Dry under water: air retaining properties of large-scale elastomer foils covered with mushroom-shaped surface microstructures

• Matthias Mail,
• Stefan Walheim,
• Thomas Schimmel,
• Wilhelm Barthlott,
• Stanislav N. Gorb and
• Lars Heepe

Beilstein J. Nanotechnol. 2022, 13, 1370–1379, doi:10.3762/bjnano.13.113

• between water and a solid surface might serve as friction reduction agents, fouling protectors, corrosion protectors or for other applications, such as sensors [11][12][13][14]. Biological examples for such air retaining surfaces with most stable and persistent air layers were found on the floating ferns

• function for biomimetic air retaining surfaces is drag reduction. If an air layer is mounted between a solid surface and water flowing over this surface, the air layer serves as slip agent [26][27][28]. Such a drag reducing coverage allows significant friction reduction (up to 30%) in applications, where

Bending and punching characteristics of aluminum sheets using the quasi-continuum method

• Man-Ping Chang,
• Shang-Jui Lin and
• Te-Hua Fang

Beilstein J. Nanotechnol. 2022, 13, 1303–1315, doi:10.3762/bjnano.13.108

• strength at a specific structural orientation [51]. Besides, Tran et al. studied the friction and scratch characteristics of pure aluminum by the QC method. The bump width to the bump pitch (W/P) value, scratch depth, surface roughness, and indenter radius were set as variables in order to explore the

• friction behaviors of different models [52]. Moreover, the QC method based on the embedded-atom method (EAM) potential was adopted to observe the fatigue crack growth and expansion characteristics of single-crystal metals under cyclic loading processes. The results showed that after compressive or shear

• of the coupled regions [54]. Results and Discussion In this section, the QC method was used to explore the effects of different crystal orientations, workpiece thickness, clearance, and taper angle on the nano-punching process. The friction characteristic of interface and residual flash phenomena

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

• morphology of the mandibles, as all examined mandibles had this characteristic. Anisotropic structures are also present on other animals such as snakes and were proposed to support anisotropic properties, for example, anisotropic friction [34]. The scales on bee mandibles are mostly oriented towards the apex

Micro-structures, nanomechanical properties and flight performance of three beetles with different folding ratios

• Jiyu Sun,
• Pengpeng Li,
• Yongwei Yan,
• Fa Song,
• Nuo Xu and
• Zhijun Zhang

Beilstein J. Nanotechnol. 2022, 13, 845–856, doi:10.3762/bjnano.13.75

• induced drag Dind, profile drag Dpro, and parasite drag Dpar. Dind represents the cost of generating lift, Dpro is the drag of the wings and Dpar is due to skin friction and the drag from the body form [45]. It was found that the wingspan b and Sw of the hind wings decrease simultaneously when passive

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 corresponds to friction. In our case, we attribute the observed hysteresis of the lateral force to the resistance to pull and drag a meniscus at the tip–metallic liquid interface. In principle, this resistance corresponds to the interfacial tension of the tip and metallic liquid. The occurrence of

Hierachical epicuticular wax coverage on leaves of Deschampsia antarctica as a possible adaptation to severe environmental conditions

• Elena V. Gorb,
• Iryna A. Kozeretska and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2022, 13, 807–816, doi:10.3762/bjnano.13.71

• /friction on the nanoscale rough surface is rather low [46][47]. Conclusion A cryo-SEM examination of the vegetative (leaf blade and ligule) and generative (pedicel and outer glume) organs in D. antarctica revealed a prominent epicuticular wax coverage on surfaces of both vegetative organs studied. Whereas

Fabrication and testing of polymer microneedles for transdermal drug delivery

• Vahid Ebrahiminejad,
• Zahra Faraji Rad,
• Philip D. Prewett and
• Graham J. Davies

Beilstein J. Nanotechnol. 2022, 13, 629–640, doi:10.3762/bjnano.13.55

• algorithm was used to create fine elements at the tip of the MNs. The coefficient of friction between the contact surfaces was set to 0.42 [29]. Upon MN penetration, with a constant impact speed of 4.5 m/s, the force-displacement data were recorded to estimate the insertion force. To enable the skin

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

• microscale energy system. Triboelectric power generation: Two materials with different work functions will gain or lose electrons when they are in contact with each other, resulting in the triboelectric effect [90]. When the switch is closed, the electrode contact friction causes the surfaces to carry

• charges, forming a dielectric charging effect. Molinero et al. [52][53] characterized the dielectric charging when the switch electrodes were contacted and proved that the surface dielectric charging caused by friction would lead to a shift of the switch voltage and shorten the life cycles of the switch

Micro- and nanotechnology in biomedical engineering for cartilage tissue regeneration in osteoarthritis

• Zahra Nabizadeh,
• Mahmoud Nasrollahzadeh,
• Hamed Daemi,
• Mohamadreza Baghaban Eslaminejad,
• Ali Akbar Shabani,
• Mehdi Dadashpour,
• Majid Mirmohammadkhani and
• Davood Nasrabadi

Beilstein J. Nanotechnol. 2022, 13, 363–389, doi:10.3762/bjnano.13.31

• -friction, wear resistant surface for joint motion [6][7]. It is an avascular, aneural, alymphatic, and hypocellular tissue consisting of a single cell type (chondrocyte) dispersed in a dense matrix [6]. Chondrocytes, which constitute only about 5% of the wet weight of the articular cartilage, are

The effect of metal surface nanomorphology on the output performance of a TENG

• Yiru Wang,
• Xin Zhao,
• Yang Liu and
• Wenjun Zhou

Beilstein J. Nanotechnol. 2022, 13, 298–312, doi:10.3762/bjnano.13.25

• principles of TENGs converting mechanical energy into electrical energy are the friction electrification effect and the electrostatic induction principle. When two materials with different electronegativity are physically contacted, positive and negative electrostatic charges are generated on each material

•  9). Generally, due to the increase of contact area and surface charge density a higher friction electrical output is produced. Large copper nanoparticles have full contact with the polymer, but small copper nanoparticles have insufficient contact with the polymer or even no contact at all. Therefore

• , the improvement of friction electrical output performance is not obvious. Experiments 4, 5, and 15, which are shown in Figure 5 and Figure 6, respectively, yielded pyramidal copper nanoparticles with sharp surfaces. Among them, experiments 4 and 5 improved the output performance only by 18% to 19

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

• are promising materials for microdevices, although corrosion and friction limit their effectiveness and durability. We investigated nanoscale friction on a metallic glass in corrosive solutions after different periods of immersion time using atomic force microscopy to elucidate the influence of

• corrosion on nanoscale friction. The evolution of friction upon repeated scanning cycles on the corroded surfaces reveals a bilayer surface oxide film, of which the outer layer is removed by the scanning tip. The measurement of friction and adhesion allows one to compare the physicochemical processes of

• surface dissolution at the interface of the two layers. The findings contribute to the understanding of mechanical contacts with metallic glasses under corrosive conditions by exploring the interrelation of microscopic corrosion mechanisms and nanoscale friction. Keywords: atomic force microscopy (AFM

Nanoscale friction and wear of a polymer coated with graphene

• Robin Vacher and
• Astrid S. de Wijn

Beilstein J. Nanotechnol. 2022, 13, 63–73, doi:10.3762/bjnano.13.4

• Robin Vacher Astrid S. de Wijn Corrosion and tribology, SINTEF, Richard Birkelands vei 2B, 7034 Trondheim, Norway Institutt for maskinteknikk og produksjon, NTNU, Richard Birkelands vei 2B, 7034 Trondheim, Norway 10.3762/bjnano.13.4 Abstract Friction and wear of polymers at the nanoscale is a

• challenging problem due to the complex viscoelastic properties and structure. Using molecular dynamics simulations, we investigate how a graphene sheet on top of the semicrystalline polymer polyvinyl alcohol affects the friction and wear. Our setup is meant to resemble an AFM experiment with a silicon tip. We

• have used two different graphene sheets, namely an unstrained, flat sheet, and one that has been crumpled before being deposited on the polymer. The graphene protects the top layer of the polymer from wear and reduces the friction. The unstrained flat graphene is stiffer, and we find that it constrains

Effect of lubricants on the rotational transmission between solid-state gears

• Huang-Hsiang Lin,
• Jonathan Heinze,
• Alexander Croy,
• Rafael Gutiérrez and
• Gianaurelio Cuniberti

Beilstein J. Nanotechnol. 2022, 13, 54–62, doi:10.3762/bjnano.13.3

• Huang-Hsiang Lin Jonathan Heinze Alexander Croy Rafael Gutierrez Gianaurelio Cuniberti Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, Germany 10.3762/bjnano.13.3 Abstract Lubricants are widely used in macroscopic mechanical systems to reduce friction

• formation process between gears. Keywords: lubricants; MD simulation; rotational transmission; solid-state gears; Introduction In mechanical systems, lubrication is the most common way to reduce friction and wear [1][2][3][4]. The idea of lubricants is preventing direct contact between surfaces to avoid

• dry friction from asperities and wear. Hence, the desirable lubrication regime would be hydrodynamic or elastohydrodynamic lubrication in the Stribeck curve [5]. The former corresponds to the situation that surfaces are completely separated by a fluid. The latter is similar but surface deformations

Topographic signatures and manipulations of Fe atoms, CO molecules and NaCl islands on superconducting Pb(111)

• Carl Drechsel,
• Philipp D’Astolfo,
• Jung-Ching Liu,
• Thilo Glatzel,
• Rémy Pawlak and
• Ernst Meyer

Beilstein J. Nanotechnol. 2022, 13, 1–9, doi:10.3762/bjnano.13.1

• features resemble typical patterns observed in friction force microscopy (FFM) [28][38] or scanning tunneling hydrogen microscopy (SThM) [70][71], since the trapped Fe atom senses the surface potential in analogy to the probing tip of FFM. For clarity, we overlay the Pb(111) surface lattice on top of the

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

• smaller than that of the three PCCs. This could be caused by the difference of the internal friction and/or vicious damping [26][27] between the normal and the cancer cells. The relative Young’s modulus distributions of different kinds of cells, according to the nanomechanical mapping (Figure 3a–d) and

Polarity in cuticular ridge development and insect attachment on leaf surfaces of Schismatoglottis calyptrata (Araceae)

• Venkata A. Surapaneni,
• Tobias Aust,
• Thomas Speck and
• Marc Thielen

Beilstein J. Nanotechnol. 2021, 12, 1326–1338, doi:10.3762/bjnano.12.98

• different. Such unevenness in the exposure of the leaf to the external environment might result in the inclined ridge progression on the S. calyptrata leaves. Also, the presence of ridges on the leaf surfaces might reduce friction, thereby, avoiding damage between the delicate rolled leaf layers during

A review on slip boundary conditions at the nanoscale: recent development and applications

• Ruifei Wang,
• Jin Chai,
• Bobo Luo,
• Xiong Liu,
• Jianting Zhang,
• Min Wu,
• Mingdan Wei and
• Zhuanyue Ma

Beilstein J. Nanotechnol. 2021, 12, 1237–1251, doi:10.3762/bjnano.12.91

• shear viscosity of the liquid, equal to the friction stress suffered by the liquid from the wall, which is expressed as σ = λνs, where λ represents the interfacial friction coefficient [46]. Therefore, the slip length can be expressed as , which indicates that the slip length is reduced with the

• increase in the friction between liquid and solid surfaces. Since the interfacial friction coefficient can be expressed in terms of the Green–Kubo expression, the microscopic expression of slip length can be written as follows [1][46]: where S is the area of the solid wall and Fl is the component of the

• interaction energy, and water slippage (or friction coefficient) may also not have a one-to-one correspondence between each other [67][68][69]. Contrary to the conventional wisdom, where slip boundary conditions are not valied for water slippage on hydrophilic surfaces, some simulation observations show that

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

• classical contact mode, the friction force can be measured; when using off-resonance dynamic modes, stiffness and adhesion in the samples can be determined. Obviously, in determining the mechanical properties, the force of tip–surface interaction should be somewhat greater than that required if the task is

The role of convolutional neural networks in scanning probe microscopy: a review

• Ido Azuri,
• Irit Rosenhek-Goldian,
• Neta Regev-Rudzki,
• Georg Fantner and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2021, 12, 878–901, doi:10.3762/bjnano.12.66

• topography, for example, adhesion, phase shift, stiffness, work function, or friction. In the following section, the utility of CNN in SPM is illustrated through several examples taken from the literature. Enhancing speed of image acquisition As discussed above, SPM imaging is inherently slow. One of the

Recent progress in actuation technologies of micro/nanorobots

• Ke Xu and
• Bing Liu

Beilstein J. Nanotechnol. 2021, 12, 756–765, doi:10.3762/bjnano.12.59

• direction of magnetization of the ISME, f represents the force of friction, ω indicates the rotation velocity of the microsphere, and θ denotes the tilt angle between the direction of the magnetic field and the direction of magnetization of the ISME. (c) Velocity–frequency profiles for ISMEs with different

Recent progress in magnetic applications for micro- and nanorobots

• Ke Xu,
• Shuang Xu and
• Fanan Wei

Beilstein J. Nanotechnol. 2021, 12, 744–755, doi:10.3762/bjnano.12.58

• on diamagnetic levitation nanomaterials. Without using strong electromagnets or bulky permanent magnets, it can make the microrobot move in three dimensions in a liquid environment through diamagnetic levitation. The main purpose of this method is to eliminate friction between the substrate surface

Physical constraints lead to parallel evolution of micro- and nanostructures of animal adhesive pads: a review

• Thies H. Büscher and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2021, 12, 725–743, doi:10.3762/bjnano.12.57

• principles of attachment pads with a special focus on insects, describe micro- and nanostructures, surface patterns, origin of different pads and their evolution, discuss the material properties (elasticity, viscoelasticity, adhesion, friction) and basic physical forces contributing to adhesion, show the

• might be potentially interesting for engineers as a kind of optimal solution by nature, the biomimetic implications of the discussed results are briefly presented. Keywords: adhesion; attachment devices; biomechanics; convergence; friction; substrate compliance; Review Animal attachment systems

• generally contribute to the attachment on rough surfaces due to friction and mechanical interlocking [83][89][92][232][233][234][235][236]. The performance of claws depends on the radius of the claw tip in relation to the curvature of the surface irregularities [83][234][237][238]. However, in combination

Nanogenerator-based self-powered sensors for data collection

• Yicheng Shao,
• Maoliang Shen,
• Yuankai Zhou,
• Xin Cui,
• Lijie Li and
• Yan Zhang

Beilstein J. Nanotechnol. 2021, 12, 680–693, doi:10.3762/bjnano.12.54

• load [7]. To detect the state of wheels at high friction and at high speed, sensors based on a harsh-environmental TENG (he-TENG) can be included in a self-powered smart brake system. TENG-based vehicle sensors can collect data on driving habits, such as the frequency of using brake pedal and

Simulation of gas sensing with a triboelectric nanogenerator

• Kaiqin Zhao,
• Hua Gan,
• Huan Li,
• Ziyu Liu and
• Zhiyuan Zhu

Beilstein J. Nanotechnol. 2021, 12, 507–516, doi:10.3762/bjnano.12.41

• layer with very small separation distance (less than 1 mm) [25], and the effective contact area of the friction material is increased by texturing its surface [26][27] to improve its electrical output. This setup is widely applied in vertical contact separation mode [28][29], sliding mode [30][31

• ], single electrode mode [32][33][34], and independent layer mode [35]. In order to explain the charge transfer process between two friction materials in contact, various models have been proposed and explored, such as electron cloud model [36][37][38], ion transfer model [39], and material transfer model

• electrification and electrostatic induction. Contact electrification refers to the electron transfer between two different materials in contact because the atoms are so close together. An electric field is generated after friction electrification, and electrostatic induction is caused by the electric field. The

A stretchable triboelectric nanogenerator made of silver-coated glass microspheres for human motion energy harvesting and self-powered sensing applications

• Hui Li,
• Yaju Zhang,
• Yonghui Wu,
• Hui Zhao,
• Weichao Wang,
• Xu He and
• Haiwu Zheng

Beilstein J. Nanotechnol. 2021, 12, 402–412, doi:10.3762/bjnano.12.32

• is 1:1.5, VOC and ISC reach the largest values of 250 V and 6 μA, respectively, under a force of 150 N. As the content of SCGMs continues to increase, VOC and ISC gradually decrease. The larger amount of SCGMs causes less air in the same volume. Hence, there is less friction between silicone rubber

• to an intensification of friction and the generation of more charges. A similar trend is observed for VOC, as expected. Because of the mismatch between AC and DC systems a full-wave rectifier circuit was introduced to the setup. Figure 4a shows the voltage of different capacitors (2.2, 4.7, 10, and