Current methods for the determination of the type and concentration of micro-organisms in the environment and food are slow and inefficient allowing no possibility of on-line process monitoring. The objective of this project is to demonstrate the feasibility of dielectrophoresis as a technique for the rapid on-line separation and detection of microorganisms (such as E. coli, coliforms and Salmonella) in real environmental and food systems. Dielectrophoretic cells will be designed using CAD and constructed using microfabrication techniques. Dielectrophoretic collection of selected microbial suspensions will be examined as a function of the field, frequency and electrode geometry and the complex permittivity and polarisability of the suspending medium and its microbial content. Work will focus initially on establishing characteristic dielectrophoretic behaviour and electrical parameters and the development of optical and/or dielectric techniques for non- invasive process control and identification of micro-organisms. It is possible that rapid pre-sample preparation (e.g. dilution or desalting) may be required for complex food matrices prior to collection and detection of the microorganisms. With food-borne (e.g. Salmonella and Listeria) and environmental (e.g. E. coli and Cryptosporidium) pathogens or indicator germs, manipulation of the cell surface and/or cellular ionic composition will be required in order to sufficiently enhance or reduce the dielectrophoretic characteristics to achieve separation of the desired pathogen. Based on the results, promising systems will be optimised and then applied to various environmental, food and beverage matrices. In particular, the dielectrophoretic cell design will be optimised for the application in mind.
Funding SchemeCSC - Cost-sharing contracts
KT22 7SA Leatherhead, Surrey