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

Quantitative determination of the interaction potential between two surfaces using frequency-modulated atomic force microscopy

• Nicholas Chan,
• Carrie Lin,
• Tevis Jacobs,
• Robert W. Carpick and
• Philip Egberts

Beilstein J. Nanotechnol. 2020, 11, 729–739, doi:10.3762/bjnano.11.60

• high mechanical stiffness, chemical inertness and stability, and interest for tribological applications [38]. It also is a good representation for other hard engineering materials and coatings, including having a low but finite surface roughness, as specified below. Spectroscopy measurements were

• represents the primary flexural resonance frequency of the cantilever far from the surface, k represents the probe stiffness, a represents the amplitude of oscillation, F represents the tip–sample interaction force, and z represents the smallest separation distance between the tip and sample during

Stochastic excitation for high-resolution atomic force acoustic microscopy imaging: a system theory approach

• Edgar Cruz Valeriano,
• José Juan Gervacio Arciniega,
• Christian Iván Enriquez Flores,
• Susana Meraz Dávila,
• Joel Moreno Palmerin,
• Martín Adelaido Hernández Landaverde,
• Yuri Lizbeth Chipatecua Godoy,
• Aime Margarita Gutiérrez Peralta,
• Rafael Ramírez Bon and
• José Martín Yañez Limón

Beilstein J. Nanotechnol. 2020, 11, 703–716, doi:10.3762/bjnano.11.58

• of force–displacement curves or of contact resonance frequencies. The techniques based on force–displacement curves are ideal when the stiffness of the cantilever and the sample are similar. The techniques based on contact resonance frequencies are appropriate when the stiffness of the sample

• material is larger than the cantilever stiffness. When the tip is out of contact, the resonance modes occur at specific frequencies, which depend on the geometrical and material properties of the cantilever. And when the tip touches the sample material, the frequencies of the resonance modes increase due

• deflection signal from the photodiodes of the AFM equipment. The classical Euler–Bernoulli beam equation is used, which is expressed by Vázquez et al. as [27][28][29]: where EI is the flexural stiffness, c is the damping due to viscous friction, m is the mass per unit length and z(x,t) is the deflection of

Comparison of fresh and aged lithium iron phosphate cathodes using a tailored electrochemical strain microscopy technique

• Matthias Simolka,
• Hanno Kaess and
• Kaspar Andreas Friedrich

Beilstein J. Nanotechnol. 2020, 11, 583–596, doi:10.3762/bjnano.11.46

• additional mechanical (stiffness, elasticity), electrical (conductivity, surface potential), electrochemical (reactivity, mobility and activity), mechanoelectrical (piezoelectricity) and chemical (chemical bonding) material properties. In situ AFM imaging of the sample topography is often used to study the

• might result from material stiffness or elasticity because these material properties influence the volume expansion. Harder materials are assumed to show a smaller surface displacement (and thus smaller volume expansion) than softer materials. Analysis of the elasticity of the cathode materials was

Examination of the relationship between viscoelastic properties and the invasion of ovarian cancer cells by atomic force microscopy

• Mengdan Chen,
• Jinshu Zeng,
• Weiwei Ruan,
• Zhenghong Zhang,
• Yuhua Wang,
• Shusen Xie,
• Zhengchao Wang and
• Hongqin Yang

Beilstein J. Nanotechnol. 2020, 11, 568–582, doi:10.3762/bjnano.11.45

• migration and invasion are the two key processes leading to the spread of cancer cells from primary tumors to distant organs during tumor metastasis [12][13]. They are largely related to cytoskeleton structure [14][15]. In addition, stiffness and deformation of cells are strongly regulated by the

• . The results are consistent with previous reports that the stiffness of normal cells is higher than that of breast cancer cells [35]. Therefore, the elasticity could be considered as an effective indicator to differentiate the state of tumor development. Another important characteristic is viscosity

• changes of viscoelastic results by AFM, indicating the relationship between migratory potential and viscoelastic properties of ovarian cancer cells. Zhou et al. found that Hey HM cells exhibited a higher migration capacity than NM cells, also indicating that the difference in stiffness in Hey A8 cells

Current measurements in the intermittent-contact mode of atomic force microscopy using the Fourier method: a feasibility analysis

• Berkin Uluutku and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 453–465, doi:10.3762/bjnano.11.37

• investigated using a custom-made, low-frequency, high-stiffness cantilever [22]. Another example is the work of Vecchiola et al. where a “pulsed force” microscopy approach was implemented, rather than traditional ICM-AFM [23]. Although the end result was intermittent-contact characterization, due to the nature

• effective mass of the cantilever, f0 its natural frequency, k its stiffness and Q its quality factor: Fexcitation is the sinusoidal driving force and the tip–sample interaction force, Finteraction, is based on the Hamaker equation [42]. The simulation parameters are provided in Table 1. In the power

Rational design of block copolymer self-assemblies in photodynamic therapy

• Maxime Demazeau,
• Laure Gibot,
• Anne-Françoise Mingotaud,
• Patricia Vicendo,
• Clément Roux and
• Barbara Lonetti

Beilstein J. Nanotechnol. 2020, 11, 180–212, doi:10.3762/bjnano.11.15

Nonclassical dynamic modeling of nano/microparticles during nanomanipulation processes

• Moharam Habibnejad Korayem,
• Ali Asghar Farid and
• Rouzbeh Nouhi Hefzabad

Beilstein J. Nanotechnol. 2020, 11, 147–166, doi:10.3762/bjnano.11.13

• cantilever frequencies to contact stiffness and investigated the variation of sensitivity with cantilever slope [3][4]. Shi and Zhao examined the contact models at the nanoscale and compared Derjaguin–Muller–Toporov (DMT), Johnson–Kendall–Roberts–Sperling (JKRS) and Maugis–Dugdale (MD) models with the Hertz

• . The results showed that for a lower contact stiffness, the sensitivity of V-shaped cantilevers based on MCST is less than that based on classical theory. They concluded that stiffer cantilevers are suitable for scanning stiffer plates while softer cantilevers, which have a higher sensitivity, could be

• considerable importance. Korayem and Saraee studied the effective forces in three-dimensional (3D) manipulation of biological nanoparticles for the first time. The simulation results were compared with those obtained from modeling the gold nanoparticle manipulation. In addition, the 3D stiffness matrix for a

A review of demodulation techniques for multifrequency atomic force microscopy

• David M. Harcombe,
• Michael G. Ruppert and
• Andrew J. Fleming

Beilstein J. Nanotechnol. 2020, 11, 76–91, doi:10.3762/bjnano.11.8

• provide further nanomechanical sample information. These include properties such as sample elasticity, stiffness and adhesiveness [17], which are mapped simultaneously with the topography. Acquiring these observables requires the accurate demodulation of amplitude and phase of multiple frequency

Fully amino acid-based hydrogel as potential scaffold for cell culturing and drug delivery

• Dávid Juriga,
• Evelin Sipos,
• Orsolya Hegedűs,
• Gábor Varga,
• Miklós Zrínyi,
• Krisztina S. Nagy and
• Angéla Jedlovszky-Hajdú

Beilstein J. Nanotechnol. 2019, 10, 2579–2593, doi:10.3762/bjnano.10.249

• with different swelling properties (and also different stiffness). The PSI-based gels show a low swelling degree at pH 8 due to the hydrophobic character of the PSI backbone (Figure 2a). Since PSI is insoluble in water, the Huggins interaction parameter increases in an aqueous medium, hence, the gels

• hydrogels. Relationship between the mechanical properties and the chemical constitution of the gels The stiffness of the hydrogel scaffold is a key parameter in the field of tissue engineering. It was described previously that different cell types prefer gels of different stiffness for proliferation [57

Abrupt elastic-to-plastic transition in pentagonal nanowires under bending

• Sergei Vlassov,
• Magnus Mets,
• Boris Polyakov,
• Jianjun Bian,
• Leonid Dorogin and
• Vahur Zadin

Beilstein J. Nanotechnol. 2019, 10, 2468–2476, doi:10.3762/bjnano.10.237

• coupled to a spring with stiffness of 30.0 N/m. In the loading procedure, the free end of the spring moves at a constant speed of 0.05 Å/ps, and the NW will be bent by the spring. We monitor the bending force exerted by the spring to the NW and the displacement of the rigid free end to characterize the

Integration of sharp silicon nitride tips into high-speed SU8 cantilevers in a batch fabrication process

• Nahid Hosseini,
• Matthias Neuenschwander,
• Oliver Peric,
• Santiago H. Andany,
• Jonathan D. Adams and
• Georg E. Fantner

Beilstein J. Nanotechnol. 2019, 10, 2357–2363, doi:10.3762/bjnano.10.226

• a high imaging speed due to the high material bandwidth product, which mainly results from the high intrinsic damping properties of the polymer. Such cantilevers have high resonance frequencies and low Q-factors for a given size and stiffness [23]. However, SU8 tips wear down quickly and become

Atomic force acoustic microscopy reveals the influence of substrate stiffness and topography on cell behavior

• Yan Liu,
• Li Li,
• Xing Chen,
• Ying Wang,
• Meng-Nan Liu,
• Jin Yan,
• Liang Cao,
• Lu Wang and
• Zuo-Bin Wang

Beilstein J. Nanotechnol. 2019, 10, 2329–2337, doi:10.3762/bjnano.10.223

• Manufacturing of China, Changchun University of Science and Technology, Changchun 130022, China Computer Department, Changchun Medical College, Changchun 130031, China JR3CN & IRAC, University of Bedfordshire, Luton LU1 3JU, UK 10.3762/bjnano.10.223 Abstract The stiffness and the topography of the substrate at

• the cell–substrate interface are two key properties influencing cell behavior. In this paper, atomic force acoustic microscopy (AFAM) is used to investigate the influence of substrate stiffness and substrate topography on the responses of L929 fibroblasts. This combined nondestructive technique is

• able to characterize materials at high lateral resolution. To produce substrates of tunable stiffness and topography, we imprint nanostripe patterns on undeveloped and developed SU-8 photoresist films using electron-beam lithography (EBL). Elastic deformations of the substrate surfaces and the cells