PhD and Postdoc openings

We employ microfabrication to create liquid-filled, nanometer-scale channels and chambers in which small numbers of molecules (and even single molecules) are detected and manipulated by electrical means. A key approach, so-called redox cycling, uses two electrodes embedded in a nanochannel. We bias the electrodes such that one electrode reduces (i.e. gives electrons to) the target molecules and the other oxidizes (i.e. strips electrons from) them. Molecules undergoing a diffusive random walk act as electron shuttles, ferrying electrons from the first electrode to the second. This leads to a measurable signal for even a single molecule, yielding the most sensitive electrochemical fluidic devices to date. We are looking for a Phd student to contribute to one or more aspects this research line. Possible projects include for example fundamental questions on reaction kinetics and ion transport in nanodevices, integrating an enzyme into the device to create a new biophysics technique, and combining redox cycling with optical detection.

Biosensors that rely solely on electrical detection are highly desirable for integration with electronics on the same chip, enabling new assays based on thousands – and potentially millions – of simultaneous stochastic measurements. An important bottleneck in realizing this vision has been the lack of a suitable transduction method for translating (bio)chemical information directly into electrical signals. Electrochemical Impedance Spectroscopy, which uses AC electrical signals to probe processes occurring at the surface of an electrode immersed in liquid, is ideally for this purpose, but stray capacitance largely prevents its use in miniaturized systems. This technical hurdle can be overcome by fabricating the electrodes directly unto a conventional microelectronics chip, yielding arrays of nanoelectrodes that can be operated at frequencies that are orders of magnitude higher than heretofore possible. This potentially revolutionary technology raises many interesting scientific questions, as it allows for the first time measuring the high-frequency response of complex fluids on the nanoscale. In this project, we will explore the physical mechanisms that underlie AC detection at nanoelectrodes. Our particular focus will be the response of individual nanoscale objects, with the ultimate aim of detecting and fingerprinting individual macromolecules solely by electrical means. This project will be carried out in close collaboration with semiconductor company NXP.