Advanced scanning probe lithography using anatase-to-rutile transition to create localized TiO₂ nanorods

• Julian Kalb,
• Vanessa Knittel and
• Lukas Schmidt-Mende

Beilstein J. Nanotechnol. 2019, 10, 412–418, doi:10.3762/bjnano.10.40

• growth observable at the breaking line. Nanorods growing around the breaking line might originate from anatase nanoparticles released during the breaking process. Besides surface roughening, charging is another candidate that could promote the growth on scratched regions. The tip causes a lot of friction

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

• 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

• substrate between the dimples. Keywords: adhesion; biomimetic micropatterned adhesive; colloidal lithography; friction; pull-off; soft substrate; Introduction Pull-off and friction forces of micropatterned adhesives as a function of geometry, feature size, and stiffness Over the last few decades

A comparison of tarsal morphology and traction force in the two burying beetles Nicrophorus nepalensis and Nicrophorus vespilloides (Coleoptera, Silphidae)

• Liesa Schnee,
• Benjamin Sampalla,
• Josef K. Müller and
• Oliver Betz

Beilstein J. Nanotechnol. 2019, 10, 47–61, doi:10.3762/bjnano.10.5

• , Hauptstr.1, 79104 Freiburg, Germany 10.3762/bjnano.10.5 Abstract Our aim was to compare friction and traction forces between two burying beetle species of the genus Nicrophorus exhibiting different attachment abilities during climbing. Specifically, the interaction of adhesive hairs and claws during

• fore tarsi performed on micro-rough and rough surfaces revealed higher friction in the proximal (pull) direction compared with the distal (push) direction. In these experiments, we detected neither differences in friction performance between the two species, nor clear trends concerning the influence of

• . Our results suggest that even subtle differences in the adhesion-mediating secretion in closely related species might result in qualitative performance shifts. Keywords: adhesion; friction; Insecta; locomotion; tarsus; Introduction Although mostly ground dwelling [1], burying beetles (Silphidae) of

Bidirectional biomimetic flow sensing with antiparallel and curved artificial hair sensors

• Claudio Abels,
• Antonio Qualtieri,
• Toni Lober,
• Alessandro Mariotti,
• Lily D. Chambers,
• Massimo De Vittorio,
• William M. Megill and
• Francesco Rizzi

Beilstein J. Nanotechnol. 2019, 10, 32–46, doi:10.3762/bjnano.10.4

• , various thermal effects on piezoresistors such as friction, self-heating and convection were described. Du et al. proposed an additional temperature resistance that could better compensate for temperature changes [41]. Other authors fabricated temperature compensation circuits together with the strain

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

• , stronger adhesion, and a more uniform stress distribution with higher tolerance to defects. However, while it is widely believed that contact splitting helps to mitigate the negative effects of roughness on adhesion- and friction-based attachment, no decisive experimental validation of this hypothesis has

• been performed so far for thin-film-based adhesives. To this end, we report on the behavior of original and split, wall-shaped adhesive microstructures on different surfaces ranging across four orders of magnitude in roughness. Our results clearly demonstrate that the adhesion- and friction-driven

• their attachment abilities are reduced if the fibril dimensions are similar to the root-mean-square roughness, the mean spacing between local peaks, and the surface waviness characteristics of the substrate [20][21][22][23]. Analogous negative effects of roughness on adhesion and friction of biomimetic

In situ characterization of nanoscale contaminations adsorbed in air using atomic force microscopy

• Jesús S. Lacasa,
• Lisa Almonte and
• Jaime Colchero

Beilstein J. Nanotechnol. 2018, 9, 2925–2935, doi:10.3762/bjnano.9.271

• contamination; tip cleaning; tip–sample interaction; van der Waals interaction; Introduction Surface science is fundamental to understand many processes in industrial applications, environmental science, biology, medicine and phenomena such as self-assembly [1], friction [2][3] and wetting [4]. In any study

Layered calcium phenylphosphonate: a hybrid material for a new generation of nanofillers

• Kateřina Kopecká,
• Ludvík Beneš,
• Klára Melánová,
• Vítězslav Zima,
• Petr Knotek and
• Kateřina Zetková

Beilstein J. Nanotechnol. 2018, 9, 2906–2915, doi:10.3762/bjnano.9.269

• friction bowl. Exfoliation of CaPhP Solvent selection A sample of CaPhP_a (10–13 mg) was put into a small glass vial to which 5 mL of a solvent (distilled water, propan-2-ol, ethanol, butanol, acetone) was added. The mixture was sonicated in an ultrasound bath (f = 37 kHz) for one hour and the temperature

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

• significantly lower than what has been observed with geckos, their structures exhibited very high friction in the direction along the tilt of fibers, termed here as gripping. Also, low adhesion allowed for an easily removable bio-inspired adhesive. Most of these works have featured softer fibers of monolithic

• elements with varying elastic modulus as shown in Figure 1b. Using these fibers, the effect of the elastic modulus of the joint between the stalk and the tip on adhesion and friction is investigated. All the fiber array stalks and the tips are made of polyurethane with elastic modulus Es = 126 MPa and Et

• Figure 1c. Friction and adhesion are measured as a function of initial compressive load (preload) using load–drag–pull (LDP) experiments. Fibers arrays were dragged in the direction of tilt (i.e., gripping direction) and against the tilt direction (i.e., releasing direction) to assess directional

Biomimetic surface structures in steel fabricated with femtosecond laser pulses: influence of laser rescanning on morphology and wettability

• Camilo Florian Baron,
• Alexandros Mimidis,
• Daniel Puerto,
• Evangelos Skoulas,
• Emmanuel Stratakis,
• Javier Solis and
• Jan Siegel

Beilstein J. Nanotechnol. 2018, 9, 2802–2812, doi:10.3762/bjnano.9.262

• wetting and friction properties of a material for numerous applications [5][6][8][23][24]. Yet the type of LIPSSs investigated so far for these applications was mostly limited to those mentioned above (ripples, groves and spikes), and less so the more complex structures that are accessible by exploring a

• surface morphology. We present experimental results of complex self-organized structures produced in commercial steel that resemble the morphology of the skin of certain reptiles and insects, which are of great interest due to their exceptional fluid transport and friction reduction properties. Surface

• well defined. In terms of biomimetics, these structures resemble the tiles found on the skin of the Python regius snake, whose microstructure makes it very resistant to damage from wear by reducing friction (c.f. Figure 2E). Laser-based surface texturing has been used to mimic this structure in steel

Characterization of the microscopic tribological properties of sandfish (Scincus scincus) scales by atomic force microscopy

• Weibin Wu,
• Christian Lutz,
• Simon Mersch,
• Richard Thelen,
• Christian Greiner,
• Guillaume Gomard and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2018, 9, 2618–2627, doi:10.3762/bjnano.9.243

• sandfish due to their ability to swim in loose, aeolian sand. Some studies report that this fascinating property of sandfish is accompanied by unique tribological properties of their skin such as ultra-low adhesion, friction and wear. The majority of these reports, however, is based on experiments

• conducted with a non-standard granular tribometer. Here, we characterise microscopic adhesion, friction and wear of single sandfish scales by atomic force microscopy. The analysis of frictional properties with different types of probes (sharp silicon tips, spherical glass tips and sand debris) demonstrates

• every two to three months [6], and we are not aware of any report of observable wear on sandfish skin caused by its swimming in loose sand. Rechenberg [3][7][8] and Baumgartner et al. [6][9][12] conducted pioneering studies analysing friction and wear of sandfish skin applying a granular friction

Friction reduction through biologically inspired scale-like laser surface textures

• Johannes Schneider,
• Vergil Djamiykov and
• Christian Greiner

Beilstein J. Nanotechnol. 2018, 9, 2561–2572, doi:10.3762/bjnano.9.238

• Reducing friction forces is a major challenge in many engineering applications involving moving parts. For the past 50 years, the morphological texturing of surfaces for improving tribological properties has been investigated. Only recently, the application of biologically inspired surface features, like

• biologically inspired surface morphology has the potential to reduce friction forces by more than 80%. However, under certain conditions, especially for slow-moving lubricated steel-on-steel and steel-on-ceramic contacts, these surface morphologies may increase friction as well. Similar to classical laser

• the potential to yield significant reduction in friction forces and are expected to spark future research in the field of biologically inspired surface morphologies applied to tribological contacts. Keywords: bioinspiration; friction; laser surface texturing; scales; tribology; Introduction Friction

Evidence of friction reduction in laterally graded materials

• Roberto Guarino,
• Gianluca Costagliola,
• Federico Bosia and
• Nicola Maria Pugno

Beilstein J. Nanotechnol. 2018, 9, 2443–2456, doi:10.3762/bjnano.9.229

• frictional and adhesive behaviour can also be achieved by exploiting a grading of the material properties. In this paper, we investigate this possibility by considering the frictional sliding of elastic surfaces in the presence of a spatial variation of the Young’s modulus and the local friction coefficients

• . Using finite-element simulations and a two-dimensional spring-block model, we investigate how graded material properties affect the macroscopic frictional behaviour, in particular, static friction values and the transition from static to dynamic friction. The results suggest that the graded material

• properties can be exploited to reduce static friction with respect to the corresponding non-graded material and to tune it to desired values, opening possibilities for the design of bio-inspired surfaces with tailor-made tribological properties. Keywords: bio-inspired materials; friction; functionally

Nanotribology

• Enrico Gnecco,
• Susan Perkin,
• Andrea Vanossi and
• Ernst Meyer

Beilstein J. Nanotechnol. 2018, 9, 2330–2331, doi:10.3762/bjnano.9.217

• : nanotribology; nanoadhesion; nanofriction; Nanotribology is a young and dynamic field of research which aims to investigate friction, wear and adhesion phenomena down to the nanometer scale. Since these phenomena occur in all natural, artificial or conceptual situations involving two surfaces (at least) in

• India, China, Argentina, Cameroon, Russia and USA back to many countries in Old Europe). The covered topics include lubrication, surface preparation and theoretical models of friction at the nanoscale. Regarding the first topic, this Thematic Series gives examples of cutting-edge aqueous solutions

• , different authors have modeled the influence of electrical double layers on hydrodynamic lubrication [6], the occurrence of a second-order phase transition in ultrathin lubricant films [7] and the velocity dependence of dry friction on crystal surfaces at the atomic scale [8]. While many experimental

Recent highlights in nanoscale and mesoscale friction

• Andrea Vanossi,
• Dirk Dietzel,
• Andre Schirmeisen,
• Ernst Meyer,
• Rémy Pawlak,
• Thilo Glatzel,
• Marcin Kisiel,
• Shigeki Kawai and
• Nicola Manini

Beilstein J. Nanotechnol. 2018, 9, 1995–2014, doi:10.3762/bjnano.9.190

• -0044, Japan Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano, Italy 10.3762/bjnano.9.190 Abstract Friction is the oldest branch of non-equilibrium condensed matter physics and, at the same time, the least established at the fundamental level. A full understanding

• and control of friction is increasingly recognized to involve all relevant size and time scales. We review here some recent advances on the research focusing of nano- and mesoscale tribology phenomena. These advances are currently pursued in a multifaceted approach starting from the fundamental atomic

• -scale friction and mechanical control of specific single-asperity combinations, e.g., nanoclusters on layered materials, then scaling up to the meso/microscale of extended, occasionally lubricated, interfaces and driven trapped optical systems, and eventually up to the macroscale. Currently, this “hot

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

• Christiane Petzold Marcus Koch Roland Bennewitz INM – Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany 10.3762/bjnano.9.157 Abstract Friction force microscopy was performed with oxidized or gold-coated silicon tips sliding on Au(111) or oxidized Si(100) surfaces in

• ultrahigh vacuum. We measured very low friction forces compared to adhesion forces and found a modulation of lateral forces reflecting the atomic structure of the surfaces. Holding the force-microscopy tip stationary for some time did not lead to an increase in static friction, i.e., no contact ageing was

• observed for these pairs of tip and surface. Passivating layers from tip or surface were removed in order to allow for contact ageing through the development of chemical bonds in the static contact. After removal of the passivating layers, tribochemical reactions resulted in strong friction forces and tip

Atomic-level characterization and cilostazol affinity of poly(lactic acid) nanoparticles conjugated with differentially charged hydrophilic molecules

• María Francisca Matus,
• Martín Ludueña,
• Cristian Vilos,
• Iván Palomo and
• Marcelo M. Mariscal

Beilstein J. Nanotechnol. 2018, 9, 1328–1338, doi:10.3762/bjnano.9.126

• , Langevin dynamics were performed on these final structures with a friction coefficient of 30 ps−1. In this way, the solvent particles are omitted, and their effects are represented by a combination of random forces and frictional terms. Simulations of 1 ns were carried out. The velocity Verlet-like

Atomistic modeling of tribological properties of Pd and Al nanoparticles on a graphene surface

• Alexei Khomenko,
• Miroslav Zakharov,
• Denis Boyko and
• Bo N. J. Persson

Beilstein J. Nanotechnol. 2018, 9, 1239–1246, doi:10.3762/bjnano.9.115

• insight into the fundamental origin of sliding friction. Results: Using molecular dynamics we investigate frictional properties of aluminum and palladium nanoparticles deposited on a graphene layer. We study the time evolution of the total momentum of the system, the total and potential energies, the

• temperature, the velocity and position of the center of mass, the dimensions of the nanoparticle, and the friction and substrate forces acting on the particle. We also study how the friction force depends on the nanoparticle–graphene contact area and the temperature. Conclusion: The tribological properties of

• nanoparticles strongly depend on the materials. The particles move in an irregular (saw-like) manner. The averaged friction force depends nearly linearly on the contact area and non-monotonously on temperature. We observe ordered crystalline domains of atoms at the bottom surface of the metal particles, but the

Surface characterization of nanoparticles using near-field light scattering

• Eunsoo Yoo,
• Yizhong Liu,
• Chukwuazam A. Nwasike,
• Sebastian R. Freeman,
• Brian C. DiPaolo,
• Bernardo Cordovez and
• Amber L. Doiron

Beilstein J. Nanotechnol. 2018, 9, 1228–1238, doi:10.3762/bjnano.9.114

• and waveguide surface is represented by a friction force, Ffric, which is a complex function of numerous dynamic properties. We use a simple approach, assuming Ffric is inversely proportional to height and increases linearly with velocity (Ffric = Av/z, where A is a constant and v is the velocity). By

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

• . [13] predicted the theoretical scanning speed limit, in terms of the maximum achievable resolution, and other researchers such as Bosse et al. [14] have created methods to more accurately measure relevant system parameters, such as the friction coefficient, at higher scan speeds. What is not fully

• has an effect on the friction [18][19]. Furthermore, this effect depends on the scan speed and can bring the system from a stick–slip state to a “steady sliding” state above a critical velocity [18]. It is noted that “a small viscous damping contribution in the tip–sample contact is sufficient enough

Effect of microtrichia on the interlocking mechanism in the Asian ladybeetle, Harmonia axyridis (Coleoptera: Coccinellidae)

• Jiyu Sun,
• Chao Liu,
• Bharat Bhushan,
• Wei Wu and
• Jin Tong

Beilstein J. Nanotechnol. 2018, 9, 812–823, doi:10.3762/bjnano.9.75

• a cyclical change from sparse to dense in each segment in the middle of the abdomen. Furthermore, the different directions of microtrichia that lead to self-locking friction on the surfaces of the hindwing, elytron and abdomen appear to facilitate interlocking. A model for the interlocking of the

• include producing stridulations through interactions with the elytra, thorax and hindwings; increasing the friction that allows the parts to integrate into a whole; creating a buffer to protect the body from damage; and sensing the surrounding environment [21]. It remains unclear how beetles package their

• hindwings during folding into the tight space between the elytra and the abdomen. Improving our understanding of the directional friction locks that enable linkage between folded wing layers and between wings, movable elytra and the abdomen and of the morphology of microtrichia (length, width, distance

Single-step process to improve the mechanical properties of carbon nanotube yarn

• Maria Cecilia Evora,
• Xinyi Lu,
• Nitilaksha Hiremath,
• Nam-Goo Kang,
• Kunlun Hong,
• Roberto Uribe,
• Gajanan Bhat and
• Jimmy Mays

Beilstein J. Nanotechnol. 2018, 9, 545–554, doi:10.3762/bjnano.9.52

• . Covalent bonding among the tubes can be obtained via simultaneous functionalization and crosslinking [19]. Possible strategies for enhancing the friction between CNTs include modifying CNT surfaces through physical processes (e.g., condensing the tubes under high pressure) [16], chemical processes [20][21

Engineering of oriented carbon nanotubes in composite materials

• Razieh Beigmoradi,
• Abdolreza Samimi and
• Davod Mohebbi-Kalhori

Beilstein J. Nanotechnol. 2018, 9, 415–435, doi:10.3762/bjnano.9.41

• hard, solid or powder, biological, and organic or inorganic surfaces. This device can measure geometric morphology, adhesion distribution, friction, surface impurities, texture, elasticity, magnetism, chemical bonding forces, distribution of electric charges and electric polarization in different parts

• of the surface. In practice, this feature is used to study corrosion, cleanness, uniformity, roughness, adhesion, friction, size, etc. AFM, like SEM and TEM, is a suitable technique to characterize the alignment of CNTs, especially horizontal alignment; for instance, when the CNTs grow horizontally

Review: Electrostatically actuated nanobeam-based nanoelectromechanical switches – materials solutions and operational conditions

• Liga Jasulaneca,
• Jelena Kosmaca,
• Raimonds Meija,
• Jana Andzane and
• Donats Erts

Beilstein J. Nanotechnol. 2018, 9, 271–300, doi:10.3762/bjnano.9.29

• -nanomanipulation techniques aimed to determine how changes in the contact electrode material and geometry of 2T NEM switch influence the device characteristics [8]. The very low coefficient of friction of Mo6S3I6 (0.03 [135]) could help to reduce surface wear originating from the tangential forces in the NEM

Exploring wear at the nanoscale with circular mode atomic force microscopy

• Olivier Noel,
• Aleksandar Vencl and
• Pierre-Emmanuel Mazeran

Beilstein J. Nanotechnol. 2017, 8, 2662–2668, doi:10.3762/bjnano.8.266

• (nanowear) have been reported in the literature [17][18][19][20], whereas AFM has been widely used for measuring nanoscale friction [21][22]. In this paper, we propose a new experimental methodology based on circular mode AFM (CM-AFM) to explore wear mechanisms and laws at the nanoscale. It consists of

• lateral force microscopy (LFM) signal proportional to the friction force) of the cantilever stemming from the circular displacement of the contact features a sinusoidal signal with the same frequency as the relative circular displacement of the contact. Then a lock-in amplifier is used to register the

• real-time amplitude of the LFM signal of the cantilever (or friction force) during the wear experiment in order to determine prospective variations of the friction properties during the experiment. For example, this option may be advantageously implemented for investigating the correlation between

Patterning of supported gold monolayers via chemical lift-off lithography

• Liane S. Slaughter,
• Kevin M. Cheung,
• Sami Kaappa,
• Huan H. Cao,
• Qing Yang,
• Thomas D. Young,
• Andrew C. Serino,
• Sami Malola,
• Jana M. Olson,
• Stephan Link,
• Hannu Häkkinen,
• Anne M. Andrews and
• Paul S. Weiss

Beilstein J. Nanotechnol. 2017, 8, 2648–2661, doi:10.3762/bjnano.8.265

• adds both a small, random contribution to the force on the atoms and a small friction factor that slows them down, aiming for an average total kinetic energy of the atoms that corresponds to the target temperature. The time step for molecular dynamics was 2 fs. To maintain the stability of hydrogen

• removal, the system was heated up to room temperature using the Langevin thermostat with a friction parameter of 0.002 s−1; the heating procedure was run for 2 ps in simulated time. The lowest layer of Au was fixed in its initial position to enable the removal of the thiolates. The pulling moved the