bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimisation of Dyes@SWCNT Raman Nanoprobes
Authors: David Carolane , Allard Charlotte , Mal Suraj , Tang Nathalie , Martel Richard 
Published: May 2020

Single-Walled Carbon Nanotubes (SCWNTs) have attracted a lot of attention in biomedical fields. Their easily functionalised surface and ability to encapsulate different materials make them interesting not only for imaging, but also for other applications, such as drug delivery and cell targeting. This work concerns specifically the use of SWCNTs to fabricate Raman nanoprobes for bio-imaging. These nanoprobes are composed of dyes encapsulated inside the SWCNTs and the nanotubes are grafted with anti-bodies functionalized on the outer surface.
First, we aim to optimize the encapsulation process so that the dye/SWCNTs nanohybrid gives a strong, uniform and reproductible signal that is easily detectable by Raman imaging. This is done by varying the parameters of the liquid-phase encapsulation process and crosschecking the results by Raman imaging. We also work to optimize the stability of the nanohybrid in biological media. This parameter is important to determine the best conditions for antibody attachment and cell/tissue interactions. Using different biological buffers, we study the dispersion of the assemblies with Dynamic Light Scattering (DLS) and their stability with Electrophoretic Light Scattering (ELS). The results of the analysis on the nanohybrids show an average hydrodynamic radius of 160 nm and a Zeta potential at -45 mV in aqueous media, proving that the stability of the short nanohybrids in water is favourable to the development of nanoprobes.
Dyes Encapsulated By Single Walled Carbon Nanotubes: A Raman Nanoprobe of Cancer Detection
Authors: Mal Suraj , Tang Nathalie , David Carolane , Allard Charlotte , Duarte Layane , Gaboury Louis , Ouellette S. Blais , Martel Richard 
Published: May 2020

Carbon nanotubes are among the most promising platforms for biological applications such as cancer targeting, medical imaging and drug delivery. Herein we present a novel approach to modify single-walled carbon nanotubes (SWCNTs) into Raman nanoprobes capable of targeting biomarkers on cancer cells. The process involves cleaning and shortening in acids followed by encapsulation of specific organic dyes. Subsequently the as-synthesized Raman nanoprobes are then covalently attached with modified NH2-PEG-COOH to make a generic nanoprobe that is bio-compatible and highly dispersed in aqueous or buffer media. When covalently linked to specific antibodies anti-E-cadherin (monoclonal mouse anti-human) and CK19 (cytokeratin), such nanoprobes can be used to detect there bio-markers in the membrane of breast cancer cell lines.
Here, we will first discuss a modified synthetic approach to densify the covalent pegylation used to link bio-molecules on the SWCNTs and show results with nanoprobes incubated with T47D antibody (ab) and MDA231 cell lines. The immunofluorescence and Raman imaging data shows that dyes@SWCNT/PEG/ab composites can specifically target cancer cells overexpressing high affinity receptors of the specific biomarkers linked to the probes. By densifying the covalently attached PEGs, the results show higher stability and improved selectivity of the Raman nanoprobes towards bio-molecules on cancer cells.
Innovation in Textile Electrode of Electrochemical Devices: Water Transport and Thread-Based Temperature and Humidity Sensors
Authors: Hasanpour Sadegh , Djilali Ned , Akbari Mohsen 
Published: May 2020

Wearable health monitoring utilizing advances in textile technologies has already been demonstrated for transport of biomarkers and physiological sensing. These advances can potentially be translated to textile electrodes of electrochemical devices to allow managing reactants and by-products transport and for monitoring environmental parameters. Herein, a wicking properties and flexibility of threads are used (1) to control transport of water (by-product) within a textile gas diffusion layer (GDL) of the electrode of polymer electrolyte membrane fuel cells (PEMFCs), and (2) to develop thread-based sensors for local temperature and humidity monitoring.
By means of ex-situ and in-situ characterizations, it was found that the threads can be introduced in the GDL structure to inscribe water highways within the GDL with minimal impact on GDL microstructure (i.e. porosity, porosity distributions) and transport properties (i.e. permeability, diffusivity and conductivity). Furthermore, a low-cost procedure was developed to transform a commodity thread into temperature and humidity sensors by dip-coating the thread with carbon nanotubes (CNTs) ink. The resistance of CNT coated threads is responsive to both parameters. In this work, the response to humidity was cancelled by coating fluorinated ethylene propylene (FEP) on top of the CNT coated thread to develop a temperature sensor independent of humidity. In addition, a second thread was coated with polydimethylsiloxane (PDMS) to monitor the relative humidity (RH).
Thread-based sensors were characterized in an environmental chamber simulating environmental conditions in an operating fuel cell. A linear change of resistance with increasing temperature (~-0.31 %/T) was achieved for the temperature sensor, and the resistance of the thread coated with PDMS showed more sensitivity in high humidity regions (RH > 60%) and followed a quadratic function of RH. The thread-based temperature sensor capability was assessed via ex-situ experiments, and showed rapid response to change of temperature, and also the ability to map temperature in non-uniform temperature distributions. The combinations of both threads can allow simultaneous monitoring of local temperature and RH in the textile GDL of PEMFCs. This work enables local sensing and monitoring within textile electrodes without compromising the performance of PEMFCs.
(Invited) Organic/Inorganic Hybrid Interfaces between Perovskite Semiconductors and Semiconducting Swcnts for Energy Harvesting and Conversion
Authors: Blackburn Jeffrey L. , Hao Ji , Kim Young-Hoon , Lu Haipeng , Habisreutinger Severin N. , Luther Joseph M. 
Published: May 2020

Low-dimensional semiconductors provide a rich tapestry of tunable optical and electrical properties for a wide variety of applications. Semiconducting single-walled carbon nanotubes (s-SWCNTs) have shown tremendous potential in applications ranging from digital logic, biological imaging, quantum information processing, photovoltaics, and thermoelectric energy harvesting. Energy harvesting applications rely critically upon the creation of tailored interfaces that enable the movement of energetic species (excitons, electrons, holes) in specified directions. While organic energy harvesting devices often employ interfaces between distinct organic species such as polymers, fullerenes, and carbon nanotubes, hybrid interfaces between organic and inorganic semiconductors have unique properties that are relatively unexplored.
In this talk, I will discuss our recent efforts at constructing novel hybrid interfaces between s-SWCNTs and low-dimensional perovskite-based semiconductors. I will highlight time-resolved spectroscopy results that illustrate long-lived photoinduced charge separation across such interfaces, demonstrating utility for photovoltaics and photodetectors. Interestingly, some systems demonstrate additional transient processes that are exceptionally slow and may indicate ion movement within the hybrid systems. Complementary device studies demonstrate exceptional efficiencies for conversion of photons into stable photocurrent, and I will highlight several novel applications in which these interfaces can be employed.
Fast Ion Diffusion in Carbon Nanotube Channels
Authors: Buchsbaum Steven F. , Jue Melinda L. , Chen Chiatai , Meshot Eric R. , Park Sei Jin , Sawvel April , Lau Edmond Y , Pham Tuan Anh , Wu Kuang Jen , Fornasiero Francesco 
Published: May 2020

Many simulations and experiments have investigated pressure-driven fluid flow in carbon nanotubes (CNTs) and demonstrated enormous transport rates through these channels. Comparatively little attention has been given so far to concentration-driven transport1,2 in CNTs despite its importance in a large variety of fields. While several studies assumed bulk/hindered diffusion for small molecules through nm-wide CNTs, other simulations have predicted self-diffusion coefficients several times larger than in the bulk. These large uncertainties in the magnitude of the diffusion rates through CNTs have hampered their full exploitation in nanofluidic devices.3

To obtain a precise quantification of the diffusive flow in CNTs, we have fabricated membranes with a large but known number of single-walled carbon nanotubes (SWCNT) as fluid transport pathways. Contrary to previous membrane systems, this platform enables us to minimize uncertainties in the calculation of the per-pore flow rate. A series of stringent control experiments confirms that these membranes are defect free and that transport occurs only through SWCNTs. Once corrected for the boundary layer resistance at the membrane/fluid interface, our measurements reveal that the transport diffusivity of small ions in single-walled carbon nanotubes is one order of magnitude faster than in the bulk.4 The dependence of the flow enhancement on the ion chemico-physical properties is also discussed. Together with indicating that CNT membranes could enable dialysis processes with unprecedented efficiency, these results have important implications for a broad range of applications, such as energy storage/harvesting and chemical separation/detection, where ion permeation through nanoporous carbon materials is key.

References

1. Bui, E. R. Meshot, S. Kim, J. Peña, P. W. Gibson, K. J. Wu, F. Fornasiero, Adv. Mater., 28 (2016) 5871.
2. Li, C. Chen, E. R. Meshot, S. F. Buchsbaum, M. Herbert, R. Zhu, O. Kulikov, B McDonald, N. Bui, M. L. Jue, S. J. Park, C. Valdez, S. Hok, C. J. Doona, K. J. Wu, T. M. Swager, F. Fornasiero, submitted (2019)
3. S. Guo, E. R. Meshot, T. Kuykendall, S. Cabrini, F. Fornasiero, Adv. Mater. 28 (2015), 5871.
4. S. Buchsbaum, M. L. Jue, C. Chen,E. R. Meshot, S. J. Park, A. Sawvel, E. Lau, T. A. Pham, K. J. Wu, F. Fornasiero, in preparation (2019)
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Charge Modulation Spectroscopy of Pristine and sp3-Functionalized Single-Walled Carbon Nanotube Networks
Authors: Zorn Nicolas Frederic , Berger Felix Julian , Zaumseil Jana 
Published: May 2020

The controlled decoration of single-walled carbon nanotubes (SWCNTs) with luminescent sp3 defects has emerged as a powerful approach to enhance their usually low photoluminescence (PL) quantum yields and achieve tuneable emission across the near-infrared even for polymer-wrapped nanotubes [ACS Nano
2019, 13, 9259]. However, their application in optoelectronic devices requires a detailed understanding of the impact of sp3 functionalization on their electrical performance. While isolated sp3 defects on single SWCNTs increase the resistance by a few kΩ, the effect of functionalization on charge transport in networks of semiconducting SWCNTs remains unexplored. Charge modulation spectroscopy is ideally suited to probe the mobile charge carriers in SWCNT networks and has previously corroborated the notion that charge accumulation and transport in mixed SWCNT networks is highly chirality- and gate voltage-dependent. Here, we use charge-modulated PL (CMPL) spectroscopy to study the current pathways in field-effect transistors based on networks of pristine and functionalized (6,5) SWCNTs. We find that the defects are very efficiently sampled by mobile carriers and consequently, sp3-functionalized SWCNTs actively participate in the charge transport in these networks. In combination with voltage-dependent PL and electroluminescence measurements, our CMPL method provides fundamental insights into the interaction of charge carriers with sp3 defects in SWCNT thin film devices.
Fig. 1: Schematic of the charge modulation PL spectroscopy setup (left) and CMPL spectra of pristine and functionalized (6,5) SWCNT network field-effect transistors (right).

Figure 1
(Invited) Graphene Aerogels: From Self-Assembly to Applications
Authors: Cerruti Marta , Hu Kaiwen , Chen Yiwen , Szkopek Thomas 
Published: May 2020

Graphene aerogels are highly porous and light structures that maintain most of the exceptional mechanical and electrical properties of graphene in a substrate that can be handled and used in practical applications. This is possible because the graphene flakes do not excessively restack during aerogel formation.
In this talk we will explore how we can direct the self-assembly of graphene oxide flakes to generate graphene aerogels with different structures and mechanical properties. We will at first show what happens during hydrothermal reduction of graphene oxide and describe the synthesis of reduced graphene oxide scaffolds with a highly reduced, compact shell and a less reduced porous core. We will then show how we can tune graphene oxide self-assembly during hydrothermal reduction by changing the amphiphilicity of the graphene oxide flaxes and generate elastic shell-less structures. We will show how composite structures can be made too, by maintaining the shell and using highly stable colloidal suspensions. Lastly, we will show that controlling amphiphilicity also allows generating scaffolds through high internal phase emulsions. We will briefly highlight applications for these structures in fields as varied as sensing, pollutant absorption, photocatalysis, and cell culture.
(Invited) Hybrid Van Der Waals Heterostructures: From Fundamentals to Applications
Authors: Orgiu Emanuele 
Published: May 2020

2D materials are held together by weak interplanar van der Waals (vdW) interactions. The incorporation of molecules in such materials holds an immense potential to understand and modify the fundamental physical properties of the pristine materials while creatin new artificial materials. Whilst nature offers a finite number of 2D materials, an almost unlimited variety of molecules can be designed and synthesized with predictable functionalities. The possibilities offered by systems in which continuous molecular layers are interfaced with inorganic 2D materials to form hybrid organic/inorganic van der Waals heterostructures (H-vdWH) are emphasized. Similar to their inorganic counterpart, the hybrid structures have been exploited to suggest novel device architectures. Moreover, specific molecular groups can be employed to modify intrinsic properties and confer new capabilities to 2D materials. In particular, I will highlight how molecular self-assembly at the surface of 2D materials can be mastered to achieve precise control over position and density of (molecular) functional groups, paving the way for a new class of hybrid functional materials.
In particular, within such vdW heterostructures, currently assembled by mechanical superposition of different layers, periodic potentials naturally occur at the interface between the 2D materials. These potentials significantly modify the electronic structure of the individual 2D components within the stack and their alignment, thus offering the possibility to build up hybrid and novel materials with unique properties.
Also, I will show how the presence of ordered supramolecular assemblies bearing different functional groups can modify the pristine Shubnikov-De Haas oscillations occurring in graphene.
Finally, an example will be given of how a carefully designed H-vdWH could be used for sensing of different biomarkers.
(Invited) Electroluminescent Hyperbolic Cooling of Graphene Field Effect Transistors
Authors: Baudin Emmanuel , Voisin Christophe , Placais Bernard 
Published: May 2020

Heat management is critical for the performance of most modern electronic devices. It was recently proposed that radiative heat transfer - which is usually negligible in the solid state - could be increased in hyperbolic metamaterials, i.e., materials having a hyperbolic electromagnetic dispersion relation. [1] However, artificial metamaterials can be difficult to fabricate and integrate.
Fortunately, most of Van der Waals materials are natural hyperbolic metamaterials. Indeed, due to their anisotropic layered structure, the in-plane and out-of-plane optical phonon energy splitting results in a hyperbolic dispersion of light in the Resstrahlen bands. As a consequence, in these materials, the strong light-matter coupling can give rise to a 102-105 increase in the e.m. local density of states, resulting in a dramatic enhancement of the radiative heat transfer. Moreover, the radiative character of heat exchange results in a propagative heat transport via hyperbolic phonon-polariton (HPhP) modes on micrometric scales.
We have studied heat transfer in graphene on hexagonal boron nitride: a natural 2D hyperbolic material. In our devices, graphene is used as a versatile heat source in the near field of a hyperbolic material, and as a sensitive noise thermometer. [2] Using mono-, bi- and trilayer graphene, we demonstrate a strong increase of the electron gas cooling resulting in a large temperature drop when the emission of HPhP sets in. This process shares many analogies with electroluminescence, except that it involves near-field modes. We experimentally evidence that the case of graphene is unique, with cooling powers reaching few milliwatts per micron square [3], i.e., nine orders of magnitude larger than previously reported in the literature.

Bibliography

[1] S. Biehs, et al "Hyperbolic metamaterials as an analog of a blackbody in the near field." Phys.
Rev. Lett.
109, 104301 (2012)
[2] W. Yang, et al "A Graphene Zener–Klein Transistor Cooled by a Hyperbolic Substrate." Nat. Nanotech.
13, 47 (2018)
[3] E. Baudin, et al "Hyperbolic Phonon Polariton Electroluminescence as an Electronic Cooling Pathway", Adv. Funct. Mat.1904783 (2019)

Figure 1
(Invited) Experimental Quantum Transport in Strain Engineered Graphene - Towards NOEMS
Authors: Champagne Alexandre R 
Published: May 2020

We measure ballistic charge conductivity in strained suspended graphene and observe the theoretically predicted [1] strain-induced scalar and vector potentials. To do so, we built an experimental platform for quantum transport strain engineering in 2D materials. This instrumentation permits low temperature (0.3 K- 70 K) transport in 0 to 9 Tesla magnetic fields. The tunable uniaxial strain (up to 3%) is completely decoupled from the gate-tunable charge density, permitting quantitative understanding of strain effects. We show slippage-free mechanical clamping of high aspect-ratio graphene crystals, where atomically ordered edges are unnecessary for quantitative straintronics. We study in detail transport in a ballistic graphene channel whose length is 90 nm and width is 600nm. By applying strain up to 0.6 % in this device, we observe that the strain-induced scalar potential shifts its low energy band structure downward by up to 30 meV. We show precise control of the gauge vector potential which reversibly suppresses the conductance by up to 14 %.
We conclude with a brief overview of other projects aimed at integrating both RF dynamic strain control and optically resonant cavities in suspended bilayer graphene devices to achieve fully tunable nano-opto-electro-mechanical (NOEMS) carbon systems. We report for instance a nitrocellulose-based dry-stamping method to manipulate and suspend individual 2D materials. Using this method we assembled optical cavities able to a widely tune light absorption in graphene. [1] A. C. McRae, G. Wei, and A. R. Champagne, Phys. Rev. Applied 11, 054019 (2019)

Figure 1
(Invited) Alteration of the Electrical Transport in Carbon Nanotube Network Field-Effect Transistors Using Polymer Encapsulants and Gate Dielectrics
Authors: Lapointe François 
Published: May 2020

Enriched semiconducting single-walled carbon nanotubes (SWCNTs) inks of high purity opens a wealth of possibilities for device fabrication using printing techniques and solution processes. [1] Logics, displays, sensors and large-scale integrated circuits [2] appear to be within reach. For those promises to concretize, a better control over parameters such as carrier type and mobility, operation power and device-to-device variability is needed. Beside the ambient effect (notably water and oxygen) on the transport of carbon nanotube network field-effect transistors (CNN-FETs), the nature of the surrounding materials (as a passivation layer or as a gate dielectric) appears to play a crucial role in determining the device’s characteristics.
Firstly, we have tested a large number of polymeric materials as the bottom gate in three-terminal CNN-FETs. We have found that the transport characteristics parameters such as the threshold voltage and the hysteresis are affected by the chemical nature of the polymer. [3] Subjecting those CNN-FETs with various gate dielectrics to a series of volatile analytes, we observed drastically different responses which suggests the usefulness of polymer gate dielectric variations in cross-reactive sensors arrays.
Secondly, polymeric materials were used as an encapsulant over bottom gate CNN-FETs. [4] A smooth and continuous variation of the threshold voltage has been achieved by using a series of poly(styrene–co–2-vinyl pyridine) copolymers with different monomer ratios. A surface charge density measurement methodology has been developed to rationalize the threshold voltage variations upon encapsulation with various polymers. Finally, we explored the use of n-doping molecules blended with polymer encapsulants as an efficient way to obtain n-type transport characteristics. This strategy is further used in the implementation of simple p-n junctions showing a modest rectification.

References

[1] Bati, A. S. R. et al. Recent Advances in Applications of Sorted Single‐Walled Carbon Nanotubes Adv. Funct. Mater.
29 1902273 (2019)
[2] Hills, G. et al. Modern Microprocessor Built from Complementary Carbon Nanotube Transistors. Nature

572
595–602 (2019)
[3] Lapointe, F. et al. Carbon Nanotube Transistors as Gas Sensors: Response Differentiation Using Polymer Gate Dielectrics. ACS Appl. Polym. Mater.
https://doi.org/10.1021/acsapm.9b00707 (2019) - Accepted for publication
[4] Lapointe, F. et al. Polymer Encapsulants for Threshold Voltage Control in Carbon Nanotube Transistors ACS Appl. Mater. Interfaces
11 36027-36034 (2019)