Electrochemical nanofluidic devices have been introduced at 2008 []. These tiny devices feature two planar microelectrodes (~ 5-10 µm) separated by a thin layer of fluid (with a desired thickness, less than 300 nm) was fabricated on a chip. The fabrication of these channels involves photolithographic patterning in a way that the nanofluidic device is encapsulated in silicon dioxide with two access holes. Access holes are created to reach the metal and etching solution is introduced to remove the metal, leaving behind a nanoscale cavity.  Redox active molecules can freely diffuse in and out of the channel and undergo electrochemical redox cycling at both suitably biased potentials. Since these molecules are capable of repetitively undergoing oxidation and reduction, each molecule can transfer, on average, thousands of electrons by repeatedly traveling between the electrodes before escaping back out into the bulk. This leads to a corresponding boost in sensitivity and selectivity. This design offer experimentalists many potential applications in designing new sensors with the option of integration on a chip. The substantial current amplifications provide researchers the opportunity to access lower detection limits. The devices are so far operated under conditions of diffusion controlled mass transport.

Here, we examine the electrochemical response of a nanofluidic device placed inside a rectangular microfluidic cell. Solution was pumped to the cell under laminar flow conditions.  In this arrangement, we expect that the material is brought to the device via both diffusion and convection in a microchannel. However, we show that the mass transfer inside nanofluidic device is not affected by the rate of flow in the microchannel. We validate our experimental data with those obtained theoretically with COMSOL multiphysics.

[1]  B. Wolfrum, M. A. G. Zevenbergen and S. G. Lemay, Analytical Chemistry 80, 972 – 977 (2008).

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/24935 must be provided.

1. Electrochemical Nanofluidic Biosensors
2. Ion Association Effects in Cellulose – Poly-(Diallyldimethylammonium) Reassembled Membranes Immersed in Acetonitrile
3. Electrochemical behaviour of carbonised cellulose nanofibril films on the ITO electrode surface