Refractive index sensing and surface-enhanced Raman spectroscopy using silver–gold layered bimetallic plasmonic crystals

• Somi Kang,
• Sean E. Lehman,
• Matthew V. Schulmerich,
• An-Phong Le,
• Tae-woo Lee,
• Stephen K. Gray,
• Rohit Bhargava and
• Ralph G. Nuzzo

Beilstein J. Nanotechnol. 2017, 8, 2492–2503, doi:10.3762/bjnano.8.249

• including response time, harshness of solution conditions, and overall spectroscopic detection figures-of-merit required. The work described herein demonstrates how a systematically varied metallic composition can be used to tailor the bulk RI and spectroscopic sensing capabilities of PC optics. The work

Dynamic behavior of a nematic liquid crystal mixed with CoFe₂O₄ ferromagnetic nanoparticles in a magnetic field

• Emil Petrescu,
• Cristina Cirtoaje and
• Cristina Stan

Beilstein J. Nanotechnol. 2017, 8, 2467–2473, doi:10.3762/bjnano.8.246

• due to their crystalline order and liquid molecular mobility. Usually, electric fields are used for LC-based phase modulators because of their short response time and low voltages, which makes them applicable for compact devices. However, electric fields have some disadvantages related to secondary

• reason is the long response time of liquid crystals to the field action. The second reason is the high threshold for the Fréedericksz transition, which requires powerful DC voltage sources and large electromagnets. By using ferromagnetic particles, the response time can be reduced, but at the cost of a

• variations of transition thresholds [27][28] or response time [29]. Ferromagnetic nanoparticles are good candidates for LC improvement due to their significant positive magnetic anisotropy and strong anchoring energy [30][31] on a large surface provided by chain clustering. All these effects help the

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

• , the trend is opposite: Au-modified MWCNTs reveal the highest NO2 sensitivity. Metal-functionalized MWCNT-based gas sensors also showed faster response and recovery kinetics, as compared to pristine ones. Specifically, the response time was reduced by about 2–3 min in the NO2 concentration range 10–0.2

• ppm. In Figure 8 the response and recovery times of pristine, and Au and Pd-modified MWCNTs at different NO2 concentrations and at the operating temperatures of 150 and 100 °C are reported. The response time decreases with an increase in the gas concentration at all operating temperatures; in contrast

• decreasing concentrations of NO2 at the sensor temperature of 100 °C. C) The corresponding calibration curves. The inset the plot is enlarged in the low concentration range (0.2–1 ppm). Variation of A) the response time (tResponse) and B) the recovery time (tRecovery) of pristine, Au- and Pd-modified MWCNTs

Graphene functionalised by laser-ablated V₂O₅ for a highly sensitive NH₃ sensor

• Margus Kodu,
• Artjom Berholts,
• Tauno Kahro,
• Mati Kook,
• Peeter Ritslaid,
• Helina Seemen,
• Tea Avarmaa,
• Harry Alles and
• Raivo Jaaniso

Beilstein J. Nanotechnol. 2017, 8, 571–578, doi:10.3762/bjnano.8.61

• response time, sensitivity and reversibility were essentially enhanced due to graphene functionalisation by laser deposited V2O5. This can be explained by an increased surface density of gas adsorption sites introduced by high energy atoms in laser ablation plasma and formation of nanophase boundaries

Thin SnO_x films for surface plasmon resonance enhanced ellipsometric gas sensing (SPREE)

• Daniel Fischer,
• Andreas Hertwig,
• Uwe Beck,
• Volkmar Lohse,
• Detlef Negendank,
• Martin Kormunda and
• Norbert Esser

Beilstein J. Nanotechnol. 2017, 8, 522–529, doi:10.3762/bjnano.8.56

• . All gases show a fast response to concentration changes. It takes approximately 3–4 measurements to reach the plateau of the signal which represents 9–12 s response time. This time is likely to be dominated by the time needed for the gas mixture to establish in the apparatus. Therefore, we suppose

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

• whole investigated concentration range the response and recovery processes were faster on Pd-modified ZnO NRs. This behavior can be attributed to the presence of Pd NPs, which catalyze the sensing process. Moreover, the response time was faster than the recovery time, in both cases, Pd-modified and

• chemical composition of pristine and Pd-functionalized ZnO NRs, annealed at 550 °C. The value for O–Zn refers to the atomic percentage of oxygen bound to zinc. Comparison of the response time (tResponse) and recovery time (tRecovery) between pristine and Pd-modified ZnO NRs at various C4H10 concentrations

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

• sensitivity to CO is still obtained. The good response time of 120 s and a complete sensor recovery was achieved in 190–280 s for the S2 sensor (see Figure 9), at a working temperature of 300 °C. The response value returns to the baseline after each tested concentration if the sensitive coating is

Noise in NC-AFM measurements with significant tip–sample interaction

• Jannis Lübbe,
• Matthias Temmen,
• Philipp Rahe and
• Michael Reichling

Beilstein J. Nanotechnol. 2016, 7, 1885–1904, doi:10.3762/bjnano.7.181

• and a significant slow-down of the step-response as shown in Figure 12 of appendix C. A small response time of the topography feedback loop causes a reduced noise in . Conclusions and System Optimisation We realise that the control and data acquisition system of a NC-AFM is a complex network of

Monolayer graphene/SiC Schottky barrier diodes with improved barrier height uniformity as a sensing platform for the detection of heavy metals

• Ivan Shtepliuk,
• Jens Eriksson,
• Volodymyr Khranovskyy,
• Tihomir Iakimov,
• Anita Lloyd Spetz and
• Rositsa Yakimova

Beilstein J. Nanotechnol. 2016, 7, 1800–1814, doi:10.3762/bjnano.7.173

• electronic properties to a change in concentrations of surface functional groups and adsorbates. However, sensors based on reduced graphene oxide are only well investigated in terms of determination of the concentration limit of heavy metals and improving the response time [18][19][20][21][22][23][24][25][26

Morphology of SiO₂ films as a key factor in alignment of liquid crystals with negative dielectric anisotropy

• Volodymyr Tkachenko,
• Antigone Marino,
• Eva Otón,
• Noureddine Bennis and
• Josè Manuel Otón

Beilstein J. Nanotechnol. 2016, 7, 1743–1748, doi:10.3762/bjnano.7.167

• control of pretilt in VAN cells is essential in many applications, as it affects display contrast and response time [2][6][7]. Pretilt depends on a number of factors such as chemical interaction forces between LC molecules and an alignment film, dielectric anisotropy of the LC, and film morphology. Many

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

• selectivity to CO(CH3)2 after sensitization by SnO2 nanoparticles. The sensor response time was of the order of several seconds. Their fast response, high sensitivity to selected gas species, improved selectivity and stability suggest that the SnO2-decorated flower-like 3D nanostructures are a promising

• to display better gas selectivity and sensitivity [1][2]. Additionally, open nanostructures facilitate the penetration of gas, and as a consequence, reduces the response time. Titanium dioxide (TiO2) is effectively used in environmental and energy production applications such as dye-sensitized solar

• the response to a specific gas was the highest. Then, the measurements at constant temperature with varied gas concentrations were carried out. For all the measurements, the sampling time was 2 s. The response time, tres, and recovery time, trec, are defined as the time required for changes in

Enhanced detection of nitrogen dioxide via combined heating and pulsed UV operation of indium oxide nano-octahedra

• Oriol Gonzalez,
• Sergio Roso,
• Xavier Vilanova and
• Eduard Llobet

Beilstein J. Nanotechnol. 2016, 7, 1507–1518, doi:10.3762/bjnano.7.144

• (light green). For any of the values reported in Figure 13, the uncertainty (variance associated to the different sensors tested and replicated measurements performed) remains below 16%. The sensitivity and response time to nitrogen dioxide of the indium oxide sensor under pulsed UV irradiation where

• computed. Sensitivity is generally defined as the change in response intensity for a given change in gas concentration. Given the fact that the calibration curves are linear, sensitivity is the slope of the calibration curves shown in Figure 13. Response time was defined as the time needed, after the

• injection of nitrogen dioxide, for the maximum to appear in the curve of the addition of reduction and oxidation rates (see Figure 12). These results are summarised in Table 2. In this table, the values for sensitivity and response time when the sensor is operated at 130 °C and without UV irradiation have

Nanostructured germanium deposited on heated substrates with enhanced photoelectric properties

• Ionel Stavarache,
• Valentin Adrian Maraloiu,
• Petronela Prepelita and
• Gheorghe Iordache

Beilstein J. Nanotechnol. 2016, 7, 1492–1500, doi:10.3762/bjnano.7.142

• electron microscopy, electrical measurements in dark or under illumination and response time investigations. Finally, we demonstrate the feasibility of the procedure by the means of an Al/n-Si/Ge:SiO2/ITO photodetector test structure. The structures, investigated at room temperature, show superior

• performance, high photoresponse gain, high responsivity (about 7 AW−1), fast response time (0.5 µs at 4 kHz) and great optoelectronic conversion efficiency of 900% in a wide operation bandwidth, from 450 to 1300 nm. The obtained photoresponse gain and the spectral width are attributed mainly to the high Ge

• devices individually or with other materials, hence the possibility of fabricating various heterojunctions on Si, glass or flexible substrates for future development of Si-based integrated optoelectronics. Keywords: germanium nanoparticle; photocurrent; photodetectors; response time; transport mechanism

Photocurrent generation in carbon nanotube/cubic-phase HfO₂ nanoparticle hybrid nanocomposites

• Protima Rauwel,
• Augustinas Galeckas,
• Martin Salumaa,
• Frédérique Ducroquet and
• Erwan Rauwel

Beilstein J. Nanotechnol. 2016, 7, 1075–1085, doi:10.3762/bjnano.7.101

• illumination, the photocurrent first presents a rapid response time defined by an initial spiking of the photocurrent, indicating a rapid filling and discharging of the defects states. This is followed by a rather stable and reproducible photoresponse, suggesting that the photogenerated electrons are

NO gas sensing at room temperature using single titanium oxide nanodot sensors created by atomic force microscopy nanolithography

• Li-Yang Hong and
• Heh-Nan Lin

Beilstein J. Nanotechnol. 2016, 7, 1044–1051, doi:10.3762/bjnano.7.97

• -recovery approaches. It is found that a sensor with a smaller ND has better performance than a larger one. A response of 31%, a response time of 91 s, and a recovery time of 184 s have been achieved at a concentration of 10 ppm for a ND with a size of around 80 nm. The present work demonstrates the

• in Supporting Information File 1.) The response time tres is defined as the time required for the current to decrease to 10% of the initial current during NO exposure. The results are 91, 86, and 81 s for 10, 15, and 20 ppm, respectively, and plotted in Figure 4b. The recovery time trec is defined as

• adsorbed molecules on the ND surface at a higher concentration, it is reasonable that the response becomes larger. Also, it takes a longer time for the molecules to leave the surface during recovery. On the other hand, the response time has an opposite trend. This can be attributed to faster molecular

Bacteriorhodopsin–ZnO hybrid as a potential sensing element for low-temperature detection of ethanol vapour

• Saurav Kumar,
• Sudeshna Bagchi,
• Senthil Prasad,
• Anupma Sharma,
• Ritesh Kumar,
• Rishemjit Kaur,
• Jagvir Singh and
• Amol P. Bhondekar

Beilstein J. Nanotechnol. 2016, 7, 501–510, doi:10.3762/bjnano.7.44

• ,b shows the response of the ZnO-TF/bR and ZnO-NR/bR structures for the consecutive concentration increase (50 ppm, 100 ppm, 200 ppm) at 70 °C. The response time for the ZnO-TF/bR and ZnO-NR/bR structures was observed to be 11 and 4.3 min, respectively, and the recovery time was 1.7 and 1.5 min

Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases

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

Beilstein J. Nanotechnol. 2016, 7, 22–31, doi:10.3762/bjnano.7.3

• ); it can be calculated by Equation 1: where cj is a defined gas concentration to which [ΔR/Ri]j is the corresponding response. The response time is defined as the time necessary to reach the 90% of the resistance variation under the presence of the gaseous analyte with respect to the initial

• -functionalized ZnO, annealed at 300 and 550 °C. The O–M percentage refers to the atomic percentage of oxygen bound to metal. Comparison of the response time (tresponse) and recovery time (trecovery) between spherical and rod-like pristine and Au-doped ZnO at various NO2 concentrations. Acknowledgements The

Blue and white light emission from zinc oxide nanoforests

• Nafisa Noor,
• Luca Lucera,
• Thomas Capuano,
• Venkata Manthina,
• Alexander G. Agrios,
• Helena Silva and
• Ali Gokirmak

Beilstein J. Nanotechnol. 2015, 6, 2463–2469, doi:10.3762/bjnano.6.255

• ) Current and PIN output voltage versus time measured by an oscilloscope. The photodiode used for this trial was very sensitive but not fast enough to capture the details, showing slow rise and fall times and saturation. The delay was primarily due to the response time of the built-in amplifier in the PIN

Optimized design of a nanostructured SPCE-based multipurpose biosensing platform formed by ferrocene-tethered electrochemically-deposited cauliflower-shaped gold nanoparticles

• Wicem Argoubi,
• Maroua Saadaoui,
• Sami Ben Aoun and
• Noureddine Raouafi

Beilstein J. Nanotechnol. 2015, 6, 1840–1852, doi:10.3762/bjnano.6.187

• to the successive additions of H2O2 at an applied potential of +0.15 V. The inset in Figure 6c shows the linearity of the calibration curve along the different additions of H2O2 (R2 = 0.9989) with a sensitivity of ca. 4.13 nA/µM. The biosensor has a fast response time since the current rapidly

A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

• Tobias Meier,
• Alexander Förste,
• Ali Tavassolizadeh,
• Karsten Rott,
• Dirk Meyners,
• Roland Gröger,
• Günter Reiss,
• Eckhard Quandt,
• Thomas Schimmel and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2015, 6, 451–461, doi:10.3762/bjnano.6.46

• resonance frequency increases the response time of the scanner to driving signals. Therefore, lever amplification can only be used for the slow lateral scanning as the z-axis of the scanner needs a high resonance frequency for a fast response to driving signals. The large-area scanner has a motion-amplified

• x–y piezo stage and a dedicated z-piezo for a short response time. Additionally, the x–y stage must only move in the x–y plane without any cross-talk to the z-axis. This is reached by flexure joints. However, as the stiffness of a lever amplified system is reduced quite significantly, the initial

Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Xabier Quintana and
• José M. Otón

Beilstein J. Nanotechnol. 2015, 6, 396–403, doi:10.3762/bjnano.6.39

• . Remarkable conductivity differences between CNT-doped and undoped LC cells have been reported, and studies about variations in the dielectric permittivity [14][15], threshold voltage [16] and response time [17][18] have been published. Yet a more detailed description of the electrical behavior of CNT-doped

Mechanical properties of MDCK II cells exposed to gold nanorods

• Anna Pietuch,
• Bastian Rouven Brückner,
• David Schneider,
• Marco Tarantola,
• Christina Rosman,
• Carsten Sönnichsen and
• Andreas Janshoff

Beilstein J. Nanotechnol. 2015, 6, 223–231, doi:10.3762/bjnano.6.21

• that both mass load (change in resonant frequency) and dissipation (representing energy loss) increase upon administration of CTAB coated gold nanorods. The response time of the cells to administration of particles is fairly fast (few hours) and depends heavily on particle concentration. We carried out

Gas sensing properties of nanocrystalline diamond at room temperature

• Marina Davydova,
• Pavel Kulha,
• Alexandr Laposa,
• Karel Hruska,
• Pavel Demo and
• Alexander Kromka

Beilstein J. Nanotechnol. 2014, 5, 2339–2345, doi:10.3762/bjnano.5.243

• . However, most of these sensors show poor selectivity, and the main drawbacks are slow sensor response times and recovery speeds. Even if the response time for the detection of reactive gases is rapid (e.g., within the range of seconds), in many cases, the recovery times at room temperature can be from

Influence of stabilising agents and pH on the size of SnO₂ nanoparticles

• Olga Rac,
• Patrycja Suchorska-Woźniak,
• Marta Fiedot and
• Helena Teterycz

Beilstein J. Nanotechnol. 2014, 5, 2192–2201, doi:10.3762/bjnano.5.228

• material increases the selectivity and sensitivity and shortens the response time of a sensor. However, the synthesis of SnO2 nanoparticles presents many difficulties. The following article presents a simple and inexpensive method for the synthesis of SnO2 nanoparticles. The influence of the surfactant and

Room temperature, ppb-level NO₂ gas sensing of multiple-networked ZnSe nanowire sensors under UV illumination

• Sunghoon Park,
• Soohyun Kim,
• Wan In Lee,
• Kyoung-Kook Kim and
• Chongmu Lee

Beilstein J. Nanotechnol. 2014, 5, 1836–1841, doi:10.3762/bjnano.5.194

• the response, response time and recovery times of the ZnSe nanowires to 5 ppm NO2 gas at room temperature on the illumination intensity of UV light used to illuminate the gas sensors. The response of the nanowires was 102% in the dark. The responses of the nanowires increased from ≈102 to ≈234% with

• the other hand, Figure 5a and Figure 5b show that both the response time and recovery time of the ZnSe nanowires at room temperature towards 5 ppm NO2 gas tend to decrease with the UV illumination intensity. These high responses at room temperature highlight the strong influence of UV irradiation on

• sensing performance could be enhanced when used at room temperature under UV illumination. The response of the ZnSe nanowires increased from 0 to ≈234% with increasing UV illumination intensity from 0 to 1.2 mW/cm2 and the response time and recovery time of the ZnSe nanowires tended to decrease with