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

Kiracofe, Daniel; Raman, Arvind

doi:10.1088/0957-4484/22/48/485502

Cited by 47 publications

(72 citation statements)

References 38 publications

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“…Further, piezo resonances can distort the tuning curve. For plain AM-AFM at the first natural frequency, piezo resonances are generally only an issue in liquid [14]. However, on our instrument, piezo resonances can distort the higher eigenmode tuning curves significantly, especially for third and higher eigenmodes.…”

Section: Methodsmentioning

confidence: 99%

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Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

Kiracofe¹,

Raman²,

Yablon³

2013

Beilstein J. Nanotechnol.

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SummaryOne of the key goals in atomic force microscopy (AFM) imaging is to enhance material property contrast with high resolution. Bimodal AFM, where two eigenmodes are simultaneously excited, confers significant advantages over conventional single-frequency tapping mode AFM due to its ability to provide contrast between regions with different material properties under gentle imaging conditions. Bimodal AFM traditionally uses the first two eigenmodes of the AFM cantilever. In this work, the authors explore the use of higher eigenmodes in bimodal AFM (e.g., exciting the first and fourth eigenmodes). It is found that such operation leads to interesting contrast reversals compared to traditional bimodal AFM. A series of experiments and numerical simulations shows that the primary cause of the contrast reversals is not the choice of eigenmode itself (e.g., second versus fourth), but rather the relative kinetic energy between the higher eigenmode and the first eigenmode. This leads to the identification of three distinct imaging regimes in bimodal AFM. This result, which is applicable even to traditional bimodal AFM, should allow researchers to choose cantilever and operating parameters in a more rational manner in order to optimize resolution and contrast during nanoscale imaging of materials.

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Section: Methodsmentioning

confidence: 99%

“…Therefore, a thermally driven spectrum was obtained when the cantilever was positioned approximately 100 nm above the surface. A curve fit to the thermal spectum was used to determine the natural frequency [14]. The drive frequency was then set to this frequency, and the phase (lag) offset was set to 90 degrees.…”

Section: Methodsmentioning

confidence: 99%

Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

Kiracofe¹,

Raman²,

Yablon³

2013

Beilstein J. Nanotechnol.

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“…Recent works indicate that in optical beam deflection setups the displacement of the cantilever base in liquid is not negligible and suggest more accurate methods to quantify the interaction [24], [25]. Since the FFM measures the absolute tip position with a fiber optic, the displacement of the cantilever base does not influence the calibration and the measurements.…”

Section: Methodsmentioning

confidence: 99%

“…Another question that may arise is the influence of spurious resonances in the cantilever transfer function in liquids on the evaluation of and The issue is well known and studied in the supplementary section of reference [25] for measuring stiffness and dissipation in the small oscillation amplitude regime for optical beam deflection operational schemes. Spurious resonances may couple to the cantilever base or directly to the tip, in which case the effect is usually called fluid-borne excitation [25].…”

Section: Methodsmentioning

confidence: 99%

“…Spurious resonances may couple to the cantilever base or directly to the tip, in which case the effect is usually called fluid-borne excitation [25]. It can be shown theoretically that the effects of both spurious resonances is directly taken into account in equations (1) and (2) through the calibration procedure of the parameters and In addition, we compared experimentally force gradients acquired in FFM mode with a conventional dither acoustic excitation with force gradients acquired in FFM mode with a direct capacitive excitation of the tip.…”

Section: Methodsmentioning

confidence: 99%

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Spectroscopic Investigation of Local Mechanical Impedance of Living Cells

et al. 2014

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We studied nanoscale mechanical properties of PC12 living cells with a Force Feedback Microscope using two experimental approaches. The first one consists in measuring the local mechanical impedance of the cell membrane while simultaneously mapping the cell morphology at constant force. As the interaction force is increased, we observe the appearance of the sub-membrane cytoskeleton. We compare our findings with the outcome of other techniques. The second experimental approach consists in a spectroscopic investigation of the cell while varying the tip indentation into the membrane and consequently the applied force. At variance with conventional dynamic Atomic Force Microscopy techniques, here it is not mandatory to work at the first oscillation eigenmode of the cantilever: the excitation frequency of the tip can be chosen arbitrary leading then to new spectroscopic AFM techniques. We found in this way that the mechanical response of the PC12 cell membrane is found to be frequency dependent in the 1 kHz - 10 kHz range. In particular, we observe that the damping coefficient consistently decreases when the excitation frequency is increased.

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