Abstract

Dielectrophoresis-based Manipulation, Separation and Detection of Micro/Bio-particles

Kun Shyong Chow, Research Fellow, DHI-NTU

For the 3D paired microelectrode system, the pairs of electrode array are constructed face to face on top and bottom of the microchannel. Dielectrophoretic gates are generated by these top and bottom electrodes when AC voltage is applied. These gates serve the function in accumulating and separating different size of particles. The particle flowing in the microchannel will experience a hydrodynamic force and when it exceeds the negative DEP force produced by the gates, the particle will penetrate the gates. The threshold velocity of the particle is the minimum velocity required by the particle in order to penetrate the gates. Particle with different size possess different threshold velocity when the rest of the parameters stay constant. Hence separation can be achievable by selecting the appropriate flow rate in the microchannel. For the microfluidic combined with impedance system, it is basically a combination of dielectrophoresis method to trap the water pathogen and impedance measurement technique to achieve the detection of bacteria in a real time manner. Conventional microbiological method may require few days to analyse the existence of bacteria whereas the system proposed here is able to detect the presence of bacteria in just hours of time. The configuration of the microfluidic is relatively simple as compared to 3D paired microelectrode system. It consists of electrode array which traps the bacteria on the tip of electrode edge. DEP Bridge is formed when more and more bacterial pearl-chains are formed. This formation of DEP Bridge would vary the impedance signal. Different kind of pathogens has different threshold voltage, a minimum voltage required to form the DEP Bridge. Hence it provides the possibility to analyse the existence of different water pathogens in a real time manner by studying the impedance signal produced.