Dielectrophoresis–Raman spectroscopy system for analysing suspended nanoparticlesElectronic supplementary information (ESI) available: In depth DEP simulations, SEM images of particles, permittivity simulations and concentration discussions. See DOI: 10.1039/c0lc00481b

A microfluidic dielectrophoresis platform consisting of curved microelectrodes was developed and integrated with a Raman spectroscopy system. The electrodes were patterned on a quartz substrate, which has insignificant Raman response, and integrated with a microfluidic channel that was imprinted in poly-dimethylsiloxane (PDMS). We will show that this novel integrated system can be efficiently used for the determination of suspended particle types and the direct mapping of their spatial concentrations. We will also illustrate the system's unique advantages over conventional optical systems. Nanoparticles of tungsten trioxide (WO3) and polystyrene were used in the investigations, as they are Raman active and can be homogeneously suspended in water. [ABSTRACT FROM AUTHOR]