The Bioelectronics group currently has openings for Master and Bachelor projects in the area of electrochemical nanofluidics and single-entitiy electrochemistry. In this research, we employ microfabrication to create liquid-filled, nanometer-scale channels and electrodes with which small numbers of molecules (and even single molecules) are detected and manipulated by electrical means. This enables both fundamental experiments on the physics and chemistry of ionic systems on the nanometer scale, and allows us to explore the ultimate limits of electrochemical detection for (bio)sensor applications.
Our research is interdisciplinary and we welcome students from all study programs with an interest in our topics. Do keep in mind, however, that much of our work includes a significant component of physics and/or physical chemistry, being at the interface between the physics of fluids, electrochemistry and condensed matter.
Below are a number of specific projects that are currently available. This list can fluctuate quickly, however: this is exploratory research and surprises do happen! To further explore possibilities, please contact Prof. Serge Lemay (email@example.com) for an appointment.
AC transport properties of single conducting polymers
We are exploring a new electronic transduction mechanism for biosensing based on the detection of conducting polymers that are freely diffusing in solution. Conducting polymers are materials of great interest in printable electronics, solar cells and OLEDs, but their use in sensors is in its infancy. Here we employ pairs of electrodes separated by about 10 nm to probe the electronic transport properties of single polymer chains. Each molecule works as a nanoscopic telegraph, effectively closing a switch every time that it touches both electrodes simultaneously. Our work so far has focused solely on measuring the DC transport properties of the molecules, but physical arguments suggest that measuring AC currents instead should improve the signal-to-noise ratio of our detectors. In this project, we will use lock-in detection to probe this hypothesis experimentally. This combines precision electronic measurements and understanding the physics of nanoscale field-effect transistors.
SIMULATIONS OF SINGLE CONDUCTING POLYMER TRANSISTORS
Our recent experiments electrically probe the internal fluctuations of the configuration of a single polymer chain. As the polymer explores its configurational space, it causes intermittent contacts between two electrodes, which we detect as jumps in the electrical current passing through the molecule. Equilibrium simulations seem to match the distributions that we observe rather well, but we want to go further and compare the observed dynamics with theoretical expectations. Specifically, we will perform molecular dynamic simulations of a single, long polymer chain and relate the resulting conformations to our experimental results. This project will be jointly supervised by Prof. Peter Bobbert from the NanoElectronics group and TU Eindhoven.
Current blockade electrochemical sensors
In current blockade sensors, single micro- or nanosized particles are detected when they interfere with an electrochemical reaction taking place at an electrode (basically the particles get in the way of molecules trying to diffuse to the electrode). A drawback of this method, however, is that particles give a different response depending on whether they hit the electrode near the edge or near its center, greatly limiting the ability to differentiate between different types of particles. In this project we will attempt to overcome this limitation by developing electrodes in the form of thin (nanoscale) disks. The project will involve the microfabrication of prototype electrodes in the NanoLab cleanroom and assessing their performance in current blockade experiments.
Scattering microscopy for probing charge injection in liquid
Scattering microscopy is an emerging optical technique in nanoscience in which the ability of modern CCD cameras to detect minute changes in light intensity is used to probe microscopic phenomena. In this project, we aim to probe the physics of what happens when charge is injected into a liquid via a microscale electrode. This process couples fluid mechanics with electrochemistry, a largely unexplored area. The project will include learning scattering microscopy in the group of Dr. Sanli Faez at Utrecht University, assembling a new microscope in our own laboratory, and performing charge injection experiments on microelectrodes.