Two dynamic modes to streamline challenging atomic force microscopy measurements

• Alexei G. Temiryazev,
• Andrey V. Krayev and
• Marina P. Temiryazeva

Beilstein J. Nanotechnol. 2021, 12, 1226–1236, doi:10.3762/bjnano.12.90

• classical contact mode, the friction force can be measured; when using off-resonance dynamic modes, stiffness and adhesion in the samples can be determined. Obviously, in determining the mechanical properties, the force of tip–surface interaction should be somewhat greater than that required if the task is

Open-loop amplitude-modulation Kelvin probe force microscopy operated in single-pass PeakForce tapping mode

• Gheorghe Stan and
• Pradeep Namboodiri

Beilstein J. Nanotechnol. 2021, 12, 1115–1126, doi:10.3762/bjnano.12.83

• oscillations is shown in Figure 2. The raw PFT signal (gray curve in Figure 2) is especially noisy right after each detachment of the AFM probe from contact due to the relative compliance of the probe used, with a nominal stiffness of 3.0 N/m and first resonance frequency of 67 kHz. This extra high-frequency

The role of convolutional neural networks in scanning probe microscopy: a review

• Ido Azuri,
• Irit Rosenhek-Goldian,
• Neta Regev-Rudzki,
• Georg Fantner and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2021, 12, 878–901, doi:10.3762/bjnano.12.66

• topography, for example, adhesion, phase shift, stiffness, work function, or friction. In the following section, the utility of CNN in SPM is illustrated through several examples taken from the literature. Enhancing speed of image acquisition As discussed above, SPM imaging is inherently slow. One of the

• quantities, that is, frequency (giving the stiffness), amplitude (giving the piezoresponse), Q (dissipation), and phase (directionality of polarization). PFM can map piezoelectric domains and the inverse piezoresponse of a sample, but signals are notoriously low. In this work, two arrays (real and imaginary

• blind reconstruction [136]. A common means to distinguish between healthy and sick cells is the elastic modulus, determined by measuring the stiffness with AFM force–distance curves and then fitting to a model. Several works have applied machine learning to analysis of the force curves. The data here is

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

• Sepand Tehrani Fateh,
• Lida Moradi,
• Elmira Kohan,
• Michael R. Hamblin and
• Amin Shiralizadeh Dezfuli

Beilstein J. Nanotechnol. 2021, 12, 808–862, doi:10.3762/bjnano.12.64

• ) gas-filled structures that are stabilized by a lipid, surfactant, protein, or polymer shell, whose stiffness or rigidity can affect the final outcome of the MBs upon exposure to US [71][72][73]. During the cavitation event, backscattered energy leads to the expanding and shrinking of the MBs, which

Reducing molecular simulation time for AFM images based on super-resolution methods

• Zhipeng Dou,
• Jianqiang Qian,
• Yingzi Li,
• Rui Lin,
• Jianhai Wang,
• Peng Cheng and
• Zeyu Xu

Beilstein J. Nanotechnol. 2021, 12, 775–785, doi:10.3762/bjnano.12.61

• virtual atom is added above the tip apex and they are connected with a spring in the z-direction. The virtual atom is excited by a sinusoidal signal, mimicking the acoustic excitation of AM-AFM. The excited frequency is adjusted by the spring stiffness. A damping force is applied on the tip to ensure the

Physical constraints lead to parallel evolution of micro- and nanostructures of animal adhesive pads: a review

• Thies H. Büscher and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2021, 12, 725–743, doi:10.3762/bjnano.12.57

• influence of different factors, such as substrate roughness and pad stiffness, on contact forces, and review the chemical composition of pad fluids, which is an important component of an adhesive function. Attachment systems are omnipresent in animals. We show parallel evolution of attachment structures on

• contact with a wide range of microscopically rough substrate profiles (Figure 2). Also, due to the low bending stiffness of their terminal plates, can even adapt to substrates with roughness on a sub-nanometre scale [1][3][4][34]. Smooth pads can also maximise their contact areas with a variety of

• spatula, terminating tips of the cuticle outgrowths in hairy systems form the superficial film. These films are responsible for proper contact formation with the substrate due to their low bending stiffness at a minimum load [239]. The film/spatula is able to adapt to the surface profile and to replicate

Local stiffness and work function variations of hexagonal boron nitride on Cu(111)

• Abhishek Grewal,
• Yuqi Wang,
• Matthias Münks,
• Klaus Kern and
• Markus Ternes

Beilstein J. Nanotechnol. 2021, 12, 559–565, doi:10.3762/bjnano.12.46

• the contact potential difference measured by Kelvin probe force microscopy. Using 3D force profiles of the same area we determine the relative stiffness of the Moiré region allowing us to analyse both electronic and mechanical properties of the 2D layer simultaneously. We obtain a sheet stiffness of

• -BN/Cu(111) substrate. Keywords: decoupling layers; hexagonal boron nitride; local stiffness; Moiré superstructure; work function variation; Introduction Two-dimensional hexagonal boron nitride (h-BN) is among the list of materials that garnered tremendous interest following the exfoliation of mono

• - and few-layer thick graphene films [1][2]. Unique properties, such as high thermal stability and conductivity, immense intra-sheet stiffness, and excellent dielectric properties, make h-BN interesting for technological applications. For example, thin films of h-BN have been used as a passivating layer

Determining amplitude and tilt of a lateral force microscopy sensor

• Oliver Gretz,
• Alfred J. Weymouth,
• Thomas Holzmann,
• Korbinian Pürckhauer and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2021, 12, 517–524, doi:10.3762/bjnano.12.42

• in Figure 1b [8]. In our group, we have used this method to quantify molecular stiffness at low temperature [9] and to evaluate the potential energy landscape above a molecule at room temperature [10]. More recently, we used LFM with a CO-terminated tip to investigate the internal structure of a

• related to the sensor parameters and the weighted average of the force gradient over the tip oscillation, ⟨kts⟩(x0, z0), where x0 and z0 define the average tip position over one oscillation cycle [14]: Here, f0 is the resonance frequency of the sensor away from the surface and k is the stiffness of the

Exploring the fabrication and transfer mechanism of metallic nanostructures on carbon nanomembranes via focused electron beam induced processing

• Christian Preischl,
• Linh Hoang Le,
• Elif Bilgilisoy,
• Armin Gölzhäuser and
• Hubertus Marbach

Beilstein J. Nanotechnol. 2021, 12, 319–329, doi:10.3762/bjnano.12.26

• arbitrary substrates or grids to obtain free-standing 2D membranes [25]. The specific choice of the self-assembling molecules determines the thickness, porosity, stiffness, and the mechanical/electrical properties of the resulting CNM [26][27]. The SAMs that are used for the fabrication of CNMs consist of

The nanomorphology of cell surfaces of adhered osteoblasts

• Christian Voelkner,
• Mirco Wendt,
• Regina Lange,
• Max Ulbrich,
• Martina Gruening,
• Susanne Staehlke,
• Barbara Nebe,
• Ingo Barke and
• Sylvia Speller

Beilstein J. Nanotechnol. 2021, 12, 242–256, doi:10.3762/bjnano.12.20

• stiffness of the ruffle structure, even when a harder (fixed) protein content is present. Note that for living cells such contrast is absent as can be seen in Figure 3c and Figure 3d. Figure 4a shows an example of a peripheral ruffle. Peripheral ruffles sometimes are attributed to loosened lamellipodia

Determination of elastic moduli of elastic–plastic microspherical materials using nanoindentation simulation without mechanical polishing

• Hongzhou Li and
• Jialian Chen

Beilstein J. Nanotechnol. 2021, 12, 213–221, doi:10.3762/bjnano.12.17

• the maximum displacement hmax (the maximum displacement of the indenter relative to the initial undeformed surface), and the third is the unloading stiffness. The initial unloading stiffness is used to extract the elastic modulus of the specimen via the well-known Oliver–Pharr method [3][4]. Cheng and

• that the shear modulus is equal to E/[2(1 + ν)], differentiating P with respect to h leads to where S = dP/dh is the initial stiffness of the unloading curve, defined as the slope of the upper portion of the unloading curve during the initial stages of unloading (also called contact stiffness), and E

• . Knowing the contact depth and the shape of the indenter, determined through the “area function”, the contact area is then determined. If contact stiffness and contact area are known, Equation 3 and Equation 4 can be used to determine the elastic modulus of a material. Effects of non-rigid indenters on the

Numerical analysis of vibration modes of a qPlus sensor with a long tip

• Kebei Chen,
• Zhenghui Liu,
• Yuchen Xie,
• Chunyu Zhang,
• Gengzhao Xu,
• Wentao Song and
• Ke Xu

Beilstein J. Nanotechnol. 2021, 12, 82–92, doi:10.3762/bjnano.12.7

• contributes to Δf. If φ < 45°, the lateral force gradient has a greater impact. For most cases, it is desirable to detect a larger vertical force gradient signal, so we need Ax/Az < 1. The in-phase modes were found to fulfil this requirement. Thirdly, we want the stiffness of the qPlus sensor to be large

• enough to allow for a stable small-amplitude operation [1]. The equivalent stiffness keq of the qPlus sensor is shown in Figure 8, which is calculated from the strain energy and the tip amplitude with an equivalent point-mass model [28]. We see in Figure 8c that for a 0.075 mm tip, there is an optimal

• slightly higher than that measured in atmosphere due to less air damping. Equivalent stiffness keq of the qPlus sensor as a function of the tip length depicted for the four different tip diameters. Q factor as a function of the tip length depicted for the four different tip diameters. Material parameters

Bulk chemical composition contrast from attractive forces in AFM force spectroscopy

• Dorothee Silbernagl,
• Media Ghasem Zadeh Khorasani,
• Natalia Cano Murillo,
• Anna Maria Elert and
• Heinz Sturm

Beilstein J. Nanotechnol. 2021, 12, 58–71, doi:10.3762/bjnano.12.5

• of atomic force microscopy (AFM) is the measurement of physical properties at sub-micrometer resolution. Methods such as force–distance curves (FDCs) or dynamic variants (such as intermodulation AFM (ImAFM)) are able to measure mechanical properties (such as the local stiffness, kr) of nanoscopic

• described by yielding a dimensionless relative spring constant (or stiffness) kr, with kr ≤ 1. A detailed derivation of kr and a discussion regarding this parameter can be found in Supporting Information File 1. For a sample that is not measurably deformed by the applied force (k >> kc), kr ≈ 1. This is the

• case when the sample is stiffer than the experimental setup, which marks the limitation of the method. Compliant or soft samples yield a stiffness value kr < 1; the lower the value the softer/more compliant the sample. The evaluation of this parameter is shown in Figure 2b, again for averaged example

Nanomechanics of few-layer materials: do individual layers slide upon folding?

• Ronaldo J. C. Batista,
• Rafael F. Dias,
• Ana P. M. Barboza,
• Alan B. de Oliveira,
• Taise M. Manhabosco,
• Thiago R. Gomes-Silva,
• Matheus J. S. Matos,
• Andreij C. Gadelha,
• Cassiano Rabelo,
• Luiz G. L. Cançado,
• Ado Jorio,
• Hélio Chacham and
• Bernardo R. A. Neves

Beilstein J. Nanotechnol. 2020, 11, 1801–1808, doi:10.3762/bjnano.11.162

• mechanical properties of folded edges, which allows for the experimental determination of the bending stiffness (κ) of multilayered 2D materials as a function of the number of layers (n). In the case of talc, we obtain κ ∝ n3 for n ≥ 5, indicating no interlayer sliding upon folding, at least in this

• all those cases, the interlayer adhesion energy (α), the substrate adhesion energy (αs), and the bending stiffness (κ) govern folding, sliding, and wrinkling of 2D materials, which are ultimately responsible for those unusual kinds of behavior. α is intimately related to tribological properties of

• of the folds in the suspended graphene [17]. After the successful synthesis of graphene in 2004 [1], many other 2D materials have been produced [12][18][19][20][21][22][23]. The investigation of their bending stiffness as a function of thickness, interlayer adhesion energy, and adhesion energy on

Application of contact-resonance AFM methods to polymer samples

• Sebastian Friedrich and
• Brunero Cappella

Beilstein J. Nanotechnol. 2020, 11, 1714–1727, doi:10.3762/bjnano.11.154

• underlying physical phenomena and of factors influencing the measurements. A commonly used method to analyze CR data requires the determination of the relative position of the tip, the calculation of the normalized contact stiffness, and the use of a calibration sample for the calculation of the elastic

• stiffness prompts an increase of the contact-resonance frequency (CR frequency). The CR frequency can be obtained from single-point measurements or tracked during scanning with techniques such as dual AC resonance tracking (DART) [6][7]. The vibrational motion of the cantilever is usually described using

• interactions. Such models allow one to calculate the contact stiffness from the measured CR frequency. Then, from the contact stiffness, the elastic modulus of the sample can be determined. This technique has been successfully applied on rather stiff materials such as silicon [11] or chalcogenide glasses [12

Design of V-shaped cantilevers for enhanced multifrequency AFM measurements

• Mehrnoosh Damircheli and
• Babak Eslami

Beilstein J. Nanotechnol. 2020, 11, 1525–1541, doi:10.3762/bjnano.11.135

• dynamics of the cantilever more accurately. Wang et al. have used the finite element method (FEM) as an alternative approach to obtain the stiffness and the natural frequencies of for both rectangular and V-shaped cantilevers [9]. Additionally, other studies were done by Cleveland et al. [10] to measure

• the stiffness of AFM cantilevers. Later on, Sader et al. developed a nondestructive method for the evaluation of the spring constant, which relies solely on the determination of the unloaded resonant frequency of the cantilever [11]. This work was in contrast to the method of Cleveland et al., which

• stiffness and high lateral stiffness. Therefore, they can apply low forces to soft matter in normal mode while having a stable lateral mode. Additionally, their high lateral stiffness is advantageous in nanomanipulation applications moving particles over surfaces [12]. Morris stated in his book that

Protruding hydrogen atoms as markers for the molecular orientation of a metallocene

• Linda Laflör,
• Michael Reichling and
• Philipp Rahe

Beilstein J. Nanotechnol. 2020, 11, 1432–1438, doi:10.3762/bjnano.11.127

• atoms were used as probe particles and frequency-shift Δf data were calculated for an oscillation amplitude of 0.5 nm. Lateral and vertical stiffness were chosen as 0.5 and 20 N/m, respectively. FDCA molecular models in the DFT-optimised geometries (using geo 1 and geo 2 from [22], see Figure 1a,b) were

• shown in Figure 2o,p. We use Lennard-Jones parameters for CO and Xe tips, a neutral probe particle, and stiffness values of (kx, ky, kz) = (0.5, 0.5, 20) N/m, yielding the results for CO reproduced in Figure 2f–i and for Xe in Figure 2k–n at the same heights. Both series of images exhibit a remarkable

On the frequency dependence of viscoelastic material characterization with intermittent-contact dynamic atomic force microscopy: avoiding mischaracterization across large frequency ranges

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

Beilstein J. Nanotechnol. 2020, 11, 1409–1418, doi:10.3762/bjnano.11.125

• cantilever with a resonance frequency of 350 kHz and a force constant of 0.5 N/m does not correspond to a realistic situation, as such high-frequency/low-stiffness cantilevers are not used in AFM. However, this example is included because it provides physical insight into the frequency dependence of

• of intricacies in the materials, which can have multiple stiffness contributions and multiple relaxation timescales, as in the above examples, while the interplay and relative dominance of their viscoelastic contributions (e.g., the different arms in the Maxwell model) varies greatly with deformation

• cantilevers used to properly characterize it. However, one should be surprised to see hardly any hysteresis in the force trajectory of material 2 despite its obvious viscoelastic nature depicted in Figure 2. One must therefore consider whether the cantilever stiffness used is appropriate, since the force

An atomic force microscope integrated with a helium ion microscope for correlative nanoscale characterization

• Santiago H. Andany,
• Gregor Hlawacek,
• Stefan Hummel,
• Charlène Brillard,
• Mustafa Kangül and
• Georg E. Fantner

Beilstein J. Nanotechnol. 2020, 11, 1272–1279, doi:10.3762/bjnano.11.111

• used, in situ, in between exposures to assess the shrinkage, stiffness change or sputtering of the resist. More applications such as conductive AFM, piezo-force microscopy or magnetic force microscopy are within reach of the presented technology and would make AFM–HIM appealing to the microelectronics

• reported tip-scanning AFM includes the AFM scan head, coarse stage and stationary sample stage. However, after integration with the HIM, stiffness is degraded through the incorporation of the HIM cradle, the four-axis sample stage, and the mounting bracket to the mechanical loop. This reduces rigidity and

Ultrasensitive detection of cadmium ions using a microcantilever-based piezoresistive sensor for groundwater

• Dinesh Rotake,
• Anand Darji and
• Nitin Kale

Beilstein J. Nanotechnol. 2020, 11, 1242–1253, doi:10.3762/bjnano.11.108

• vapor deposition (LPCVD) furnace at 630 °C and boron doping (1018 per cm3) is carried out using ion implantation at 35 keV. The upper SiO2 layer is formed by re-oxidizing the polysilicon in an oxidation furnace [40]. The stiffness (k) of the fabricated piezoresistive sensor measured using AFM is 131–146

• mN/m, which is well below the stiffness required for BioMEMS applications (1000 mN/m [41][42]). COMSOL 5.3 software is used to perform design and simulation of the piezoresistive sensor to optimize the dimensions for better stiffness and sensitivity [43]. The fabricated piezoresistive sensor layer

Thermophoretic tweezers for single nanoparticle manipulation

• Jošt Stergar and
• Natan Osterman

Beilstein J. Nanotechnol. 2020, 11, 1126–1133, doi:10.3762/bjnano.11.97

• potential is symmetric in x- and y-directions. With the aim of comparing the trap stiffness with that of optical tweezers we have introduced a parabolic approximation of the potential around the minimum. It is important to note, however, that true form of the potential is not harmonic, but rather approaches

• constant force potential at larger distances, which is due to the feedback loop methodology. From the fit of parabolic function U(x) = kx2 we obtained the trap stiffness coefficient k = 1.47kBT/µm2 = 6.0 fN/µm. Larger particles are even easier to trap due to their lower diffusion and higher Soret

• coefficient. For 1 μm diameter polystyrene beads in the same solution (D = 0.5 µm2/s and ST = 10/K) we obtained k = 15kBT/µm2 = 61.5 fN/µm, which is a value approximately 2 to 3 orders of magnitude lower than the stiffness of typical optical tweezers experiments. The stiffness of a parabolic trapping

Vibration analysis and pull-in instability behavior in a multiwalled piezoelectric nanosensor with fluid flow conveyance

• Sayyid H. Hashemi Kachapi

Beilstein J. Nanotechnol. 2020, 11, 1072–1081, doi:10.3762/bjnano.11.92

• case of higher surface/interface density (case 1), the inertia of the shell is increased and its stiffness is reduced, which leads to a decreased DNF compared to the case without surface/interface effects. Also, with decreasing surface/interface density (case 2), the inertia of the system is increased

• , and with increasing stiffness, DNF increases compared to the case without surface/interface effects. In all of the following results, the lower surface/interface density (case 2) is used in the analysis of DNF on viscous fluid velocity and pull-in voltage The effects of viscous fluid velocity and

• constants, and for viscous fluid velocity and pull-in instability analysis on DNF of FC-MWPENS. It is clear that the increasing surface/interface Lame’s constants λI,S, due to increasing FC-MWPENS stiffness, DNF and critical fluid velocity increase and pull-in voltage in λI,S = 0 and λI,S = −2 has a

Extracting viscoelastic material parameters using an atomic force microscope and static force spectroscopy

• Cameron H. Parvini,
• M. A. S. R. Saadi and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 922–937, doi:10.3762/bjnano.11.77

• produce large errors when estimating the surface stiffness, leading to poor and inconsistent data quality. To avoid complex analytical derivations, it can be convenient to ignore well-established viscoelastic models in favor of elastic relationships. Unfortunately, these equations are sometimes

• using the cantilever stiffness (kc), the minimum deflection offsets (z0, d0), the deflection (d(t)), and the following relations: where kc in Equation 14 is the AFM cantilever stiffness. This data is not used directly in the fit, but can be useful for showing the indentation and force during the

Band tail state related photoluminescence and photoresponse of ZnMgO solid solution nanostructured films

• Vadim Morari,
• Aida Pantazi,
• Nicolai Curmei,
• Vitalie Postolache,
• Emil V. Rusu,
• Marius Enachescu,
• Ion M. Tiginyanu and
• Veaceslav V. Ursaki

Beilstein J. Nanotechnol. 2020, 11, 899–910, doi:10.3762/bjnano.11.75

• tapping mode with a SOLVER Next (NT-MDT) instrument equipped with cone-shaped tips from monocrystalline silicon (tip radius ≈ 10 nm) on cantilevers with a stiffness of about 17 N/m. The root mean square (RMS) roughness parameters were calculated from the acquired topographic images using image processing

Integrated photonics multi-waveguide devices for optical trapping and Raman spectroscopy: design, fabrication and performance demonstration

• Gyllion B. Loozen,
• Arnica Karuna,
• Mohammad M. R. Fanood,
• Erik Schreuder and
• Jacob Caro

Beilstein J. Nanotechnol. 2020, 11, 829–842, doi:10.3762/bjnano.11.68

• -waveguide and a 16-waveguide device, using 1 and 3 μm polystyrene beads. Study of the confined Brownian motion of the trapped beads yields experimental values of the normalized trap stiffness for the in-plane directions. The stiffness values for the 16-waveguide device are comparable to those of tightly

• Figure 4b. Assuming that the traps are harmonic and using the equipartition theorem [13], we may write . Here kx(y) is the trap stiffness for the in-plane directions, σΔx(Δy) is the standard deviation of the Gaussian curve describing the 1D histogram reflecting the bead position for these directions, kB

• yields the normalized experimental trap stiffness kx(y),exp,n (unit: pN·nm−1·W−1), a quantity suitable for comparison. The resulting values of kx(y),exp,n are compiled in Table 1, along with the values of kx(y),sim,n obtained from the force–distance relations derived from the FDTD simulations of the type