Bio-inspired micro-to-nanoporous polymers with tunable stiffness

• Julia Syurik,
• Ruth Schwaiger,
• Prerna Sudera,
• Stephan Weyand,
• Siegbert Johnsen,
• Gabriele Wiegand and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2017, 8, 906–914, doi:10.3762/bjnano.8.92

• regime by dynamic flat-punch indentation. Interestingly, the storage modulus was observed to increase with increasing pore-area fraction. Conclusion: This outcome appears counterintuitive at first sight, but can be rationalized by an increase of the pore wall thickness as determined by our quantitative

• ). Prior to SEM analysis the samples were sputtered with silver for 100 s at 25 mA with a sputter-coater (K575X, Emitech) in order to avoid charging effects and ensure a good resolution. SEM images of the surface of interest were taken before and after the indentation experiments. For the quantitative

• -specific characterisation routine yields the complex modulus E* = E' + iE'' as a function of the frequency for a specific indentation, with E' and E'' being the storage modulus and the loss modulus of the material, respectively. The ratio E''/E', also known as the loss factor tan δ = α, represents the

Dispersion of single-wall carbon nanotubes with supramolecular Congo red – properties of the complexes and mechanism of the interaction

• Anna Jagusiak,
• Barbara Piekarska,
• Tomasz Pańczyk,
• Małgorzata Jemioła-Rzemińska,
• Elżbieta Bielańska,
• Barbara Stopa,
• Grzegorz Zemanek,
• Janina Rybarska,
• Irena Roterman and
• Leszek Konieczny

Beilstein J. Nanotechnol. 2017, 8, 636–648, doi:10.3762/bjnano.8.68

• ), deformation (the indentation of the surface under the tip), dispersion (dissipation, loss of energy of microcantilever of scanning probe when passing through different areas on the sample surface). Absorption spectra of free Congo red (A) and SWNT-bound Congo red (D) (0.05 M Tris/HCl buffer, pH 7.4); Congo

Analysis and modification of defective surface aggregates on PCDTBT:PCBM solar cell blends using combined Kelvin probe, conductive and bimodal atomic force microscopy

• Hanaul Noh,
• Alfredo J. Diaz and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2017, 8, 579–589, doi:10.3762/bjnano.8.62

• aggregates with KPFM does not work for fresh samples. Thus, we apply controlled bimodal AFM indentation [35][36] to the surface aggregates of fresh samples in order to demonstrate the modification process. Since the aggregates are very thin, we vary the peak force of bimodal AFM just enough to break the

• the spring constant of the third eigenmode is ca. 308 times the spring constant of the first mode [18], the indentation depth and peak force of the bimodal treatment are mainly controlled by the higher eigenmode [36]. The small free amplitude of the third eigenmode (ca. 3 nm, Figure S7, Supporting

• Information File 1) ensures controlled shallow indentation into the surface. Since the volume of aggregates in the scan area is about 0.58·10−18 L (with a total mass less than 1·10−15 g) [39], calculated from the dark region (36%) in Figure 6e and the thickness of aggregates previously obtained (ca. 0.8 nm

Anodization-based process for the fabrication of all niobium nitride Josephson junction structures

• Massimiliano Lucci,
• Ivano Ottaviani,
• Matteo Cirillo,
• Fabio De Matteis,
• Roberto Francini,
• Vittorio Merlo and
• Ivan Davoli

Beilstein J. Nanotechnol. 2017, 8, 539–546, doi:10.3762/bjnano.8.58

• compliance voltage to obtain a controlled and stable oxidation of a NbN thin film. Auger electron spectroscopy and nano-indentation analysis has been employed to verify respectively the complete oxidation of the surface and the mechanical stability of the film. We have also found a relationship between the

Structural and tribometric characterization of biomimetically inspired synthetic "insect adhesives"

• Matthias W. Speidel,
• Malte Kleemeier,
• Andreas Hartwig,
• Klaus Rischka,
• Angelika Ellermann,
• Rolf Daniels and
• Oliver Betz

Beilstein J. Nanotechnol. 2017, 8, 45–63, doi:10.3762/bjnano.8.6

When the going gets rough – studying the effect of surface roughness on the adhesive abilities of tree frogs

• Niall Crawford,
• Thomas Endlein,
• Jonathan T. Pham,
• Mathis Riehle and
• W. Jon P. Barnes

Beilstein J. Nanotechnol. 2016, 7, 2116–2131, doi:10.3762/bjnano.7.201

• difficult. The pads of tree frogs are very soft and so should deform to mould around rough surfaces, as is seen in smooth padded insects [17]. The Young’s modulus of the toe pads has been measured in several studies, an elastic modulus of 40–55 kPa based on AFM indentation being the most recent estimate [18

• indentation depth of h (i.e., bead diameter) and bead radius R, leading to Uelastic = 4/3E*R1/2h5/2. Since the glass bead is taken to be infinitely stiff, here 1/E* = (1 – ν2)/E where ν is Poisson’s ratio of the toe pad (taken to be 0.5), the surface term is given by the circular opening that is produced by

• the results of indentation experiments carried out on tree frogs by Barnes et al. [19] and Barnes et al. [18] which showed equivalently low toe pad elastic modulus values (in the 5–40 kPa range). Although our results are consistent with prior reports, we note that there are a few points regarding our

Annealing-induced recovery of indents in thin Au(Fe) bilayer films

• Anna Kosinova,
• Ruth Schwaiger,
• Leonid Klinger and
• Eugen Rabkin

Beilstein J. Nanotechnol. 2016, 7, 2088–2099, doi:10.3762/bjnano.7.199

• dissipation and the formation of shallow depressions nearby after subsequent annealing treatments. This annealing-induced evolution of nanoindents was interpreted in terms of annihilation of dislocation loops generated during indentation, accompanied by the formation of nanopores at the grain boundaries and

• strain in thin films. Here, we present the results of a study investigating the recovery of indentation-induced defects in Au(Fe) bilayer films. The motivation for our work is two-fold: (i) to explore the concept of thermo-mechanical treatment of thin films by combining localized plastic strain

• microstructural changes and phase transformations induced by nanoindentation and annealing in Ni [1] and Ag thin films [2] on Si substrates. They revealed that the distortion of the crystalline structure induced by indentation enhances the diffusivity of metal atoms and prompts the formation of nickel and silver

A new approach to grain boundary engineering for nanocrystalline materials

• Shigeaki Kobayashi,
• Sadahiro Tsurekawa and
• Tadao Watanabe

Beilstein J. Nanotechnol. 2016, 7, 1829–1849, doi:10.3762/bjnano.7.176

• micrographs of the propagation path of cracks produced by Vickers indentation tests at a load of 1.96 N for the sulfur-doped submicrometer-grained Ni specimens with different grain boundary microstructures [85]. Type A and Type B specimens had different fractions of low-Σ CSL boundaries (including low-angle

• boundaries) of 49 and 40%, but almost the same average grain size of 300 and 340 nm, respectively. It was found that the crack length from the tip of indentation in the Type A specimen with a higher fraction of low-Σ CSL boundaries (FΣ = 49%) was shorter than in the Type B specimen with a lower fraction of

• low-Σ CSL boundaries (FΣ = 40%). The fracture toughness KIC measured by indentation fracture (IF) method for the Type A and the Type B specimens were 2.5 MPa m1/2 and 1.1 MPa m1/2, respectively. Evidently, the fracture toughness of the Type A specimen with a higher fraction of low-Σ CSL boundaries is

Functional diversity of resilin in Arthropoda

• Jan Michels,
• Esther Appel and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2016, 7, 1241–1259, doi:10.3762/bjnano.7.115

• layer as well as a higher density of rods than those of T. viridissima (Figure 6A–D). In addition, indentation experiments revealed a higher effective Young’s modulus and a lower work of adhesion for L. migratoria pads (Figure 6F,G). The lower adhesive properties of L. migratoria pads can be explained

Advanced atomic force microscopy techniques III

• Thilo Glatzel and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2016, 7, 1052–1054, doi:10.3762/bjnano.7.98

• indentation in UHV to quantitatively determine the hardness and deformation mechanisms by Arnaud Caron and Roland Bennewitz [22]. Santiago Solares and Enrique A. López-Guerra presented different approaches to model such viscoelastic properties within AFM simulations [23]. Sliding contact properties like

Generalized Hertz model for bimodal nanomechanical mapping

• Aleksander Labuda,
• Marta Kocuń,
• Waiman Meinhold,
• Deron Walters and
• Roger Proksch

Beilstein J. Nanotechnol. 2016, 7, 970–982, doi:10.3762/bjnano.7.89

• and loss moduli, as they cannot be distinguished from changes in indentation depth. In tapping mode, only the ratio of the storage to loss modulus can be measured [10][21][22]. The same limitation applies to many other parametric techniques, such as force modulation [6][7] and other single-frequency

• interaction stiffness for both resonant modes, each yielding a simple analytical expression. These two independent pieces of information are refactored to provide information about modulus and indentation depth. While the theory is generally applicable to a wide range of tip–sample interaction models, the

• theory presented in the following three sections. Methods Hertzian contact mechanics The Hertzian contact model involves the interaction stiffness kint versus indentation depth δ between a paraboloidal tip of radius R and a flat sample as where the effective Young’s modulus Eeff combines deformation of

Nanoscale effects in the characterization of viscoelastic materials with atomic force microscopy: coupling of a quasi-three-dimensional standard linear solid model with in-plane surface interactions

• Santiago D. Solares

Beilstein J. Nanotechnol. 2016, 7, 554–571, doi:10.3762/bjnano.7.49

• indentation profiles and tip–sample interaction force curves, as well as their implications with regards to experimental interpretation. A variety of phenomena are examined in detail, which highlight the need for further development of more physically accurate sample models that are specifically designed for

• axis of the indentation. Second, at the scale of an AFM measurement, the surface layer mechanical properties (which often differ from the bulk properties, as discussed below) may play a prominent role. Specifically, as the tip compresses the sample, it is easy to imagine how the indentation leads to an

• free energy and elastic energy effects are often neither isotropic nor uniform, as there is generally a variation in the structure and morphology of most viscoelastic surfaces (e.g., polymers) in the horizontal direction (examples are provided below). Furthermore, at the scale of an AFM indentation it

Synthesis and applications of carbon nanomaterials for energy generation and storage

• Marco Notarianni,
• Jinzhang Liu,
• Kristy Vernon and
• Nunzio Motta

Beilstein J. Nanotechnol. 2016, 7, 149–196, doi:10.3762/bjnano.7.17

Nanoscale rippling on polymer surfaces induced by AFM manipulation

• Mario D’Acunto,
• Franco Dinelli and
• Pasqualantonio Pingue

Beilstein J. Nanotechnol. 2015, 6, 2278–2289, doi:10.3762/bjnano.6.234

• evolution in single scratch tests. In this model, the atomic structure of the substrate is not considered. This makes the continuum model more suitable for polymeric materials that are amorphous and have fully entangled molecules, i.e., for Mw >> Mc. They have also introduced an indentation rate N, varying

• or v fall below the critical values of vc and kc, respectively (Figure 7). A transition from stick–slip to gliding can be also predicted for an indentation rate below a critical value or, alternatively, for large values of the sliding velocity, the lateral stiffness or the tip width. It is suggested

• also that this approach might be used to describe the evolution of similar rippling processes, by simply employing a proper indentation law. This analytical model could be also useful in order to understand phenomena such as the rippling of unpaved roads, ski slopes and rail tracks. A model fully

A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

• Santiago D. Solares

Beilstein J. Nanotechnol. 2015, 6, 2233–2241, doi:10.3762/bjnano.6.229

• analytical tip–sample interaction expressions in which the force is expressed as the sum of a Hertzian conservative interaction plus an indentation- and velocity-dependent dissipative interaction. Such 1-dimensional (1D) models have, for example, been used in the characterization of polymers [8][9

• contact at a fixed stress, the model must exhibit a time-dependent relaxation of the position of the sample directly under the tip. That is, the sample must yield, allowing the tip to gradually increase the depth of indentation. Furthermore, if the tip is quickly removed following yielding of the surface

• terms of a real 3D tip interacting with a flat surface, and thus makes it impossible to extract approximate parameters such as the Young’s modulus [12]. It is clear in Figure 1a that the geometry of the tip and its indentation depth into the surface have absolutely no effect on the nature of the tip

Development of a novel nanoindentation technique by utilizing a dual-probe AFM system

• Eyup Cinar,
• Ferat Sahin and
• Dalia Yablon

Beilstein J. Nanotechnol. 2015, 6, 2015–2027, doi:10.3762/bjnano.6.205

• nanoindentation is described that exhibits improved resolution and depth sensing. The approach is based on a multi-probe scanning probe microscopy (SPM) tool that utilizes tuning-fork based probes for both indentation and depth sensing. Unlike nanoindentation experiments performed with conventional AFM systems

• . An indenter probe fabricated with a known tip geometry is used to penetrate into the sample. By utilizing the force and small amount of depth information measured during indentation, material properties such as elastic (Young’s) modulus of the sample can be estimated. For example, a growing

• constants below 500 N/m. Depending on the material hardness, the applied load could result in bending of the cantilever. With optical lever method, the displacement is measured by laser deflection, which includes laser deflection caused by both the indentation depth (motion in Z) and the cantilever bending

A simple method for the determination of qPlus sensor spring constants

• John Melcher,
• Julian Stirling and
• Gordon A. Shaw

Beilstein J. Nanotechnol. 2015, 6, 1733–1742, doi:10.3762/bjnano.6.177

• System of Units (SI) [19][21][37], measures a force vs displacement curve by pressing a sharp indenter tip into the qPlus sensor surface at a known axial distance from the distal edge of the tine. From the indentation curve, a stiffness kI is inferred, taking care to remove the machine compliance and

• contact compliance by performing additional measurements at the base of the sensor. Applying this method at two or more distinct locations along the axis of the tine determines the flexural rigidity EI and effective cantilever length Leff of the qPlus sensor. Moreover, the indentation data provides

• were acquired along the axis of the tine and additionally at the base of the sensor in order to remove the contact stiffness and machine compliance from the spring constant prediction. To avoid interference with the indenter tip, tips were not attached to the tine. Figure 7 shows the indentation

Lower nanometer-scale size limit for the deformation of a metallic glass by shear transformations revealed by quantitative AFM indentation

• Arnaud Caron and
• Roland Bennewitz

Beilstein J. Nanotechnol. 2015, 6, 1721–1732, doi:10.3762/bjnano.6.176

• Abstract We combine non-contact atomic force microscopy (AFM) imaging and AFM indentation in ultra-high vacuum to quantitatively and reproducibly determine the hardness and deformation mechanisms of Pt(111) and a Pt57.5Cu14.7Ni5.3P22.5 metallic glass with unprecedented spatial resolution. Our results on

• mechanisms are not activated by indentation. In the case of metallic glass, we conclude that the energy stored in the stressed volume during nanometer-scale indentation is insufficient to account for the interfacial energy of a shear band in the glassy matrix. Keywords: AFM indentation; dislocation

• the projected area of the remaining indent is evaluated by optical microscopy and hardness measurements are limited to the macro-scale. With the development of depth-sensing indentation techniques such as instrumented nanoindentation, the recording of load–displacement curves has been recognized as a

Atomic force microscopy as analytical tool to study physico-mechanical properties of intestinal cells

• Christa Schimpel,
• Oliver Werzer,
• Eleonore Fröhlich,
• Gerd Leitinger,
• Markus Absenger-Novak,
• Birgit Teubl,
• Andreas Zimmer and
• Eva Roblegg

Beilstein J. Nanotechnol. 2015, 6, 1457–1466, doi:10.3762/bjnano.6.151

• topographies of Caco-2 cells and M cells. Furthermore, cell elasticity (i.e., the mechanical response of a cell on a tip indentation), was elucidated by force curve measurements. Besides elasticity, adhesion was evaluated by recording the attraction and repulsion forces between the tip and the cell surface

• against the plasma membranes. As a consequence, indentation occurs. The amount of force acting on the cantilever as a function of indentation enables an estimation of the nanomechanical properties of living cells, such as elasticity and adhesion [21][25][26][27]. To get a basic understanding regarding

• developed brush border (Figure 3A). In contrast, F-actin staining at the apex of M cells was markedly decreased due to a reduced or absent brush border (Figure 3B–D). Elasticity (force-indentation) measurements of Caco-2 cells and M cells Villin is not only involved in the formation and/or regulation of the

Nano-contact microscopy of supracrystals

• Adam Sweetman,
• Nicolas Goubet,
• Ioannis Lekkas,
• Marie Paule Pileni and
• Philip Moriarty

Beilstein J. Nanotechnol. 2015, 6, 1229–1236, doi:10.3762/bjnano.6.126

• increasing tip indentation in the same region (Figure 3A). We only began to detect comparable tunnel current signals to the STM setpoint at indentations of −1 to −1.5 nm closer to the sample than the constant height imaging position (Figure 3B), which we previously established was already at a tip–sample

• separation corresponding to the repulsive branch of the short range force curve. The simultaneously acquired Δf curve also shows strongly repulsive behaviour, but we note that the quantitative short range force cannot be extracted in this case as at this level of indentation there is no complementary “off

Optimization of phase contrast in bimodal amplitude modulation AFM

• Mehrnoosh Damircheli,
• Amir F. Payam and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2015, 6, 1072–1081, doi:10.3762/bjnano.6.108

• and detected. The feedback operates on the amplitude of the first mode while both second and third modes are in open loops. It has been shown the usefulness of the third mode to modulate the indentation [23]. A comparison of the trade-offs in sensitivity and sample depth have been performed with

• AFM offers two additional channels for compositional contrast. The value of A03 has been used modulate the indentation while imaging embedded nanoparticles in a soft polymer [23]. To understand some of the fundamental aspects of trimodal AFM and the differences with respect to bimodal AM we study the

Mapping of elasticity and damping in an α + β titanium alloy through atomic force acoustic microscopy

• M. Kalyan Phani,
• Anish Kumar,
• T. Jayakumar,
• Walter Arnold and
• Konrad Samwer

Beilstein J. Nanotechnol. 2015, 6, 767–776, doi:10.3762/bjnano.6.79

• cantilever with damped flexural modes. The cantilever dynamics model considering damping, which was proposed recently, has been used for mapping of indentation modulus and damping of different phases in a metallic structural material. The study indicated that in a Ti-6Al-4V alloy the metastable β phase has

• acoustic microscopy; contact resonances; damping; indentation modulus; Ti-6Al-4V; Introduction The physical and mechanical properties of the individual phases govern the respective properties of the multiphase structural materials. The knowledge of elastic properties of the individual phases is important

• successfully mapped the indentation modulus of α- and β-phases in a Ti-6Al-4V alloy by using AFAM while using a cantilever dynamic model in which damping, however, was neglected. In this paper, we report mapping of elastic modulus and damping using a modified cantilever dynamic model in various phases, such as

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

• Horacio V. Guzman,
• Pablo D. Garcia and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2015, 6, 369–379, doi:10.3762/bjnano.6.36

• tip–surface charge density and σs is the sample surface charge density. Hertz contact mechanics The elastic contact between the tip and sample is usually modelled with the Hertz model [46] whereby for a spherical tip and a half-space sample the force is given by where δ is the indentation and Eeff is

• applied to describe contacts characterized by a relatively small Young modulus, and large adhesion and contact area [48]. In this model the force is calculated as an implicit equation of the indentation where and Tatara contact mechanics The Tatara contact mechanics are applied to describe a sample with a

Mechanical properties of MDCK II cells exposed to gold nanorods

• Anna Pietuch,
• Bastian Rouven Brückner,
• David Schneider,
• Marco Tarantola,
• Christina Rosman,
• Carsten Sönnichsen and
• Andreas Janshoff

Beilstein J. Nanotechnol. 2015, 6, 223–231, doi:10.3762/bjnano.6.21

• atomic force microscope (AFM) by taking force curves at each spot the probe touches the sample surface. These force indentation curves are frequently subject to regression analysis employing Hertzian contact models that permit to assess the cell’s Young’s modulus. The modulus bears invaluable information

• environmental cues also adhesion and uptake of nanoparticles is reflected in the mechanical properties of cells. Figure 3A shows averaged force indentation curves performed on the center of confluent MDCK II cells. Two different models were used to extract mechanical parameters from these data. The first one

• force in response to indentation with a conical indenter originating from two sources, linear elasticity due to area dilatation and pre-stress (constant tension). Pre-stress is mainly generated by contractile actomyosin, strong adhesion at the cell-borders and interaction of the plasma membrane with the

Boosting the local anodic oxidation of silicon through carbon nanofiber atomic force microscopy probes

• Gemma Rius,
• Matteo Lorenzoni,
• Soichiro Matsui,
• Masaki Tanemura and
• Francesc Perez-Murano

Beilstein J. Nanotechnol. 2015, 6, 215–222, doi:10.3762/bjnano.6.20

• –sample direct mechanical contact or long range interactions, such as based on van der Waals or electrostatic forces. Because of this, AFM-based SPL can be achieved through oxidation, indentation, as well as various other implementations such as dip-pen nanolithography [5]. Early works on AFM-based SPL