Tunable Resistive Pulse Sensing (TRPS) is a single-particle technique used to measure the size, concentration and zeta potential of particles as they pass through a size-tunable nanopore.

The technique adapts the principle of resistive pulse sensing, which monitors current flow through an aperture, combined with the use of tunable nanopore technology, allowing the passage of ionic current and particles to be regulated by adjusting the pore size.

Particles crossing a pore are detected one at a time as a transient change in the ionic current flow, which is denoted as a blockade event with its amplitude denoted as the blockade magnitude. As blockade magnitude is proportional to particle size, accurate particle sizing can be achieved after calibration with a known standard.

Nanopore-based detection allows particle-by-particle assessment of complex mixtures. Optimization of pore size to particle size, by adjusting the stretch of the pore, can improve measurement accuracy.

Through combination with fine-control of pressure TRPS has been used to determine sample concentration and to accurately derive particle electrophoretic mobility & surface charge in addition to particle size information. wikipedia