Nanofluidics

The team is recognized in the field of nanohydrodynamics and electrokinetics for having developed experimental tools that allow to probe the dynamics of fluids at the nanoscale. Among them, nanorheology is probed by SFA and AFM, and very small flow rates (fL/s) have been recently measured via Coulter counting or confocal microscopy (dye profile analysis). With these tools, we explore fluid transport in single nanopores, nanotubes or nanochannels obtained from nano-fabrication techniques or more complex self-assembled structures such as soap films.  

One goal is to investigate the unexpected properties that emerge at the nanoscale and to focus on the particular liquid/surface interaction on the flow properties. Recent projects involve flow probes coupled to static surface characterization in collaboration with ONLI team for example.
 
Applications of these studies are numerous in material science engineering and energy recovery processes.
 
 

  

 

Members:

Biance, Anne-Laure
Cottin-Bizonne, Cécile
Detcheverry, François
Fulcrand, Rémy
Ybert, Christophe 

Highlights

 

Measuring flow rate with a Coulter counter

The authors designed a technique to measure extremely small flow rates, of the order of a few femto-liters per second. They used the famous Coulter counter technique (1953), aiming at detecting electrically a probe (here a nanobead) blocking partially an orifice. By counting the number of beads going through the pore per second and the dwell time of each bead inside the hole, a hydrodynamic permeability can be measured.

Ultra-sensitive flow measurement in individual nanopores...., Gadaleta et al. Nanoscale  (2015).

 

 

Mechanism of Coulter counting: each bead passing through the pore induces a drop in the current.

 

Osmosis with out a rejecting membrane

Osmosis -a liquid flow or a pressure difference induced by concentration differences- is a key phenomenon in cell exchanges, plant mechanics food processing or water desalination. While the usual view of osmosis requires a semi-permeable membrane, we report for the first time an osmotic flow generated without selective channels. The  flow in a single nanochannel, could be evidenced using a fluorescence imaging technique with unprecedented resolution. This work could open  new ways of manipulating flow at the nanoscale

Osmotic flow through fully permeable nanochannels, Lee et al. Phys. Rev. Lett. (2014).

 

Flow induced by a concentration gradient in a single non-selective nano-canal. Flow rates are measured through fluorescence microscopy with a resolution of 50fL/min !

 

Anomalous electro-osmosis in foam films

Electro-osmosis is the flow of liquid induced by an eletric field in the vicinity of a charged interface. In this work, using molecular dynamics simulations, we study this phenomenon at a liquid/air interface covered with charged surfactant molecules, a situation commonly encountered in soap film or foams. In contrast with the traditional case of liquid-solid interface, we find that electro-osmosis remains very efficient, even when there is only a few surfactant molecules.

Anomalous zeta potential in foam films, L. Joly et al., Phys. Rev. Lett. (2014).

 

(a) Snapshot of a typical simulated system water molecules are not represented. (b)-(c) Sketches of electro-osmosis and streaming current numerical experiments in foam film

 

Conductance of an array of nanopores

We study ionic transport through a regular array of nanopores. Numerous applications use this device, from the sensing of biological molecules to desalination. We show that due to long-range interactions between pores, the conductance is not extensive, with a sub-additive growth with the number of pores. This counter-intuitive behaviour sheds a light on other transport phenomena obeying laplace equations.

Sub-additive ionic transport in arrays of solid-state nanopores, Gadaleta et al., Phys. of Fluids (2014).

 

(Left) computed stream lines of the electric field around two nanopores. Their deformation is due to electrostatic interactions. (Right)  experimental normalized conductance as a function of the number of pores, for a square lattice of nanopores.

 

FIB for nanofluidics

he focused ion beam technique has clearly found its place among the more commonly used photo and electron beam lithography as a tool for researchers in the field of nanofluidic. The versatility of this method gives the opportunity to the researchers to create an infinite variety of shapes in the nanoscale range. We hope that we can demonstrate that FIB is and will continue to be among the fabrication techniques in a nanofluidics researcher’s “toolbox”.

FIB design for nanofluidic applications, Fulcrand et al., Springer, book chapter (2013).

 

(a) Nanopores array etching in a thin silicon nitride membrane (50nm) by using FIB. (b) ILM logo etched on a silicon substrate.

 

 

More highlights

      

Scroll To Top