Gelatin nanoparticles with tunable mechanical properties: effect of crosslinking time and loading

• Agnes-Valencia Weiss,
• Daniel Schorr,
• Julia K. Metz,
• Metin Yildirim,
• Saeed Ahmad Khan and
• Marc Schneider

Beilstein J. Nanotechnol. 2022, 13, 778–787, doi:10.3762/bjnano.13.68

• same day. AFM measurements were carried out with a JPK NanoWizard® 3 AFM (JPK Instruments, Berlin, Germany) using the MLCT cantilever tip D (Bruker France Nano Surfaces, Wissembourg, France) with a nominal resonance frequency of 15 kHz and a spring constant of 0.03 N/m. Before each measurement, the

• actual sensitivity and the spring constant of the used cantilever were calibrated on a cleaned silica wafer by the thermal noise method by Hutter et al. [27] using a correction factor of 0.251. The data was acquired using the quantitative imaging mode (QI™) with image sizes of 5 × 5 µm and a resolution

• single nanoparticles. For the values of Young’s moduli, the respective curves were treated as follows: The determined spring constant and sensitivity must be applied to calibrate the cantilever deflection. To correct the vertical offset, a baseline subtraction is applied, and the contact point is

Direct measurement of surface photovoltage by AC bias Kelvin probe force microscopy

• Masato Miyazaki,
• Yasuhiro Sugawara and
• Yan Jun Li

Beilstein J. Nanotechnol. 2022, 13, 712–720, doi:10.3762/bjnano.13.63

• force This signal is measured with a lock-in amplifier and compensated by VAC control, yielding the SPV value. To improve the sensitivity, ωm is usually tuned to the second (first) resonance frequency of the cantilever, while the first (second) resonance frequency is assigned to the AFM measurement [29

• -AFM was operated in the FM mode [32] with a constant oscillation amplitude A of 500 pm. The cantilever deflection was measured by an optical beam deflection (OBD) method [33]. AC-KPFM was carried out in the FM mode, in which the topography and SPV were measured simultaneously. An AC bias VAC with

• was arranged in front of a photodetector of the OBD system to suppress the influence of the UV light on the deflection sensor. We used a commercial Ir-coated Si cantilever (NANOSENSORS, SD-T7L100) with a resonant frequency f0 of 913 kHz, a spring constant k of 650 N/m, and a quality factor Q of 7748

Quantitative dynamic force microscopy with inclined tip oscillation

• Philipp Rahe,
• Daniel Heile,
• Reinhard Olbrich and
• Michael Reichling

Beilstein J. Nanotechnol. 2022, 13, 610–619, doi:10.3762/bjnano.13.53

• measuring a heterogeneous atomic surface. We propose to measure the AFM observables along a path parallel to the oscillation direction in order to reliably recover the force along this direction. Keywords: atomic force microscopy; cantilever; quantitative force measurement; sampling path; Introduction

• for technical reasons. Consequences of this inclined AFM cantilever mount have been identified before, in particular for atomic force microscopy performed in static (“contact”) mode where an effective spring constant [6][7][8] has been introduced and a torque [9][10] as well as load [11] correction

• has been applied. Additionally, a tilted cantilever has been found to lead to a modification of the tip–sample convolution [12], to enhance the sensitivity of the measurement to the probe side [13], and to influence results of multifrequency AFM and Kelvin probe force microscopy [14]. In the presence

Effects of substrate stiffness on the viscoelasticity and migration of prostate cancer cells examined by atomic force microscopy

• Xiaoqiong Tang,
• Yan Zhang,
• Jiangbing Mao,
• Yuhua Wang,
• Zhenghong Zhang,
• Zhengchao Wang and
• Hongqin Yang

Beilstein J. Nanotechnol. 2022, 13, 560–569, doi:10.3762/bjnano.13.47

• Germany) for 2 h to prevent damage to the cells. Before the experiment, the thermal noise method was used to adjust the cantilever spring constant, and then the experiment was carried out in contact mode. The AFM probe (MLCT probe, Bruker, USA) slightly contacted the cell surface and a constant force was

Electrostatic pull-in application in flexible devices: A review

• Teng Cai,
• Yuming Fang,
• Yingli Fang,
• Ruozhou Li,
• Ying Yu and
• Mingyang Huang

Beilstein J. Nanotechnol. 2022, 13, 390–403, doi:10.3762/bjnano.13.32

• the first time. They used single-walled carbon nanotubes (SWCNTs) to prepare a suspended cross bistable switch array. Table 1 summarizes the structures and the voltage of CNT-NEM switches described in the literature. In addition to bridge and cantilever structures, the vertical structure further

• the critical voltage is about 3.6 V. Abbasi et al. [2] prepared a bistable switch based on SWCNTs, with a pull-in voltage of 2.5–3 V, which is suitable for nonvolatile memory applications. Cantilever model: A typical cantilever structure is shown in Figure 2b. Lee et al. [22][23] prepared a three

• -terminal cantilever MWCNT NEM switch. The diameter of the CNTs is 50 nm, the length is 2 µm, and the gap is 150 nm. When Vds is 0.5 V, Vgs is in the range of 6–30 V. Loh et al. [24] prepared a cantilever SWCNT and diamond electrode structure with a pull-in voltage of 23.4 V. C–C bonds can greatly improve

Relationship between corrosion and nanoscale friction on a metallic glass

• Haoran Ma and
• Roland Bennewitz

Beilstein J. Nanotechnol. 2022, 13, 236–244, doi:10.3762/bjnano.13.18

• corrosive solution was added. For these experiments, we used an electrochemical atomic force microscope (ECAFM, Agilent 5500) and the oxidized tip (radius of ca. 30 nm) of a single-crystalline Si cantilever (PPP-CONT, NanoSensors, Germany). We adopted the beam geometry method to calibrate the force

• constants of the cantilever [47]. The resonance frequency of the cantilever at the first normal oscillation mode measured in the air was used to calculate the thickness of the cantilever [47]. The AFM tip sliding velocity was 8.0 μm·s−1 and the scan field was 1.0 × 0.125 μm2. Sixteen cycles of repetitive

Measurement of polarization effects in dual-phase ceria-based oxygen permeation membranes using Kelvin probe force microscopy

• Kerstin Neuhaus,
• Christina Schmidt,
• Liudmila Fischer,
• Wilhelm Albert Meulenberg,
• Ke Ran,
• Joachim Mayer and
• Stefan Baumann

Beilstein J. Nanotechnol. 2021, 12, 1380–1391, doi:10.3762/bjnano.12.102

• were performed in a single-pass experiment. For this kind of measurements, the surface potential and the sample topography are mapped in a single pass in intermittent contact mode with the cantilever vibrating at its resonance frequency (i.e., the cantilever is not in lift mode during this experiment

Alteration of nanomechanical properties of pancreatic cancer cells through anticancer drug treatment revealed by atomic force microscopy

• Xiaoteng Liang,
• Shuai Liu,
• Xiuchao Wang,
• Dan Xia and
• Qiang Li

Beilstein J. Nanotechnol. 2021, 12, 1372–1379, doi:10.3762/bjnano.12.101

• characterized by AFM is shown in Figure 1. For the mechanical mapping, the AFM cantilever needs to be calibrated first. During the scanning process, the applied force should be less than 3 nN to prevent cell destruction. For force mapping, 400 force curves were collected for each selected area and at least 30

Cantilever signature of tip detachment during contact resonance AFM

• Devin Kalafut,
• Ryan Wagner,
• Maria Jose Cadena,
• Anil Bajaj and
• Arvind Raman

Beilstein J. Nanotechnol. 2021, 12, 1286–1296, doi:10.3762/bjnano.12.96

• atomic force microscopy modes in which the cantilever is held in contact with the sample at a constant average force while monitoring the cantilever motion under the influence of a small, superimposed vibrational signal. Though these modes depend on permanent contact, there is a lack of detailed analysis

• on how the cantilever motion evolves when this essential condition is violated. This is not an uncommon occurrence since higher operating amplitudes tend to yield better signal-to-noise ratio, so users may inadvertently reduce their experimental accuracy by inducing tip–sample detachment in an effort

• to improve their measurements. We shed light on this issue by deliberately pushing both our experimental equipment and numerical simulations to the point of tip–sample detachment to explore cantilever dynamics during a useful and observable threshold feature in the measured response. Numerical

Enhancement of the piezoelectric coefficient in PVDF-TrFe/CoFe₂O₄ nanocomposites through DC magnetic poling

• Marco Fortunato,
• Alessio Tamburrano,
• Maria Paola Bracciale,
• Maria Laura Santarelli and
• Maria Sabrina Sarto

Beilstein J. Nanotechnol. 2021, 12, 1262–1270, doi:10.3762/bjnano.12.93

• through PFM [1][5][27] using a commercial Bruker-Veeco Dimension Icon AFM with a Co/Cr-coated-tip silicon cantilever (MESP-RC-V2, Bruker). Following the procedure described in [2][3], we scanned three different areas, 5 × 5 μm2 in size, of each sample, with 256 × 256 acquisition points per scanning area

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

• tip and to visualize the contamination there. Such a sample is available in any AFM laboratory and allows one to demonstrate some of the features that make it difficult to work in standard modes. On the one hand, next to the scan area, there is a high console of the cantilever; on the other hand

• parameters: 256 by 256 points, A0 = 10 nm, Tline = 0.5 s, Tdir = 0.4 s, Vup = 5 µm/s, Vdown = 2 µm/s, p1 = 70%, p2 = p1 + 4%. We used a Mikromasch NSC15 cantilever with a nominal force constant 46 N/m and resonance frequency of 328 kHz. This scan took Tscan = 6 min. Figure 3b shows the time spent on the

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

• the measured electrical tip–sample interaction is directly affixed to the topography rendered by the mechanical PFT modulation at each tap. Furthermore, because the detailed response of the cantilever to the bias stimulation was recorded, it was possible to analyze and separate an average contribution

• of the cantilever to the determined local contact potential difference between the AFM probe and the imaged sample. The removal of this unwanted contribution greatly improved the accuracy of the AM-KPFM measurements to the level of the FM-KPFM counterpart. Keywords: electrostatic interaction; Kelvin

• -excitation OL BE-KPFM [37][38][39], intermodulation electrostatic force microscopy [40], and dual-harmonic KPFM (DH-KPFM) [34][41][42]. In DH-KPFM, the CPD is obtained from the ratio of the amplitudes of the first two harmonics of the cantilever response to an AC bias modulation and requires a prior

A new method for obtaining model-free viscoelastic material properties from atomic force microscopy experiments using discrete integral transform techniques

• Berkin Uluutku,
• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2021, 12, 1063–1077, doi:10.3762/bjnano.12.79

• unbounded inputs traditionally used to acquire force–distance relationships in AFM, such as ramp functions, in which the cantilever position is displaced linearly with time for a finite period of time. Keywords: atomic force microscopy; force spectroscopy; material properties; viscoelasticity

• force–distance curve, where the cantilever position above the sample follows a ramp function. In the case of intermittent-contact methods (e.g., tapping-mode AFM), the cantilever tip oscillates nearly sinusoidally, but since tip–sample contact is intermittent, the sample does not experience purely

• experiments one observes the deflection of the AFM cantilever as a function of the cantilever base position instead of directly observing stress and strain. From the available observables, one can calculate the tip–sample force and the indentation. In order to account for the AFM probe and sample geometry and

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

• , independent method to detect the variation in Φ. For this we record the frequency shift, Δf, of the resonance frequency of the cantilever oscillating perpendicular to the surface as a function of the bias voltage (see Figure 3b). At the extrema of the parabolic Δf curves, the electrostatic force is minimised

• . Experimental We employ a custom-built ultrahigh-vacuum (below 10−10 mbar) low-temperature (T = 1.4 K) nc-AFM operated in frequency-modulated mode. A stiff qPlus cantilever design [49] (k0 = 1800 N·m−1, f0 = 29077 Hz, Q = 60000) at an oscillation amplitude Aosc = 50 pm enables the nc-AFM functionality. We

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

• have to be subtracted in order to isolate the short-range contributions from the surface feature [2]. If the cantilever is rotated by 90° so that the tip oscillates lateral to the surface, long-range forces with large vertical components do not contribute to the Δf signal [3]. This microscopy technique

• setup) or biaxial AFM with normal force detection is required. Experimentally, there are several methods for performing frequency-modulation lateral force microscopy, what we refer to as LFM in this manuscript. In 2002, Pfeiffer and co-workers excited a silicon cantilever in the first torsional mode [4

• method developed by Giessibl [15], a Laplace transform method developed by Sader and Jarvis [16], and a Fourier method developed by Seeholzer and co-workers [17]. All of these methods require the knowledge of the oscillation amplitude A of the cantilever. Amplitude determination means determining a

Mapping the local dielectric constant of a biological nanostructured system

• Wescley Walison Valeriano,
• Rodrigo Ribeiro Andrade,
• Juan Pablo Vasco,
• Angelo Malachias,
• Bernardo Ruegger Almeida Neves,
• Paulo Sergio Soares Guimarães and
• Wagner Nunes Rodrigues

Beilstein J. Nanotechnol. 2021, 12, 139–150, doi:10.3762/bjnano.12.11

• oscillate, during the second pass, at the resonance frequency of the cantilever, f0. Variations in the local relative permittivity properties of the sample will lead to different tip–sample force gradients, which promote a shift Δf0 in the tip oscillation frequency [21][22] which is, approximately, where dF

• /dz is the tip–sample force gradient and K is the spring constant of the cantilever. The tip–sample-substrate system constitutes a capacitor with the sample (wing) as part of the relative permittivity region, so the force between tip and substrate can be modeled as where C is the system capacitance

• sample and the conductive substrate need to be present within the AFM image. This is a key condition since the conductive substrate establishes a reference level in the analysis. Having both in the imaged region guarantees that the cantilever amplitude and, consequently, the effective radius of the tip

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

• . The vibration modes of a qPlus sensor with a long tip are quite different from those of a cantilever with a short tip. Flexural vibration of the tungsten tip will occur. The tip can no longer be considered as a rigid body that moves with the prong of the tuning fork. Instead, it oscillates both

• which one prong is fixed onto a substrate and the other prong with an attached tip serves as a self-sensing cantilever [2]. In 1996, F. J. Giessibl et al. first used the qPlus sensor to measure the morphology of a grating and a CD at room temperature [3]. Since then, this technique has been used

• of the cantilever is utilized to detect the forces between tip and sample. The shift Δf induced by the vertical force gradient is tan|φ| times as large as that induced by the lateral force gradient [17]. In other words, in the range from 0 to 90°, if φ > 45°, mainly the vertical force gradient

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

• mode: The AFM probe, a paraboloid-shaped tip with a typical radius 4 nm < R < 40 nm is held at a defined x,y position while it approaches the sample surface by using a Z-piezo positioner. The tip is attached to a cantilever which can be described as an elastic spring following Hooke’s law: with force F

• , spring constant of the cantilever kc, and cantilever deflection δ. In this way, the forces acting on the tip are measured by recording the deflection δ of the cantilever. While decreasing the distance between the tip and the sample, the cantilever deflects toward the sample (attractive forces Fattr, −δ

• depicted in Figure 1. Figure 1(I) zero line: when the tip and the sample are far away from each other. Interacting forces are not detectable and δ is zero which equals the free equilibrium position of the cantilever. Figure 1(II) regime of attractive forces: upon further approach of the sample and the tip

Atomic layer deposited films of Al₂O₃ on fluorine-doped tin oxide electrodes: stability and barrier properties

• Hana Krýsová,
• Michael Neumann-Spallart,
• Hana Tarábková,
• Pavel Janda,
• Ladislav Kavan and
• Josef Krýsa

Beilstein J. Nanotechnol. 2021, 12, 24–34, doi:10.3762/bjnano.12.2

• cantilever (TESPA-V2) with a resonant frequency fres of approx. 300 kHz, a spring constant k of 0.42 N·m−1, and a nominal tip radius of 8 nm (Bruker, USA) was employed. The Gwyddion software (v. 2.53) was utilized for processing AFM image data. Results and Discussion AFM was used to compare the morphology of

Mapping of integrated PIN diodes with a 3D architecture by scanning microwave impedance microscopy and dynamic spectroscopy

• Rosine Coq Germanicus,
• Peter De Wolf,
• Florent Lallemand,
• Catherine Bunel,
• Serge Bardy,
• Hugues Murray and
• Ulrike Lüders

Beilstein J. Nanotechnol. 2020, 11, 1764–1775, doi:10.3762/bjnano.11.159

• capacitor in parallel with a resistance (Figure 1). The incident microwave signal interacts with the sample resulting in a transmitted wave and a reflected wave. Since the probe is shielded, the stray capacitance formed by the cantilever and the sample can be neglected. After a calibration step and

•  9 represents a force curve recorded as function of time for one pixel. In the first step (1) the tip approaches the surface until the force on the cantilever reaches the setpoint force of 50 nN. During the dwell segment, the sMIM tip is maintained in contact (2). During this time, the voltage sweep

Direct observation of the Si(110)-(16×2) surface reconstruction by atomic force microscopy

• Tatsuya Yamamoto,
• Ryo Izumi,
• Kazushi Miki,
• Takahiro Yamasaki,
• Yasuhiro Sugawara and
• Yan Jun Li

Beilstein J. Nanotechnol. 2020, 11, 1750–1756, doi:10.3762/bjnano.11.157

• cantilever was used, which was cleaned by Ar+ sputtering to remove the oxide and contamination on the tip. The deflection of the cantilever was measured by the optical beam deflection method. The topography of the surface was imaged while feedback electronics were used to adjust the tip–sample distance to

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

• analysis, it is concluded that CR measurements are not appropriate for polymer samples. Major drawbacks are the bad resolution for moduli lower than ca. 10 GPa and the lack of a comprehensive physical model accounting for many factors affecting the dynamic response of a cantilever in contact with a sample

• phase image. The resulting contrast is, however, hard to analyze quantitatively. Contact-resonance AFM (CR-AFM) [4][5] is a dynamic contact technique that makes use of the vibrational behavior of the cantilever while the tip is in permanent contact with the sample. Generally, an increase in sample

• 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

Fabrication of nano/microstructures for SERS substrates using an electrochemical method

• Jingran Zhang,
• Tianqi Jia,
• Xiaoping Li,
• Junjie Yang,
• Zhengkai Li,
• Guangfeng Shi,
• Xinming Zhang and
• Zuobin Wang

Beilstein J. Nanotechnol. 2020, 11, 1568–1576, doi:10.3762/bjnano.11.139

• three-dimensional topographies of the nanopores. Imaging was performed in contact mode and an elastic constant of 0.2 N/m was selected for the silicon cantilever. The scanning area was 50 × 50 μm2. In addition, a scanning electron microscopy (SEM) system (Zeiss, Germany) was employed to characterize the

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

• dimensions, the optimum V-shaped cantilever that can provide the maximum phase contrast in bimodal AFM between gold (Au) and polystyrene (PS) is found. Based on this study, it is found that as the length of the cantilever increases the 2nd eigenmode phase contrast decreases. However, the base width exhibits

• the opposite relationship. It is also found that the leg width does not have a monotone relationship similar to length and base width. The phase contrast increases for the range of 14 to 32 µm but decreases afterwards. The thickness of a V-shaped cantilever does not play a major role in defining the

• dynamics of the cantilever compared to other parameters. This work shows that in order to maximize the phase contrast, the ratio of second to first eigenmode frequencies should be minimized and be close to a whole number. Additionally, since V-shaped cantilevers are mostly used for soft matter imaging

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

• response of the cantilever with respect to the excitation, within amplitude-modulation AFM (AM-AFM)), which generally yields high-contrast images for dissipative materials [22]. Dynamic contact-mode techniques such as contact-resonance AFM [11][12][13][28], dual-amplitude resonance tracking AFM (DART [10

• -static force spectroscopy (i.e., using force–distance curves acquired at frequencies much lower than the resonance frequency of the cantilever). Specifically, we have introduced a methodology based on the Generalized Voigt (Kelvin) or Maxwell viscoelastic model (Figure 1), including an arbitrary number

• performed with different types of cantilevers (short high-frequency cantilevers as well as traditional cantilevers) and with different methods, involving wide frequency ranges and different cantilever eigenmodes. In general, this is routinely done without considering the types of viscoelastic behavior