The resistive pulse sensing (RPS) method has been widely used for characterization of particles, cells, and biomolecules due to its merits of high sensitivity and resolution. This paper investigates working parameters involved in detecting submicron and micron-sized particles by the differential RPS method on microfluidic chips. Effects of particle-to-sensor size ratio, ionic concentration and pH of the electrolyte solution, and applied electric field are studied systematically by using polystyrene particles with a size range from 140 nm to 5 µm. The results show that both the amplitude and the signal-to-noise ratio (SNR) of the RPS signals increase with the particle-to-sensor size ratio as well as the ionic concentration of the electrolyte media. The amplitude of the RPS signals also increases with increasing applied voltage, while the SNR experiences an upslope at low voltages and a decline under the condition of high voltages. pH has little effect on the background noise of the differential RPS signals but reduces the amplitude of the RPS signals at high pH. Grouping of RPS signals is considered to be caused by interactions between the sensor walls and the particles. Nanoparticle detection by the differential RPS method can be enhanced by optimizing these working parameters.

电阻脉冲感测（RPS）方法具有高灵敏度和高分辨率的优点，已被广泛用于表征颗粒，细胞和生物分子。本文研究了通过微流体芯片上的差分RPS方法检测亚微米和微米大小的颗粒所涉及的工作参数。通过使用尺寸范围为140 nm至5 µm的聚苯乙烯颗粒，系统地研究了颗粒与传感器的尺寸比，电解质溶液的离子浓度和pH值以及施加的电场的影响。结果表明，RPS信号的幅度和信噪比（SNR）均随颗粒与传感器的尺寸比以及电解质介质的离子浓度而增加。RPS信号的幅度也随着施加电压的增加而增加，SNR在低电压下会上升，而在高电压下会下降。pH对差分RPS信号的背景噪声影响很小，但会降低高pH时RPS信号的幅度。RPS信号的分组被认为是由传感器壁和粒子之间的相互作用引起的。通过优化这些工作参数，可以增强通过差分RPS方法进行的纳米颗粒检测。