Ion Transport Through Nanopores: From Living Cells to Diodes and Transistors


Department of Chemical Engineering and Materials Science

Featuring Zuzanna S. Siwy, Ph.D.
Assistant Professor
Department of Physics and Astronomy
UC Irvine

Location: Engineering Lecture Hall 110
Free and open to the public.
Light refreshments served following the event.

Abstract:
Transport through nanopores and ion channels exists in virtually all biological cells and is important in such things as the regulation of heart function, nerve signals, and delivery of nutrients to the cell. Nanopores have also started to play a major role in contemporary biotechnology, because many separation and sensing processes require pores with nanometer-sized openings.


Siwy’s scientific interests have been focused on fabricating synthetic single nanopores with applications in biophysics and nanotechnology.  The nanopores that we fabricate by the track-etching technique have diameters as small as one nanometer, and they have controlled geometry and surface chemistry. Siwy will show application of these nanopores as (i) models of biological channels and (ii) devices for controlling the flow of ions and charged molecules in a solution e.g. ionic diodes and transistors. Focus will be placed on the results of fabrication of an ionic diode. The diode is based on a single asymmetric nanopore whose surface is patterned so that a sharp boundary between positively and negatively charged regions is created. This boundary defines a zone that is enriched with positive and negative ions or creates a depletion zone. The principle of operation of the nanofluidic diode is analogous to that of a bipolar semiconductor diode. The nanofluidic diodes rectify ion current with degrees of rectification reaching several hundreds at voltage range (-5V, +5V).


1. Vlassiouk, I.; Siwy, Z. Nanofluidic diode. Nano Letters 7, 552-556 (2007).
2. Siwy, Z. Ion Current Rectification in Nanopores and Nanotubes with Broken Symmetry – Revisited, Advanced Functional Materials 16, 735-746 (2006).

About the Speaker:


Prof. Siwy was awarded the Habilitation in Chemical Physics by the Polish National Committee of Science in July 2004 on the basis of research achievements and the dissertation, “Studies on preparation, structure and transport properties of nanopores in polymer membranes.”  She received her Ph.D. from the Silesian University of Technology, Gliwice.