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Accueil du site > Offres d’emploi > Stages > [Master 2] Ionic current measurements in individual alumina nanochannel : synthesis and development of an experimental cell

[Master 2] Ionic current measurements in individual alumina nanochannel : synthesis and development of an experimental cell

par Nicolas Jouault - 23 octobre

Internship period : 5 months

Encadrement : Nicolas Jouault (équipe MEM)

Description of the project

The confinement in nanoporous medium induces structural and dynamical changes of condensed matter compared to its “bulk” behavior that can be used to design materials or develop new nanofluidic devices with enhanced properties. In particular, the temporalfluctuations of ionic current in nanopores provide information about the nature of the interaction between ions and the nanopore walls and more generally about the origin of ionic transport properties at the nanoscale. Such study is important to optimize single molecule detection, nanosensorsor to better understand the unexpected ionic conductance behavior[1]or the observed increase of conductivity in carbon nanotubes[2]with potential applications in sensing[3], water desalination[4] and energy conversion[5]. To access these ionic current fluctuations at the nanoscale, typical experiments consist in measuring the current through individual nanopore, under a constant voltage, as a function of time (see Fig. 1). Then, the Fourier transform of the autocorrelation function of the ionic current gives the power spectral density (PSD), also called noise, whose analysis can be interpreted by ionic processes inside the single pore. In particular, the low-frequency regimeof the PSD shows anomalous behavior (in scaling or amplitude) whose origin is still under debate[1,6-8].Thus, we aim at better understanding the origin of these ionic current fluctuationsin confined mediaand we propose a progressive approach by studying ionic current fluctuations in a single alumina nanochannel (see Fig. 1, left image). To achieve it, the internship will be divided in different steps :

  1. Synthesis of alumina by anodization to obtain individual nanochannel[9]
  2. Design and optimization of an experimental cell to measure the ionic current through this individual nanochannel
  3. Perform a parametric study to investigate the influence of different experimental parameters (electrolyte concentration, voltage or nanochannel characteristic sizes) on the ionic fluctuations

Specific techniques or methods

Synthesis of nanoporous alumina by anodization, scanning electron microscopy, ionic current measurements

References

[1]E. Secchi, A. Niguès, L. Jubin, A. Siria, and L. Bocquet, Physical Review Letters 116, 154501 (2016).
[2]Q. Berrod et al., Nanoscale 8, 7845 (2016).
[3]C. C. Harrell, Y. Choi, L. P. Horne, L. A. Baker, Z. S. Siwy, and C. R. Martin, Langmuir 22, 10837 (2006).
[4]Y. Zhang and G. C. Schatz, The Journal of Physical Chemistry Letters 8, 2842 (2017).
[5]A. Siria, P. Poncharal, A.-L. Biance, R. Fulcrand, X. Blase, S. T. Purcell, and L. Bocquet, Nature 494, 455 (2013).
[6]R. M. M. Smeets, U. F. Keyser, N. H. Dekker, and C. Dekker, Proceedings of the National Academy of Sciences 105, 417 (2008).
[7]D. P. Hoogerheide,S. Garaj, and J. A. Golovchenko, Physical review letters 102, 256804 (2009).
[8]C. Tasserit, A. Koutsioubas, D. Lairez, G. Zalczer, and M. C. Clochard, Physical Review Letters 105, 260602 (2010).
[9]M. Lillo and D. Losic, Materials letters 63, 457 (2009).