Self-driving capacitive cantilevers for high-frequency atomic force microscopy

Brown, Keith A.; Yang, Benjamin; Westervelt, Robert

doi:10.1063/1.3679684

Cited by 9 publications

(5 citation statements)

References 25 publications

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“…To compare these measurements with theory, we use our simulations for C 13 and C 12 from figure 3(d). We include a constant contribution to C 13 from deformation of the cantilever capacitor [26], which for identically prepared probes is ∼0.1 aF nm −1 . The simulated cantilever-sample interaction is C 12 ∼ 0.03 aF nm −1 , roughly an order of magnitude smaller than an unshielded cantilever.…”

Section: Resultsmentioning

confidence: 99%

High spatial resolution Kelvin probe force microscopy with coaxial probes

2012

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Kelvin probe force microscopy (KPFM) is a widely used technique to measure the local contact potential difference (CPD) between an AFM probe and the sample surface via the electrostatic force. The spatial resolution of KPFM is intrinsically limited by the long range of the electrostatic interaction, which includes contributions from the macroscopic cantilever and the conical tip. Here, we present coaxial AFM probes in which the cantilever and cone are shielded by a conducting shell, confining the tip-sample electrostatic interaction to a small region near the end of the tip. We have developed a technique to measure the true CPD despite the presence of the shell electrode. We find the behavior of these probes agrees with an electrostatic model of the force, and we observe a factor of 5 improvement in spatial resolution relative to unshielded probes. Our discussion centers on KPFM, but the field confinement offered by these probes may improve any variant of electrostatic force microscopy.

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Section: Resultsmentioning

confidence: 99%

High spatial resolution Kelvin probe force microscopy with coaxial probes

2012

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“…We have shown that it is possible to measure a second harmonic mode to provide an independent measurement of drop location [21], however the challenge arises when considering measuring second harmonics of high frequency and ultrafast probes. Not only is the bandwidth of the deflection sensor limited to 2 MHz, but actively tuning modes at MHz frequencies using a shake piezo leads to large artifacts due to the frequency response of the AFM chip [28]. Thus, it is impractical to operate with ultrafast or even noncontact mode AFM tipless cantilevers.…”

Section: Probe Selection and Frequency Measurementmentioning

confidence: 99%

Quantitative nanopatterning of fg-scale liquids with dip-pen nanolithography

2023

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The ability to precisely pattern nanoscale amounts of liquids is essential for biotechnology and high-throughput chemistry, but controlling fluid flow on these scales is very challenging. Scanning probe lithography methods such as dip-pen nanolithography provide a mechanism to write fluids at the nanoscale, but this is an open loop process as methods to provide feedback while patterning sub-pg features have yet to be reported. Here, we demonstrate a novel method for programmably nanopatterning liquid features at the fg-scale through a combination of ultrafast atomic force microscopy (AFM) probes, the use of spherical tips, and inertial mass sensing. We begin by investigating the required probe properties that would provide sufficeint mass responsivity to detect fg-scale mass changes and find ultrafast probes to be capable of this resolution. Further, we attach a spherical bead to the tip of an ultrast probe as we hypothesize that the spherical tip could hold a drop at its apex which both facilitates interpretation of inertial sensing and maintains a consistent fluid environment for reliable patterning. We experimentally find that sphere-tipped ultrafast probes are capable of reliably patterning hundreds of features in a single experiment. Analyzing the changes in the vibrational resonance frequency during the patterning process, we find that drift in the resonance frequency complicates analysis, but that it can be removed through a systemmatic correction. Subsequently, we quantitatively study patterning using sphere-tipped ultrafast probes as a function of retraction speed and dwell time to find that the mass of fluid transferred can be modulated by greater than an order of magnitude and that liquid featues as small as 6 fg can be patterned and resolved. Taken together, this work addresses a persistent concern in DPN by enabling quantitative feedback for nanopatterning of aL-scale features and lays the foundations for programmably nanopatterning fluids.

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“…The statistically relevant information is contained only in the first four components. This is expected since capacitive driving actuates the cantilever directly and does not result in the so-called 'forest-of-peaks' [64] seen in conventional piezoelectric actuation or liquid imaging [65][66][67][68][69][70][71]. The first loading map and the eigenvector show the mean response.…”

mentioning

confidence: 93%

Imaging via complete cantilever dynamic detection: general dynamic mode imaging and spectroscopy in scanning probe microscopy

et al. 2016

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We develop and implement a multifrequency spectroscopy and spectroscopic imaging mode, referred to as general dynamic mode (GDM), that captures the complete spatially- and stimulus dependent information on nonlinear cantilever dynamics in scanning probe microscopy (SPM). GDM acquires the cantilever response including harmonics and mode mixing products across the entire broadband cantilever spectrum as a function of excitation frequency. GDM spectra substitute the classical measurements in SPM, e.g. amplitude and phase in lock-in detection. Here, GDM is used to investigate the response of a purely capacitively driven cantilever. We use information theory techniques to mine the data and verify the findings with governing equations and classical lock-in based approaches. We explore the dependence of the cantilever dynamics on the tip-sample distance, AC and DC driving bias. This approach can be applied to investigate the dynamic behavior of other systems within and beyond dynamic SPM. GDM is expected to be useful for separating the contribution of different physical phenomena in the cantilever response and understanding the role of cantilever dynamics in dynamic AFM techniques.

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Self-driving capacitive cantilevers for high-frequency atomic force microscopy

Cited by 9 publications

References 25 publications

High spatial resolution Kelvin probe force microscopy with coaxial probes

High spatial resolution Kelvin probe force microscopy with coaxial probes

Quantitative nanopatterning of fg-scale liquids with dip-pen nanolithography

Imaging via complete cantilever dynamic detection: general dynamic mode imaging and spectroscopy in scanning probe microscopy

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