Dynamic force microscopy in fluid

Lantz, Mark A.; Liu, Y. Z.; Cui, Xiaodong; Tokumoto, Hiroshi; Lindsay, Stuart

doi:10.1002/(sici)1096-9918(199905/06)27:5/6<354::aid-sia541>3.0.co;2-4

Cited by 68 publications

(13 citation statements)

References 20 publications

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“…However, when a cantilever is in permanent contact with a stiff sample such as mica, the tip is not moving up and down (the indentation is small because the sample is stiff), but the cantilever is still flexing due to the base motion. Because the optical beam deflection method measures the slope at the free end of the cantilever, there is still some measured motion [25], which we refer to as the residual amplitude A res and phase φ res . Some authors [13] have suggested that A res ≈ Y and thus used A res to measure Y (and then A fluid ).…”

Section: Proposed Methods To Quantitatively Determine the Fluid-borne mentioning

confidence: 99%

Quantitative force and dissipation measurements in liquids using piezo-excited atomic force microscopy: a unifying theory

Kiracofe

Raman

2011

Nanotechnology

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The use of a piezoelectric element (acoustic excitation) to vibrate the base of microcantilevers is a popular method for dynamic atomic force microscopy. In air or vacuum, the base motion is so small (relative to tip motion) that it can be neglected. However, in liquid environments the base motion can be large and cannot be neglected. Yet it cannot be directly observed in most AFMs. Therefore, in liquids, quantitative force and energy dissipation spectroscopy with acoustic AFM relies on theoretical formulae and models to estimate the magnitude of the base motion. However, such formulae can be inaccurate due to several effects. For example, a significant component of the piezo excitation does not mechanically excite the cantilever but rather transmits acoustic waves through the surrounding liquid, which in turn indirectly excites the cantilever. Moreover, resonances of the piezo, chip and holder can obscure the true cantilever dynamics even in well-designed liquid cells. Although some groups have tried to overcome these limitations (either by theory modification or better design of piezos and liquid cells), it is generally accepted that acoustic excitation is unsuitable for quantitative force and dissipation spectroscopy in liquids. In this paper the authors present a careful study of the base motion and excitation forces and propose a method by which quantitative analysis is in fact possible, thus opening this popular method for quantitative force and dissipation spectroscopy using dynamic AFM in liquids. This method is validated by experiments in water on mica using a scanning laser Doppler vibrometer, which can measure the actual base motion. Finally, the method is demonstrated by using small-amplitude dynamic AFM to extract the force gradients and dissipation on solvation shells of octamethylcyclotetrasiloxane (OMCTS) molecules on mica.

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Section: Proposed Methods To Quantitatively Determine the Fluid-borne mentioning

confidence: 99%

Quantitative force and dissipation measurements in liquids using piezo-excited atomic force microscopy: a unifying theory

Kiracofe

Raman

2011

Nanotechnology

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“…The equivalent mechanical system is a spring in series with a spring and a dashpot. By assuming a contact mechanism as described by Hertz contact mechanics, we deduce the force as (21) where E 0 and E ∞ represent the Young's modulus of the material at fast and slow loading rates, respectively.…”

Section: Standard Linear Solid Viscoelastic Model (Sls)mentioning

confidence: 99%

“…In the process, the cross talk between modes and harmonics has been clarified [16][17][18][19][20]. The complicated cantilever motion in liquid and the differences observed between the excitation methods have been analyzed by simulations [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Dynamic force microscopy simulator (dForce): A tool for planning and understanding tapping and bimodal AFM experiments

Guzman¹,

Garcı́a²,

García³

2016

Nano Online

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We present a simulation environment, dForce, which can be used for a better understanding of dynamic force microscopy experiments. The simulator presents the cantilever-tip dynamics for two dynamic AFM methods, tapping mode AFM and bimodal AFM. It can be applied for a wide variety of experimental situations in air or liquid. The code provides all the variables and parameters relevant in those modes, for example, the instantaneous deflection and tip-surface force, velocity, virial, dissipated energy, sample deformation and peak force as a function of time or distance. The simulator includes a variety of interactions and contact mechanics models to describe AFM experiments including: van der Waals, Hertz, DMT, JKR, bottom effect cone correction, linear viscoelastic forces or the standard linear solid viscoelastic model. We have compared two numerical integration methods to select the one that offers optimal accuracy and speed. The graphical user interface has been designed to facilitate the navigation of nonexperts in simulations. Finally, the accuracy of dForce has been tested against numerical simulations performed during the last 18 years.

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“…A commercial atomic force microscope (Nanoscope IIIa with Multi Mode head, Veeco Digital Instruments) with a liquid cell was used with either magnetic or acoustic excitation. To enable magnetic excitation (Han et al, 1996;Lantz et al, 1999) a coil was wound into a recess in the fluid cell normally used to retain a rubber o-ring. Both methods used silicon nitride cantilevers with a nominal spring constant of 0.37 N/m.…”

Section: Methodsmentioning

confidence: 99%

High-Q Dynamic Force Microscopy in Liquid and Its Application to Living Cells

Tamayo¹,

Humphris

Owen

et al. 2001

Biophysical Journal

141

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We present a new dynamic force microscopy technique for imaging in liquids in the piconewton regime. The low quality factor (Q) of the cantilever is increased up to three orders of magnitude by the implementation of a positive feedback control. The technique also includes a phase-locked loop unit to track the resonance of the cantilever. Experiments and computer simulations indicate that the tip-sample forces are below 100 pN, about two orders of magnitude lower than in conventional tapping mode atomic force microscopy. Furthermore, the spectroscopic ability is greatly enhanced. Either the phase shift or the resonant frequency shows a high sensitivity to variations in either the energy dissipation or conservative interactions between the tip and the sample, respectively. The potential of this technique is demonstrated by imaging living cells.

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Dynamic force microscopy in fluid

Cited by 68 publications

References 20 publications

Quantitative force and dissipation measurements in liquids using piezo-excited atomic force microscopy: a unifying theory

Quantitative force and dissipation measurements in liquids using piezo-excited atomic force microscopy: a unifying theory

Dynamic force microscopy simulator (dForce): A tool for planning and understanding tapping and bimodal AFM experiments

High-Q Dynamic Force Microscopy in Liquid and Its Application to Living Cells

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