Research On The Detecting Mechanism Of The Micro-particles Resistive Pulse Sensing Technique

The Resistive Pulse Sensor (RPS) based on microfluidic chips has the advantages of simple device, fast detection, high sensitivity and low cost, which is favorable to the development of an instrument for the on-site detection of marine pollutants. With the diversification of the particle and the structure of the micro channel, the existing theories cannot explain some new experimental phenomena reasonably. In-depth study on these phenomena can not only improve the RPS theory, but also is important to expand the application of the technique.The thesis studied the effect of the conductive particle, the shape of the particle and the channel on RPS detection by experiment and Simulation. The specific contents are as follows:(1) Under the same conditions, the relationship between the magnitude of the RPS signal and the applied voltage was experimentally studied with 5μm polystyrene particles and 5μm magnetic beads (surface coating of Fe3O4) in a microfluidic chip. The experimental results show that the magnitude of RPS signal of the magnetic particles is larger than that of the polystyrene particle under the same measuring voltage. The mainly reason is the electric double layer on the surface of the magnetic beads becomes thicker under the electric field.(2) Under the same applied voltage, the magnitudes of the RPS signal were studied by numerical simulation with five kinds of ellipsoidal particles which have the same volume but different shapes in the same RPS detection channel. The simulation results show that the shape and orientation angle of the particle have great effect on the RPS detection. The magnitude of RPS signal generated by the ellipsoidal particles increases with the increasing of the ratio of the equatorial semiaxis to the polar semiaxis; the magnitude of RPS signal generated by the same prolate ellipsoidal particle increases with the increasing of the orientation angle of the prolate ellipsoidal particle; the magnitude of RPS signal generated by the same oblate ellipsoidal particle decreases with the increasing of the orientation angle of the oblate ellipsoidal particle.(3) Under the same applied voltage, the magnitudes of the RPS signal were studied by numerical simulation with the same spherical insulating particle in five kinds of RPS detection channels which have the same volume but different channel cross-sectional shapes. The simulation results show that the shape of the channel has great effect on the RPS detection. Under the same conditions, the magnitude of RPS signal generated by the same spherical insulating particle in different kinds of RPS detection channels increases with the increasing of the depth-width ratio of the detection channel.The study in this thesis enriches the theory of the RPS technique and has a certain reference value for widening the practical application of the technique.