Piezotronic effect in AlGaN/AlN/GaN heterojunction nanowires used as a flexible strain sensor

• Jianqi Dong,
• Liang Chen,
• Yuqing Yang and
• Xingfu Wang

Beilstein J. Nanotechnol. 2020, 11, 1847–1853, doi:10.3762/bjnano.11.166

• synthesize AlGaN/AlN/GaN heterojunction NWs with controllable size. A single NW is transferred to a flexible poly(ethylene terephthalate) substrate and fixed by indium tin oxide electrodes to form an ohmic contact for the strain sensor. An external mechanical stress is introduced to study the performance of

• the fabricated piezotronic strain sensor. The gauge factor is as high as 30 under compressive or tensile stress, which indicates a high sensitivity of the strain sensor. Periodic strain tests show the high stability and repeatability of the sensor. The working mechanism of the strain sensor is

• % tensile strain, which shows its high sensitivity. Furthermore, the current increases with an increase in the tensile strain and decreases with an increase in the compressive strain along the c-axis. The current returns to its original value after release of the mechanical stress. At the same time, the

Nanomechanics of few-layer materials: do individual layers slide upon folding?

• Ronaldo J. C. Batista,
• Rafael F. Dias,
• Ana P. M. Barboza,
• Alan B. de Oliveira,
• Taise M. Manhabosco,
• Thiago R. Gomes-Silva,
• Matheus J. S. Matos,
• Andreij C. Gadelha,
• Cassiano Rabelo,
• Luiz G. L. Cançado,
• Ado Jorio,
• Hélio Chacham and
• Bernardo R. A. Neves

Beilstein J. Nanotechnol. 2020, 11, 1801–1808, doi:10.3762/bjnano.11.162

• thickness range. In contrast, tip-enhanced Raman spectroscopy measurements on edges in folded graphene flakes, 14 layers thick, show no significant strain. This indicates that layers in graphene flakes, up to 5 nm thick, can still slip to relieve stress, showing the richness of the effect in 2D systems. The

• layered materials as it determines the interlayer slip, which is the dominant mechanism to relieve stress at van der Waals interfaces, leading to phenomena such as the change from plate-like to membrane-like shapes in graphene, hBN, and MoS2 bubbles [12] or the circumferential faceting of multi-walled

• measurements on edges in folded graphene flakes that were 5 nm, or 14 layers, thick shows no significant strain indicating that layers in graphene flakes up to 5 nm thickness can still slip to relieve stress. Even though it is applied here to homolayers, the present methodology could also bring invaluable

Out-of-plane surface patterning by subsurface processing of polymer substrates with focused ion beams

• Serguei Chiriaev,
• Luciana Tavares,
• Vadzim Adashkevich,
• Arkadiusz J. Goszczak and
• Horst-Günter Rubahn

Beilstein J. Nanotechnol. 2020, 11, 1693–1703, doi:10.3762/bjnano.11.151

• surface elevations or depressions at the corners of the irradiated squares in Figure 7b. Considering continuum mechanics, these features are places where mechanical stress can concentrate, resulting in the enhancement of local deformations. In numerous previous studies, the occurrence of ripples (also

• the entire fluence range. The only ripple patterns we observed were those generated by the stress field outside the irradiated regions, where there is no skin or any other structural or compositional material modification. One of the likely reasons for the absence of rippling inside of the irradiated

• areas in our PDMS samples is that the density of the total energy lost by He+ ions in the samples is not large enough to build up a sufficiently high stress to trigger rippling. This result is also interesting with regard to potential applications, because it opens up for a possibility of changing the

Piezoelectric sensor based on graphene-doped PVDF nanofibers for sign language translation

• Shuai Yang,
• Xiaojing Cui,
• Rui Guo,
• Zhiyi Zhang,
• Shengbo Sang and
• Hulin Zhang

Beilstein J. Nanotechnol. 2020, 11, 1655–1662, doi:10.3762/bjnano.11.148

• bending-induced piezoelectric model was constructed, and the calculated stress and potential distribution were obtained through finite element analysis, as shown in Figure 1c and Figure 1d. Figure 1c shows the stress distribution under bending. It can be clearly found that the stress is mainly

• ) Schematic diagram of an efficient sign language translation system using self-powered PESs. (c) Calculated stress in the PES during bending. (d) Potential distribution in the PES under bending. (a) Preparation of the self-powered GR-doped PVDF PES. (b) SEM images of PVDF fibers with different GR doping

• concentrations. (c) FTIR spectra of the PVDF fibers. (d) XRD patterns of the PVDF fibers. (e) Stress–strain curves of the PVDF fibers. (a) Schematic diagram of the PES under external pressure. (b) Output voltage as a function of the applied pressure for different doping concentrations. (c) Waveforms

Selective detection of complex gas mixtures using point contacts: concept, method and tools

• Alexander P. Pospelov,
• Victor I. Belan,
• Dmytro O. Harbuz,
• Volodymyr L. Vakula,
• Lyudmila V. Kamarchuk,
• Yuliya V. Volkova and
• Gennadii V. Kamarchuk

Beilstein J. Nanotechnol. 2020, 11, 1631–1643, doi:10.3762/bjnano.11.146

• energy conservation in the organism, and affects the synthesis of cellular enzymes. Cortisol generates the defense reactions of the organism against external threats and stressful situations [52]; therefore, it is called the “stress hormone”. In the case of heavy stress, cortisol changes the muscle

• their quantity through a chain of mediators (transmitters), the last of which is recognized by the surfaces of the atomic structures of the gas-sensitive array (i.e., the Yanson point contacts). As a result, we can quantitatively estimate, with a probability of 95%, the stress level in the body. Wide

Oxidation of Au/Ag films by oxygen plasma: phase separation and generation of nanoporosity

• Abdel-Aziz El Mel,
• Said A. Mansour,
• Mujaheed Pasha,
• Atef Zekri,
• Janarthanan Ponraj,
• Akshath Shetty and
• Yousef Haik

Beilstein J. Nanotechnol. 2020, 11, 1608–1614, doi:10.3762/bjnano.11.143

• residual stress. The repeated oxidation and cracking events result in the transformation of the metallic silver into nanoporous silver oxide when it reaches the surface of the film. In parallel to the oxidation reaction, silver keeps diffusing from the alloy film toward the surface, feeding the metallic

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

• loading resistance; inset: long-term stability. The ability of the u-TENG to harvesting energy from human walking. The electric output profile of a man (a), a woman (b), and a child (c). (d) The output voltage of u-TENG under different stress values. (e) The dependence of the output voltage on the impact

Antimicrobial metal-based nanoparticles: a review on their synthesis, types and antimicrobial action

• Matías Guerrero Correa,
• Fernanda B. Martínez,
• Cristian Patiño Vidal,
• Camilo Streitt,
• Juan Escrig and
• Carol Lopez de Dicastillo

Beilstein J. Nanotechnol. 2020, 11, 1450–1469, doi:10.3762/bjnano.11.129

• induction of oxidative stress, the release of metal ions and the non-oxidative damage. Synthesis of antimicrobial nanoparticles Over the last years, techniques for synthesizing antimicrobial nanoparticles have advanced significantly due to their use in both biomedical and industrial applications. The

• ][132]. When the size of titanium dioxide is reduced to the nanoscale (TiO2 NPs), its photocatalytic property is greatly improved, generating more reactive oxygen species (ROS). ROS damages bacterial cells, DNA chains, and other cellular structures through oxidative stress. Therefore, the use of TiO2

• simpler way without major equipment requirements. Mechanisms of antimicrobial action The exact antibacterial mechanisms of NPs are being exhaustively investigated and some processes have been elucidated, including oxidative stress induction, metal ion release, and non-oxidative damage, which affect

One-step synthesis of carbon-supported electrocatalysts

• Sebastian Tigges,
• Nicolas Wöhrl,
• Ivan Radev,
• Ulrich Hagemann,
• Markus Heidelmann,
• Thai Binh Nguyen,
• Stanislav Gorelkov,
• Stephan Schulz and
• Axel Lorke

Beilstein J. Nanotechnol. 2020, 11, 1419–1431, doi:10.3762/bjnano.11.126

• Supporting Information File 1, Figures S7–10. After 2000 accelerated stress test (AST) cycles, the most durable Pt/CNW layers still retain 50–70% of their maximum ECSA, while the commercial catalyst only has 30% left. Even after 5000 cycles, 20–30% of the maximum ECSA of the Pt/CNW layers are retained, at

• the future, a broader electrochemical study of our Pt/CNW catalysts is required to further uncover the relations between particle embedding, ECSA, utilization, and ORR activity. From the results of the ECSA, ORR, and accelerated stress test measurements, we find CV1 and CV2 to be the most promising

• adsorption charge of 210 mC/cm²(Pt). An accelerated stress test (AST) consists of 10,000 triangular potentiodynamic cycles between 0.4–1 V vs NHE with a scan rate of 1 V/s. ORR mass activities were measured at 1600 rpm in oxygen-saturated 0.1M HClO4 at 25 °C and determined at 0.9 V vs NHE. When using GCEs as

On the frequency dependence of viscoelastic material characterization with intermittent-contact dynamic atomic force microscopy: avoiding mischaracterization across large frequency ranges

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 1409–1418, doi:10.3762/bjnano.11.125

• ), is the retardance of the material, relating stress and strain, and R is the indenter radius. The indentation and load are available from the force–distance curve, and an expression for can be easily derived for the Generalized Voigt or Maxwell models (Figure 1), whereby the constants of springs and

• ][35]. Mechanical model diagrams representing the relationship between stress and strain in the complex plane for a linear viscoelastic material with multiple characteristic times [33]. (a) Generalized Voigt or Kelvin model, (b) Generalized Maxwell or Wiechert model, both describing arrheodictic

• transformed strain is generally regarded as the excitation and the transformed stress as the response; in (b) the opposite generally occurs. (a) Storage moduli and (b) and loss moduli as function of frequency for two hypothetical materials, the Generalized Maxwell model parameters of which are provided in

Structural and electronic properties of SnO₂ doped with non-metal elements

• Jianyuan Yu,
• Yingeng Wang,
• Yan Huang,
• Xiuwen Wang,
• Jing Guo,
• Jingkai Yang and
• Hongli Zhao

Beilstein J. Nanotechnol. 2020, 11, 1321–1328, doi:10.3762/bjnano.11.116

• 10−5 eV/atom, the internal stress between atoms was less than 0.05 GPa, and the atom displacement was less than 0.0001 nm. Results and Discussion Structural optimization Table 1 shows the results of geometric optimization of the crystal structure of SnO2 doped with non-metal elements. After replacing

Cryogenic low-noise amplifiers for measurements with superconducting detectors

• Ilya L. Novikov,
• Boris I. Ivanov,
• Dmitri V. Ponomarev and
• Aleksey G. Vostretsov

Beilstein J. Nanotechnol. 2020, 11, 1316–1320, doi:10.3762/bjnano.11.115

• and the capacitors have a C0G-type of dielectric. All the components were mounted on the designed layout of the printed circuit board (PCB) from FR4 material. We did not solder the electrodes of the capacitors directly to the PCB in order to reduce the mechanical stress during the cooldown cycles

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

• colloidal mixture of nanoparticles and a base fluid. Evidence has shown that metallic particles transfer more heat energy as compared to nonmetallic particles. A Casson fluid is a non-Newtonian fluid in nature and therefore, behaves similarly to an elastic solid. When the stress rate is zero, the Casson

• fluid can be considered as a shear-thinning liquid, with infinite viscosity. On the other hand, when the stress rate approaches an infinite value the viscosity of the Casson fluid drops to zero [6]. Jam, tomato ketchup, honey, and concentrated fruit syrups are some quotidian examples of Casson fluids

Growth of a self-assembled monolayer decoupled from the substrate: nucleation on-command using buffer layers

• Robby Reynaerts,
• Kunal S. Mali and
• Steven De Feyter

Beilstein J. Nanotechnol. 2020, 11, 1291–1302, doi:10.3762/bjnano.11.113

• –HOPG interface, we moved on to the self-assembly experiments with the buffer layer. Although the buffer layer experiments described below were carried out using sequential deposition of solutions of n-C50 and BA-OC14 (in that sequence), we stress that the outcome of the experiments remained the same

Ultrasensitive detection of cadmium ions using a microcantilever-based piezoresistive sensor for groundwater

• Dinesh Rotake,
• Anand Darji and
• Nitin Kale

Beilstein J. Nanotechnol. 2020, 11, 1242–1253, doi:10.3762/bjnano.11.108

• . Here, SAMs of cysteamine–glyceraldehyde were created on top of microcantilever-based sensors with integrated piezoresistive readout to get the change in resistance due to changes in surface stress. Until now, many people have used lab-based optical setups to measure the change in surface stress of the

• cantilever sensors. Moreover, the proposed piezoresistive device has capabilities to directly capture the surface stress make this a better option for HMI applications. Microfluidic Platform with Piezosensor In the proposed method, the benefits of three different technologies are combined, namely thin film

• . Results and Discussion The performance of the fabricated device in the selective detection of Cd(II) in a microfluidic environment is evaluated using the OmniCant setup shown in Figure 1d. The non-stress calibrated resistance values of the piezoresistive sensor using SAMs of cysteamine cross-linked with

Revealing the local crystallinity of single silicon core–shell nanowires using tip-enhanced Raman spectroscopy

• Marius van den Berg,
• Ardeshir Moeinian,
• Arne Kobald,
• Yu-Ting Chen,
• Anke Horneber,
• Steffen Strehle,
• Alfred J. Meixner and
• Dai Zhang

Beilstein J. Nanotechnol. 2020, 11, 1147–1156, doi:10.3762/bjnano.11.99

• popular method to investigate structural properties of silicon samples [16][17]. Mizoguchi et al. [18] and Hopkins et al. [19] utilized it to show the influence of stress on the crystal lattice orientation angles and to determine the degree of surface roughness. Kolb et al. measured the lattice

Photothermally active nanoparticles as a promising tool for eliminating bacteria and biofilms

• Mykola Borzenkov,
• Piersandro Pallavicini,
• Angelo Taglietti,
• Laura D’Alfonso,
• Maddalena Collini and
• Giuseppe Chirico

Beilstein J. Nanotechnol. 2020, 11, 1134–1146, doi:10.3762/bjnano.11.98

• membrane stress, which is enhanced by the photothermal effect upon sunlight irradiation [102]. Antibacterial continuous flow poly(dimethylsiloxane)-based microreactors with microchannels were fabricated using catechol-grafted poly(N-vinylpyrrolidone) and NIR-active Cs0.33WO3 nanoparticles [103]. Upon NIR

Applications of superparamagnetic iron oxide nanoparticles in drug and therapeutic delivery, and biotechnological advancements

• Maria Suciu,
• Corina M. Ionescu,
• Alexandra Ciorita,
• Septimiu C. Tripon,
• Dragos Nica,
• Hani Al-Salami and
• Lucian Barbu-Tudoran

Beilstein J. Nanotechnol. 2020, 11, 1092–1109, doi:10.3762/bjnano.11.94

• are considered the most effective, but unfortunately pure iron is toxic because it leads to high oxidative stress. To avoid this problem there is a lot of ongoing work regarding the design of core–shell particles with pure iron cores [63][64]. Octopod SPIONs (30 nm) were also shown to be better than

• later by iron oxidative stress [81]. Dextran-coated SPIONs were found to accumulate in large amounts in tumor sites in mice, in contrast to PEG-coated SPIONs, which did not accumulate, even in the presence of an external magnet at the tumor site. The PEG-coated SPIONs exhibited a longer blood

• biological fluids at physiological pH values and which remain stable with low toxicity in vitro [38][46][98][99][100][101][102][103]. Still, Hong and collaborators [104] stress the fact that we should pay more attention to the charge effects of SPIONs because not all types of cytotoxicity can be easily and

Vibration analysis and pull-in instability behavior in a multiwalled piezoelectric nanosensor with fluid flow conveyance

• Sayyid H. Hashemi Kachapi

Beilstein J. Nanotechnol. 2020, 11, 1072–1081, doi:10.3762/bjnano.11.92

• constants, residual stress, piezoelectric constants and mass density, are considered for analysis of the dimensionless natural frequency with respect to the viscous fluid velocity and pull-in voltage of the FC-MWPENSs. Keywords: electrostatic excitation; piezoelectric nanosensor; pull-in voltage; stability

• stress theory to investigate the effects of various fluid parameters on the pull-in voltage of carbon nanotubes conveying viscous fluid [15]. Also, the vibration analysis of viscoelastic double-walled carbon nanotubes (DWCNTs) combined with ZnO layers and subjected to magnetic and electric fields were

• couple stress theory [29]. Liu et al. utilized a new finite element method for modeling thin structures with surface effects by using layered shell elements [30]. To the best knowledge of the author, the surface/interface effect on pull-in voltage, viscous fluid velocity effects and dimensionless natural

A few-layer graphene/chlorin e6 hybrid nanomaterial and its application in photodynamic therapy against Candida albicans

• Selene Acosta,
• Carlos Moreno-Aguilar,
• Dania Hernández-Sánchez,
• Beatriz Morales-Cruzado,
• Erick Sarmiento-Gomez,
• Carla Bittencourt,
• Luis Octavio Sánchez-Vargas and
• Mildred Quintana

Beilstein J. Nanotechnol. 2020, 11, 1054–1061, doi:10.3762/bjnano.11.90

• environment. ROS refer to molecules like singlet oxygen, superoxide anion, and radicals, which are responsible for producing oxidative stress in cells followed by cell death [4]. Photosensitizer molecules must be nontoxic before irradiated with light, must produce high amounts of ROS when irradiated with

Wet-spinning of magneto-responsive helical chitosan microfibers

• Dorothea Brüggemann,
• Johanna Michel,
• Naiana Suter,
• Matheus Grande de Aguiar and
• Michael Maas

Beilstein J. Nanotechnol. 2020, 11, 991–999, doi:10.3762/bjnano.11.83

• rheometer (Malvern, Herrenberg, Germany) with a cone-plate geometry (1° angle and 50 mm diameter). The shear stress was measured at 20 °C with a stepwise increase in the shear rate and a one minute holding time at each shear-rate step. The size and zeta potential measurements were performed with 10 mg·mL−1

• fiber was measured in an optical microscope (SENSOFAR PLl 2300, Nikon, Tokyo, Japan). Thus, the stress–strain relation of each individual fiber could be determined by taking into account the gauge length of 25 mm. (A, B) Shear viscosity and shear stress of bare chitosan solutions (black lines) and

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

• proportional to the local sheet stress, and l is the slip length constant. The similarity transformations The similarity transformations to solve the governing equations are as follows: By substituting the similarity transformations in Equation 9 into the governing boundary layer Equations 1–4 they reduce to

Atomic layer deposition for efficient oxygen evolution reaction at Pt/Ir catalyst layers

• Stefanie Schlicht,
• Korcan Percin,
• Stefanie Kriescher,
• André Hofer,
• Claudia Weidlich,
• Matthias Wessling and
• Julien Bachmann

Beilstein J. Nanotechnol. 2020, 11, 952–959, doi:10.3762/bjnano.11.79

• ), a rather thick layer of the order of 1 μm is observed. Some cracks can be detected on the egdes of the coating where the fibers cross, due to low transport rates at these locations and high mechanical stress. The existence of the noble metals is proven by energy-dispersive X-ray analysis (EDX

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

• for a given stress or strain excitation. The mechanical-equivalent approach is simple to explain, but can require more assumptions and some additional knowledge of the Laplace transform to derive analytical stress–strain relationships. Alternatively, continuum mechanics can be used to create more

• ] recently formulated a generalized solution to the physical contact problem in AFM-SFS experiments, particularly for cases where the sample is viscoelastic. The approach is also capable of being adapted to any linear viscoelastic stress–strain model. Their method utilized a theoretical basis for

• solution for the AFM experiment. It is originally presented as Equation 3 in their paper [17]. Extending the solution to an arbitrary load history Traditionally, when using creep-recovery experiments to parameterize the viscoelastic models under study, a constant stress is first applied to a sample and

Integrated photonics multi-waveguide devices for optical trapping and Raman spectroscopy: design, fabrication and performance demonstration

• Gyllion B. Loozen,
• Arnica Karuna,
• Mohammad M. R. Fanood,
• Erik Schreuder and
• Jacob Caro

Beilstein J. Nanotechnol. 2020, 11, 829–842, doi:10.3762/bjnano.11.68

• waveguide width wdet of 13.5 μm, the actual width varying among the devices. For the different microbaths, the number of waveguides varies between two and ten. For the waveguide thickness we choose the maximum value of 200 nm, which is determined by the maximum tolerable film stress for the deposition

• results in layer cracking due to stress after deposition. Then, a 3 µm thick layer of SiO2 is deposited by LPCVD, which acts as the top cladding for the detection waveguides and as a protection layer (Figure 5h). The final in-line step is the etching of the cylindrical microbath centered at each chip