Wet chemistry route for the decoration of carbon nanotubes with iron oxide nanoparticles for gas sensing

• Hussam M. Elnabawy,
• Juan Casanova-Chafer,
• Badawi Anis,
• Mostafa Fedawy,
• Mattia Scardamaglia,
• Carla Bittencourt,
• Ahmed S. G. Khalil,
• Eduard Llobet and
• Xavier Vilanova

Beilstein J. Nanotechnol. 2019, 10, 105–118, doi:10.3762/bjnano.10.10

• electrical resistance against time. Nitrogen dioxide was found to strongly interact with carbon nanotube sensors, and as a result, the sensors did not fully recover their baseline resistance value during the cleaning phase, which was conducted at room temperature without heating. Applying mild heating or UV

• an increase in the electrical resistance of the active layer. This fact can be attributed to the p–n junctions formed between the p-type CNTs and the n-type iron oxide nanoparticles, with the formation of associated depletion layers. The p-type behavior of the decorated nanotubes suggests that, when

• of Fe 2p with a fitting curve for sample C (a), O 1s (b) and C 1s (c) for the samples A (black curve), B (red curve) and C (green curve). The C 1s spectra has been normalized and aligned. XRD pattern for Fe2O3 nanoparticles (a) and decorated CNTs with Fe2O3 nanoparticles (b). Electrical resistance 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

• sensitivity or best direction. Depolarising events are associated with decreasing membrane electrical resistance while hyperpolarization responses with an increase in membrane electrical resistance [15]. A new flow stimulus which occurs on top of already existing flow is difficult to decouple using one sensor

• electrical resistance even at the tiniest stretching and compressing of the beam. A built-in Wheatstone bridge circuit, which implements a half-bridge strain gauge configuration, maximizes the signal transduction and provides measurable differences in voltage proportional to the deformation of the beams

• strain gauge thickness is expected, which in turn decreases the electrical resistance. For a previously described cantilever beam under maximal compression in nitrogen flow, the least possible resistance value was found to be approximately 0.07% smaller than the resistance value in resting, bent position

Graphene-enhanced metal oxide gas sensors at room temperature: a review

• Dongjin Sun,
• Yifan Luo,
• Marc Debliquy and
• Chao Zhang

Beilstein J. Nanotechnol. 2018, 9, 2832–2844, doi:10.3762/bjnano.9.264

• exposed to oxidizing gases, increasing the electrical resistance. The gas molecules act as electron donors to the semiconductors when exposed to reducing gases, meaning that the width of electron depletion layer decreases, which decreases the resistance of the sensor. For p-type semiconductors, the width

Electrical characterization of single nanometer-wide Si fins in dense arrays

• Steven Folkersma,
• Janusz Bogdanowicz,
• Andreas Schulze,
• Paola Favia,
• Dirch H. Petersen,
• Ole Hansen,
• Henrik H. Henrichsen,
• Peter F. Nielsen,
• Lior Shiv and
• Wilfried Vandervorst

Beilstein J. Nanotechnol. 2018, 9, 1863–1867, doi:10.3762/bjnano.9.178

• with a high precision. Finally, we use the technique to determine the electrical resistance of individual fins in a dense array and we demonstrate that the measured resistance correlates with the geometrical width of the fins, as measured with transmission electron microscopy (TEM). Due to the

• ) larger than dcontact, the procedure is identical to the previously described case of blanket materials. The electrical contact is indeed created, i.e., contacts j = 1, 2, 3, 4 are activated, when Ipulse ≥ Ithreshold and the electrical resistance Rfin of the region of the fin included between the two

Surface-plasmon-enhanced ultraviolet emission of Au-decorated ZnO structures for gas sensing and photocatalytic devices

• T. Anh Thu Do,
• Truong Giang Ho,
• Thu Hoai Bui,
• Quang Ngan Pham,
• Hong Thai Giang,
• Thi Thu Do,
• Duc Van Nguyen and
• Dai Lam Tran

Beilstein J. Nanotechnol. 2018, 9, 771–779, doi:10.3762/bjnano.9.70

• effective surfaces. The adsorbed oxygen species can be easily captured by the electrons from the conduction band and adsorbed onto the surface, leading to a depletion region that broadens again, and thus the electrical resistance of the sensor increases. By decorating the ZnO nanostructures with plasmonic

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

• concluding subsection. Metals Metal–metal contacts in NEM switches are particularly advantageous for radio frequency (RF) applications due to their low electrical resistance. Experimental studies of elastic properties of metals, supported by atomistic simulations, have revealed several different ways the

Comparative study of post-growth annealing of Cu(hfac)₂, Co₂(CO)₈ and Me₂Au(acac) metal precursors deposited by FEBID

• Marcos V. Puydinger dos Santos,
• Aleksandra Szkudlarek,
• Artur Rydosz,
• Carlos Guerra-Nuñez,
• Fanny Béron,
• Kleber R. Pirota,
• Stanislav Moshkalev,
• José Alexandre Diniz and
• Ivo Utke

Beilstein J. Nanotechnol. 2018, 9, 91–101, doi:10.3762/bjnano.9.11

• removing the carbon matrix and drastically reducing the electrical resistance of the deposit. Keywords: copper; gold; cobalt; focused-electron-beam-induced deposition; noble metal; non-noble metals; post-growth annealing; Introduction Focused-electron-beam-induced deposition (FEBID) constitutes a well

• precursor flux, under a pressure of around 3 × 10−5 mbar. Furthermore, for the H2-assisted purification of Au–C deposits, a 200 ppm H2 atmosphere was utilized while the sample was heated from room temperature to 360 °C over a period of 6.5 h. The electrical resistance was monitored in situ using a two-wire

• increment (Figure 5a). The electrical resistance, which was monitored with a two-wire setup, monotonically decreased three orders of magnitude during this annealing procedure. The initial resistance of 2 GΩ decreased down to around 500 MΩ below 300 °C, where it abruptly decreases to 2 MΩ. Then, as the

Gas-sensing behaviour of ZnO/diamond nanostructures

• Marina Davydova,
• Alexandr Laposa,
• Jiri Smarhak,
• Alexander Kromka,
• Neda Neykova,
• Josef Nahlik,
• Jiri Kroutil,
• Jan Drahokoupil and
• Jan Voves

Beilstein J. Nanotechnol. 2018, 9, 22–29, doi:10.3762/bjnano.9.4

• tube (λ = 0.178901 nm) and Göbel mirror in primary beam and parallel plate collimator with divergence 0.09° in diffracted beam were used. The gas sensing experiments for all sensor designs were performed in an airtight chamber with electrical feedthroughs. The electrical resistance of the sensor

The role of ligands in coinage-metal nanoparticles for electronics

• Ioannis Kanelidis and
• Tobias Kraus

Beilstein J. Nanotechnol. 2017, 8, 2625–2639, doi:10.3762/bjnano.8.263

• interface, and transferred to a substrate by using a Langmuir–Blodgett trough. The single-layer nanomembrane that formed on the water surface had excellent optical transmittance of 90–97% and an electrical resistance of 1.14 × 106 Ω/sq; it reacted to mechanical bending with a 14% increase in resistance

Au nanostructure fabrication by pulsed laser deposition in open air: Influence of the deposition geometry

• Rumen G. Nikov,
• Anna Og. Dikovska,
• Nikolay N. Nedyalkov,
• Georgi V. Avdeev and
• Petar A. Atanasov

Beilstein J. Nanotechnol. 2017, 8, 2438–2445, doi:10.3762/bjnano.8.242

• conductive properties of the structures produced, we measured their electrical resistance. Table 2 shows the electrical resistance of the Au samples discussed in this study. As can be seen, the open-air laser deposition resulted in the formation of conductive structures. The resistance of the structures was

• measured in the range from a few ohms to several kΩ. It was found that the electrical properties of nanostructures produced by PLD in open air strongly depend on the density and morphology of the structure. The columnar structure presented in Figure 4c demonstrates an electrical resistance twice as a high

• adequate simulation based on thermal effects cannot be performed due to the complicated morphology and unknown thermophysical parameters values of the produced structures. It should be mentioned that the observed effect is more pronounced for the samples with electrical resistance in the range of kΩ

Process-specific mechanisms of vertically oriented graphene growth in plasmas

• Subrata Ghosh,
• Shyamal R. Polaki,
• Niranjan Kumar,
• Sankarakumar Amirthapandian,
• Mohamed Kamruddin and
• Kostya (Ken) Ostrikov

Beilstein J. Nanotechnol. 2017, 8, 1658–1670, doi:10.3762/bjnano.8.166

• transmission electron microscopy (HRTEM) and Raman spectroscopy. Contact angle and electrical resistance measurements of the VGNs are carried out as well. Results and Discussion Growth and optimization Case I: Influence of growth temperature We investigated the early-stage nucleation and growth of VGNs over a

Low uptake of silica nanoparticles in Caco-2 intestinal epithelial barriers

• Dong Ye,
• Mattia Bramini,
• Delyan R. Hristov,
• Sha Wan,
• Anna Salvati,
• Christoffer Åberg and
• Kenneth A. Dawson

Beilstein J. Nanotechnol. 2017, 8, 1396–1406, doi:10.3762/bjnano.8.141

• . Transepithelial electrical resistance (TEER) was used to further confirm barrier formation and test the integrity of the barriers before and after exposure to the nanoparticles. TEER measurements confirmed that the Caco-2 cell-monolayers exerted high resistance values (up to 1000 Ω·cm2 on a 12-well transwell

BTEX detection with composites of ethylenevinyl acetate and nanostructured carbon

• Santa Stepina,
• Astrida Berzina,
• Gita Sakale and
• Maris Knite

Beilstein J. Nanotechnol. 2017, 8, 982–988, doi:10.3762/bjnano.8.100

• specialized sample holder and an Agilent 34972A (Keysight 34972A data acquisition/data logger switch unit) were used to measure the electrical resistance of the sample during the tests. The Agilent 34972A also was used for gasoline and ethylbenzene vapour measurements. The composite was characterized using

• change of the electrical resistance is measured when VOC vapours are applied in a certain concentration for a certain amount of time. Stage 3 is the relaxation: The electrical resistance gradually decreases to the initial value. During the three stages the relative change of the electrical resistance

• varies as shown in Figure 2. The highest peak of this curve is marked as ΔR/R0 max. This is the maximal relative change of the electrical resistance at the end of the exposure time, for example, at 60 s. By changing the exposure time, the value of ΔR/R0 max and the relaxation time will change. If the

Synthesis of coaxial nanotubes of polyaniline and poly(hydroxyethyl methacrylate) by oxidative/initiated chemical vapor deposition

• Alper Balkan,
• Efe Armagan and
• Gozde Ozaydin Ince

Beilstein J. Nanotechnol. 2017, 8, 872–882, doi:10.3762/bjnano.8.89

• humidity increased due to charge transfer between CeO2 and PANI. However, incorporating CeO2 in the polymer decreases flexibility and increases the overall electrical resistance, which may limit the range of applications. Lin et al. [35] fabricated electrospun PANI nanofibers and introduced hydrophilic

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

• Arpita Jana,
• Elke Scheer and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2017, 8, 688–714, doi:10.3762/bjnano.8.74

• material for both organic and aqueous LIB owing to high capacity, unique structure and suitable electrode potential. However, its cyclic performance is limited by its high charge-transfer resistance. The incorporation of graphene solves its electrical resistance problem with the VO2 electrodes and it acts

Gas sensing properties of MWCNT layers electrochemically decorated with Au and Pd nanoparticles

• Elena Dilonardo,
• Michele Penza,
• Marco Alvisi,
• Riccardo Rossi,
• Gennaro Cassano,
• Cinzia Di Franco,
• Francesco Palmisano,
• Luisa Torsi and
• Nicola Cioffi

Beilstein J. Nanotechnol. 2017, 8, 592–603, doi:10.3762/bjnano.8.64

• and active layer surface. The response at a defined gas concentration was evaluated as the relative resistance variation in percentage, ΔR/Ri (%), where ΔR is the resistance variation between the values of the steady-state of the electrical resistance of the sensor under the target gas and under the

• conductivity of MWCNTs [46]. This results in the consequent lowering of the energy barrier, and therefore, a decrease of the sensing response [47][48]. Considering the specific optimum operating temperature of each hybrid sensing system, the sensing response, in terms of electrical resistance variation (ΔR

• ), towards NO2 of pristine and metal-doped MWCNTs at 150 °C and 100 °C are reported in Figure 6A,B, and Figure 7A,B, respectively. In all cases, at both operating temperatures, the sensing response, in terms of electrical resistance change (ΔR), of functionalized MWCNTs is higher compared to pristine MWCNTs

Anodization-based process for the fabrication of all niobium nitride Josephson junction structures

• Massimiliano Lucci,
• Ivano Ottaviani,
• Matteo Cirillo,
• Fabio De Matteis,
• Roberto Francini,
• Vittorio Merlo and
• Ivan Davoli

Beilstein J. Nanotechnol. 2017, 8, 539–546, doi:10.3762/bjnano.8.58

• function of the dc power applied on the target and the N2 flux inlet in the deposition chamber for 40 different recipes. Tc is the temperature for which the electrical resistance, measured with the four-point probe technique, drops to zero. We have fabricated more than 100 films with a thickness maintained

Advances in the fabrication of graphene transistors on flexible substrates

• Gabriele Fisichella,
• Stella Lo Verso,
• Silvestra Di Marco,
• Vincenzo Vinciguerra,
• Emanuela Schilirò,
• Salvatore Di Franco,
• Raffaella Lo Nigro,
• Fabrizio Roccaforte,
• Amaia Zurutuza,
• Alba Centeno,
• Sebastiano Ravesi and
• Filippo Giannazzo

Beilstein J. Nanotechnol. 2017, 8, 467–474, doi:10.3762/bjnano.8.50

• determine the total electrical resistance, RTOT, between source and drain contacts are also illustrated in Figure 4d. Here, the gate-bias-dependent graphene channel resistance, Rch(Vg), the source and drain contact resistance, Rc, and the access resistance, Racc, associated with the ungated graphene access

Nanocrystalline TiO₂/SnO₂ heterostructures for gas sensing

• Barbara Lyson-Sypien,
• Anna Kusior,
• Mieczylaw Rekas,
• Jan Zukrowski,
• Marta Gajewska,
• Katarzyna Michalow-Mauke,
• Thomas Graule,
• Marta Radecka and
• Katarzyna Zakrzewska

Beilstein J. Nanotechnol. 2017, 8, 108–122, doi:10.3762/bjnano.8.12

• behavior begins to prevail upon water desorption/oxygen adsorption depends on the TiO2/SnO2 composition. The electrical resistance of sensing materials exhibits a power-law dependence on the H2 partial pressure. This allows us to draw a conclusion about the first step in the gas sensing mechanism related

• electrical resistance, R, of the sensor for any reducing gas can be expressed as [1][20]: where pgas is the partial pressure of the reducing gas while the power coefficient n is specific to the kind of the target gas and particular reaction with oxygen species preadsorbed at the surface of the semiconductor

• , electrical properties, H2 sensing behavior and the power-law nature of the electrical resistance of TiO2/SnO2 heterostructures is presented. The influence of water adsorption and desorption on the electrical properties of TiO2/SnO2 is also taken into account. The detection threshold is studied for the first

Sensitive detection of hydrocarbon gases using electrochemically Pd-modified ZnO chemiresistors

• Elena Dilonardo,
• Michele Penza,
• Marco Alvisi,
• Gennaro Cassano,
• Cinzia Di Franco,
• Francesco Palmisano,
• Luisa Torsi and
• Nicola Cioffi

Beilstein J. Nanotechnol. 2017, 8, 82–90, doi:10.3762/bjnano.8.9

• , causing changes in the surface potential and resistivity of the sensing material. The electrical resistance can increase or decrease, depending on the type of doping of MOx (p- or n-type) and on the analyte gas. There are oxidizing gases, such as nitrogen oxide (NO2), and ozone (O3), and reducing gases

• such as carbon monoxide (CO) and hydrocarbons (HCs) [26]. The magnitude of the variation of the electrical resistance gives a direct measure of the concentration of the analyte gas [25]. In the last decades, different nanostructured MOx-based gas sensors with improved performance in the HC gas

• . The presence of Pd NPs on ZnO NRs strongly affects gas adsorption and reactivity and, hence, the gas sensing as discussed in the following section. Gas-sensing performance Figure 4A shows the time responses of the electrical resistance of chemiresistors based on pristine and Pd-modified ZnO NRs to

Graphene–polymer coating for the realization of strain sensors

• Carmela Bonavolontà,
• Carla Aramo,
• Massimo Valentino,
• Giampiero Pepe,
• Sergio De Nicola,
• Gianfranco Carotenuto,
• Angela Longo,
• Mariano Palomba,
• Simone Boccardi and
• Carosena Meola

Beilstein J. Nanotechnol. 2017, 8, 21–27, doi:10.3762/bjnano.8.3

• the gauge factor (GF), that is, the ratio of the relative change in electrical resistance, R, to the mechanical strain, ε, namely the GF is given as ΔR/(εR0), where R0 is the unstrained resistance. The values of GF for graphene range from 1.9–2.4 [2][3]. The GF has been considerably improved by using

• constitutes the maximum achievable performance of silicon-based sensors. The electrical resistance and mechanical properties of the graphene-coated PMMA slat were investigated by current–voltage (I–V) measurements and micro-Raman spectroscopy (μ-RS) during bending tests. Moreover, infrared thermographic

• –voltage measurements of the PMMA/graphene sample with and without tensile stress. Noteworthy, the graphene/PMMA sample exhibits a good Ohmic behavior with a linear increase in electrical resistance to value of about 0.3 MΩ upon application of load up to F = 6.9 N. The time dependence of the electrical

Nanostructured SnO₂–ZnO composite gas sensors for selective detection of carbon monoxide

• Paul Chesler,
• Cristian Hornoiu,
• Susana Mihaiu,
• Cristina Vladut,
• Jose Maria Calderon Moreno,
• Mihai Anastasescu,
• Carmen Moldovan,
• Bogdan Firtat,
• Costin Brasoveanu,
• George Muscalu,
• Ion Stan and
• Mariuca Gartner

Beilstein J. Nanotechnol. 2016, 7, 2045–2056, doi:10.3762/bjnano.7.195

• oxide semiconductors were used for the first time as sensing materials in 1962, when a report was released by Siyama et al. [4] regarding a thin film of ZnO. The principle of sensing, when a resistive chemical sensor is used, involves measuring the changes in electrical resistance that occur in the

• . Precise test gas concentrations (5–2000 ppm) are provided by Aalborg mass flow controllers (MFCs). The variation of the electrical resistance was recorded using a Hioki 3522-50 high performance RLC bridge. On the sensor surface, a DC voltage of 1.5 V was applied. The sensor response was defined as the

• ratio between the electrical resistance of the sensor in the carrier gas (Rair) and the electrical resistance of the sensor in the target gas (Rgas): Results and Discussion Sensor morphology The sensor morphology was investigated by SEM and AFM. From the SEM images (see Figure 8) it can be observed that

A new approach to grain boundary engineering for nanocrystalline materials

• Shigeaki Kobayashi,
• Sadahiro Tsurekawa and
• Tadao Watanabe

Beilstein J. Nanotechnol. 2016, 7, 1829–1849, doi:10.3762/bjnano.7.176

• performance nanocrystalline or submicrometer-grained materials with desirable mechanical properties such as enhanced fracture resistance. Finally, the potential power of GBE is demonstrated for high performance functional materials like gold thin films through precise control of electrical resistance based on

Nanostructured TiO₂-based gas sensors with enhanced sensitivity to reducing gases

• Wojciech Maziarz,
• Anna Kusior and
• Anita Trenczek-Zajac

Beilstein J. Nanotechnol. 2016, 7, 1718–1726, doi:10.3762/bjnano.7.164

• electrical resistance to occur, from the base resistance measured in air or gas (tres and trec, respectively) to 90% of stable signal after the gas or air introduction. On the other hand, the sensor response, S, was calculated as a ratio of resistance in air to resistance in gas: Results and Discussion The

• , respectively, are shown in Figure 4a,b. For both gases the sensor reacts with a large, stable and repeatable response, with step changes in the concentration range of 1.6–8.0 ppm for acetone and 80–400 ppm for nitric oxides. One can also see that there is a systematic decrease in the electrical resistance upon

• TiO2 nanostructures prepared via chemical oxidation before (a–c) and after (d,e) SnO2 deposition, and TiO2-based nanostructures prepared via thermal oxidation (f–h). Gas sensing characteristics for the T30 sensor: dynamic changes in the electrical resistance upon exposure to (a) 1.6–8.0 ppm acetone at

Thickness-modulated tungsten–carbon superconducting nanostructures grown by focused ion beam induced deposition for vortex pinning up to high magnetic fields

• Ismael García Serrano,
• Javier Sesé,
• Isabel Guillamón,
• Hermann Suderow,
• Sebastián Vieira,
• Manuel Ricardo Ibarra and
• José María De Teresa

Beilstein J. Nanotechnol. 2016, 7, 1698–1708, doi:10.3762/bjnano.7.162

• film starts the growth on a flat surface. In the final step, the linear Pt contacts are soldered to the Ti pads by the addition of thick, square, Pt deposits by FIBID. (a) Scheme of the experiment performed to measure the electrical resistance under perpendicular magnetic field. Due to the Lorentz