erc logomicrmega

Micromégas project
Nanofluidic transport in individual nanotubes

This challenging (and long-term) project aims at studying fundamentally water and ion transport at the nanoscales. This project is supported by an ERC advanced grant.

General context:
New paradigms for fluid transport are expected to emerge from the confinement of liquids at the nanoscales, which is the domain of nanofluidics, with potential breakthroughs in ultrafiltration, desalination, and energy harvesting. Nevertheless, advancing the fundamental understanding of fluid transport at the smallest scales requires mass and ion dynamics to be ultimately characterized across an individual channel so to avoid averaging over many pores.

Fluidic transport in nanotubes:
To this aim, we have developped a trans-membrane nanofluidic plateform, made of an individual nanotube that transpierces a thin membrane. Such a transmembrane geometry allows the versatile exploration of fluidic transport through a single nanotube, which we currently explore. Using this plateform, we have been able to measure transport inside a single nanotube under electric fields, pressure drops or osmotic gradients, as well as combinations of these.

Our first results demonstrate a huge osmotic energy conversion through a Boron-Nitride nanotube (Siria et al., Nature, 2013). This result demonstrate the huge potential interest of BN membranes in the context of osmotic energy harvesting, using salinity gradients as a source of energy, see below.

Soft nanofluidics:
We have also explored fluidic transport in 100nm thick soap films, as alternative versatile fluidic systems with nanometric scales. The nanometric confinement is here ensured by capillarity and electrostatic repulsion between the charged surfactants layers. An interesting outcome is the interplay between ion transport and deformabiliy of the nanochannel, which leads to a thickening of the film under electric field (Bonhomme, Biance et al., Phys. Rev. Lett., 2013).

Theory and modelization:
In parallel we are conducting theoretical studies and numerical modelisation to explore and understand new transport phenomena occuring at nanometric scales.

In particular we have demonstrated the superlubricity of carbon nanotubes for water, via a (quite unexpected) curvature-induced incommensurability mechanism (Falk et al., Nanoletters 2010, Langmuir 2012). We have also explore the impact of hydrodynamic fluctuations in nanoscale transport, showing a supplementary diffusive like behavior boosting transport (Detcheverry-Bocquet, Phys. Rev. Lett. 2012). We are now exploring novel fluidic functionalities which are made possible at the nanoscales. This involves in particular osmotic diodes, allowing for osmotic flow rectification and in fine desalination (Picallo et al., Phys. Rev. Lett., 2013).

Passing through the eye of the needle
nanomanipulation 2
(A. Siria et al., Nature 2013)
MD simulations of water transport in CNT


Sketch of water transport through single nanotubes
(Falk et al. Nanoletters, 2010)

Soap film

Nanofluidic transport inside a cylindrical, 100nm thick, soap film
(Bonhomme, Biance et al. PRL 2013)

Renewable energy: Nanotubes to channel osmotic power

(CNRS press release)

The salinity difference between fresh water and salt water could be a source of renewable energy. However, power yields from existing techniques are not high enough to make them viable. A solution to this problem may now have been found. A team led by physicists at the Institut Lumière Matière in Lyon (CNRS / Université Claude Bernard Lyon 1), in collaboration with the Institut Néel (CNRS), has discovered a new means of harnessing this energy: osmotic flow through boron nitride nanotubes generates huge electric currents, with 1,000 times the efficiency of any previous system. To achieve this result, the researchers developed a highly novel experimental device that enabled them, for the first time, to study osmotic fluid transport through a single nanotube. Their findings are published in the 28 February issue of Nature.

When a reservoir of salt water is brought into contact with a reservoir of fresh water through a special kind of semipermeable membrane, the resulting osmotic phenomena make it possible to produce electricity from the salinity gradients. This can be done in two different ways: either the osmotic pressure differential between the two reservoirs can drive a turbine, or a membrane that only passes ions can be used to produce an electric current.

Concentrated at the mouths of rivers, the Earth's osmotic energy potential has a theoretical capacity of at least 1 terawatt - the equivalent of 1,000 nuclear reactors. However, the technologies available for harnessing this energy are relatively inefficient, producing only about 3 watts per square meter of membrane. Today, a team of physicists at the Institut Lumière Matière in Lyon (CNRS / Université Claude Bernard Lyon 1), in collaboration with the Institut Néel (CNRS), may have found a solution to overcome this obstacle.

Their primary goal was to study the dynamics of fluids confined in nanometric spaces, such as nanotubes. Drawing inspiration from biology and cell channel research, they achieved a world first in measuring the osmotic flow through a single nanotube. Their experimental device consisted of an impermeable and electrically insulating membrane pierced by a single hole through which the researchers, using the tip of a scanning tunneling microscope, inserted a boron nitride nanotube with an external diameter of a few dozen nanometers. Two electrodes immersed in the fluid on either side of the nanotube enabled them to measure the electric current passing through the membrane..

Using this membrane to separate a salt water reservoir and a fresh water reservoir, the team was able to generate a massive electric current through the nanotube, induced by the strong negative surface charge characteristic of boron nitride nanotubes, which attracts the cations contained in the salt water. The intensity of the current passing through the nanotube was on the order of the nanoampere, more than 1,000 times the yield of the other known techniques for retrieving osmotic energy.

Boron nitride nanotubes thus provide an extremely efficient solution for converting the energy of salinity gradients into immediately usable electrical power. Extrapolating these results to a larger scale, a 1-m2 boron nitride nanotube membrane should have a capacity of about 4 kW and be capable of generating up to 30 megawatt-hours (1) per year. This performance is three orders of magnitude greater than that of the prototype osmotic power plants currently in operation. The next step for the researchers in the project will be to study the production of membranes made of boron nitride nanotubes and test the performances of nanotubes made from other materials.

This project was made possible largely through the support of the ERC and ANR.

(1) One watt-hour corresponds to the energy consumed or delivered by a system with a power of 1 watt for one hour.

Publications within the ERC Micromega project

«Nanofluidic osmotic diodes»,
C. Picallo, S. Gravelle, L. Joly, E. Charlaix and L. Bocquet,
Phys. Rev. Lett. 111 244501 (2013)

- «Optimizing water permeability through the hourglass shape of aquaporins »,
S. Gravelle, L. Joly, F. Detcheverry, C. Ybert, C. Cottin and L. Bocquet, Proc. Nat. Acad. Sci. USA 110 16367 (2013)

« FIB design for nanofluidic applications»,
R. Fulcrand, N.P. Blanchard, A.-L. Biance, A. Siria, P. Poncharal, L. Bocquet,
in  "Lecture Notes on Nanoscale Science and Technology", Springer (in press, 2013)

« Giant energy conversion measured in a single transmembrane boron-nitride nanotube»,
A. Siria, P. Poncharal, A.-L. Biance, R. Fulcrand, X. Blase, S. Purcell, L. Bocquet, Nature 494 455-458 (2013)
; press release

« Soft nanofluidic transport in a soap film »,
O. Bonhomme, O. Liot, A.-L. Biance, and L. Bocquet, Phys. Rev. Lett. 110 054102 (2013) Physics Focus & Science Mag

« Large apparent electric size of solid-state nanopores due to spatially extended surface conduction»,
C.Y. Lee, L. Joly, A. Siria, A.-L. Biance, R. Fulcrand, L. Bocquet, NanoLetters 12, 4037-4044 (2012)

« Ultra-low liquid/solid friction in carbon nanotubes: comprehensive theory for alcohols, alkanes, OMCTS and water»,
K. Falk, F. Sedlmeier, L. Joly, R. R. Netz and L. Bocquet, Langmuir 28 14261-14272 (2012)

« Thermal fluctuations in nanofluidic transport »,
F. Detcheverry and L. Bocquet,  Phys. Rev. Lett. 109, 024501 (2012)

« Nanofluidics, from bulk to interfaces»,
L. Bocquet
, E. Charlaix, Chemical Society Reviews  39, 1073 - 1095 (2010) 

« Molecular origin of fast water transport in carbon nanotube membranes»,
K. Falk, F. Sedlmeier, L. Joly, R. R. Netz andL. Bocquet  NanoLetters 10, 4067 (2010)