Mark A. Reed
Yale University
Title: Nanofluidic Ionic Devices
Abstract:
Solid-state
nanofluidic devices have proven to be ideal systems for studying the physics of
ionic transport at the nanometer length scale. When the geometrical confining
size of fluids approaches the ionic Debye screening length, a number of new
transport phenomena occur, which have wide ranging implications to diverse
areas such as biological ion channels, desalination, and energy storage and
conversion. We have demonstrated a variety of nanofluidic ionic devices which
utilize controllable ion selectivity, allowing us to realize ionic diodes and
field effect transistors.1 These devices have remarkable analogies
to their semiconductor counterparts, but with some important differences.
One of the most intriguing implications
of nanofluidic ionics is the ability to construct artificial ion channels. We have demonstrated2 that we can
create membrane potentials similar to cellular systems, with the additional
ability to tune the ion selectivity ratio. The detailed dynamics of the
transport allows us to identify relevant relaxation times and mechanisms, which
could enable engineering of faster ionic and neural systems.
The study of nanofluidic ionic systems
has primarily used monovalent ion systems.
However, divalent ions comprise some of the most important ion channels
in biological systems. We have
investigated divalent nanofluidic ion transport, and have observed charge
inversion at the channel/fluid interface.3 The observation of charge
inversion has important implications to the theory of a strongly correlated
liquid (SCL) and biological permselectivity.