Confinement-Controlled Water Engenders Unusually High Electrochemical Capacitance

S. Melnik; A. Ryzhov; A. Kiselev; A. Radenovic; T. Weil et al. 

The electrodynamicsof nanoconfined water have been shownto changedramatically compared to bulk water, opening room for safe electrochemicalsystems. We demonstrate a nanofluidic “water-only” batterythat exploits anomalously high electrolytic properties of pure waterat firm confinement. The device consists of a membrane electrode assemblyof carbon-based nanomaterials, forming continuously interconnectedwater-filled nanochannels between the separator and electrodes. Theefficiency of the cell in the 1-100 nm pore size range showsa maximum energy density at 3 nm, challenging the region of the currentmetal-ion batteries. Our results establish the electrodynamic fundamentalsof nanoconfined water and pave the way for low-cost and inherentlysafe energy storage solutions that are much needed in the renewableenergy sector.

Selective Growth of van der Waals Heterostructures Enabled by Electron-Beam Irradiation

J. Sitek; K. Czerniak-Losiewicz; A. P. Gertych; M. Giza; P. Dabrowski et al. 

Van der Waals heterostructures (vdWHSs) enable the fabricationof complex electronic devices based on two-dimensional (2D) materials.Ideally, these vdWHSs should be fabricated in a scalable and repeatableway and only in the specific areas of the substrate to lower the numberof technological operations inducing defects and impurities. Here,we present a method of selective fabrication of vdWHSs via chemicalvapor deposition by electron-beam (EB) irradiation. We distinguishtwo growth modes: positive (2D materials nucleate on the irradiatedregions) on graphene and tungsten disulfide (WS2) substrates,and negative (2D materials do not nucleate on the irradiated regions)on the graphene substrate. The growth mode is controlled by limitingthe air exposure of the irradiated substrate and the time betweenirradiation and growth. We conducted Raman mapping, Kelvin-probe forcemicroscopy, X-ray photoelectron spectroscopy, and density-functionaltheory modeling studies to investigate the selective growth mechanism.We conclude that the selective growth is explained by the competitionof three effects: EB-induced defects, adsorption of carbon species,and electrostatic interaction. The method here is a critical steptoward the industry-scale fabrication of 2D-materials-based devices.

Nature-Inspired Stalactite Nanopores for Biosensing and Energy Harvesting

A. Chernev; Y. Teng; M. Thakur; V. Boureau; L. Navratilova et al. 

Nature provides a wide range of self-assembled structures from the nanoscale to the macroscale. Under the right thermodynamic conditions and with the appropriate material supply, structures like stalactites, icicles, and corals can grow. However, the natural growth process is time-consuming. This work demonstrates a fast, nature-inspired method for growing stalactite nanopores using heterogeneous atomic deposition of hafnium dioxide at the orifice of templated silicon nitride apertures. The stalactite nanostructures combine the benefits of reduced sensing region typically for 2-dimensional material nanopores with the asymmetric geometry of capillaries, resulting in ionic selectivity, stability, and scalability. The proposed growing method provides an adaptable nanopore platform for basic and applied nanofluidic research, including biosensing, energy science, and filtration technologies.

Spatially multiplexed single-molecule translocations through a nanopore at controlled speeds

S. M. Leitao; V. Navikas; H. Miljkovic; B. Drake; S. Marion et al. 

In current nanopore-based label-free single-molecule sensing technologies, stochastic processes influence the selection of translocating molecule, translocation rate and translocation velocity. As a result, single-molecule translocations are challenging to control both spatially and temporally. Here we present a method using a glass nanopore mounted on a three-dimensional nanopositioner to spatially select molecules, deterministically tethered on a glass surface, for controlled translocations. By controlling the distance between the nanopore and glass surface, we can actively select the region of interest on the molecule and scan it a controlled number of times and at a controlled velocity. Decreasing the velocity and averaging thousands of consecutive readings of the same molecule increases the signal-to-noise ratio by two orders of magnitude compared with free translocations. We demonstrate the method’s versatility by assessing DNA-protein complexes, DNA rulers and DNA gaps, achieving down to single-nucleotide gap detection. In single-molecule characterization, the near-infinite re-read capability on the same region of interest has the potential to unlock greater sensing capacity. A nanopore-based method, named scanning ion conductance spectroscopy, provides complete control over the translocation speed and nanopore position along a selected region and can detect a single 3 angstrom gap in a long strand of DNA.

Nanoscale thermal control of a single living cell enabled by diamond heater-thermometer

A. M. Romshin; V. Zeeb; E. Glushkov; A. Radenovic; A. G. Sinogeikin et al. 

We report a new approach to controllable thermal stimulation of a single living cell and its compartments. The technique is based on the use of a single polycrystalline diamond particle containing silicon-vacancy (SiV) color centers. Due to the presence of amorphous carbon at its intercrystalline boundaries, such a particle is an efficient light absorber and becomes a local heat source when illuminated by a laser. Furthermore, the temperature of such a local heater is tracked by the spectral shift of the zero-phonon line of SiV centers. Thus, the diamond particle acts simultaneously as a heater and a thermometer. In the current work, we demonstrate the ability of such a Diamond Heater-Thermometer (DHT) to locally alter the temperature, one of the numerous parameters that play a decisive role for the living organisms at the nanoscale. In particular, we show that the local heating of 11-12 degrees C relative to the ambient temperature (22 degrees C) next to individual HeLa cells and neurons, isolated from the mouse hippocampus, leads to a change in the intracellular distribution of the concentration of free calcium ions. For individual HeLa cells, a long-term (about 30 s) increase in the integral intensity of Fluo-4 NW fluorescence by about three times is observed, which characterizes an increase in the [Ca2+](cyt) concentration of free calcium in the cytoplasm. Heating near mouse hippocampal neurons also caused a calcium surge-an increase in the intensity of Fluo-4 NW fluorescence by 30% and a duration of similar to 0.4 ms.

The Three-Phase Contact Potential Difference Modulates the Water Surface Charge

V. Artemov; L. Frank; R. Doronin; P. Staerk; A. Schlaich et al. 

The surface charge of an open water surface is crucialfor solvationphenomena and interfacial processes in aqueous systems. However, themagnitude of the charge is controversial, and the physical mechanismof charging remains incompletely understood. Here we identify a previouslyoverlooked physical mechanism determining the surface charge of water.Using accurate charge measurements of water microdrops, we demonstratethat the water surface charge originates from the electrostatic effectsin the contact line vicinity of three phases, one of which is water.Our experiments, theory, and simulations provide evidence that a junctionof two aqueous interfaces (e.g., liquid-solid and liquid-air)develops a pH-dependent contact potential difference Delta phi due to the longitudinal charge redistribution between two contactinginterfaces. This universal static charging mechanism may have implicationsfor the origin of electrical potentials in biological, nanofluidic,and electrochemical systems and helps to predict and control the surfacecharge of water in various experimental environments.

The Three-Phase Contact Potential Difference Modulates the Water Surface Charge

V. Artemov; L. Frank; R. Doronin; P. Staerk; A. Schlaich et al. 

The surface charge of an open water surface is crucialfor solvationphenomena and interfacial processes in aqueous systems. However, themagnitude of the charge is controversial, and the physical mechanismof charging remains incompletely understood. Here we identify a previouslyoverlooked physical mechanism determining the surface charge of water.Using accurate charge measurements of water microdrops, we demonstratethat the water surface charge originates from the electrostatic effectsin the contact line vicinity of three phases, one of which is water.Our experiments, theory, and simulations provide evidence that a junctionof two aqueous interfaces (e.g., liquid-solid and liquid-air)develops a pH-dependent contact potential difference Delta phi due to the longitudinal charge redistribution between two contactinginterfaces. This universal static charging mechanism may have implicationsfor the origin of electrical potentials in biological, nanofluidic,and electrochemical systems and helps to predict and control the surfacecharge of water in various experimental environments.

Optical imaging of the small intestine immune compartment across scales

A. L. Planchette; C. Schmidt; O. Burri; M. G. de Agueero; A. Radenovic et al. 

A workflow for 3D characterization of the mouse small intestine with optical projection tomography allows the identification of sparsely-distributed regions of interest in large volumes while retaining compatibility with high-resolution microscopy modalities.

High durability and stability of 2D nanofluidic devices for long-term single-molecule sensing

M. Thakur; N. Cai; M. Zhang; Y. Teng; A. Chernev et al. 

Nanopores in two-dimensional (2D) membranes hold immense potential in single-molecule sensing, osmotic power generation, and information storage. Recent advances in 2D nanopores, especially on single-layer MoS2, focus on the scalable growth and manufacturing of nanopore devices. However, there still remains a bottleneck in controlling the nanopore stability in atomically thin membranes. Here, we evaluate the major factors responsible for the instability of the monolayer MoS2 nanopores. We identify chemical oxidation and delamination of monolayers from their underlying substrates as the major reasons for the instability of MoS2 nanopores. Surface modification of the substrate and reducing the oxygen from the measurement solution improves nanopore stability and dramatically increases their shelf-life. Understanding nanopore growth and stability can provide insights into controlling the pore size, shape and can enable long-term measurements with a high signal-to-noise ratio and engineering durable nanopore devices.

Defect engineering of 2D material for biosensing applications

W. Yang; J. Sulzle; Y. Shimoda; E. Mayner; M. Macha et al.