Effect of induced surface charge of metal particles on particle sizing by resistive pulse sensing technique

Effect of induced surface charge of metal particles on particle sizing by Resistive Pulse Sensing (RPS) technique is reported in this paper. The relationship between the magnitude of the RPS signal and the applied voltage was experimentally studied with 5 μm polystyrene particles and 5 μm magnetic particles in a microfluidic chip. It is shown that the magnitude of RPS signal of the magnetic particles is larger than that of the polystyrene particle under the same measuring voltage. This may be understood by the induced thicker electrical double layer (EDL) around the magnetic particles. This effect is important and should be considered when sizing metal particles and other highly-polarizable particles by using the RPS technique.