Conductive and biphasic pulses in tunable resistive pulse sensing

Area of Science:

• Colloid and surface science
• Nanoparticle characterization
• Electrochemistry

Background:

• Tunable resistive pulse sensing (TRPS) is a technique for single-particle analysis.
• TRPS typically generates resistive pulses as particles translocate through a pore.
• Conductive and biphasic pulses can occur under specific experimental conditions.

Purpose of the Study:

• To investigate the occurrence and characteristics of biphasic pulses in TRPS.
• To determine the influence of experimental variables on biphasic pulse generation.
• To provide fundamental understanding for the application of TRPS.

Main Methods:

• Experimental study using tunable resistive pulse sensing (TRPS).
• Analysis of 200 nm carboxylate polystyrene spheres.
• Systematic variation of electrolyte concentration, particle charge, pore size, applied voltage, and particle motion direction.

Main Results:

• Biphasic pulses were observed in TRPS under specific conditions.
• The onset upper electrolyte concentration for biphasic pulses was determined to be approximately 50 mM.
• The observed pulse components can be explained by ionic concentration polarization phenomena.

Conclusions:

• Biphasic pulses in TRPS are influenced by electrolyte concentration and particle properties.
• Understanding biphasic pulse formation enhances the interpretation of TRPS data.
• The findings contribute to the broader application of TRPS for submicron colloid characterization.