Measuring adhesion on rough surfaces using atomic force microscopy with a liquid probe

• Juan V. Escobar,
• Cristina Garza and
• Rolando Castillo

Beilstein J. Nanotechnol. 2017, 8, 813–825, doi:10.3762/bjnano.8.84

• of the cantilever we use the thermal noise method that appeals to the energy equipartition theorem, which states that the thermal energy contribution of each quadratic term in the Hamiltonian of a system is kBT/2 where kB is the Boltzmann constant and T is the absolute temperature. The cantilever is

• modeled as an ideal spring with a spring constant kc. The thermal noise of the mean square displacement, , allows us to determine the constant using [31][32]. With a spectral analyzer (Stanford Research Systems, 760 FFT, USA), we identify the peak corresponding to the first fundamental resonant mode of

Optimizing qPlus sensor assemblies for simultaneous scanning tunneling and noncontact atomic force microscopy operation based on finite element method analysis

• Omur E. Dagdeviren and
• Udo D. Schwarz

Beilstein J. Nanotechnol. 2017, 8, 657–666, doi:10.3762/bjnano.8.70

• individually. This is in particular important as any change in f0 is an indication that some change in k may have taken place as well, as f0 and k are entangled properties [26]. In contrast, the thermal noise δfthermal of the measurement, which is one of the main noise sources in FM-AFM, scales with Q−1/2

Graphene–polymer coating for the realization of strain sensors

• Carmela Bonavolontà,
• Carla Aramo,
• Massimo Valentino,
• Giampiero Pepe,
• Sergio De Nicola,
• Gianfranco Carotenuto,
• Angela Longo,
• Mariano Palomba,
• Simone Boccardi and
• Carosena Meola

Beilstein J. Nanotechnol. 2017, 8, 21–27, doi:10.3762/bjnano.8.3

• thermal noise, as shown in the Figure 5. It is interesting to stress here that this result is obtained on a graphene/PMMA sample where the graphene layer is about 1 μm thick. This behavior can be ascribed to the high thermal conductivity of graphene compared to the other materials reported in Figure 5

Noise in NC-AFM measurements with significant tip–sample interaction

• Jannis Lübbe,
• Matthias Temmen,
• Philipp Rahe and
• Michael Reichling

Beilstein J. Nanotechnol. 2016, 7, 1885–1904, doi:10.3762/bjnano.7.181

• & Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK 10.3762/bjnano.7.181 Abstract The frequency shift noise in non-contact atomic force microscopy (NC-AFM) imaging and spectroscopy consists of thermal noise and detection system noise with an additional contribution from

• : amplitude noise; cantilever stiffness; closed loop; detection system noise; frequency shift noise; non-contact atomic force microscopy (NC-AFM); Q-factor; spectral analysis; thermal noise; tip–sample interaction; Introduction Non-contact atomic force microscopy (NC-AFM) [1][2] is an unmatched surface

• demodulator (mostly a phase-locked loop detector, PLL), cantilever properties and ultimately thermal noise [11]. The footing of our work are these precursor studies, and the rigorous system analysis introduced by Polesel-Maris et al. [12], showing that the frequency shift noise at close tip–sample distance is

Monolayer graphene/SiC Schottky barrier diodes with improved barrier height uniformity as a sensing platform for the detection of heavy metals

• Ivan Shtepliuk,
• Jens Eriksson,
• Volodymyr Khranovskyy,
• Tihomir Iakimov,
• Anita Lloyd Spetz and
• Rositsa Yakimova

Beilstein J. Nanotechnol. 2016, 7, 1800–1814, doi:10.3762/bjnano.7.173

• to literature, graphene oxide is more toxic than pristine graphene [27], has a lower carrier mobility [28], higher thermal noise and a natural tendency to agglomerate [29]. In addition, because of the high material inhomogeneity and small domain sizes, it is complicated to fabricate sensing devices

Signal enhancement in cantilever magnetometry based on a co-resonantly coupled sensor

• Julia Körner,
• Christopher F. Reiche,
• Thomas Gemming,
• Bernd Büchner,
• Gerald Gerlach and
• Thomas Mühl

Beilstein J. Nanotechnol. 2016, 7, 1033–1043, doi:10.3762/bjnano.7.96

• [3][22][23], leading to three main considerations which have to be taken into account: the sensitivity of the detection setup and thermal and magnetic noise in the oscillating system. From these, thermal noise is considered to be the most dominant one [24], followed by the detector noise which is

• statistically independent of the former [25]. For our discussion, we will only focus on thermal noise. Even if only this single noise source is considered it is still an open question how the noise is distributed in the co-resonantly coupled sensor system [26]. We will therefore use the approach of discussing

Contact-free experimental determination of the static flexural spring constant of cantilever sensors using a microfluidic force tool

• John D. Parkin and
• Georg Hähner

Beilstein J. Nanotechnol. 2016, 7, 492–500, doi:10.3762/bjnano.7.43

• and demonstrate that this, in combination with a thermal noise spectrum, can provide the static flexural spring constant for cantilever sensors of different geometric shapes over a wide range of spring constant values (≈0.8–160 N/m). Keywords: AFM; cantilever sensors; microfluidic force tool; spring

• the photodiode signal in native units of the instrument (volts) and σ1 is the optical lever sensitivity for thermal oscillations [34][35]. Knowledge of σ1 is required for calibration of the spring constant via the thermal noise method [16]. It can be experimentally obtained, for example, from a force

• sensitivity ratio α = σ1/σ2 can still be theoretically obtained. This conversion is similar to the dynamic-to-static optical lever sensitivity conversion required in the thermal noise method [33]. From the photodiode signal, the deflection for a total force and the peak area under a thermal noise curve are

Active multi-point microrheology of cytoskeletal networks

• Tobias Paust,
• Tobias Neckernuss,
• Lina Katinka Mertens,
• Ines Martin,
• Michael Beil,
• Paul Walther,
• Thomas Schimmel and
• Othmar Marti

Beilstein J. Nanotechnol. 2016, 7, 484–491, doi:10.3762/bjnano.7.42

• , amplitude A and direction θ. Consequently, the motion of the reference particle is a superposition of thermal noise and the sinusoidal oscillation. The motion of the response particles is also a superposition of thermal noise, the same sinusoidal function and additionally several terms of the sinusoidal

Length-extension resonator as a force sensor for high-resolution frequency-modulation atomic force microscopy in air

• Hannes Beyer,
• Tino Wagner and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2016, 7, 432–438, doi:10.3762/bjnano.7.38

• temperature and humidity sensor (SHT71, Sensirion AG [22]). Basic image processing (e.g., levelling) is done with the Gwyddion software [23]. To determine the sensitivity S of the LER a thermal noise spectrum was acquired around the resonance frequency (Figure 1c). Integration over the noise power spectral

• ) Thermal noise spectrum (black) of a LER with a SSS-NCHR tip attached and a fit of a damped harmonic oscillator (red). The right axis is obtained by multiplying the left axis with the inverse sensitivity 1/S = 2.2 nm/Vrms. Parameters derived from the fit: Q = 17,000, f0 = 999.3 kHz. The detector noise

Molecular machines operating on the nanoscale: from classical to quantum

• Igor Goychuk

Beilstein J. Nanotechnol. 2016, 7, 328–350, doi:10.3762/bjnano.7.31

• ; nanoscale friction and thermal noise; quantum effects; thermodynamic efficiency; Introduction A myriad of minuscule molecular nanomotors (not visible in standard, classical, optical microscopes) operate in living cells and perform various tasks. These utilize metabolic energy, for example, the energy

• forever even at thermal equilibrium. The energy necessary for this is supplied by thermal fluctuations. Therefore, friction and thermal noise are intimately related, which is the physical context of the fluctuation–dissipation theorem [10]. Statistical mechanics allows the development of a coherent

• the Wiener–Khinchin theorem, , as S(ω) = 2kBTJ(ω)/ω. The strict ohmic model, J(ω) = ηω, without a frequency cutoff, corresponds to the standard Langevin equation: with uncorrelated white Gaussian thermal noise, . Such noise is singular, and its mean-square amplitude is infinite. This is, of course, a

Determination of Young’s modulus of Sb₂S₃ nanowires by in situ resonance and bending methods

• Liga Jasulaneca,
• Raimonds Meija,
• Alexander I. Livshits,
• Juris Prikulis,
• Subhajit Biswas,
• Justin D. Holmes and
• Donats Erts

Beilstein J. Nanotechnol. 2016, 7, 278–283, doi:10.3762/bjnano.7.25

• BIO) using the thermal noise method [36]. Results and Discussion Figure 1a,b shows SEM images of Sb2S3 nanowires with a length of 10 μm and a radius of 67 nm with applied AC voltage at two different frequencies, where one is far from the resonance and second matches resonant excitation. The force

Kelvin probe force microscopy for local characterisation of active nanoelectronic devices

• Tino Wagner,
• Hannes Beyer,
• Patrick Reissner,
• Philipp Mensch,
• Heike Riel,
• Bernd Gotsmann and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2015, 6, 2193–2206, doi:10.3762/bjnano.6.225

• below the thermal noise limited bandwidth of the cantilever [24], but the modulation induced by rough surfaces as well as the desired scan bandwidth establish lower limits. Furthermore, the sideband transfer function explains the higher resolution obtained by heterodyne amplitude-modulated KFM [47]. In

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

• were used (Nanosensors PPP-CONTR). The cantilever spring constant was calibrated in situ using the thermal noise method implemented in the MFP-3D microscope and the deflection in volts converted to deflection in nanometers by means of sensitivity calculations on dry CaF2 crystals. Thin slices of CaF2

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

• 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

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

• experiments. 200 µm-long, tip-less, v-shaped, silicon nitride cantilevers having nominal spring constants of 0.06 N/m (NP-O, Bruker) were used for adhesion measurements. The spring constant of every cantilever was determined prior to the experiment using the thermal noise method. Prior to experiments, cells

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

• 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

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

• tune method and a FastScan A cantilever in air, we measured a baseline noise level of 45 fm/ for our deflection readout. Figure 3c shows the thermal noise peak of the first flexural mode, while Figure 3d shows the thermal noise peak of the second flexural mode. We expect that further optimization of

• 6.0 for the FastScan A and FastScan C cantilevers, respectively. The spring constants of the two cantilevers are calibrated by using the thermal noise method. We measure k0 = 15.4 N·m−1, k1 = 470 N·m−1 for the first and second eigenmode of the used FastScan A and k0 = 0.85 N·m−1, k1 = 94 N·m−1

• ), torsional resonances can be excited (red curve). Visible are the first three flexural modes (f0, f1 and f2), the first two torsional modes (t1 and t2), and a complex higher resonant mode (hm). c) Thermal noise peak of the first flexural mode of a FastScan A cantilever, with a baseline noise floor of 45 fm

Modification of a single-molecule AFM probe with highly defined surface functionality

• Fei Long,
• Bin Cao,
• Ashok Khanal,
• Shiyue Fang and
• Reza Shahbazian-Yassar

Beilstein J. Nanotechnol. 2014, 5, 2122–2128, doi:10.3762/bjnano.5.221

• . When the probe is retracted, the force to break the hydrogen bonds should be detectable. The force spectroscopy experiments were carried out in contact mode at room temperature in isopropanol. The spring constant of the AFM probes were calibrated by using the thermal noise method [30]. The measured

Unlocking higher harmonics in atomic force microscopy with gentle interactions

• Sergio Santos,
• Victor Barcons,
• Josep Font and
• Albert Verdaguer

Beilstein J. Nanotechnol. 2014, 5, 268–277, doi:10.3762/bjnano.5.29

• to apparent topography induced by chemistry or other compositional variations. Thermal noise and higher harmonic external drives As stated in the introduction, it has long been known that under ambient conditions higher harmonic amplitudes might be too small to be detected [3][15][42]. This is

• phase shifts Δ have been employed to map the composition through variations in the tip–sample Hamaker constant, H, in Equation 10. In this section, the presence of thermal noise is discussed with respect to the contrast in amplitude ΔAn and phase Δ in the presence and absence of external drive forces at

• their effects on amplitude and phase shifts. This should provide a measure of the impact of thermal noise on the enhanced contrast reported in this work (Figure 2 and Figure 3). Other technical issues such as tilt and probe geometry have also been ignored for simplicity since these typically involve a

Manipulation of nanoparticles of different shapes inside a scanning electron microscope

• Boris Polyakov,
• Sergei Vlassov,
• Leonid M. Dorogin,
• Jelena Butikova,
• Mikk Antsov,
• Sven Oras,
• Rünno Lõhmus and
• Ilmar Kink

Beilstein J. Nanotechnol. 2014, 5, 133–140, doi:10.3762/bjnano.5.13

• by the thermal noise method. A detailed description of calibration procedure is given in Supporting Information File 1. Each manipulation experiment started with a displacement of the NP from its initial position by an abrupt tip motion in the step regime to reduce the initial adhesion, which is

Noise performance of frequency modulation Kelvin force microscopy

• Heinrich Diesinger,
• Dominique Deresmes and
• Thierry Mélin

Beilstein J. Nanotechnol. 2014, 5, 1–18, doi:10.3762/bjnano.5.1

• PSD decomposed into thermal noise (red) and sensor noise (blue) is computed according to the approximation of Equation 17 (see Equation 20 below). Regarding the approximation of Equation 17, we note that it is valid in the range in which the closed loop gain is unity and |APLLFPLL| >> 1. Hence, the

• voltage noise PSD The thermal noise PSD of the PLL frequency noise Equation 20 is constant and hence invariant under the frequency translation, yielding as Kelvin noise PSD, by dividing through the Kelvin gain Equation 26, indicated as red curve in Figure 14. The integrated noise is while the sensor noise

• temperature above which at a given bandwidth, the integrated thermal noise of Equation 38 exceeds the integrated sensor noise Equation 40, while the design rule is respected: Regarding the effective probed surface Seff, its absolute value is not known, but the relation between tip–sample distance and probed

Dynamic nanoindentation by instrumented nanoindentation and force microscopy: a comparative review

• Sidney R. Cohen and
• Estelle Kalfon-Cohen

Beilstein J. Nanotechnol. 2013, 4, 815–833, doi:10.3762/bjnano.4.93

• the sample in the AFM (Bruker, multimode). Prior to the experiment, the cantilever spring constant and the deflection sensitivity were determined with the Nanoscope software (former from the thermal noise and the latter by measuring the deflection of the cantilever with the displacement on a hard

Determining cantilever stiffness from thermal noise

• Jannis Lübbe,
• Matthias Temmen,
• Philipp Rahe,
• Angelika Kühnle and
• Michael Reichling

Beilstein J. Nanotechnol. 2013, 4, 227–233, doi:10.3762/bjnano.4.23

• oscillation mode from thermal noise by an analysis of the power spectral density of displacement fluctuations of the cantilever in contact with a thermal bath. The practical applicability of this approach is demonstrated for several cantilevers with eigenfrequencies ranging from 50 kHz to 2 MHz. As such an

• excited near their fundamental eigenfrequency f0, higher eigenmodes [7] have been investigated in the context of noise analysis [8], and it has been debated whether the thermal noise limitations in NC-AFM measurements could be reduced by operating cantilevers at higher eigenmodes [9]. It has further been

• known temperature [10]. A practical implementation of this notion, focused on the determination of cantilever stiffness from thermal noise, demonstrated the validity of the approach by a critical comparison of the results against corresponding results from other methods [11]. While the properties fn and

High-resolution dynamic atomic force microscopy in liquids with different feedback architectures

• John Melcher,
• David Martínez-Martín,
• Miriam Jaafar,
• Julio Gómez-Herrero and
• Arvind Raman

Beilstein J. Nanotechnol. 2013, 4, 153–163, doi:10.3762/bjnano.4.15

• resolution we must also obtain some estimate of the resolution of the amplitude measurement δa. Two important noise sources that contribute to δa are the thermal noise and deflection-sensor noise. In light of recent efforts to reduce the deflection-sensor noise [42], we will focus on the thermodynamic lower

Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy

• Jannis Lübbe,
• Matthias Temmen,
• Sebastian Rode,
• Philipp Rahe,
• Angelika Kühnle and
• Michael Reichling

Beilstein J. Nanotechnol. 2013, 4, 32–44, doi:10.3762/bjnano.4.4

• ) consists of cantilever thermal noise, tip–surface-interaction noise and instrumental noise from the detection and signal processing systems. We investigate how the displacement-noise spectral density dz at the input of the frequency demodulator propagates to the frequency-shift-noise spectral density dΔf

• displacement signal and determine the transfer function of the signal-processing electronics. From the transfer function and the measured dz, we predict dΔf for specific filter settings, a given level of detection-system noise spectral density dzds and the cantilever-thermal-noise spectral density dzth. We

• find an excellent agreement between the calculated and measured values for dΔf. Furthermore, we demonstrate that thermal noise in dΔf, defining the ultimate limit in NC-AFM signal detection, can be kept low by a proper choice of the cantilever whereby its Q-factor should be given most attention. A