Natural nanofibers embedded in the seed mucilage envelope: composite hydrogels with specific adhesive and frictional properties

• Agnieszka Kreitschitz and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2024, 15, 1603–1618, doi:10.3762/bjnano.15.126

• ][28]. Hydrated mucilage can very strongly adhere to surfaces (e.g., stone or glass) when completely dried out after contact, with pull-off forces reaching values around 6.5 N [29]. Such strong adhesion can enable seed attachment to the soil, preventing removal and damage by other organisms [16][30

The effect of age on the attachment ability of stick insects (Phasmatodea)

• Marie Grote,
• Stanislav N. Gorb and
• Thies H. Büscher

Beilstein J. Nanotechnol. 2024, 15, 867–883, doi:10.3762/bjnano.15.72

• animals were compared in two directions. The pull-off force was measured perpendicular to the substrate, and the traction force parallel to the substrate, to assess the ability of the insect to attach itself in the respective direction and evaluate potential differences arising from performance decay of

• either of the two components of the overall attachment system. The aim of this study was to answer the following research questions: (1) Does the attachment ability of older animals differ from that of younger animals? (2) Do pull-off and traction forces on the same substrates change during age? (3) Does

• force measurements were conducted using a BIOPAC MP100 data acquisition system with a TCI-102 interface (BIOPAC Systems, Inc., USA) and a 100g force transducer (Fort100, World Precision Instruments, Sarasota, FL) using the setup described in Winand and coworkers [37]. We measured pull-off (perpendicular

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

• sample is prevented. The previously proposed one-pass CL-KPFM implementations operating on top of a PFT-type mode used a continuous KPFM modulation during the out-of-contact intervals of the PFT oscillation [65][66]. This might affect the snap-in and pull-off acts of the PFT motion and, being operated in

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

• half-space. This procedure results in a theoretical LJ F(z) curve unique to the geometry of the tip used in the study. Multiple LJ F(z) curves were generated for a range of Wadh and z0 values and compared to experimental measurements of pull-off forces and snap-in distances to determine best-fit

• 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

• -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

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

• with a spherical shape, separated by hourglass-shaped walls. These voids penetrate the terminal layer, resulting in an array of holes at the surface. We found that on soft substrates, generally, the size of the dimples did not affect pull-off forces. The positive effects of sub-microscale features on

• pull-off and friction forces, such as defect control and crack trapping, as reported in the literature for hard substrates, seem to disappear on soft substrates. The dimple geometry with a terminal layer generated significantly higher pull-off forces compared to other geometries, presumably due to

• interlocking of the soft substrate into the holes of the terminal layer. Pull-off from soft substrates increased with the substrate stiffness for all tested geometries. Friction forces on soft substrates were the highest for microscale dimples without a terminal layer, likely due to interlocking of the soft

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

• magnitude in roughness. Results and Discussion Pull-off forces measured with original and split wall-shaped adhesive microstructures against different rough surfaces (Figure 1, see Experimental for details) are shown in Figure 2. The surfaces are represented using the traditional root-mean-square deviation

• 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

• may differ greatly. This effect is evident in Figure 2a,b, where several surfaces having similar profile characteristics demonstrate very different pull-off forces. The lack of correlation between waviness-dominated characteristics and adhesion suggests that filtering the waviness out may result in a

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

• kPa in shear and 110 kPa in pull-off stress in the gripping direction, which are twice and ten times higher than that in the releasing direction, respectively. A model to optimize the elastic modulus of the joint-like elements to enable sliding without peeling of the tips has been proposed. Keywords

• 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

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

• brush is shown in blue while the green color map shows the surface deformation of the elastic half-space during pull-off. It is known that in the approximation of independent asperities, adhesion can be described in a most general and elegant way if the distribution of asperity heights is described by

• following pull-off. The quantities which we are interested in, and which will be presented in the following diagrams, are solely the maximum force during the indentation stage, Fp, and the force of adhesion, FA, defined as the absolute value of the minimum (negative) value of the normal force during 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

• protein is pulled from the surface of the adhesive fibrils and the “hidden length” of the amino acid chain is extended [1]. When probed directly in milli-Q water, pull-off forces around 63 ± 40 pN were needed to break these sacrificial bonds [1]. As for barnacle cyprid larvae they use glycoproteinaceous

• 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

• sawtooth appearance for both tip types, but higher pull-off forces were obtained with CH3-tips (2.2 ± 0.4 nN) than with Si3N4-tips (1.1 ± 0.2 nN) [3]. As for the adhesive morphology of B. amphitrite, it was shown to be identical to S. balanoides, and force curves also presented the above-mentioned

Friction force microscopy of tribochemistry and interfacial ageing for the SiO_x/Si/Au system

• Christiane Petzold,
• Marcus Koch and
• Roland Bennewitz

Beilstein J. Nanotechnol. 2018, 9, 1647–1658, doi:10.3762/bjnano.9.157

• oxidized silicon surfaces, the chemical bond formation leading to contact ageing does not occur in the absence of water in UHV. Both systems show very low lateral forces compared to pull-off forces, modulated by the atomic structure of the surface. When passivating layers are removed from tips or surfaces

Scanning speed phenomenon in contact-resonance atomic force microscopy

• Christopher C. Glover,
• Jason P. Killgore and
• Ryan C. Tung

Beilstein J. Nanotechnol. 2018, 9, 945–952, doi:10.3762/bjnano.9.87

• thick [16][17] and is usually studied by measuring adhesive forces between the AFM tip and sample. Capillary necking between the adsorbed water layer and AFM tip creates additional adhesive forces that can be easily measured with a typical AFM system. These measurements are conducted using force pull

• -off techniques and are not conducted while the AFM tip is dynamically rastered across the sample. Figure 1 depicts the dynamic phenomenon we are investigating. In Figure 1a, the AFM tip is in contact with the elastic sample oscillating with a frequency ω and is moved across the sample at a fixed

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

• break during pull-off and results in a small residual water droplet on the surface. In the present study, we choose mercury as the liquid because it presents many advantages. Hg possesses a very high surface tension and negligible evaporation, plus it is relatively easy to attach to a tipless cantilever

Biological and biomimetic materials and surfaces

• Stanislav Gorb and
• Thomas Speck

Beilstein J. Nanotechnol. 2017, 8, 403–407, doi:10.3762/bjnano.8.42

• systems [16]. The adhesive tongues of frogs are an efficient tool capable of capturing fast moving prey. It is plausible that the interaction between the tongue surface and the adhesive mucus coating is important for generating strong pull-off forces. The paper by Kleinteich and Gorb is a comparative

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

Frog tongue surface microstructures: functional and evolutionary patterns

• Thomas Kleinteich and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2016, 7, 893–903, doi:10.3762/bjnano.7.81

• adhere instantaneously to various prey surfaces. Recently, the functional morphology of frog tongues was discussed in context of their adhesive performance. It was suggested that the interaction between the tongue surface and the mucus coating is important for generating strong pull-off forces. However

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

• are II and III, as opposed to mode I, which operates during pull-off [18]. Gao and Yao find that the crack propagation mechanism becomes inefficient once the contact diameter falls to below 100 nm. For small contacts, the stress concentration at the edge becomes less and less significant. Translated

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

• interaction. This method also assumes that the distribution of the average number of interactions at the pull-off point follows a Poisson distribution, where P(n) is the possibility of the specific interaction, and is the variance of the number of interacting bonds. The expectation of a Poisson-distributed

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

• different characteristics of crystalline wax surfaces influence the attachment? We also measured adhesion (pull-off) forces of artificial adhesive systems on these surfaces. Here, tacky and deformable polydimethylsiloxane (PDMS) semi-spheres, having elasticity moduli similar to those of insect adhesive pads

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

• , M.; Gorb, S. J. R. Soc., Interface 2008, 5, 383–385] proposed to explain the strong underwater adhesion of mushroom-shaped adhesive microstructures (MSAMSs). For this purpose, we measured the pull-off forces of individual MSAMSs by detaching them from a glass substrate under different wetting

• negative pressure (tension), the pull-off forces were consistently lower, around 50%, of those measured under ambient conditions. This result supports the assumption that the recently observed strong underwater adhesion of MSAMS is due to an air layer between individual MSAMSs [Kizilkan, E.; Heepe, L

• in predominantly liquid environments. Keywords: bio-inspired; biomimetic; cavitation; contact mechanics; gecko; interface; negative pressure; pull-off; surface; tribology; Introduction During the past two decades, bio-inspired microstructured adhesives became a new class of adhesive materials with

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

• mushroom-like fibers is investigated by implementing the Dugdale–Barenblatt cohesive zone model into finite elements simulations. It is found that the magnitude of pull-off stress depends on the edge angle θ and the ratio of the tip radius to the stalk radius β of the mushroom-like fiber. Pull-off stress

• β and θ. An analytical model for pull-off stress, which depends on the location of crack initiation as well as on θ and β, is proposed and found to agree with the simulation results. Results obtained in this work provide a geometrical guideline for designing robust bio-inspired dry fibrillar

• . Furthermore, measured adhesive strengths have matched, and in some instances such as smooth surface applications, surpassed the adhesive strengths recorded for gecko footpads [21][30][33][37]. Work by del Campo et al. [21] reports enhancements in pull-off loads as much as 40-fold with mushroom-like fibers