Tattoo ink nanoparticles in skin tissue and fibroblasts

• Colin A. Grant,
• Peter C. Twigg,
• Richard Baker and
• Desmond J. Tobin

Beilstein J. Nanotechnol. 2015, 6, 1183–1191, doi:10.3762/bjnano.6.120

• ]. With highly specialised instrumentation and techniques, it is even possible to resolve molecular bonds [16][17]. Details of AFM operation and capabilities can be found elsewhere [18][19]. However, in brief, the AFM instrument involves a sharp probe at the end of a cantilever interacting with a surface

• . Microscopy of tattoo particles in skin tissue Using the AFM top down optical microscope it was straightforward to manipulate the skin tissue section so that the cantilever was at the periphery of a clump of ink particles in the dermis (Figure 2a). A number of images were taken at various locations; Figure 2b

• fibril networks without particle matter, but were of lower quality (Figure 5). AFM fluid imaging has to use a cantilever spring constant that is about two orders of magnitude lower, which makes scanning trickier. Also, the tissue surface becomes softer. Tattoos inevitably fade over time with a

Probing fibronectin–antibody interactions using AFM force spectroscopy and lateral force microscopy

• Andrzej J. Kulik,
• Małgorzata Lekka,
• Kyumin Lee,
• Grazyna Pyka-Fościak and
• Wieslaw Nowak

Beilstein J. Nanotechnol. 2015, 6, 1164–1175, doi:10.3762/bjnano.6.118

• , resolution, and/or force sensitivity are essential in nanotechnology development. In the majority of AFMs, the cantilever deflection is recorded by an optical detection system composed of a laser and a position-sensitive photodiode having an active area divided into four quadrants. The deflection (referred

• to here as the normal deflection) and torsion (referred to here as the lateral deflection) signals are determined as follows: the signal difference between the two upper and lower quadrants is a measure of the normal deflection, while torsion of the cantilever is represented as the signal difference

• between the two left and two right quadrants. For an AFM working in force spectroscopy mode (referred to here as AFM-FS), the interactions forces are determined from the analysis of force curves. A force curve represents the dependence between the deflection of the AFM cantilever in the direction

Electrical characterization of single molecule and Langmuir–Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative

• Henrry M. Osorio,
• Santiago Martín,
• María Carmen López,
• Santiago Marqués-González,
• Simon J. Higgins,
• Richard J. Nichols,
• Paul J. Low and
• Pilar Cea

Beilstein J. Nanotechnol. 2015, 6, 1145–1157, doi:10.3762/bjnano.6.116

• experiments employed to study the topography of the monolayers were performed by means of a Multimode 8 AFM system from Veeco, using tapping mode. The data were collected with a scan rate of 1 Hz and in ambient air conditions by using a silicon cantilever provided by Bruker, with a force constant of 40 N·m−1

Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt heterostructures

• Oleksandr V. Dobrovolskiy,
• Maksym Kompaniiets,
• Roland Sachser,
• Fabrizio Porrati,
• Christian Gspan,
• Harald Plank and
• Michael Huth

Beilstein J. Nanotechnol. 2015, 6, 1082–1090, doi:10.3762/bjnano.6.109

• [3] and memory [4], fabrication of Hall sensors [5] and cantilever tips [6] for magnetic force microscopy (MFM). In particular, the ability to tune the magnetization is the basic property needed for the realization of stacked nanomagnets [7], pinning of magnetic domain walls [8] and Abrikosov

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

• microscopy (AM-AFM) was designed to excite the cantilever near or at its fundamental free resonant frequency [2]. However, the need to improve and/or provide quantitative compositional contrast without compromising the data acquisition speed has led to the development of several AFM modes, specifically

• different parameters we have used numerical simulations. For this we consider that bimodal AFM is characterized by the simultaneous excitation of two cantilever resonant frequencies, usually the lowest flexural eigenmodes [42]. The total driving force is expressed as Then, the cantilever–tip ensemble will

• be described by the system of two differential modal equations, with i = 1,2; ωi, ki, Qi, , Ai and A0i are, respectively, the angular frequency, the force constant, quality factor, phase shift, amplitude and free amplitude of mode i; m = 0.25mc is an effective mass while mc is the real cantilever–tip

Automatic morphological characterization of nanobubbles with a novel image segmentation method and its application in the study of nanobubble coalescence

• Yuliang Wang,
• Huimin Wang,
• Shusheng Bi and
• Bin Guo

Beilstein J. Nanotechnol. 2015, 6, 952–963, doi:10.3762/bjnano.6.98

• (MultiMode III, Digital Instruments) operating in tapping mode was used for imaging the sample. A silicon rotated force-modulated etched silicon probe (RFESP, Bruker Corporation) cantilever with a tip radius of 8 nm and a stiffness of 3 N/m was used. A modified tip holder was used for tapping mode atomic

• determine the resonance frequency of a cantilever. In this study, a tapping mode tip holder for non-fluid use in air was modified, as shown in Figure 1. A horizontal slot was carved out above the piezo element in the opening of the tip holder to insert a glass slide. When the liquid is added between the

• frequency. The measured resonance frequency in water was about 25 Hz. The free oscillation amplitude of the cantilever at the working frequency was 7.3 nm. To minimize the force applied to the samples, the setpoint was set at 95% of the free amplitude, which was 6.9 nm. The sample surface was scanned at a

Stiffness of sphere–plate contacts at MHz frequencies: dependence on normal load, oscillation amplitude, and ambient medium

• Jana Vlachová,
• Rebekka König and
• Diethelm Johannsmann

Beilstein J. Nanotechnol. 2015, 6, 845–856, doi:10.3762/bjnano.6.87

• experiments. A contact is established between a resonator (which is a quartz crystal microbalance here and is the cantilever in AFM experiments) and an external object. The geometry is configured such that the contact does not overdamp the resonance, but rather shifts the resonance frequency and the resonance

Stick–slip behaviour on Au(111) with adsorption of copper and sulfate

• Nikolay Podgaynyy,
• Sabine Wezisla,
• Christoph Molls,
• Shahid Iqbal and
• Helmut Baltruschat

Beilstein J. Nanotechnol. 2015, 6, 820–830, doi:10.3762/bjnano.6.85

• ; Introduction Atomic-scale friction processes constitute a fascinating field of research which has been opened by the invention of the atomic force microscope (AFM) [1]. The AFM allows us to determine the force necessary to move a cantilever tip laterally across the surface with atomic resolution. A theoretical

• quality factor of the cantilever. All AFM measurements were performed at room temperature. Friction force maps shown here are the difference images between both scan directions. Due to the relatively high load used in our experiments, the tip radius quickly approached a value of around 100 nm, but then

• below the figure) characterizes the effective lateral stiffness of the surface–tip contact. In our case it is 10 N/m and therefore much smaller than the lateral stiffness of the cantilever (190 N/m). The somewhat rounded shape might be due to a not completely commensurable tip–substrate contact [32

Capillary and van der Waals interactions on CaF₂ crystals from amplitude modulation AFM force reconstruction profiles under ambient conditions

• Annalisa Calò,
• Oriol Vidal Robles,
• Sergio Santos and
• Albert Verdaguer

Beilstein J. Nanotechnol. 2015, 6, 809–819, doi:10.3762/bjnano.6.84

• large tip–sample distances [12][13] and can exhibit unexpected distance dependencies [14]. Contact AFM measurements, in which the force is determined from the static deflection of the cantilever during approach [15], can readily record the tip–sample interaction force and have been used extensively to

• in air and when soft cantilevers were employed to increase the sensitivity [6][7][15][24]. Dynamic modes proved to overcome the limitations of contact measurements in detecting attractive forces [11][25][26][27]. In these modes the cantilever is mechanically driven at a fixed oscillation frequency

• measurements, as for example amplitude modulation AM-AFM measurements, is that experimental observables, i.e., the phase lag of the cantilever relative to the driving force, can be directly related to the energy dissipated in the tip–sample interaction [31][32][33]. Identifying and separating individual

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

• cantilever. In UAFM the cantilever is excited by attaching a transducer to the cantilever base. In AFAM, the transducer is placed under the sample and periodic displacements of the sample are sensed by the cantilever when in contact. Rabe et al. [4], Hurley et al. [5] have discussed in detail the development

• 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

A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

• Tobias Meier,
• Alexander Förste,
• Ali Tavassolizadeh,
• Karsten Rott,
• Dirk Meyners,
• Roland Gröger,
• Günter Reiss,
• Eckhard Quandt,
• Thomas Schimmel and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2015, 6, 451–461, doi:10.3762/bjnano.6.46

• read-out of a micro-fabricated cantilever [10][11]. However, the optical read-out contains bulky mechanical parts to focus a laser on the backside of the cantilever and to move the position sensitive photodetector (PSD) or a mirror which puts severe limits on a compact instrument design. Additionally

• , optical read-outs have to be readjusted not only after every cantilever exchange but also after temperature drifts which can offset the focal position of the laser and photo-detector due to thermal expansion. Additionally, the optical read-out can influence the cantilevers deflection by photothermal

• and set their sensitivity at maximum for imaging atomic step edges. Setup of a nonmagnetic large scan range AFM In order to characterize magnetoresistive strain sensors integrated into AFM cantilevers, the deflection of the cantilever has to be measured in parallel by independent means. Therefore, our

Influence of spurious resonances on the interaction force in dynamic AFM

• Luca Costa and
• Mario S. Rodrigues

Beilstein J. Nanotechnol. 2015, 6, 420–427, doi:10.3762/bjnano.6.42

• force microscopy is challenging, especially when measuring in liquid media. Here, we derive formulas for the tip–sample interactions and investigate the effect of spurious resonances on the measured interaction. Highlighting the differences between measuring directly the tip position or the cantilever

• deflection, and considering both direct and acoustic excitation, we show that the cantilever behavior is insensitive to spurious resonances as long as the measured signal corresponds to the tip position, or if the excitation force is correctly considered. Since the effective excitation force may depend on

• morphology during the scan. Obviously, the cantilever excitation plays a central role in AM-AFM. Conventionally, mechanical vibration of the cantilever holder is provided through the excitation of a small piezoelectric element (dither). The setup is widely employed in many commercial and custom-made AFMs and

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

• 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

• the presence of higher harmonic components in the tip motion with the presence of nonlinear interactions [15]. 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]. The tip–surface force controls the cantilever motion, however, the force itself is not an observable. Numerical simulations have been used to derive parametric approximations [24], scaling laws [25] and insights about the role of different

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

• ) mounted on an inverted optical microscope (Axiovert 200, Zeiss, Oberkochen, Germany) to localize cell position. Silicon nitride cantilever (MLCT-AUHW, Bruker, Germany) were used with a nominal force constant of ≈0.05 N/m. Imaging of cells has been carried out using a fluid-heating chamber (Biocell, JPK

• Instrument AG, Berlin, Germany) with HEPES buffered culture medium kept at 37 °C. AFM images were performed in contact mode. Before force spectroscopy measurements the exact spring constant of the used cantilever was determined by thermal noise analysis using software provided by the manufacturer. Local

• mechanical measurements were carried out on confluent MDCK II monolayers directly after imaging using the same cantilever. Force curves were collected with a z-scan velocity of 1 μm/s. Analysis of the elasticity modulus was done with a tool developed in our laboratory using IGOR Pro (WaveMetrics, Lake Oswego

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

• relatively stiff cantilevers as specified above. The routines and conditions to perform LAO-AFM in the dynamic mode have been described in [1][19]. In brief, a target location onto the Si substrate is inspected for surface cleanliness. Then, the cantilever free oscillation is set to a low amplitude value

Kelvin probe force microscopy in liquid using electrochemical force microscopy

• Liam Collins,
• Stephen Jesse,
• Jason I. Kilpatrick,
• Alexander Tselev,
• M. Baris Okatan,
• Sergei V. Kalinin and
• Brian J. Rodriguez

Beilstein J. Nanotechnol. 2015, 6, 201–214, doi:10.3762/bjnano.6.19

• second harmonic cantilever amplitude (Aω and A2ω) and phase (θω and θ2ω) using lock-in techniques. Equation 2 predicts a linear dependence of Fω with respect to the probe–sample DC bias, which is minimized when Vdc = Vcpd. KPFM employs this principle via a feedback loop to minimize Aω. Depending on the

• . Raiteri et al. reported similar hysteretic behavior in the static electrochemical stress experienced for biased Au electrodes in a variety of electrolytes [54]. Umeda et al. also observed similar hysteresis in this bias range for a cantilever above a platinum surface in water [55]. For all bias sweeps

• electrode. In OLBS measurements, when using bias sweeps larger than 2 V, large changes in the AFM cantilever deflection signal occurred (not shown), often followed by visible bubble nucleation in the probe–sample gap (e.g., Figure 1f). Attempts at implementing KPFM in ionically-active liquids will often

Increasing throughput of AFM-based single cell adhesion measurements through multisubstrate surfaces

• Miao Yu,
• Nico Strohmeyer,
• Jinghe Wang,
• Daniel J. Müller and
• Jonne Helenius

Beilstein J. Nanotechnol. 2015, 6, 157–166, doi:10.3762/bjnano.6.15

• SCFS, a single cell is attached to a cantilever (Figure 1A,B), commonly facilitated by an adhesive coating (e.g., concanavalin A, poly-L-lysine or CellTak) [17][18][19][20][21][22]. The attached cell is lowered (approach) onto a substrate (Figure 1A(i)), which is a protein-coated surface, another cell

• or a biomaterial [23], until a set force is reached and the cell is kept stationary for a set time to allow the formation of adhesive interactions (Figure 1A(ii)). During the subsequent raising (retraction) of the cantilever (Figure 1A(iii)), the force acting on the cell and the distance between cell

• and substrate is recorded in a force–distance curve (Figure 1C). The force range that can be detected with AFM-based SCFS is from ≈10 pN up to ≈100 nN [14], thereby, SCFS allows both the overall cell adhesion and the contribution of single adhesion receptors to be quantified. During initial cantilever

Accurate, explicit formulae for higher harmonic force spectroscopy by frequency modulation-AFM

• Kfir Kuchuk and
• Uri Sivan

Beilstein J. Nanotechnol. 2015, 6, 149–156, doi:10.3762/bjnano.6.14

• Kfir Kuchuk Uri Sivan Department of Physics and The Russell Berrie Nanotechnology Institute, Technion – Israel Institute of Technology, Haifa 32000, Israel 10.3762/bjnano.6.14 Abstract The nonlinear interaction between an AFM tip and a sample gives rise to oscillations of the cantilever at

• generated by the nonlinear tip–surface interaction (to be distinguished from higher flexural modes of the cantilever) are related to higher derivatives of the force, and thus carry additional information on the interaction [5][6][7][8][9][10][11]. Broad implementation of force spectroscopy by analysing

• formulae for both conservative and dissipative forces. In FM-AFM, a cantilever is oscillated at its resonance frequency using an external driving force and a feedback loop. The motion of the cantilever is often modelled as a driven damped harmonic oscillator with an additional force, Fts, stemming from tip

Multifunctional layered magnetic composites

• Maria Siglreitmeier,
• Baohu Wu,
• Tina Kollmann,
• Martin Neubauer,
• Gergely Nagy,
• Dietmar Schwahn,
• Vitaliy Pipich,
• Damien Faivre,
• Dirk Zahn,
• Andreas Fery and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2015, 6, 134–148, doi:10.3762/bjnano.6.13

• , Germany). All measurements were performed in Milli-Q-water at room temperature. As a probe a tipless silicon nitride cantilever (NSC 12, no Al coating, MikroMasch, Tallinn, Estonia) was used with a glass sphere (35 µm in diameter, Polysciences Europe GmbH, Eppelheim, Germany) attached to its front

• of the cantilever from the raw displacement data. The spring constant of the cantilever (0.56 N/m) was deduced from its thermal noise spectrum prior to the attachment of the colloidal probe [66]. Magnetite formation inside a gelatin gel matrix (grey) that is placed inside the chitin scaffold of

The capillary adhesion technique: a versatile method for determining the liquid adhesion force and sample stiffness

• Daniel Gandyra,
• Stefan Walheim,
• Stanislav Gorb,
• Wilhelm Barthlott and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2015, 6, 11–18, doi:10.3762/bjnano.6.2

• cantilevers, reproducing the spring constants calibrated using other methods. Keywords: adhesion; AFM cantilever; air layer; capillary forces; hairs; measurement; micromechanical systems; microstructures; Salvinia effect; Salvinia molesta; sensors; stiffness; superhydrophobic surfaces; Introduction Surface

• . Validating the capillary adhesion technique using calibrated AFM cantilevers A proof of the validity of the CAT method is given by examining a calibrated atomic force microscopy (AFM) cantilever. The cantilever was studied under the same conditions as the human head hairs (i.e., the chip on which the

• cantilever was attached was approximately horizontally fixed (11°) in the tweezers, see Figure 5). 15 independent measurements of the same calibrated cantilever were performed using the CAT, resulting in an average value for the water adhesion force of the cantilever tip of (11.8 ± 0.4 ± 0.3) µN and a spring

High-frequency multimodal atomic force microscopy

• Adrian P. Nievergelt,
• Jonathan D. Adams,
• Pascal D. Odermatt and
• Georg E. Fantner

Beilstein J. Nanotechnol. 2014, 5, 2459–2467, doi:10.3762/bjnano.5.255

• topography as well as mechanical properties. Nevertheless, instrument bandwidth limitations on cantilever excitation and readout have restricted the ability of multifrequency techniques to fully benefit from small cantilevers. We present an approach for cantilever excitation and deflection readout with a

• mechanical information by using AFM, opening up new possibilities for biology and materials science [1][2][3][4][5][6][7][8][9]. A key enabling trend in the technological development of AFM has been the drive to minimize the cantilever size and maximize the resonance frequency, while maintaining acceptable

• spring constants [10][11][12]. Increasing the cantilever resonance frequency enables faster imaging and force spectroscopy [12][13][14][15][16][17], and small, high-frequency AFM cantilevers have less viscous drag, lowering force noise [18]. Many of the techniques for extracting mechanical information

Nanobioarchitectures based on chlorophyll photopigment, artificial lipid bilayers and carbon nanotubes

• Marcela Elisabeta Barbinta-Patrascu,
• Stefan Marian Iordache,
• Ana Maria Iordache,
• Nicoleta Badea and
• Camelia Ungureanu

Beilstein J. Nanotechnol. 2014, 5, 2316–2325, doi:10.3762/bjnano.5.240

• Prima, NT-MDT, USA) in semi-contact mode (scanning area range 1.2 × 1.2 µm2) using an NSG01 cantilever with a typical radius of curvature of 10 nm. All AFM measurements were obtained on samples deposited on Si plate substrates. Chemiluminescence (CL) assay The in vitro antioxidant activity of the

Modeling viscoelasticity through spring–dashpot models in intermittent-contact atomic force microscopy

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 2149–2163, doi:10.3762/bjnano.5.224

• techniques operate in a regime of quasi-linear tip–sample forces by using very small cantilever oscillation amplitudes, but as a result only provide linear viscoelasticity information and characterization can be slow for CR-AFM and BE-AFM due to the pixel-based measurement procedures used. Significant

• the cantilever to the surface during approach) and the energy output (energy returned by the surface to the cantilever during retract). In spring–dashpot models this gap is caused by the relief of some of the stress accumulated in the springs through the dashpots. Another advantage of the Linear

• coefficient of the damper (cd), since the force in a linear dashpot is given by F = cd × v. Since the tip approaches the sample with a velocity governed by the imaging and cantilever parameters, the sample surface experiences an instantaneous velocity immediately upon contact, which gives rise to the sudden

Optical properties and electrical transport of thin films of terbium(III) bis(phthalocyanine) on cobalt

• Peter Robaschik,
• Pablo F. Siles,
• Daniel Bülz,
• Peter Richter,
• Manuel Monecke,
• Michael Fronk,
• Svetlana Klyatskaya,
• Daniel Grimm,
• Oliver G. Schmidt,
• Mario Ruben,
• Dietrich R. T. Zahn and
• Georgeta Salvan

Beilstein J. Nanotechnol. 2014, 5, 2070–2078, doi:10.3762/bjnano.5.215

• of 0.2 N/m and typical radii of about 20–25 nm. The voltage is applied directly to the bottom Co electrode. The grounded conductive cantilever is therefore used as a top electrode for local I–V spectroscopy as well as current mapping experiments. AFM topography analysis and current maps images were

Dissipation signals due to lateral tip oscillations in FM-AFM

• Michael Klocke and
• Dietrich E. Wolf

Beilstein J. Nanotechnol. 2014, 5, 2048–2057, doi:10.3762/bjnano.5.213

• microscopy. The coupling is induced by the interaction between tip and surface. Energy is transferred from the normal to the lateral excitation, which can be detected as damping of the cantilever oscillation. However, energy can be transferred back into the normal oscillation, if not dissipated by the

• -effect of the FM-AFM principle. The height (the topography) of a point on the surface is measured by shifting the probe such that the resonant frequency of the cantilever oscillation is detuned by a given amount due to surface–tip interactions. The amplitude is kept constant, which requires to drive the

• oscillation. Energy loss of the oscillation occurs not only due to mechanical damping of the cantilever, but also due to interaction between tip and surface, so that the damping signal can be used for imaging, even with atomic resolution [4]. There is a broad consensus, that the observed dissipation is due to