Contact: Casper Hyttel Clausen, cahu@nanotech.dtu.dk
Introduction: Detection and identification of bacteria in real-time is a task with great commercial potential and something that has not yet been solved in industry. Today, identification and numeration of a single bacteria sample often requires several days of tedious work. This project focuses on performing detection of bacteria in real-time using a unique new biosensor. The biosensor uses a label-free technology that can provide instantaneous results on the sample contents.
Goal: The aim of this project is to differentiate gram positive and gram negative bacteria strains by multi-frequency electrical impedance spectroscopy (MEIS). As opposed to current bacteria measurement methods today, MEIS is a continuous and real-time detection method, which applies a mix of several frequencies to a set of electrodes and uses a lock-in amplifier for readout. The experiment will be carried out using an already built setup, which incorporates a microfluidic chip as detection area. The data readout from MEIS will give information about the bacteria structural composition, and hence their type. For the experiments two types of bacteria will be used: Enterobacter aerogenes (gram negative) and Bacillus cereus (gram positive).
Project plan: The students will during this project learn to operate the MEIS system as well as basic biology routine needed for the measurements of the bacteria. Furthermore, Maxwell mixture theory (MMT) will be applied in order to interpret the obtained data. The first part of the project will focus on familiarization with the system and its operation procedure. In the second part the student will learn to handle bacteria samples as well as perform the measurements with the two types of bacteria. Last the student will apply MMT in order to understand the obtain data with respect to bacteria structure.
Figure: Phase shift at 7 MHz plotted against the low frequency signal of bacteria and polystyrene beads in drinking water.