Synthesis and acetone sensing properties of ZnFe₂O₄/rGO gas sensors

• Kaidi Wu,
• Yifan Luo,
• Ying Li and
• Chao Zhang

Beilstein J. Nanotechnol. 2019, 10, 2516–2526, doi:10.3762/bjnano.10.242

• shorter response/recovery time to 10 ppm acetone at 200 °C. The response time has been measured as 60 s for the pure ZnFe2O4 sensor and only 23 s for the 0.5 wt % ZnFe2O4/rGO sensor. Figure 9 shows the responses of the pure ZnFe2O4 sensor and the 0.5 wt % ZnFe2O4/rGO sensor to acetone at different

Integration of sharp silicon nitride tips into high-speed SU8 cantilevers in a batch fabrication process

• Nahid Hosseini,
• Matthias Neuenschwander,
• Oliver Peric,
• Santiago H. Andany,
• Jonathan D. Adams and
• Georg E. Fantner

Beilstein J. Nanotechnol. 2019, 10, 2357–2363, doi:10.3762/bjnano.10.226

• and to increase the detection speed and sensitivity. The detection speed in amplitude-modulation mode is determined by the amplitude response time of the cantilever. The tapping-mode bandwidth is given by BW = πf0/Q, where f0 is the resonance frequency and Q is the Q-factor [32]. The resonance

Remarkable electronic and optical anisotropy of layered 1T’-WTe₂ 2D materials

• Qiankun Zhang,
• Rongjie Zhang,
• Jiancui Chen,
• Wanfu Shen,
• Chunhua An,
• Xiaodong Hu,
• Mingli Dong,
• Jing Liu and
• Lianqing Zhu

Beilstein J. Nanotechnol. 2019, 10, 1745–1753, doi:10.3762/bjnano.10.170

• angles (from 0° to 150°, spaced at 30° apart) under the following conditions: Vds = 5 mV, incident power = 1.4 mW, incident wavelength = 633 nm. b) The magnified photocurrent response of test angle at 60° with a response time of around 200 ms. c) Angle-resolved photosensitivity of the photodetector

Review of time-resolved non-contact electrostatic force microscopy techniques with applications to ionic transport measurements

• Aaron Mascaro,
• Yoichi Miyahara,
• Tyler Enright,
• Omur E. Dagdeviren and
• Peter Grütter

Beilstein J. Nanotechnol. 2019, 10, 617–633, doi:10.3762/bjnano.10.62

• various PLL settings. Limitation: direct frequency detection A critically damped second-order PLL (i.e., optimized settings) has an exponentially decaying time response to abrupt changes in the frequency being tracked (the center frequency, f0) [28]. The response time-constant of the phase detector is

• determined directly by the center frequency: τPD = 1/f0. Thus, the theoretical minimum response time to achieve more than 95% tracking is three cycles. This is difficult to realize in practice as it neglects amplification/filtering before and after the phase detector and other non-ideal effects such as

• jitter and noise. The overall response time of the system (τPLL, inversely proportional to the overall bandwidth) serves as a more practical metric as it takes all contributions into account. This can either be measured by stepping the frequency of a known signal and measuring the response time or in the

Temperature-dependent Raman spectroscopy and sensor applications of PtSe₂ nanosheets synthesized by wet chemistry

• Mahendra S. Pawar and
• Dattatray J. Late

Beilstein J. Nanotechnol. 2019, 10, 467–474, doi:10.3762/bjnano.10.46

• . Figure 7d shows the I–t plot for the photodetector based on PtSe2 nanosheets with a response time of ≈110 s and a recovery time of ≈129 s. Conclusion In conclusion, we report on a wet chemistry method to grow PtSe2 nanosheets. The SEM and TEM analysis confirm the formation of PtSe2 nanosheets. Further

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

• response time. Studying effect of calcination period on nanocluster size TEM images for two samples with the same decoration ratio (CNT/Fe = 1:1.5) but with different calcination periods of 15 or 30 minutes were taken to investigate the effect of the duration of the calcination on the size of iron

Nanostructure-induced performance degradation of WO₃·nH₂O for energy conversion and storage devices

• Zhenyin Hai,
• Mohammad Karbalaei Akbari,
• Zihan Wei,
• Danfeng Cui,
• Chenyang Xue,
• Hongyan Xu,
• Philippe M. Heynderickx,
• Francis Verpoort and
• Serge Zhuiykov

Beilstein J. Nanotechnol. 2018, 9, 2845–2854, doi:10.3762/bjnano.9.265

• thin films displayed a maximum response of 80% for 1% of hydrogen gas at 250 °C [36]. 2D WO3·2H2O films developed by a facile dipping process exhibited a significantly improved response time as electrochromic electrodes compared to WO3 thin films [37]. The acidic precipitation reaction was also adopted

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

• porous structure and defects for detecting NO2. The sensor showed high sensitivity to NO2 at low concentrations. In another work, Hu et al. [18] fabricated an ultra-sensitive rGO gas sensor, which reached a response of 2.4% to 1 ppb NH3 with an ultra-fast response time of 1.4 s at room temperature. The

• . Consequently, the resistance of composite sensor decreased sharply, leading to high sensitivity and rapid response time. The reaction equations are as follows: In an early work, Liu et al. [57] stated that a ZnO nanowalls–rGO sensor, which was prepared by growing ZnO nanowalls on rGO films, reached a response

• of 9.61 to 50 ppm NO2 and the response/recovery times were only 25 s/15 s with good stability at room temperature. As a comparison, the response of the ZnO sensor was 6.2 and the response time was over 150 s under the same conditions. The pure rGO sensor only showed a response of 1.2 and a recovery

Accurate control of the covalent functionalization of single-walled carbon nanotubes for the electro-enzymatically controlled oxidation of biomolecules

• Naoual Allali,
• Veronika Urbanova,
• Mathieu Etienne,
• Xavier Devaux,
• Martine Mallet,
• Brigitte Vigolo,
• Jean-Joseph Adjizian,
• Chris P. Ewels,
• Sven Oberg,
• Alexander V. Soldatov,
• Edward McRae,
• Yves Fort,
• Manuel Dossot and
• Victor Mamane

Beilstein J. Nanotechnol. 2018, 9, 2750–2762, doi:10.3762/bjnano.9.257

• and decrease electrode response time [3][5]. We and others have reported some interesting electrocatalytic effects when using CNT-modified GCEs for the voltamperometric detection of (bio)molecules [6][7][8][9][10][11][12][13][14]. Two major hurdles have to be tackled when designing CNT-modified GCEs

Electrospun one-dimensional nanostructures: a new horizon for gas sensing materials

• Muhammad Imran,
• Nunzio Motta and
• Mahnaz Shafiei

Beilstein J. Nanotechnol. 2018, 9, 2128–2170, doi:10.3762/bjnano.9.202

• annealing and calcination [83]. A very low detection limit (9.7 ppb NOx) with an optimal response time (20 s) is achieved with nanocrystalline (5–10 nm) SnO2 NTs at room temperature [141]. Similar behaviour is exhibited by p-type NiO and CuO toward CO and NO2 [111][112]. The gas sensing behaviour also

• acetone at 250 °C compared with solid NFs with average diameter of 275 nm. These latter NFs give a response of 60.2 at 270 °C. The response time of WO3 NTs (5 s) is smaller than WO3 NFs (6–13 s) but the recovery time is longer (22 s) than WO3 NFs (4–9 s) because of different desorption rates in NTs

• concentration range of 1–5 ppm. The response of Pd@ZnO–WO3 NFs is (Rair/Rgas = 22.22 to 1 ppm) as compared with pristine WO3 (Rair/Rgas = 1.10), ZnO–WO3 NFs (Rair/Rgas = 1.16), Pd(polyol)–WO3 NFs (Rair/Rgas = 5.31), and Pd(polyol)–ZnO–WO3 NFs (Rair/Rgas = 5.47) as shown in Figure 9h. The response time of Pd@ZnO

Quantitative comparison of wideband low-latency phase-locked loop circuit designs for high-speed frequency modulation atomic force microscopy

• Kazuki Miyata and
• Takeshi Fukuma

Beilstein J. Nanotechnol. 2018, 9, 1844–1855, doi:10.3762/bjnano.9.176

• clocks (380 ns), which is large enough to impact the PLL response time significantly. PLL circuit with subtraction-based PC Recently, we proposed a PLL circuit using a subtraction-based PC (S-PLL) [32]. Figure 1b depicts the basic design of an S-PLL circuit. In this design, a phase-output VCO (-VCO) is

• a wide input range has a high latency at its pass band. This high latency results in a slow cantilever excitation loop response time. Therefore, in spite of the fast response of the phase feedback loop, the investigated S-PLL circuit was not suitable for high-speed FM-AFM operation. One of the most

• much more significant for the NCH cantilever (from 4.87 to 1.65) than for the USC cantilever (from 4.87 to 2.94). For the NCH cantilever, the response time of the cantilever itself (1/f0 = 6.6 μs) is significant compared with the latency of the PD–PC unit (9.1 μs or 1.1 μs). Thus, its contribution

Colorimetric detection of Cu²⁺ based on the formation of peptide–copper complexes on silver nanoparticle surfaces

• Gajanan Sampatrao Ghodake,
• Surendra Krishna Shinde,
• Rijuta Ganesh Saratale,
• Avinash Ashok Kadam,
• Ganesh Dattatraya Saratale,
• Asad Syed,
• Fuad Ameen and
• Dae-Young Kim

Beilstein J. Nanotechnol. 2018, 9, 1414–1422, doi:10.3762/bjnano.9.134

• the spectral response time of the AgNPs-casein peptides at 0.64, 0.96, and 1.28 µM Cu2+ within a time frame of 20 to 120 min. Initially, the absorbance intensity increased to a maximum and then remained stable for an extended period (120 min). The stability of sensing probe is noticed as no gradual

New 2D graphene hybrid composites as an effective base element of optical nanodevices

• Olga E. Glukhova,
• Igor S. Nefedov,
• Alexander S. Shalin and
• Мichael М. Slepchenkov

Beilstein J. Nanotechnol. 2018, 9, 1321–1327, doi:10.3762/bjnano.9.125

• absorbed by the film induces electron transport of 105 electrons, and the response time amounts to ca. 100 microseconds [9]. It should be noted that modern synthesis technologies for such composites have allowed us to provide “cross-linking” between CNTs and graphene during synthesis without further

Artifacts in time-resolved Kelvin probe force microscopy

• Sascha Sadewasser,
• Nicoleta Nicoara and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2018, 9, 1272–1281, doi:10.3762/bjnano.9.119

• transport in organic materials was studied [18][19][20][21]. The time resolution in these approaches is limited by the KPFM controller (to typically the millisecond range) or the response time of the cantilever to changes in the sample’s CPD (on the order of 100 μs [14]). A better time resolution was

• achieved by using a light-intensity modulated (IM) KPFM measurement, presented by Takihara et al. [22]. Charge carriers are excited during the illuminated fraction of the modulation, and decay during the subsequent dark fraction of the modulation. If the modulation frequency is faster than the response

• time of the KPFM controller, only an averaged CPD will be measured, for which the value will depend on how fast the changes in charge carrier separation follow the light modulation. Thus, the average CPD carries information about the charge carrier dynamics. This technique was subsequently used by

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

• exposure to 4, 6, 8 and 12 ppm NO2 at optimum operating temperature. Interestingly, the sensor response of Au NP/ZnO was fast reaching saturation at concentrations above 8 ppm. The response time (τRes) upon exposure to 10 ppm NO2 was dramatically decreased from 42 s to 9 s and the recovery time (τRec

Sensing behavior of flower-shaped MoS₂ nanoflakes: case study with methanol and xylene

• Maryam Barzegar,
• Masoud Berahman and
• Azam Iraji zad

Beilstein J. Nanotechnol. 2018, 9, 608–615, doi:10.3762/bjnano.9.57

• clearly illustrates the reversible behavior of about 120 s and 370 s as the response and recovery times for 200 ppm, respectively. When the working temperature was increased, the sensitivity was improved from 25 to 55 for 200 °C and the response time decreased from about 800 s to 120 s (Figure 4b). In

Dynamic behavior of nematic liquid crystal mixtures with quantum dots in electric fields

• Emil Petrescu,
• Cristina Cirtoaje and
• Octavian Danila

Beilstein J. Nanotechnol. 2018, 9, 399–406, doi:10.3762/bjnano.9.39

• field is high enough to exceed the Fréedericksz transition threshold some of the molecules are already parallel to the field and only those placed on the horizontal sphere circumference are parallel to the cell plates, so the response time is shorter in the quantum dots sample (Figure 7a). When the

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

• our knowledge, the highest durability (106 on/off cycles, 10 ns response time) of a 2T CNT-based switch was demonstrated by Loh et al. for carbon–carbon contacts, using multiwall CNT as a switching element and diamond-like carbon (DLC) as a contact material [12]. However, the reported actuation

Dynamic behavior of a nematic liquid crystal with added carbon nanotubes in an electric field

• Emil Petrescu and
• Cristina Cirtoaje

Beilstein J. Nanotechnol. 2018, 9, 233–241, doi:10.3762/bjnano.9.25

• to become parallel to the field, but the carbon nanotubes remain still parallel to the cell support (Figure 4a). If the field is switched off immediately, the nematic molecules return to their original position, “helped” by the anchoring forces on the nanotube surface, leading to a shorter response

• time compared to the liquid crystal sample (Figure 4b). If the voltage is applied for a long period of time (at least 1 hour) the nanotubes align parallel to the field, due to their positive anisotropy [18][19][20][21]. When the field is then switched off, the LC molecules return to their original

Electrical properties of a liquid crystal dispersed in an electrospun cellulose acetate network

• Doina Manaila Maximean,
• Octavian Danila,
• Pedro L. Almeida and
• Constantin Paul Ganea

Beilstein J. Nanotechnol. 2018, 9, 155–163, doi:10.3762/bjnano.9.18

• value of Z″ is obtained (Figure 8). Also, the electrical response time is τ = 1/(RpCp), and knowing the angular frequency, the capacitance can be determined. Based on the fitting technique, we modeled the sample behavior by a simple three-element electric circuit (Figure 10), which describes a single

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

• . For instance, a hydrogen-terminated nanocone array exhibited a fast response time (4.7 s) towards 10 ppm of NO2 at 150 °C [13]. On the other hand, a room-temperature-operated gas sensor based on H-terminated diamond films showed a long response time and recovery time towards nitrogen dioxide [24

Study of the vertically aligned in-plane switching liquid crystal mode in microscale periodic electric fields

• Artur R. Geivandov,
• Mikhail I. Barnik,
• Irina V. Kasyanova and
• Serguei P. Palto

Beilstein J. Nanotechnol. 2018, 9, 11–19, doi:10.3762/bjnano.9.2

• inaccuracy. Thus, the smaller electrodes period is desirable for shortening the response time. At an electrode grating period of 3 μm the relaxation time (τoff) is below 1 ms for ZLI-1957/5 LC. Note that for the typical modes used in practice (such as for example the twisted nematic mode) the relaxation time

• electrodes width-to-gap ratio we have found the LC cell parameters enabling both high transmittance and fast response times. The VA-IPS mode with transparent microelectrodes is a perspective for display application requiring small pixel size and fast response time. Experimental Samples preparation: We used

Electro-optical characteristics of a liquid crystal cell with graphene electrodes

• Nune H. Hakobyan,
• Hakob L. Margaryan,
• Valeri K. Abrahamyan,
• Vladimir M. Aroutiounian,
• Arpi S. Dilanchian Gharghani,
• Amalya B. Kostanyan,
• Timothy D. Wilkinson and
• Nelson Tabirian

Beilstein J. Nanotechnol. 2017, 8, 2802–2806, doi:10.3762/bjnano.8.279

• the binding energy of the LC molecules with the surface of the substrate. Despite the short response time there are undesirable backflows, making a device operating in such mode less attractive. In the slow switching mode, reorientation occurs in the bulk of the LC. In this case, the operation time is

Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles

• Agata Siarkowska,
• Miłosz Chychłowski,
• Daniel Budaszewski,
• Bartłomiej Jankiewicz,
• Bartosz Bartosewicz and
• Tomasz R. Woliński

Beilstein J. Nanotechnol. 2017, 8, 2790–2801, doi:10.3762/bjnano.8.278

• properties of LCs as they can influence, for example, the LC response time and decrease the Freedericksz threshold voltage [6][7][8]. Promising results were reported for metallic (mostly gold and silver), ferroelectric and dielectric NPs [9][10][11][12]. It appeared that NP/LC molecule size matching can

• of the response time under an external electric field. In the present research we used a 6CHBT nematic LC [19] and 4 nm diameter, spherical Au NPs (Figure 1a), both synthesized in the Military University of Technology, Warsaw, Poland. Au NPs have been used for applications both in photonics and

• nematic–isotropic phase transition temperature [21][22], but with a specific surface coating, the effect can be reversed [23]. The presence of Au NPs in an LC has proven to influence the response time and lower the threshold voltage [24][25][26][27][28]. In this paper we compare four different

Impact of titanium dioxide nanoparticles on purification and contamination of nematic liquid crystals

• Dmitrii Pavlovich Shcherbinin and
• Elena A. Konshina

Beilstein J. Nanotechnol. 2017, 8, 2766–2770, doi:10.3762/bjnano.8.275

• addition, nanoparticles can induce other new functions in liquid crystals, including improved response time [14][15], surface plasmon resonance [16], and improvements in alignment [17]. The ionic contamination of LCs remains one of the challenges to LC technology. Ionic conductivity negatively affects LC