Paper-based triboelectric nanogenerators and their applications: a review

• Jing Han,
• Nuo Xu,
• Yuchen Liang,
• Mei Ding,
• Junyi Zhai,
• Qijun Sun and
• Zhong Lin Wang

Beilstein J. Nanotechnol. 2021, 12, 151–171, doi:10.3762/bjnano.12.12

• moisture-retention capacity. This provides an efficient method to prepare paper electrodes for TENGs. Paper has also been proven to be a natural TENG friction layer. Due to that, it shows a tendency of easily losing electrons (i.e., electropositive) when contacting a material that can easily gain electrons

• (most common design in previous works) as a typical representative example, we further systematically analyze the working mechanism of the detailed charge-transfer process. Figure 2b elucidates the charge generation and the electron-transfer process at the friction interfaces (paper/the other dielectric

• negative charges) are induced by the same amount on the surfaces of the friction layers. As there is no electric potential at this stage, there is no electron transfer between the two conductive layers (Figure 2b-I). When the two friction layers start to separate along the vertical direction, opposite

Walking energy harvesting and self-powered tracking system based on triboelectric nanogenerators

• Mingliang Yao,
• Guangzhong Xie,
• Qichen Gong and
• Yuanjie Su

Beilstein J. Nanotechnol. 2020, 11, 1590–1595, doi:10.3762/bjnano.11.141

• area with the undulated electrode but also promotes the triboelectric charge density on the friction surface. The prepared u-TENGs are flexible, rugged, light, and small devices, as revealed in Figure 1c. It is worth noting that the application of the undulated electrode structure in this work is

Triboelectric nanogenerator based on Teflon/vitamin B1 powder for self-powered humidity sensing

• Liangyi Zhang,
• Huan Li,
• Yiyuan Xie,
• Jing Guo and
• Zhiyuan Zhu

Beilstein J. Nanotechnol. 2020, 11, 1394–1401, doi:10.3762/bjnano.11.123

• lubricant to make a friction nanogenerator. Due to its sustainability and flexibility, paper can be used as a substrate and supporting structure. The conductive electrode is made of copper foil, while the triboelectric pair is comprised of Teflon tape and vitamin B1 powder. The approximate values of the

Magnetohydrodynamic stagnation point on a Casson nanofluid flow over a radially stretching sheet

• Ganji Narender,
• Kamatam Govardhan and
• Gobburu Sreedhar Sarma

Beilstein J. Nanotechnol. 2020, 11, 1303–1315, doi:10.3762/bjnano.11.114

• written as The transformed boundary conditions are and the dimensionless parameters are defined as The formulas for the dimensional form of the skin-friction coefficient Cf, the Nusselt number Nu, and Sherwood number Sh, are given by and the formulas for τw, qw, and qm are The result of the transformation

• criteria for the shooting method is set as: in which ε is set as a very small positive number. In this work, ε is set as 10−5 whereas η∞ is set as 7. Results and Discussion In this section, the numerical results of the skin-friction coefficient, Nusselt and Sherwood numbers are listed in tables and shown

• ≤ 2.0, γ = 1.0, 1 ≤ Bi1 ≤ 2.0, and 1 ≤ Bi2 ≤ 2.0. Skin-friction coefficient, Nusselt and Sherwood numbers Prabhakar et al. [24] used a fourth-order Runge–Kutta method to obtain the numerical solution of the discussed model, whereas Attia [37] used the shooting technique and the computational software

Influence of the magnetic nanoparticle coating on the magnetic relaxation time

• Mihaela Osaci and
• Matteo Cacciola

Beilstein J. Nanotechnol. 2020, 11, 1207–1216, doi:10.3762/bjnano.11.105

• the particle) and Brown relaxation (an external phenomenon driven by the rotation of the nanoparticle along the magnetic moment). Both internal and external sources of friction lead to a delay in the orientation of the particle magnetic moment in the direction of the applied magnetic field, thus

• nanoparticle i in the fluid environment [19] given as where mi is the mass of the i-th nanoparticle, is the linear speed of the i-th nanoparticle, is the resultant of the conservative forces acting on the i-th nanoparticle, αi,tr and αi,rot are the translational and rotational friction coefficients

Effect of magnetic field, heat generation and absorption on nanofluid flow over a nonlinear stretching sheet

• Santoshi Misra and
• Govardhan Kamatam

Beilstein J. Nanotechnol. 2020, 11, 976–990, doi:10.3762/bjnano.11.82

• the boundary layer, thus causing a reduction in its thickness for nanofluids. This is due to the fact that an increase in the slip parameter causes a reduction in the skin friction at the surface acting between the stretching sheet and the fluid flow, thus drastically decreasing the velocity gradient

• . Impact of ξ on θ(η) The temperature variation component, θ(η), increases with an increase in the slip parameter, ξ, which further leads to an increase in the fluid temperature, thus intensifying the thermal boundary layer thickness (Figure 3). An increase in the slip parameter causes friction at the

• slip parameter, ξ, at a given constant surface temperature. An increase in the slip parameter causes friction at the surface which, in turn, generates a frictional force allowing more fluid to flow passed the stretching sheet. This causes an increase in concentration distribution of the fluid as shown

Microwave photon detection by an Al Josephson junction

• Leonid S. Revin,
• Andrey L. Pankratov,
• Anna V. Gordeeva,
• Anton A. Yablokov,
• Igor V. Rakut,
• Victor O. Zbrozhek and
• Leonid S. Kuzmin

Beilstein J. Nanotechnol. 2020, 11, 960–965, doi:10.3762/bjnano.11.80

• particle moves along the potential in the presence of friction, the strength of which is characterized by α = ωp/ωc, where is the plasma frequency, ωc = 2eICRN/ℏ is the characteristic frequency, RN is the normal state resistance and C is the capacitance. The superconducting state of the JJ corresponds to

Extracting viscoelastic material parameters using an atomic force microscope and static force spectroscopy

• Cameron H. Parvini,
• M. A. S. R. Saadi and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 922–937, doi:10.3762/bjnano.11.77

• fluids) will have a low storage modulus and high loss modulus. In this case, most of that input energy will be lost to friction and heat, and therefore the material will return far less energy than the stiff elastic material when unloaded. To acquire storage and loss modulus as functions of the frequency

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

• . It also determines interfacial properties, such as adhesion and friction, and is a key input into mechanics models and atomistic simulations of contacts. We have developed a novel methodology to experimentally determine interaction potential parameters, given a particular potential form, using

• microscopy (AFM) [4][5], and nanolithography techniques [6]. In particular, material parameters, such as interfacial adhesion, friction and wear (in the case of translating surfaces), significantly impact the success of the aforementioned examples. For instance, micromirrors, present in DLP technology

• such issues. For example, the adsorption of self-assembled monolayers on contacting surfaces is one method by which the surface can be modified to reduce the detrimental impacts of adhesion, friction and wear [15][16][17]. The nanometer length scales over which these processes modify surface

Stochastic excitation for high-resolution atomic force acoustic microscopy imaging: a system theory approach

• Edgar Cruz Valeriano,
• José Juan Gervacio Arciniega,
• Christian Iván Enriquez Flores,
• Susana Meraz Dávila,
• Joel Moreno Palmerin,
• Martín Adelaido Hernández Landaverde,
• Yuri Lizbeth Chipatecua Godoy,
• Aime Margarita Gutiérrez Peralta,
• Rafael Ramírez Bon and
• José Martín Yañez Limón

Beilstein J. Nanotechnol. 2020, 11, 703–716, doi:10.3762/bjnano.11.58

• deflection signal from the photodiodes of the AFM equipment. The classical Euler–Bernoulli beam equation is used, which is expressed by Vázquez et al. as [27][28][29]: where EI is the flexural stiffness, c is the damping due to viscous friction, m is the mass per unit length and z(x,t) is the deflection of

Understanding nanoparticle flow with a new in vitro experimental and computational approach using hydrogel channels

• Armel Boutchuen,
• Dell Zimmerman,
• Abdollah Arabshahi,
• John Melnyczuk and
• Soubantika Palchoudhury

Beilstein J. Nanotechnol. 2020, 11, 296–309, doi:10.3762/bjnano.11.22

• the new 3D flow channels. pHEMA hydrogels synthesized with 1, 1.1, and 1.2 mL of DI water showed uneven surface textures owing to the increased softness of these materials. These formulations were not used for the flow channels as their rough surfaces could lead to friction artifacts in the flow of

• showed the smoothest surface of all gel formulations. The gels prepared with 1.5 mL DI water showed a distinctly porous surface structure. Therefore, the 1.3 mL DI water hydrogels were most suitable for making flow channels of negligible friction to resemble the vascular microenvironment. The hollow 3D

Nonclassical dynamic modeling of nano/microparticles during nanomanipulation processes

• Moharam Habibnejad Korayem,
• Ali Asghar Farid and
• Rouzbeh Nouhi Hefzabad

Beilstein J. Nanotechnol. 2020, 11, 147–166, doi:10.3762/bjnano.11.13

• –Grenoble (LuGre) theories for frictional models [9]. Hou et al. studied the behavior of cylindrical nanoparticle motion during the manipulation process. They considered the viscous friction and studied two states: turning the axis inside or outside of the nanoparticle [10]. Kahrobaiyan et al. investigated

• used for biological nanoparticles [13]. Using MSCT for modeling AFM with a piezoelectric system was considered in another study [14]. Polyakov et al. examined the dependence of static friction and contact area on nanoparticle geometry in the manipulation of spherical silver and polyhedral gold

• critical time and force of the dominant motion mode are used as the inputs of next steps. After applying the exerted force on the nanoparticle by AFM and distributed resistant force resulting from friction and adhesion, deflections of the cylindrical nanoparticle before the onset of motion in the dominant

The effect of heat treatment on the morphology and mobility of Au nanoparticles

• Sven Oras,
• Sergei Vlassov,
• Simon Vigonski,
• Boris Polyakov,
• Mikk Antsov,
• Vahur Zadin,
• Rünno Lõhmus and
• Karine Mougin

Beilstein J. Nanotechnol. 2020, 11, 61–67, doi:10.3762/bjnano.11.6

• should decrease the contact area compared to faceted particles, and hence reduce the friction forces in accordance with the known relation τ = F/A [6], where τ is the contact strength, F is the friction force and A is the contact area. For a round particle, the contact area is determined by contact

• power for a displacement than the experimental setup could provide. Therefore, the actual average friction determined for the NPs annealed at 200 °C is even higher. The power required to displace NPs is the highest for particles annealed at 200 °C and the lowest for NPs annealed at 600 °C. This finding

• from the ellipsometry measurements presented in Figure 7. How exactly the rapid growth of the SiO2 layer may be related to the drastic increase in friction remains unclear and can be the subject for future studies. Overall, we demonstrated that heat treatment, which is widely used as a surfactant

An investigation on the drag reduction performance of bioinspired pipeline surfaces with transverse microgrooves

• Weili Liu,
• Hongjian Ni,
• Peng Wang and
• Yi Zhou

Beilstein J. Nanotechnol. 2020, 11, 24–40, doi:10.3762/bjnano.11.3

• transportation, the transport drag originates from skin friction drag, which is the main reason affecting the transport efficiency of long-distance pipelines [2][3]. In drilling engineering, the high pressure loss often encountered is mainly caused by a skin friction drag of the circulating drilling fluid, which

• severely hinders the exploration of oil and gas resources in deep wells [4][5][6]; therefore, it is necessary to put additional effort into reducing the skin friction drag. Conventional hydraulic drag reduction methods include the development of high-performance polymer additives to reduce fluid viscosity

• the direct numerical simulation (DNS) results, as shown in Figure 5. The agreement with DNS was satisfactory so that the accuracy of the numerical simulation method could be validated again. Dimensionless parameters: where uτ was the friction velocity (m/s); U was the instantaneous velocity (m/s); y

Dynamics of superparamagnetic nanoparticles in viscous liquids in rotating magnetic fields

• Nikolai A. Usov,
• Ruslan A. Rytov and
• Vasiliy A. Bautin

Beilstein J. Nanotechnol. 2019, 10, 2294–2303, doi:10.3762/bjnano.10.221

• ][53][54] where γ1 = |γ|/(1 + κ2), κ is the phenomenological damping parameter, and is the random thermal magnetic field that causes thermal fluctuations of the particle magnetic moment. The stochastic equation for the nanoparticle director is given by [25][54][55] where ξ = 6ηV is the friction

Nanoscale spatial mapping of mechanical properties through dynamic atomic force microscopy

• Zahra Abooalizadeh,
• Leszek Josef Sudak and
• Philip Egberts

Beilstein J. Nanotechnol. 2019, 10, 1332–1347, doi:10.3762/bjnano.10.132

• have been several studies, particularly in the field of tribology, that have attributed observations or proposed mechanisms of friction that result from a weaker elastic constant at an atomic step edge [21][24][25]. Despite the number of proposed mechanisms relying on weakened graphite step edges

• made about HOPG and graphene step edges to interpret friction and AFM tip-convolution measurements made previously. In this paper, CR AFM is used to clearly identify atomic-scale defects, such as atomic step edges, that show mechanical property variations on surfaces of HOPG. FMM is then used to scan

• uncovered step appears sharper than the covered step, this contrast difference is not as reliable as the smaller measured lateral and friction forces on the covered steps compared with the uncovered steps, as reported in [39]. Figure 3c shows the line profile extracted along the dashed line in Figure 3b for

Biological and biomimetic surfaces: adhesion, friction and wetting phenomena

• Stanislav N. Gorb,
• Kerstin Koch and
• Lars Heepe

Beilstein J. Nanotechnol. 2019, 10, 481–482, doi:10.3762/bjnano.10.48

• Keywords: adhesion; air retention; contact mechanics; fluid transport; friction; functional gradients; wetting; This Thematic Series is the continuation of the previous series on the broad topic of biological and bioinspired materials and surfaces [1][2][3]. This collection of articles displays a current

• cross section of recent developments in this highly diverse and interdisciplinary field of research. The articles highlight recent achievements in the understanding of animal and plant surfaces in the broadest context of adhesion, friction, and wetting phenomena on one hand. On the other hand, they

• novel flow and pressure sensors. While most of the articles represent experimental work, two are devoted to theoretical and numerical work on the adhesion of rough brush systems and the friction of functionally graded materials. The metrics mentioned above illustrate that this compilation of articles

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