Research

The physics of ions in liquid are directly relevant to a surprisingly wide array of research areas of current scientific and societal interest. These include nanoscience (the ‘natural’ length scale for ions), energy (fuel cells, supercapacitors), neuroscience (signal transduction, new experimental tools), and health and environment monitoring (new and better sensors).

Our research is currently divided into two main lines:

Fundamentals of ionic screening: Screening by mobile ions dominates electrostatics in water (and, in particular, under biologically relevant conditions), yet the underlying physics remain largely unexplored. Experimentally, the main challenge lies in the extremely short length scales involved: typical screening and interparticle distances are of the order of a few nanometers. We harness recent advances in the fabrication of nanostructures and the manipulation of single molecules to probe ions in solution on their natural microscopic scale.

Representative publications:

Origin of the Electrophoretic Force on DNA in Solid-State Nanopores

van Dorp et al., Nature Physics 5, 347 (2009).

Charge noise in liquid-gated single-layer and bilayer graphene transistors

Heller et al., Nano Letters 10, 1563–1567 (2010).

Charge inversion accompanies DNA condensation by multivalent ions

Besteman et al., Nature Physics 3, 641 – 644 (2007).

Electrochemical nanofluidics: We employ micro/nanofabrication to create liquid-filled, nanometer-scale channels and chambers in which small amounts of molecules (and even single molecules) are detected and manipulated using electrical signals. Our devices count among the most sensitive electrochemical sensors built to date.

Representative publications:

Electrochemical Correlation Spectroscopy in nanofluidic cavities

Zevenbergen et al., Analytical Chemistry 81, 8203 (2009).

Fast electron-transfer kinetics probed in nanofluidic channels
Zevenbergen et al., J. Am. Chem. Soc. 131, 11471 (2009).