Visual force sensing with flexible nanowire buckling springs

Dobrokhotov, Vladimir; Yazdanpanah, Masoud; Pabba, Santosh; Safir, Abdelilah; Cohn, Robert W.

doi:10.1088/0957-4484/19/03/035502

Cited by 25 publications

(25 citation statements)

References 21 publications

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“…Besides the bending behaviors of nanowires, during practical applications, for example, in nanodevices or nanoelectromechanical systems (NEMs), it is unavoidable for nanowires to sustain an axial compressive load, which, as a result, would induce buckling of nanowires [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

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Buckling behavior of nanowires predicted by a new surface energy density model

Yao

Chen

2016

Acta Mech

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The axial buckling behavior of nanowires is investigated with a new continuum theory, in which the surface effect of nanomaterials is characterized by the surface energy density. Only the surface energy density of bulk materials and the surface relaxation parameter are involved, instead of the surface elastic constants in the classical surface elasticity theory. Two kinds of nanowires with different boundary conditions are discussed. It is demonstrated that the new continuum theory can predict the buckling behavior of nanowires very well. Similar to the prediction of the classical elasticity theory, the critical compressive load of axial buckling of nanowires predicted by the new continuum theory increases with an increasing characteristic length, such as the diameter or height of nanowires. With the same aspect ratio, a nanowire with a rectangular cross section possesses a larger critical buckling load than that with a circular one. However, the surface effect could enhance the critical buckling load not only for a fixed-fixed nanowire but also for a cantilevered one in contrast to the classical elastic model. All the results predicted by the new continuum theory agree well with predictions by the surface elasticity models. The present research not only verifies the validation of the new continuum theory, but also gives a much more convenient characterization of buckling behaviors of nanowires. This should be helpful for the design of nanodevices based on nanomaterials, for example, nanobeams in NEMS or high-precision instruments.

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Section: Introductionmentioning

confidence: 99%

“…A decreasing aspect ratio of a fixed-fixed silicon nanowire would induce an increasing critical buckling load [25]. The critical buckling force of a cantilevered silver-gallium alloy nanowire was measured by Dobrokhotov et al [24]. MD calculations about the buckling behavior of nanowires were also done [26,29].…”

Section: Introductionmentioning

confidence: 99%

Buckling behavior of nanowires predicted by a new surface energy density model

Yao

Chen

2016

Acta Mech

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“…Timoshenko beam theory, which is valid for large deflections, was used to model the deflection shape of the nanoneedle. From these experiments, a E of 68.3 GPa was calculated for a 157-nm diameter, 15.6-µm long Ag 2 Ga nanoneedle [49].…”

Section: Prior Measurements Of E Q and K C Of Ag 2 Ga Nanoneedlesmentioning

confidence: 99%

Vibrational spectra of nanowires measured using laser doppler vibrometry and STM studies of epitaxial graphene : an LDRD fellowship report.

Biedermann¹

2009

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A few of the many applications for nanowires are high-aspect ratio conductive atomic force microscope (AFM) cantilever tips, force and mass sensors, and high-frequency resonators. Reliable estimates for the elastic modulus of nanowires and the quality factor of their oscillations are of interest to help enable these applications. Furthermore, a real-time, non-destructive technique to measure the vibrational spectra of nanowires will help enable sensor applications based on nanowires and the use of nanowires as AFM cantilevers (rather than as tips for AFM cantilevers).Laser Doppler vibrometry is used to measure the vibration spectra of individual cantilevered nanowires, specifically multiwalled carbon nanotubes (MWNTs) and silver gallium nanoneedles. Since the entire vibration spectrum is measured with high frequency resolution (100 Hz for a 10 MHz frequency scan), the resonant frequencies and quality factors of the nanowires are accurately determined. Using Euler-Bernoulli beam theory, the elastic modulus and spring constant can be calculated from the resonance frequencies of the oscillation spectrum and the dimensions of the nanowires, which are obtained from parallel SEM studies. Because the diameters of the nanowires 3 studied are smaller than the wavelength of the vibrometer's laser, Mie scattering is used to estimate the lower diameter limit for nanowires whose vibration can be measured in this way. The techniques developed in this thesis can be used to measure the vibrational spectra of any suspended nanowire with high frequency resolution Two different nanowires were measured-MWNTs and Ag 2 Ga nanoneedles. Measurements of the thermal vibration spectra of MWNTs under ambient conditions showed that the elastic modulus, E, of plasma-enhanced chemical vapor deposition (PECVD) MWNTs is 37±26 GPa, well within the range of E previously reported for CVD-grown MWNTs. Since the Ag 2 Ga nanoneedles have a greater optical scattering efficiency than MWNTs, their vibration spectra was more extensively studied. The thermal vibration spectra of Ag 2 Ga nanoneedles was measured under both ambient and low-vacuum conditions. The operational deflection shapes of the vibrating Ag 2 Ga nanoneedles was also measured, allowing confirmation of the eigenmodes of vibration. The modulus of the crystalline nanoneedles was 84.3±1.0 GPa.Gas damping is the dominate mechanism of energy loss for nanowires oscillating under ambient conditions. The measured quality factors, Q, of oscillation are in line with theoretical predictions of air damping in the free molecular gas damping regime. In the free molecular regime, Q gas is linearly proportional to the density and diameter of the nanowire and inversely proportional to the air pressure. Since the density of the Ag 2 Ga nanoneedles is three times that of the MWNTs, the Ag 2 Ga nanoneedles have greater Q at atmospheric pressures. Our initial measurements of Q for Ag 2 Ga nanoneedles in low-vacuum (10 Torr) suggest that the intrinsic Q of these nanoneedles may be on the order of 1000....

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“…The nano-probes that were grown on atomic force microscopy (AFM) probes were able to perform AFM topography, in both tapping and non-contact modes; and nano-probes on AFM probes were used in voltage lithography [4,77]. Additional studies by Biedermann et al and Dobrokhotov, et al [80,81] used the self-assembled silver gallium nanostructures in force and mass sensing applications.…”

Section: Dmentioning

confidence: 99%

Trapping of nanoparticles with dielectrophoretic nano-probes.

Wood¹

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negative dielectrophoresis repels particles from the region of the highest electric field gradient. The dielectrophoretic force is directly proportional to the square of the electric field gradient, as well as the cube of the radius of the particles involved.As particles decrease in size, the gradient of the electric field must increase rapidly in order to capture or repel the particles. The intense electric field gradients were produced using fabricated silver gallium (Ag 2 Ga) nano-probes electrodes in conjunction with indium tin oxide (ITO) coated microscope cover slips, which served as the opposite electrode. The silver gallium nano-probes ranged from approximately 100-500 nm in diameter and were typically positioned less than 40 µm above the ITO cover slips.Positive and negative dielectrophoretic forces were able to dominate the other electrokinetic forces acting on sub-micron particles, which were suspended in deionized water and aqueous potassium chloride, using the nano-probes and ITO cover slips as electrodes. Colloidal quantum dots of gold, as small as 5 nm in diameter, were captured using positive DEP forces, as were sub-micron fluorescent polystyrene particles.Negative DEP forces repelled sub-micron fluorescent polystyrene particles suspended in a low conductivity solution.

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Visual force sensing with flexible nanowire buckling springs

Cited by 25 publications

References 21 publications

Buckling behavior of nanowires predicted by a new surface energy density model

Buckling behavior of nanowires predicted by a new surface energy density model

Vibrational spectra of nanowires measured using laser doppler vibrometry and STM studies of epitaxial graphene : an LDRD fellowship report.

Trapping of nanoparticles with dielectrophoretic nano-probes.

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