised platforms.

  17. Optically Controlled Bimorph Cantilever of Poly(vinylidene difluoride)

    NASA Astrophysics Data System (ADS)

    Mizutani, Yasuhiro; Otani, Yukitoshi; Umeda, Norihiro

    2008-04-01

    Optically driven actuators are a non-contact method for the remote application of light energy. We propose a new optically driven actuator that employs bimorph poly(vinylidene difluoride) (PVDF) cantilevers. PVDF is an effective polymer from which to prepare actuators since it has both pyroelectric and piezoelectric properties. We have produced a bimorph cantilever from a PVDF film with a thin Ag electrode on one side. A bending model of the PVDF cantilever has been established and its bending characteristics have been experimentally measured. The mechanism can be explained by taking into consideration the model and its dielectric breakdown.

  18. Voltage generation of piezoelectric cantilevers by laser heating

    NASA Astrophysics Data System (ADS)

    Hsieh, Chun-Yi; Liu, Wei-Hung; Chen, Yang-Fang; Shih, Wan Y.; Gao, Xiaotong; Shih, Wei-Heng

    2012-11-01

    Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity.

  19. Noise canceling in-situ detection

    SciTech Connect

    Walsh, David O.

    2014-08-26

    Technologies applicable to noise canceling in-situ NMR detection and imaging are disclosed. An example noise canceling in-situ NMR detection apparatus may comprise one or more of a static magnetic field generator, an alternating magnetic field generator, an in-situ NMR detection device, an auxiliary noise detection device, and a computer.

  20. Dynamic performance analysis of a micro cantilever embedded in elastomer

    NASA Astrophysics Data System (ADS)

    Hosono, Minako; Noda, Kentaro; Matsumoto, Kiyoshi; Shimoyama, Isao

    2015-07-01

    This paper reports on the dynamic characteristics of a micro silicon standing cantilever embedded in a silicone elastomer, polydimethylsiloxane (PDMS). This combined structure, which consists of materials with significantly different Young’s moduli, is employed as a tactile sensor for shear-strain measurement. The frequency responses of the tactile sensor show no resonance near the intrinsic resonant frequency of the standing cantilever, whereas the resonant point was observed near the intrinsic resonant frequency of the PDMS covering. In addition, when the oscillation frequency is below the resonant frequency of the tactile sensor, the standing cantilever can follow the oscillating deformation of the PDMS covering with no delay, and the sensitivity of the tactile sensor does not change. The analytical and experimental results show that the PDMS covering has a dominant influence on the dynamic behavior of the embedded cantilever, and the tactile sensor can be applied to both static and oscillating input in the same way.

  1. 57. VIEW WEST, DETAIL OF CANTILEVER SPAN SHOWING OVERHANG FRAMING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    57. VIEW WEST, DETAIL OF CANTILEVER SPAN SHOWING OVERHANG FRAMING AND UNDERSIDE FRAMING - Route 1 Extension, Southbound Viaduct, Spanning Conrail Yards, Wilson Avenue, Delancy Street, & South Street on Routes 1 & 9 Southbound, Newark, Essex County, NJ

  2. 21. DETAIL OF WEST (AMERICAN) CANTILEVER AND ANCHOR ARMS OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. DETAIL OF WEST (AMERICAN) CANTILEVER AND ANCHOR ARMS OF MAIN SPAN, SHOWING PIER M. VIEW TO NORTH. - Blue Water Bridge, Spanning St. Clair River at I-69, I-94, & Canadian Route 402, Port Huron, St. Clair County, MI

  3. 13. VIEW OF CANTILEVERED NORTHERN TRUSS SECTION (LOWER CENTER OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. VIEW OF CANTILEVERED NORTHERN TRUSS SECTION (LOWER CENTER OF PHOTOGRAPH), SHOWING LINKAGES TO THE CENTRAL BRIDGE SUPERSTRUCTURE. FACING NORTHEAST. - Coverts Crossing Bridge, Spanning Mahoning River along Township Route 372 (Covert Road), New Castle, Lawrence County, PA

  4. 19. Cantilevered barn in Cades Cove looking SSW. Great ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. Cantilevered barn in Cades Cove looking SSW. - Great Smoky Mountains National Park Roads & Bridges, Cades Cove Road & Laurel Creek Road, From Townsend Wye to Cades Cove, Gatlinburg, Sevier County, TN

  5. 12. VIEW EAST ALONG DECK CENTERLINE, PRIOR TO CANTILEVERING SIDEWALK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW EAST ALONG DECK CENTERLINE, PRIOR TO CANTILEVERING SIDEWALK ON DOWNSTREAM SIDE File photo, Caltrans Office of Strutures Maintenance, March 1938. Photographer unknown. Photocopy of photograph - San Roque Canyon Bridge, State Highway 192, Santa Barbara, Santa Barbara County, CA

  6. 14. VIEW OF CANTILEVERED SOUTHERN TRUSS SECTION AND WOOD DECK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. VIEW OF CANTILEVERED SOUTHERN TRUSS SECTION AND WOOD DECK FROM THE CENTRAL BRIDGE SUPERSTRUCTURE SHOWN IN PA-474-13. - Coverts Crossing Bridge, Spanning Mahoning River along Township Route 372 (Covert Road), New Castle, Lawrence County, PA

  7. 22. DETAIL OF EAST (CANADIAN) CANTILEVER AND ANCHOR ARMS OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. DETAIL OF EAST (CANADIAN) CANTILEVER AND ANCHOR ARMS OF MAIN SPAN, SHOWING PIER C. VIEW TO NORTH. - Blue Water Bridge, Spanning St. Clair River at I-69, I-94, & Canadian Route 402, Port Huron, St. Clair County, MI

  8. Perspective view of cantilever truss over back channel, looking SW. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view of cantilever truss over back channel, looking SW. - Bessemer & Lake Erie Railroad, Allegheny River Bridge, Spanning Allegheny River, East of Pennsylvania Turnpike (I-76), Oakmont, Allegheny County, PA

  9. 10. VIEW, LOOKING NORTHWEST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWER, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. VIEW, LOOKING NORTHWEST, ALONG CENTERLINE FROM SOUTH CANTILEVER TOWER, BACK TO SOUTH PORTAL. Note emergency bracing and crumpled vertical members. - Smith River Bridge, CA State Highway 199 Spanning Smith River, Crescent City, Del Norte County, CA

  10. Low temperature scanning force microscopy using piezoresistive cantilevers

    NASA Astrophysics Data System (ADS)

    Meiser, P.; Koblischka, M. R.; Hartmann, U.

    2015-08-01

    A low temperature dynamic scanning force microscope has been constructed using commercially available piezoresistive cantilevers that can be coated with a ferromagnetic material for MFM application. The setup is able to work in a temperature range from room temperature down to 1.5 K. The performance of the piezoresistive cantilevers has been investigated under different working conditions. Topographic as well as magnetic images of a magnetite thin film sample have been taken at 50 and 4.2 K confirming the proper operation of the microscope at cryogenic temperatures. Furthermore, force-distance-curves taken on thin lead films at 4.2 K demonstrate the levitation forces between the magnetized cantilever tip and the superconducting films. Flux lines were generated by the magnetized cantilever tip itself when approaching the sample. It has also been shown that the microscope is sensitive to the detection of single magnetic flux lines penetrating the lead films.

  11. 12. VIEW, LOOKING NORTHWEST, ALONG CENTERLINE FROM NORTH CANTILEVER TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW, LOOKING NORTHWEST, ALONG CENTERLINE FROM NORTH CANTILEVER TOWER TOWARD SOUTH PORTAL. As with previous photo, note vertical displacement in deck. - Smith River Bridge, CA State Highway 199 Spanning Smith River, Crescent City, Del Norte County, CA

  12. 7. Detail of sidewalk cantilevers and walkway between viaduct and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Detail of sidewalk cantilevers and walkway between viaduct and livestock exchange building. View to southwest. - South Omaha Union Stock Yards, Buckingham Road Viaduct, Twenty-ninth Street spanning Stockyard Cattle Pens, Omaha, Douglas County, NE

  13. DETAIL OF CANTILEVERED MEZZANINE OBSERVATION ROOM ON SOUTH WEST CORNER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF CANTILEVERED MEZZANINE OBSERVATION ROOM ON SOUTH- WEST CORNER OF BUILDING. VIEW TO NORTHEAST. - Plattsburgh Air Force Base, Base Engineer Pavement & Grounds Facility, Off Colorado Street, Plattsburgh, Clinton County, NY

  14. 23. OBLIQUE VIEW OF SOUTH SIDE OF COOPER RIVER CANTILEVER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. OBLIQUE VIEW OF SOUTH SIDE OF COOPER RIVER CANTILEVER SPAN FROM CHANNEL BELOW BRIDGE, FACING NORTHEAST - Grace Memorial Bridge, U.S. Highway 17 spanning Cooper River & Town Creek , Charleston, Charleston County, SC

  15. 31. OBLIQUE VIEW OF SOUTH SIDE OF COOPER RIVER CANTILEVER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    31. OBLIQUE VIEW OF SOUTH SIDE OF COOPER RIVER CANTILEVER SPAN FROM WATER, PEARMAN BRIDGE ON LEFT, FACING WEST TOWARDS DRUM ISLAND - Grace Memorial Bridge, U.S. Highway 17 spanning Cooper River & Town Creek , Charleston, Charleston County, SC

  16. 30. SOUTH SIDE OF COOPER RIVER CANTILEVER SPAN FROM WATER, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. SOUTH SIDE OF COOPER RIVER CANTILEVER SPAN FROM WATER, FACING WEST TOWARDS DRUM ISLAND - Grace Memorial Bridge, U.S. Highway 17 spanning Cooper River & Town Creek , Charleston, Charleston County, SC

  17. Composite with In Situ Plenums

    NASA Technical Reports Server (NTRS)

    Montesano, Mark

    2012-01-01

    A document describes a high-performance thermal distribution panel (TDP) concept using high-conductivity (greater than 800 W/mK) macro composite skin with in situ heat pipes. The processing technologies proposed to build such a panel result in a one-piece, inseparable assembly with high conductance in both the X and Y planes. The TDP configuration can also be used to produce panels with high structural stiffness. The one-piece construction of the TDP eliminates the thermal interface between the cooling plenums and the heat spreader base, and obviates the need for bulky mounting flanges and thick heat spreaders used on baseline designs. The conductivity of the TDP can be configured to exceed 800 W/mK with a mass density below 2.5 grams per cubic centimeter. This material can provide efficient conductive heat transfer between the in situ heat plenums, permitting the use of thinner panel thicknesses. The plenums may be used as heat pipes, loop heat pipes, or liquid cooling channels. The panel technology used in the TDP is a macro-composite comprised of aluminum-encapsulated annealed pyrolytic graphite (APG). APG is highly aligned crystalline graphite with an in-plane thermal conductivity of 1,700 W/mK. APG has low shear strength and does not constrain the encapsulating material. The proposed concept has no thermal interfaces between the heat pipes and the spreader plate, further improving the overall conductance of the system. The in situ plenums can also be used for liquid cooling applications. The process can be used to fabricate structural panels by adding a second thin sheet.

  18. Interaction of the carbon monoxide-releasing molecule Ru(CO)3Cl(glycinate) (CORM-3) with Salmonella enterica serovar Typhimurium: in situ measurements of carbon monoxide binding by integrating cavity dual-beam spectrophotometry.

    PubMed

    Rana, Namrata; McLean, Samantha; Mann, Brian E; Poole, Robert K

    2014-12-01

    Carbon monoxide (CO) is a toxic gas that binds to haems, but also plays critical signalling and cytoprotective roles in mammalian systems; despite problems associated with systemic delivery by inhalation of the gas, it may be employed therapeutically. CO delivered to cells and tissues by CO-releasing molecules (CO-RMs) has beneficial and toxic effects not mimicked by CO gas; CO-RMs are also attractive candidates as novel antimicrobial agents. Salmonella enterica serovar Typhimurium is an enteropathogen causing gastroenteritis in humans. Recent studies have implicated haem oxygenase-1 (HO-1), the protein that catalyses the degradation of haem into biliverdin, free iron and CO, in the host immune response to Salmonella infection. In several studies, CO administration via CO-RMs elicited many of the protective roles of HO-1 induction and so we investigated the effects of a well-characterized water-soluble CO-RM, Ru(CO)3Cl(glycinate) (CORM-3), on Salmonella. CORM-3 exhibits toxic effects at concentrations significantly lower than those reported to cause toxicity to RAW 264.7 macrophages. We demonstrated here, through oxyhaemoglobin assays, that CORM-3 did not release CO spontaneously in phosphate buffer, buffered minimal medium or very rich medium. CORM-3 was, however, accumulated to high levels intracellularly (as shown by inductively coupled plasma MS) and released CO inside cells. Using growing Salmonella cultures without prior concentration, we showed for the first time that sensitive dual-beam integrating cavity absorption spectrophotometry can detect directly the CO released from CORM-3 binding in real-time to haems of the bacterial electron transport chain. The toxic effects of CO-RMs suggested potential applications as adjuvants to antibiotics in antimicrobial therapy. PMID:25085864

  19. Interaction of the carbon monoxide-releasing molecule Ru(CO)3Cl(glycinate) (CORM-3) with Salmonella enterica serovar Typhimurium: in situ measurements of carbon monoxide binding by integrating cavity dual-beam spectrophotometry.

    PubMed

    Rana, Namrata; McLean, Samantha; Mann, Brian E; Poole, Robert K

    2014-12-01

    Carbon monoxide (CO) is a toxic gas that binds to haems, but also plays critical signalling and cytoprotective roles in mammalian systems; despite problems associated with systemic delivery by inhalation of the gas, it may be employed therapeutically. CO delivered to cells and tissues by CO-releasing molecules (CO-RMs) has beneficial and toxic effects not mimicked by CO gas; CO-RMs are also attractive candidates as novel antimicrobial agents. Salmonella enterica serovar Typhimurium is an enteropathogen causing gastroenteritis in humans. Recent studies have implicated haem oxygenase-1 (HO-1), the protein that catalyses the degradation of haem into biliverdin, free iron and CO, in the host immune response to Salmonella infection. In several studies, CO administration via CO-RMs elicited many of the protective roles of HO-1 induction and so we investigated the effects of a well-characterized water-soluble CO-RM, Ru(CO)3Cl(glycinate) (CORM-3), on Salmonella. CORM-3 exhibits toxic effects at concentrations significantly lower than those reported to cause toxicity to RAW 264.7 macrophages. We demonstrated here, through oxyhaemoglobin assays, that CORM-3 did not release CO spontaneously in phosphate buffer, buffered minimal medium or very rich medium. CORM-3 was, however, accumulated to high levels intracellularly (as shown by inductively coupled plasma MS) and released CO inside cells. Using growing Salmonella cultures without prior concentration, we showed for the first time that sensitive dual-beam integrating cavity absorption spectrophotometry can detect directly the CO released from CORM-3 binding in real-time to haems of the bacterial electron transport chain. The toxic effects of CO-RMs suggested potential applications as adjuvants to antibiotics in antimicrobial therapy.

  20. In Situ Mosaic Brightness Correction

    NASA Technical Reports Server (NTRS)

    Deen, Robert G.; Lorre, Jean J.

    2012-01-01

    In situ missions typically have pointable, mast-mounted cameras, which are capable of taking panoramic mosaics comprised of many individual frames. These frames are mosaicked together. While the mosaic software applies radiometric correction to the images, in many cases brightness/contrast seams still exist between frames. This is largely due to errors in the radiometric correction, and the absence of correction for photometric effects in the mosaic processing chain. The software analyzes the overlaps between adjacent frames in the mosaic and determines correction factors for each image in an attempt to reduce or eliminate these brightness seams.

  1. In situ electron energy-loss spectroscopy in liquids.

    PubMed

    Holtz, Megan E; Yu, Yingchao; Gao, Jie; Abruña, Héctor D; Muller, David A

    2013-08-01

    In situ scanning transmission electron microscopy (STEM) through liquids is a promising approach for exploring biological and materials processes. However, options for in situ chemical identification are limited: X-ray analysis is precluded because the liquid cell holder shadows the detector and electron energy-loss spectroscopy (EELS) is degraded by multiple scattering events in thick layers. Here, we explore the limits of EELS in the study of chemical reactions in their native environments in real time and on the nanometer scale. The determination of the local electron density, optical gap, and thickness of the liquid layer by valence EELS is demonstrated. By comparing theoretical and experimental plasmon energies, we find that liquids appear to follow the free-electron model that has been previously established for solids. Signals at energies below the optical gap and plasmon energy of the liquid provide a high signal-to-background ratio regime as demonstrated for LiFePO4 in an aqueous solution. The potential for the use of valence EELS to understand in situ STEM reactions is demonstrated for beam-induced deposition of metallic copper: as copper clusters grow, EELS develops low-loss peaks corresponding to metallic copper. From these techniques, in situ imaging and valence EELS offer insights into the local electronic structure of nanoparticles and chemical reactions. PMID:23721691

  2. Approximate study of the free vibrations of a cantilever anisotropic plate carrying a concentrated mass

    NASA Astrophysics Data System (ADS)

    Ciancio, P. M.; Rossit, C. A.; Laura, P. A. A.

    2007-05-01

    This study is concerned with the vibration analysis of a cantilevered rectangular anisotropic plate when a concentrated mass is rigidly attached to its center point. Based on the classical theory of anisotropic plates, the Ritz method is employed to perform the analysis. The deflection of the plate is approximated by a set of beam functions in each principal coordinate direction. The influence of the mass magnitude on the natural frequencies and modal shapes of vibration is studied for a boron-epoxy plate and also in the case of a generic anisotropic material. The classical Ritz method with beam functions as the spatial approximation proved to be a suitable procedure to solve a problem of this analytical complexity.

  3. Finite amplitude vibrations of cantilevers of rectangular cross sections in viscous fluids

    NASA Astrophysics Data System (ADS)

    Phan, Catherine N.; Aureli, Matteo; Porfiri, Maurizio

    2013-07-01

    In this paper, we study finite amplitude vibrations of a cantilever beam of rectangular cross section immersed in a viscous fluid under harmonic base excitation. Fluid-structure interactions are modeled through a complex hydrodynamic function that describes added mass and damping effects in response to moderately large oscillation amplitudes. The hydrodynamic function is identified from the analysis of the two-dimensional flow physics generated by a rigid rectangle undergoing harmonic oscillations in a quiescent fluid. Computational fluid dynamics is used to investigate the effects of three salient non-dimensional parameters on the flow physics and inform the formulation of a tractable expression for the hydrodynamic function. Theoretical results are validated against experimental findings on underwater vibration of compliant beams of varying cross sections.

  4. Measurement of Mechanical Properties of Cantilever Shaped Materials

    PubMed Central

    Finot, Eric; Passian, Ali; Thundat, Thomas

    2008-01-01

    Microcantilevers were first introduced as imaging probes in Atomic Force Microscopy (AFM) due to their extremely high sensitivity in measuring surface forces. The versatility of these probes, however, allows the sensing and measurement of a host of mechanical properties of various materials. Sensor parameters such as resonance frequency, quality factor, amplitude of vibration and bending due to a differential stress can all be simultaneously determined for a cantilever. When measuring the mechanical properties of materials, identifying and discerning the most influential parameters responsible for the observed changes in the cantilever response are important. We will, therefore, discuss the effects of various force fields such as those induced by mass loading, residual stress, internal friction of the material, and other changes in the mechanical properties of the microcantilevers. Methods to measure variations in temperature, pressure, or molecular adsorption of water molecules are also discussed. Often these effects occur simultaneously, increasing the number of parameters that need to be concurrently measured to ensure the reliability of the sensors. We therefore systematically investigate the geometric and environmental effects on cantilever measurements including the chemical nature of the underlying interactions. To address the geometric effects we have considered cantilevers with a rectangular or circular cross section. The chemical nature is addressed by using cantilevers fabricated with metals and/or dielectrics. Selective chemical etching, swelling or changes in Young's modulus of the surface were investigated by means of polymeric and inorganic coatings. Finally to address the effect of the environment in which the cantilever operates, the Knudsen number was determined to characterize the molecule-cantilever collisions. Also bimaterial cantilevers with high thermal sensitivity were used to discern the effect of temperature variations. When appropriate

  5. In situ exposimetry: the ovarian ultrasound examination.

    PubMed

    Siddiqi, T A; O'Brien, W D; Meyer, R A; Sullivan, J M; Miodovnik, M

    1991-01-01

    We have constructed a specialized in vivo exposimetry system and developed and tested customized software using specially fabricated hydrophones. We placed the hydrophones in the lateral vaginal fornix as close to the ovary as possible (usually 1-2 cm from the ovary) and determined selected first-order and second-order ultrasonic field quantities during a routine ultrasound examination of the ovary. Our sonographic measurements yielded mean ultrasound beam path distances of 7.6 cm. (n = 18) in the presence of a distended bladder and 7.0 cm. (n = 25) in the presence of an empty bladder with an average group insertion loss of 6.2 dB and 7.3 dB, respectively. Using a Fixed Attenuation Model, the tissue attenuation coefficient value was 2.98 dB/MHz; whereas for the Overlying Tissue Model the value was 0.72 dB/cm-MHz. These data are both specific and unique in that they have been systematically obtained in situ.

  6. Dynamic response of cantilever retaining walls

    SciTech Connect

    Veletsos, A.S.; Younan, A.H.; Bandyopadhyay, K.

    1996-10-01

    A critical evaluation is made of the response to horizontal ground shaking of flexible cantilever retaining walls that are elastically constrained against rotation at their base. The retained medium is idealized as a uniform, linear, viscoelastic stratum of constant thickness and semi-infinite extent in the horizontal direction. The parameters varied include the flexibilities of the wall and its base, the properties of the retained medium, and the characteristics of the ground motion. In addition to long-period, effectively static excitations, both harmonic base motions and an actual earthquake record are considered. The response quantities examined include the displacements of the wall relative to the moving base, the wall pressures, and the associated shears and bending moments. The method of analysis employed is described only briefly, emphasis being placed on the presentation and interpretation of the comprehensive numerical solutions. It is shown that, for realistic wall flexibilities, the maximum wall forces are significantly lower than those obtained for fixed-based rigid walls and potentially of the same order of magnitude as those computed by the Mononobe-Okabe method.

  7. Piezoresistive cantilever force-clamp system

    NASA Astrophysics Data System (ADS)

    Park, Sung-Jin; Petzold, Bryan C.; Goodman, Miriam B.; Pruitt, Beth L.

    2011-04-01

    We present a microelectromechanical device-based tool, namely, a force-clamp system that sets or "clamps" the scaled force and can apply designed loading profiles (e.g., constant, sinusoidal) of a desired magnitude. The system implements a piezoresistive cantilever as a force sensor and the built-in capacitive sensor of a piezoelectric actuator as a displacement sensor, such that sample indentation depth can be directly calculated from the force and displacement signals. A programmable real-time controller operating at 100 kHz feedback calculates the driving voltage of the actuator. The system has two distinct modes: a force-clamp mode that controls the force applied to a sample and a displacement-clamp mode that controls the moving distance of the actuator. We demonstrate that the system has a large dynamic range (sub-nN up to tens of μN force and nm up to tens of μm displacement) in both air and water, and excellent dynamic response (fast response time, <2 ms and large bandwidth, 1 Hz up to 1 kHz). In addition, the system has been specifically designed to be integrated with other instruments such as a microscope with patch-clamp electronics. We demonstrate the capabilities of the system by using it to calibrate the stiffness and sensitivity of an electrostatic actuator and to measure the mechanics of a living, freely moving Caenorhabditis elegans nematode.

  8. Piezoresistive cantilever force-clamp system

    SciTech Connect

    Park, Sung-Jin; Petzold, Bryan C.; Pruitt, Beth L.; Goodman, Miriam B.

    2011-04-15

    We present a microelectromechanical device-based tool, namely, a force-clamp system that sets or ''clamps'' the scaled force and can apply designed loading profiles (e.g., constant, sinusoidal) of a desired magnitude. The system implements a piezoresistive cantilever as a force sensor and the built-in capacitive sensor of a piezoelectric actuator as a displacement sensor, such that sample indentation depth can be directly calculated from the force and displacement signals. A programmable real-time controller operating at 100 kHz feedback calculates the driving voltage of the actuator. The system has two distinct modes: a force-clamp mode that controls the force applied to a sample and a displacement-clamp mode that controls the moving distance of the actuator. We demonstrate that the system has a large dynamic range (sub-nN up to tens of {mu}N force and nm up to tens of {mu}m displacement) in both air and water, and excellent dynamic response (fast response time, <2 ms and large bandwidth, 1 Hz up to 1 kHz). In addition, the system has been specifically designed to be integrated with other instruments such as a microscope with patch-clamp electronics. We demonstrate the capabilities of the system by using it to calibrate the stiffness and sensitivity of an electrostatic actuator and to measure the mechanics of a living, freely moving Caenorhabditis elegans nematode.

  9. An elastography method based on the scanning contact resonance of a piezoelectric cantilever

    SciTech Connect

    Fu, Ji; Li, Faxin

    2013-12-15

    Purpose: Most tissues may become significantly stiffer than their normal states when there are lesions inside. The tissue's modulus can then act as an identification parameter for clinic diagnosis of tumors or fibrosis, which leads to elastography. This study introduces a novel elastography method that can be used for modulus imaging of superficial organs. Methods: This method is based on the scanning contact-resonance of a unimorph piezoelectric cantilever. The cantilever vibrates in its bending mode with the tip pressed tightly on the sample. The contact resonance frequency of the cantilever-sample system is tracked at each scanning point, from which the sample's modulus can be derived based on a beam dynamic model and a contact mechanics model. Scanning is performed by a three-dimensional motorized stage and the whole system is controlled by a homemade software program based on LabVIEW. Results: Testing onin vitro beef tissues indicates that the fat and the muscle can be easily distinguished using this system, and the accuracy of the modulus measurement can be comparable with that of nanoindentation. Imaging on homemade gelatin phantoms shows that the depth information of the abnormalities can be qualitatively obtained by varying the pressing force. The detection limit of this elastography method is specially examined both experimentally and numerically. Results show that it can detect the typical lesions in superficial organs with the depth of several centimeters. The lateral resolution of this elastography method/system is better than 0.5 mm, and could be further enhanced by using more scanning points. Conclusions: The proposed elastography system can be regarded as a sensitive palpation robot, which may be very promising in early diagnosis of tumors in superficial organs such as breast and thyroid.

  10. In-situ measurement system

    DOEpatents

    Lord, David E.

    1983-01-01

    A multipurpose in situ underground measurement system comprising a plurality of long electrical resistance elements in the form of rigid reinforcing bars, each having an open loop "hairpin" configuration of shorter length than the other resistance elements. The resistance elements are arranged in pairs in a unitized structure, and grouted in place in the underground volume. The electrical resistance of each element and the difference in electrical resistance of the paired elements are obtained, which difference values may be used in analytical methods involving resistance as a function of temperature. A scanner sequentially connects the resistance-measuring apparatus to each individual pair of elements. A source of heating current is also selectively connectable for heating the elements to an initial predetermined temperature prior to electrical resistance measurements when used as an anemometer.

  11. Unintended and in situ amorphisation of pharmaceuticals.

    PubMed

    Priemel, P A; Grohganz, H; Rades, T

    2016-05-01

    Amorphisation of poorly water-soluble drugs is one approach that can be applied to improve their solubility and thus their bioavailability. Amorphisation is a process that usually requires deliberate external energy input. However, amorphisation can happen both unintentionally, as in process-induced amorphisation during manufacturing, or in situ during dissolution, vaporisation, or lipolysis. The systems in which unintended and in situ amorphisation has been observed normally contain a drug and a carrier. Common carriers include polymers and mesoporous silica particles. However, the precise mechanisms by which in situ amorphisation occurs are often not fully understood. In situ amorphisation can be exploited and performed before administration of the drug or possibly even within the gastrointestinal tract, as can be inferred from in situ amorphisation observed during in vitro lipolysis. The use of in situ amorphisation can thus confer the advantages of the amorphous form, such as higher apparent solubility and faster dissolution rate, without the disadvantage of its physical instability. PMID:26724250

  12. In-situ observation of xenon nanocrystals in aluminum under electron and ion irradiation in transmission electron microscope.

    SciTech Connect

    Furuya, K.

    1998-11-11

    In-situ ion irradiation in the transmission electron microscope (TEM) is one of the unique techniques to investigate the structural evolution of materials induced by particle bombardments. In spite of many efforts to get clear results from in-situ ion irradiation, the results were sometimes unclear because of physical and technical problems associated with TEM and ion beam hardwares. This paper describes a newly developed ion beam interface with an ultra-high voltage TEM (HVTEM) for in-situ observation of ion implantation of metals and alloys in atomic scale.

  13. Amplification of chromosomal DNA in situ

    DOEpatents

    Christian, Allen T.; Coleman, Matthew A.; Tucker, James D.

    2002-01-01

    Amplification of chromosomal DNA in situ to increase the amount of DNA associated with a chromosome or chromosome region is described. The amplification of chromosomal DNA in situ provides for the synthesis of Fluorescence in situ Hybridization (FISH) painting probes from single dissected chromosome fragments, the production of cDNA libraries from low copy mRNAs and improved in Comparative Genomic Hybridization (CGH) procedures.

  14. SiC-Based Miniature High-Temperature Cantilever Anemometer

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S.; Fralick, Gustave; Saad, George J.

    2004-01-01

    The figure depicts a miniature cantilever-type anemometer that has been developed as a prototype of compact, relatively nonintrusive anemometers that can function at temperatures up to 600 C and that can be expected to be commercially mass-producible at low cost. The design of this anemometer, and especially the packaging aspect of the design, is intended to enable measurement of turbulence in the high-temperature, high-vibration environment of a turbine engine or in any similar environment. The main structural components of the anemometer include a single-crystal SiC cantilever and two polycrystalline SiC clamping plates, all made from chemical-vapor-deposited silicon carbide. Fabrication of these components from the same basic material eliminates thermal-expansion mismatch, which has introduced spurious thermomechanical stresses in cantilever-type anemometers of prior design. The clamping plates are heavily oxidized to improve electrical insulation at high temperature. A cavity that serves as a receptacle for the clamped end of the cantilever is etched into one end of one clamping plate. Trenches that collectively constitute a socket for a multipin electrical plug (for connection to external electronic circuitry) are etched into the opposite end of this clamping plate. Metal strips for electrical contact are deposited on one face of the other clamping plate. Piezoresistive single-crystal SiC thin-film strain gauges are etched in the n-type SiC epilayer in a Wheatstone-bridge configuration. Metal contact pads on the cantilever that extend into the clamping-receptacle area, are obtained by deposition and patterning using standard semiconductor photolithography and etching methods. The cantilever and the two clamping plates are assembled into a sandwich structure that is then clamped in a stainless-steel housing. The Wheatstone- bridge carrying SiC cantilever with the metal contact pads on the piezoresistors is slid into the receptacle in the bottom clamping plate

  15. Planar dynamics of a uniform beam with rigid bodies affixed to the ends

    NASA Technical Reports Server (NTRS)

    Storch, J.; Gates, S.

    1983-01-01

    The planar dynamics of a uniform elastic beam subject to a variety of geometric and natural boundary conditions and external excitations were analyzed. The beams are inextensible and capable of small transverse bending deformations only. Classical beam vibration eigenvalue problems for a cantilever with tip mass, a cantilever with tip body and an unconstrained beam with rigid bodies at each are examined. The characteristic equations, eigenfunctions and orthogonality relations for each are derived. The forced vibration of a cantilever with tip body subject to base acceleration is analyzed. The exact solution of the governing nonhomogeneous partial differential equation with time dependent boundary conditions is presented and compared with a Rayleigh-Ritz approximate solution. The arbitrary planar motion of an elastic beam with rigid bodies at the ends is addressed. Equations of motion are derived for two modal expansions of the beam deflection. The motion equations are cast in a first order form suitable for numerical integration. Selected FORTRAN programs are provided.

  16. Cantilever with immobilized antibody for liver cancer biomarker detection

    NASA Astrophysics Data System (ADS)

    Shuaipeng, Wang; Jingjing, Wang; Yinfang, Zhu; Jinling, Yang; Fuhua, Yang

    2014-10-01

    A novel cantilever array-based bio-sensor was batch-fabricated with IC compatible MEMS technology for precise liver cancer bio-marker detection. A micro-cavity was designed in the free end of the cantilever for local antibody-immobilization, thus the adsorption of the cancer biomarker takes place only in the local region of the cantilever instead of the whole lever, and the effect of adsorption-induced k variation can be dramatically reduced. These structural features offer several advantages: high sensitivity, high throughput, high mass detection accuracy, and a portable system. In addition, an analytical model has been established to eliminate the effect of the adsorption-induced lever stiffness change and has been applied to the precise mass detection of the cancer biomarker AFP; the experimentally detected AFP antigen mass by the sensor (7.6 pg/mL) is quite close to the calculated one (5.5 pg/mL), two orders of magnitude better than those of the fully antibody-immobilized cantilever sensor. These approaches can promote real applications of the cantilever sensors in cancer diagnosis.

  17. Vertical electrostatic force in MEMS cantilever IR sensor

    NASA Astrophysics Data System (ADS)

    Rezadad, Imen; Boroumand Azad, Javaneh; Smith, Evan M.; Alhasan, Ammar; Peale, Robert E.

    2014-06-01

    A MEMS cantilever IR detector that repetitively lifts from the surface under the influence of a saw-tooth electrostatic force, where the contact duty cycle is a measure of the absorbed IR radiation, is analyzed. The design is comprised of three parallel conducting plates. Fixed buried and surface plates are held at opposite potential. A moveable cantilever is biased the same as the surface plate. Calculations based on energy methods with position-dependent capacity and electrostatic induction coefficients demonstrate the upward sign of the force on the cantilever and determine the force magnitude. 2D finite element method calculations of the local fields confirm the sign of the force and determine its distribution across the cantilever. The upward force is maximized when the surface plate is slightly larger than the other two. The electrostatic repulsion is compared with Casimir sticking force to determine the maximum useful contact area. MEMS devices were fabricated and the vertical displacement of the cantilever was observed in a number of experiments. The approach may be applied also to MEMS actuators and micromirrors.

  18. Bimodal frequency-modulated atomic force microscopy with small cantilevers.

    PubMed

    Dietz, Christian; Schulze, Marcus; Voss, Agnieszka; Riesch, Christian; Stark, Robert W

    2015-02-01

    Small cantilevers with ultra-high resonant frequencies (1-3 MHz) have paved the way for high-speed atomic force microscopy. However, their potential for multi-frequency atomic force microscopy is unexplored. Because small cantilevers have small spring constants but large resonant frequencies, they are well-suited for the characterisation of delicate specimens with high imaging rates. We demonstrate their imaging capabilities in a bimodal frequency modulation mode in constant excitation on semi-crystalline polypropylene. The first two flexural modes of the cantilever were simultaneously excited. The detected frequency shift of the first eigenmode was held constant for topographical feedback, whereas the second eigenmode frequency shift was used to map the local properties of the specimen. High-resolution images were acquired depicting crystalline lamellae of approximately 12 nm in width. Additionally, dynamic force curves revealed that the contrast originated from different interaction forces between the tip and the distinct polymer regions. The technique uses gentle forces during scanning and quantified the elastic moduli Eam = 300 MPa and Ecr = 600 MPa on amorphous and crystalline regions, respectively. Thus, multimode measurements with small cantilevers allow one to map material properties on the nanoscale at high resolutions and increase the force sensitivity compared with standard cantilevers.

  19. Defect reduction in gallium nitride using cantilever epitaxy.

    SciTech Connect

    Mitchell, Christine Charlotte

    2003-08-01

    Cantilever epitaxy (CE) has been developed to produce GaN on sapphire with low dislocation densities as needed for improved devices. The basic mechanism of seeding growth on sapphire mesas and lateral growth of cantilevers until they coalesce has been modified with an initial growth step at 950 C. This step produces a gable with (11{bar 2}2) facets over the mesas, which turns threading dislocations from vertical to horizontal in order to reduce the local density above mesas. This technique has produced material with densities as low as 2-3x10{sup 7}/cm{sup 2} averaged across extended areas of GaN on sapphire, as determined with AFM, TEM and cathodoluminescence (CL). This density is about two orders of magnitude below that of conventional planar growths; these improvements suggest that locating wide-area devices across both cantilever and mesa regions is possible. However, the first implementation of this technique also produced a new defect: cracks at cantilever coalescences with associated arrays of lateral dislocations. These defects have been labeled 'dark-block defects' because they are non-radiative and appear as dark rectangles in CL images. Material has been grown that does not have dark-block defects. Examination of the evolution of the cantilever films for many growths, both partial and complete, indicates that producing a film without these defects requires careful control of growth conditions and crystal morphology at multiple steps. Their elimination enhances optical emission and uniformity over large (mm) size areas.

  20. Mechanical properties of graphene cantilever from atomic force microscopy and density functional theory.

    PubMed

    Rasuli, R; Iraji Zad, A; Ahadian, M M

    2010-05-01

    We have studied the mechanical properties of a few-layer graphene cantilever (FLGC) using atomic force microscopy (AFM). The mechanical properties of the suspended FLGC over an open hole have been derived from the AFM data. Force displacement curves using the Derjaguin-Müller-Toporov (DMT) and the massless cantilever beam models yield a Young modulus of E(c) approximately 37, E(a) approximately 0.7 TPa and a Hamakar constant of approximately 3 x 10( - 18) J. The threshold force to shear the FLGC was determined from a breaking force and modeling. In addition, we studied a graphene nanoribbon (GNR), which is a system similar to the FLGC; using density functional theory (DFT). The in-plane Young's modulus for the GNRs were calculated from the DFT outcomes approximately 0.82 TPa and the results were compared with the experiment. We found that the Young's modulus and the threshold shearing force are dependent on the direction of applied force and the values are different for zigzag edge and armchair edge GNRs.