Interaction between honeybee mandibles and propolis

• Leonie Saccardi,
• Franz Brümmer,
• Jonas Schiebl,
• Oliver Schwarz,
• Alexander Kovalev and
• Stanislav Gorb

Beilstein J. Nanotechnol. 2022, 13, 958–974, doi:10.3762/bjnano.13.84

• radii of the circles were measured and then averaged. The effective elastic modulus and pull-off force of propolis were measured with a microforce measurement device (Basalt-01; Tetra GmbH, Ilmenau, Germany) [22][23][24]. The device mainly consists of micromanipulators as a platform holding the

• contacted the cuticle. However, in the unloading curve the adhesive failure (pull-off) was easy to identify in most cases. In contrast to the pull-off force, the work of adhesion does not depend on the radius of the sample. Therefore, the work of adhesion value is hereafter used to compare adhesion from

• measured to be 1.01 ± 0.21 J/m2 (pull-off force: 0.71 ± 0.33 mN), which is significantly lower than adhesion on dry glass (2.96 ± 1.27 J/m2, P < 0.0001) (as well as all other analysed dry technical surfaces) [1]. Moreover, work of adhesion on fresh mandibles of bees was comparable to adhesion measured on

Temperature and chemical effects on the interfacial energy between a Ga–In–Sn eutectic liquid alloy and nanoscopic asperities

• Yujin Han,
• Pierre-Marie Thebault,
• Corentin Audes,
• Xuelin Wang,
• Haiwoong Park,
• Jian-Zhong Jiang and
• Arnaud Caron

Beilstein J. Nanotechnol. 2022, 13, 817–827, doi:10.3762/bjnano.13.72

• and calculate the corresponding work of adhesion Wad as suggested in [19] for solid interfaces. The authors measured the adhesion between atomically smooth quasicrystalline surfaces of TiN-coated AFM tips in ultrahigh vacuum by analyzing the pull-off force during atomic force spectroscopy measurements

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

• out in one-pass, with the CPD value affixed to the topographical feature and other PFT quantities (e.g., elastic modulus, pull-off force, and dissipation) at each location during scanning. A typical cantilever deflection to the synchronized PFT and KPFM modulations over three consecutive PFT

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

• -off force and the snap-in distance are measured. The use of in situ TEM allows for a direct characterization of the AFM tip shape. Furthermore, TEM allows for measurements of probe deflection, which can be converted to the normal force using the calibrated normal force constant of the cantilever and

• measurements is extended from the experimental method proposed by Jacobs et al. [35][47], which is based on static force–displacement measurements. The procedure is as follows: In situ force–separation measurements between an AFM probe and a nominally flat diamond punch are performed in a TEM, where the pull

Pull-off and friction forces of micropatterned elastomers on soft substrates: the effects of pattern length scale and stiffness

• Peter van Assenbergh,
• Marike Fokker,
• Julian Langowski,
• Jan van Esch,
• Marleen Kamperman and
• Dimitra Dodou

Beilstein J. Nanotechnol. 2019, 10, 79–94, doi:10.3762/bjnano.10.8

• authors empirically showed that suction forces are responsible for about 10% of the pull-off force mushroom micropatterns [16]. The presence of a terminal layer connecting neighboring micropillars at their tips has also shown to have a favorable effect on pull-off and friction forces on hard substrates

• off a micropattern from a soft substrate, the substrate deforms, and the detachment of neighboring pillars is no longer independent [24]. Accordingly, the pull-off force of mushroom-pillar micropatterns on a soft elastic substrate (Young’s modulus E = 200 kPa) has been found to be lower than on a

• micropatterns on PVA and glass Figure 4 shows representative force–time plots of pull-off force measurements of microscale dimples without a terminal layer on PVA-18 and glass. It can be seen that detachment during pull-off (phase II) was slower on PVA than on glass. Figure 5 shows the pull-off force on PVA-12

Contact splitting in dry adhesion and friction: reducing the influence of roughness

• Jae-Kang Kim and
• Michael Varenberg

Beilstein J. Nanotechnol. 2019, 10, 1–8, doi:10.3762/bjnano.10.1

• of the new integrative characteristic (σs/βη) were obtained by analyzing asperity peaks identified in a 3D surface profile with a deterministic method based on eight nearest neighboring points [38]. Studying the relationship between the pull-off force and either the height (Figure 2a) or the hybrid

• information from the primary profiles with the Gaussian high-pass filter [41]. The pull-off force, represented as a function of the parameters calculated based on the filtered roughness profiles, is shown in Figure 2c,d (root-mean-square deviation (Rq) and new integrative characteristic (Ri = σs/βη

• ), respectively, Table 1). In line with the performance of thin-film-covered surface architectures [42][43], we can now see a clear negative correlation between the pull-off force and the roughness, with the integrative roughness Ri having better resolving power (4 vs 2 orders of magnitude in range) and higher

The effect of flexible joint-like elements on the adhesive performance of nature-inspired bent mushroom-like fibers

• Elliot Geikowsky,
• Serdar Gorumlu and
• Burak Aksak

Beilstein J. Nanotechnol. 2018, 9, 2893–2905, doi:10.3762/bjnano.9.268

• from the substrate in the “pull” stage of the LDP experiment, exhibiting a pull-off peak. This negative peak is recorded as the pull-off force. The relatively large pull-off force observed in soft joint fibers suggests minimal loss of contact. 27 seconds of the contact performance of the tips while

• sliding, producing the consequent detachment, which does not necessarily result in damage of the fibers. In contrast, the higher bending compliance of soft joint fibers keep them attached to the substrate while sliding, allowing superior performance in terms of pull-off force. Similar observations can be

• , labeled as 2’’’, returns towards the origin of the graph due to the decrease in both normal and shear forces, indicating a gradual loss of contact with dragging distance. The dissimilar performance in sliding for both samples implies a completely different response for the pull-off force. The pull-off

Adhesive contact of rough brushes

• Qiang Li and
• Valentin L. Popov

Beilstein J. Nanotechnol. 2018, 9, 2405–2412, doi:10.3762/bjnano.9.225

• , the pull-off force becomes dependent on the previously applied compression force and disappears completely at some critical roughness. For roughness with a subcritical value, the pressure dependence of the pull-off force qualitatively follows the known theory of Fuller and Tabor with moderate

• force decreases with the power k and fill factor ρ (Figure 6b). Here one should note that the FA0 in the normalization is different for different exponents k. Discussion Simulations show that the roughness of a brush has two main effects: (1) the pull-off force becomes pressure-dependent and (2) the

Nanoscale characterization of the temporary adhesive of the sea urchin Paracentrotus lividus

• Ana S. Viana and
• Romana Santos

Beilstein J. Nanotechnol. 2018, 9, 2277–2286, doi:10.3762/bjnano.9.212

• artificial seawater (ASW)) exhibited a mean pull-off force of 0.41 ± 0.20 nN [2]. Later on, adhesive footprints were probed in a moist environment with ASW using different AFM tips (Si3N4 and functionalized with CH3 terminal groups) and the obtained force–extension curves exhibited the characteristic

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

• Juan V. Escobar Cristina Garza Rolando Castillo Instituto de Física, Universidad Nacional Autónoma de México; P. O. Box 20-364, DF, México, 01000, Mexico 10.3762/bjnano.8.84 Abstract We present a procedure to perform and interpret pull-off force measurements during the jump-off-contact process

• and adhesion can be mentioned. Samuel et al. [22] found that when a water drop is retracting from a solid surface, the pull-off force correlates well with the receding contact angle. The pull-off force decreases monotonically as the receding contact angle increases. An important phenomenon that also

• Experimental section, materials, experimental procedures and setup are described. In the Results and Discussion section, we first validate our method for determining the pull-off force by measuring the force of adhesion between a commercial Si3N4 AFM tip and a mica surface. Then, we present our results as well

When the going gets rough – studying the effect of surface roughness on the adhesive abilities of tree frogs

• Niall Crawford,
• Thomas Endlein,
• Jonathan T. Pham,
• Mathis Riehle and
• W. Jon P. Barnes

Beilstein J. Nanotechnol. 2016, 7, 2116–2131, doi:10.3762/bjnano.7.201

• adhesion. It is important to remember, however, that what is important to a climbing frog is the pull-off force, which has components of both adhesion and friction for all angles below 90° (and above 0°). The maximum adhesive capabilities of frogs can depend hugely on friction, for friction forces keep the

• pad/ground angle low, maximising the resultant (pull-off) force and preventing peeling of the pad from the surface [21]. Similar interactions occur in geckos [27]. This means that it is not possible to separate adhesion and friction unambiguously from whole animal tilting experiments, but the data

• increase in the pad/surface angle with a concomitant reduction in the pull-off force (peeling theory of Kendall [34]). Interestingly, on the largest asperities tested, (the 562.5 µm beads surface), the frogs began to show an increase in adhesive ability (also noted by Barnes et al. [15]). This could be due

“Sticky invasion” – the physical properties of Plantago lanceolata L. seed mucilage

• Agnieszka Kreitschitz,
• Alexander Kovalev and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2016, 7, 1918–1927, doi:10.3762/bjnano.7.183

• Linum usitatissimum [1]. In addition to the characterization of mucilage, three types of experiments were performed in this study with P. lanceolata mucilaginous seeds: (1) measurement of the desiccation dynamics of the hydrated seeds; (2) pull-off force estimation and (3) characterisation of frictional

• humidity were continuously recorded using a Tinytag TGP-4500 (Gemini Data Loggers Ltd, United Kingdom). The measured temperature was 22–23 °C, the relative humidity was 30–37%. Pull-off force measurements of the mucilage For the pull-off force measurements five sets of measurements were made on five

• evaporation rate of a water drop. Adhesive forces and contact area The pull-off force of individual P. lanceolata mucilaginous seeds varied up to two orders of magnitude, 0.3–32 mN (Figure 3). Immediately after hydration, the pull-off force was low whereas the contact area between the mucilage and substrate

Atomic force microscopy as analytical tool to study physico-mechanical properties of intestinal cells

• Christa Schimpel,
• Oliver Werzer,
• Eleonore Fröhlich,
• Gerd Leitinger,
• Markus Absenger-Novak,
• Birgit Teubl,
• Andreas Zimmer and
• Eva Roblegg

Beilstein J. Nanotechnol. 2015, 6, 1457–1466, doi:10.3762/bjnano.6.151

• the cantilever got in contact with the sample. Due to strong adhesion forces (van der Waals forces), the tip snapped in contact with the cell membrane. When retracting the tip, adhesion was maintained until the cantilever-force overcame the pull-off force (also referred as adhesion force) [51]. Lowest

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

• ]. Such a contact displays a peak in tensile stress at the edge, which governs the pull-off force if the contact diameter is larger than about 100 nm. Pull-off then results in crack propagation. Partial slip in the Cattaneo–Mindlin sense also results in crack propagation, where the modes of crack opening

Equilibrium states and stability of pre-tensioned adhesive tapes

• Carmine Putignano,
• Luciano Afferrante,
• Luigi Mangialardi and
• Giuseppe Carbone

Beilstein J. Nanotechnol. 2014, 5, 1725–1731, doi:10.3762/bjnano.5.182

• the presence of pre-tension in the tape does not modify the stability behavior of the system, but significantly affects the pull-off force which can be sustained by the tape before complete detachment. Moreover, above a critical value of the pre-tension, which depends on the surface energy of adhesion

• happens at a fixed pull-off force , when the system is initially in non-equilibrium conditions, let us consider the starting configurations A, B, C and D shown in Figure 2a. Starting from point A, the tape evolves towards smaller and smaller peeling angles in order to minimize the total energy. At the end

• regions. Figure 3 shows the dimensionless pull-off force as a function of the peeling angle θeq at equilibrium, for different dimensionless values of . Again, unstable solutions are plotted with dashed lines, and the stable ones with solid lines. Note that the maximum pull-off force that can be

Insect attachment on crystalline bioinspired wax surfaces formed by alkanes of varying chain lengths

• Elena Gorb,
• Sandro Böhm,
• Nadine Jacky,
• Louis-Philippe Maier,
• Kirstin Dening,
• Sasha Pechook,
• Boaz Pokroy and
• Stanislav Gorb

Beilstein J. Nanotechnol. 2014, 5, 1031–1041, doi:10.3762/bjnano.5.116

• experimental studies. The aim of this study was to examine the effect of different parameters of crystalline wax coverage on insect attachment. We performed traction experiments with the beetle Coccinella septempunctata and pull-off force measurements with artificial adhesive systems (tacky

• attachment and higher pull-off forces of polydimethylsiloxane probes on wax surfaces having a higher density of wax coverage, created by smaller crystals. Keywords: Coccinella septempunctata; insect–plant interactions; plant waxes; pull-off force; traction force; Introduction During their locomotion

• density (P = 0.002, linear regression; Figure 4a). The pull-off force showed significant negative correlations with the crystal thickness (P = 0.011, linear regression; Figure 4b), mean roughness Ra (P = 0.034, linear regression; Figure 4c), and root mean square of roughness r.m.s. (P = 0.032, linear

Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure

• Lars Heepe,
• Alexander E. Kovalev and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 903–909, doi:10.3762/bjnano.5.103

• pull-off force aimed at testing the cavitation hypothesis, an effect that have never been experimentally observed in artificial bio-inspired microstructured adhesives. Experimental Experimental setup In the experiments, two individual MSAMSs, denoted by sample 1 and sample 2, were detached from a

• . Pull-off forces were measured at ambient conditions, further called 'dry state' (Figure 1B). 2. After reattachment, i.e., contact formation in dry state, pull-off force was measured with the sample 1 submerged in water by applying a drop of deionized water onto the individual MSAMS with a syringe

• conditions (Figure 4). Pull-off forces were normalized with respect to those obtained in the dry state. Dry state pull-off forces were averaged over five individual measurements for both samples. For the sample 1, the median dry state pull-off force was ca. 570 µN (N = 5, min. value ca. 540 µN, and max

The optimal shape of elastomer mushroom-like fibers for high and robust adhesion

• Burak Aksak,
• Korhan Sahin and
• Metin Sitti

Beilstein J. Nanotechnol. 2014, 5, 630–638, doi:10.3762/bjnano.5.74

• , the relatively higher energy release rate for a cylindrical fiber induced pull-off at significantly lower loads than mushroom-like fibers. In their analysis, the ratio of pull-off force of a mushroom-like fiber to that of a cylindrical fiber varies significantly depending on the size of the annular

• the interface can no longer support stress, resulting in a crack to initiate. The region where the separation of interface occurs is referred to as the cohesive zone. In this model, the work of adhesion is given by wadh = σoδc. Tang et al. [15] found the pull-off force of a soft, elastic cylindrical

• used the Griffith method to design an optimal fiber shape based on the synthetic adhesives developed by Gorb et al. [33]. They concluded that for optimal adhesion, which is essentially a measure of pull-off force for a single fiber, 2 ≤ β ≤ 3 and s/a = 0.2–0.3. Here, s is the thickness of the circular

Hairy suckers: the surface microstructure and its possible functional significance in the Octopus vulgaris sucker

• Francesca Tramacere,
• Esther Appel,
• Barbara Mazzolai and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 561–565, doi:10.3762/bjnano.5.66

• generated in a binary on/off state [14]. These studies also reveal that structured surfaces show a 25% increase in pull-off force when immersed in water, and their underwater attachment is 20 times more effective than that of flat surfaces [15]. The grooves found in the infundibulum area generating a dense

Single-asperity contact mechanics with positive and negative work of adhesion: Influence of finite-range interactions and a continuum description for the squeeze-out of wetting fluids

• Martin H. Müser

Beilstein J. Nanotechnol. 2014, 5, 419–437, doi:10.3762/bjnano.5.50

• the behavior near pull-off for Δγ > 0. For the latter, it is straightforward to deduce from established results how the ac(FN) relation depends on the Tabor coefficient in the DMT and the JKR limit. Specifically, ac − ap (FN + Fp)κ for FN ≥ −Fp, where Fp and ap are pull-off force and pull-off radius

• -range potential, I will treat the COS equation as a guessed approximation containing the correct functional form in the limits of large and small μT. The primary COS equation (Equation 47) is designed such that the contact radius at zero load ac(0,μT) as well as the pull-off force Fp(μT) can be

• including the correct asymptotics in the ac(FN) expression does not necessarily improve the fits in the range from slightly above the pull-off force at negative loads to several times the absolute pull-off force. This is demonstrated in Figure 13. Moreover, convergence to the correct ac(FN) dependence at

Exploring the retention properties of CaF₂ nanoparticles as possible additives for dental care application with tapping-mode atomic force microscope in liquid

• Matthias Wasem,
• Joachim Köser,
• Sylvia Hess,
• Enrico Gnecco and
• Ernst Meyer

Beilstein J. Nanotechnol. 2014, 5, 36–43, doi:10.3762/bjnano.5.4

• , the tooth enamel, which was mechanically polished before use, had a mean square roughness (RMS) ranging between 3.4–4.0 nm. The higher substrate roughness of enamel would lower the particle–substrate contact area. This has been experimentally verified in earlier studies by measuring the pull-off force

Ni nanocrystals on HOPG(0001): A scanning tunnelling microscope study

• Michael Marz,
• Keisuke Sagisaka and
• Daisuke Fujita

Beilstein J. Nanotechnol. 2013, 4, 406–417, doi:10.3762/bjnano.4.48

• theory [27]), i.e., in the limit of small deformations. Thus, the adhesive force can be written as where γx is the surface tension and R the radius of the cluster, assuming a spherical particle. With γHOPG = 1.75 J/m2, γNi = 2.45 J/m2, and R = 5.9 nm, a pull off force of Fa = −4.36 nN is expected. The

Switching adhesion forces by crossing the metal–insulator transition in Magnéli-type vanadium oxide crystals

• Bert Stegemann,
• Matthias Klemm,
• Siegfried Horn and
• Mathias Woydt

Beilstein J. Nanotechnol. 2011, 2, 59–65, doi:10.3762/bjnano.2.8

• Johnson–Kendall–Roberts (JKR) model [19]. These two models improved the Hertzian theory [18] by including the effect of adhesion and present the limiting cases of more general contact theories by Maugis [32]. Both models have in common that the pull-off-force is independent of the elastic material

• crystal plane at 120 K and 298 K. The curves show the force interaction during approach and retraction of the tip from the surface. The adhesion force corresponds to the pull-off force between the tip and sample surface. Statistical analysis of the adhesion forces acquired at the V4O7 cleavage plane at (a