zur Hauptseite

Navigation und Service

Seminar: Klaus Mathwig (Twente)

28.01.2013 11:00 Uhr
Gebäude 2.4w, Seminarraum 309b

Seminar des PGI-8 / ICS-8:

Titel: Electrical Spectroscopy in Nanofluidic Channels

Sprecher: Klaus Mathwig (Nanoionics, MESA+ Institute of Technology, University of Twente)

Datum: 28. Januar 2013 Zeit: 11:00

Ort: Gebäude 2.4w, Seminarraum 309b

In nanofluidic thin layers cells, electroactive molecules undergo redox cycling in between two closely spaced (100 nm) electrodes. This leads to a high gain of the detected faradaic current and makes the most sensitive electrochemical detection possible; even single molecules can be detected in these nanogap sensors.

Due to the Brownian motion undergone by analyte molecules, their number fluctuates considerably in a nanoscale detection volume. These mesoscopic number fluctuations contain a multiplicity of microscopic information, which is explored by techniques such as fluorescence correlation spectroscopy. Here, we introduce the equivalent electrochemical cross-correlation spectroscopy.

Moreover, using an electrical flash-release, molecules can be accumulated or depleted locally in the nanochannel. By monitoring the transient equilibration, we can conduct electrochemical transient spectroscopy to study adsorptivity and diffusivity of molecules.

We demonstrate the utility of our methods by measuring ultra-low flow rates. Liquid flow is driven through a nanochannel and molecular number fluctuations (or a concentration plug) is transported along. By employing two consecutive sensors in a single nanochannel, we can then perform a time-of-flight measurement to detect record-low flow rates below 1 pL/min.

K. Mathwig., D. Mampallil, S. Kang, S. G. Lemay, Phys. Rev. Lett. 109, 118302 (2012).