Experimental Studies of Resolution in Scanning Ion Conductance Microscopy

Weber, Anita L.; Baker, Lane A.

doi:10.1149/2.0701414jes

Cited by 27 publications

(38 citation statements)

References 14 publications

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“…and 2d) make it clear that with V = 0, the phase shift can be used as a set point for determining topography and being able to position the probe at close tip-to-substrate separations, which is important for enhancing the resolution of SICM. 56,57 In a similar way to the experimental approaches at non-zero bias (Figure 2), the model predicts a dramatic change of the phase-distance behavior for V  0.…”

Section: Resultssupporting

confidence: 63%

Simultaneous Nanoscale Surface Charge and Topographical Mapping

et al. 2015

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Nanopipettes are playing an increasingly prominent role in nanoscience, for sizing, sequencing, delivery, detection and mapping interfacial properties. Herein, the question of how to best resolve topography and surface charge effects when using a nanopipette as a probe for mapping in scanning ion conductance microscopy (SICM) is addressed. It is shown that using a bias modulated (BM) SICM scheme it is possible to map the topography faithfully, while also allowing surface charge to be estimated. This is achieved by applying zero net bias between the electrode in the SICM tip and the one in bulk solution for topographical mapping, with just a small harmonic perturbation of the potential to create an AC current for tip positioning.Then a net bias is applied, whereupon the ion conductance current becomes sensitive to surface charge. Practically this is optimally implemented in a hopping-cyclic voltammetry mode where the probe is approached at zero net bias at a series of pixels across the surface to reach a defined separation, and then a triangular potential waveform is applied and the current response is recorded. Underpinned with theoretical analysis, including finite element modeling of the DC and AC components of the ionic current flowing through the nanopipette tip, the powerful capabilities of this approach are demonstrated with the probing of interfacial acid-base equilibria and high resolution imaging of surface charge heterogeneities, simultaneously with topography, on modified substrates.

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Section: Resultssupporting

confidence: 63%

Simultaneous Nanoscale Surface Charge and Topographical Mapping

et al. 2015

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“…While there are some limitations of these simulations, in that they assumed nanopipettes to exhibit a conical geometry, the results help to understand the SICM response and various factors such as the nanopipette size required to achieve a desired resolution, and the tip-surface separation distances that would be needed. It should be noted that there is some discrepancy between simulated and experimental studies of resolution in SICM [98], because experiments have suggested that a resolution as small as 0.5r in [98,99] is possible.…”

Section: Modellingmentioning

confidence: 98%

Multifunctional scanning ion conductance microscopy

2017

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Scanning ion conductance microscopy (SICM) is a nanopipette-based technique that has traditionally been used to image topography or to deliver species to an interface, particularly in a biological setting. This article highlights the recent blossoming of SICM into a technique with a much greater diversity of applications and capability that can be used either standalone, with advanced control (potential-time) functions, or in tandem with other methods. SICM can be used to elucidate functional information about interfaces, such as surface charge density or electrochemical activity (ion fluxes). Using a multi-barrel probe format, SICM-related techniques can be employed to deposit nanoscale three-dimensional structures and further functionality is realized when SICM is combined with scanning electrochemical microscopy (SECM), with simultaneous measurements from a single probe opening up considerable prospects for multifunctional imaging. SICM studies are greatly enhanced by finite-element method modelling for quantitative treatment of issues such as resolution, surface charge and (tip) geometry effects. SICM is particularly applicable to the study of living systems, notably single cells, although applications extend to materials characterization and to new methods of printing and nanofabrication. A more thorough understanding of the electrochemical principles and properties of SICM provides a foundation for significant applications of SICM in electrochemistry and interfacial science.

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“…105 Initial adoption of this technique was slow but in recent times the popularity of SICM has dramatically increased, particularly for the biological sciences due to the potential to provide contact-free imaging of so, delicate surfaces, such as living cells. [116][117][118][119][120][121] The simplest means of positional feedback is by measuring DC between the pipette and bulk solution electrodes but, more commonly, the tip is modulated via a small, vertical oscillation to give an AC signal. [116][117][118][119][120][121] The simplest means of positional feedback is by measuring DC between the pipette and bulk solution electrodes but, more commonly, the tip is modulated via a small, vertical oscillation to give an AC signal.…”

Section: Ion Conductance Positioningmentioning

confidence: 99%

“…117 Experimentally, the limit of lateral resolution has been independently shown to be 0.5 r i , 110,117 where r i is the inner radius of the pipette, although theoretical studies suggest this should be closer to 2-3 times r i . The exact denition of resolution for SICM varies greatly: Baker and co-workers have recently examined previous experimental and theoretical limits of SICM resolution and highlight these discrepancies.…”

Section: Ion Conductance Positioningmentioning

confidence: 99%

“…An interesting development exploits the miniaturized electrochemical cell formed by the meniscus at the apex of a solution-lled capillary. This technique is still in relative infancy; recent work has improved understanding [117][118][119]121,146 and imaging protocols, 113,114 and further improvements will undoubtedly expand the possibilities. 139,140 However, by employing a theta capillary and measuring an ion current between the two barrels it is possible to simultaneously measure a positional feedback signal, typically by locking into an AC signal whilst undergoing vertical modulation.…”

Section: Ion Conductance Positioningmentioning

confidence: 99%

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Combined electrochemical-topographical imaging: a critical review

O’Connell

Wain

2015

Anal. Methods

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The ability to characterise electrochemical interfaces on a localised scale has revolutionised our understanding of spatially heterogeneous surface processes. Advances in scanning electrochemical microscopy (SECM) over the past decade have not only permitted access to information at progressively smaller scales but have moreover enabled the simultaneous imaging of interfacial activity and surface topography. Such measurements play a key role in developing a better grasp of structure-activity relationships relevant to a wide range of applications in chemistry and biology. This review critically analyses the state-of-the-art in correlative electrochemical-topographical imaging, focusing on four predominant approaches to probe positional feedback: atomic force microscopy (AFM); shear-force; ion conductance; and electrochemical positioning. The relative advantages and disadvantages of each of these techniques is considered and their imaging characteristics critically compared, with a perspective on the potential for future improvement. Fig. 7 Shear-force SECM of an embedded diamond nanoelectrode measured in feedback mode. The position of the embedded electrode is clear from the electrochemical signal (a) but not on the topography (b). Images adapted with permission from ref. 96.

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Experimental Studies of Resolution in Scanning Ion Conductance Microscopy

Cited by 27 publications

References 14 publications

Simultaneous Nanoscale Surface Charge and Topographical Mapping

Simultaneous Nanoscale Surface Charge and Topographical Mapping

Multifunctional scanning ion conductance microscopy

Combined electrochemical-topographical imaging: a critical review

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