Tunable Resistive Pulse Sensing: Better Size and Charge Measurements for Submicrometer Colloids.

Tunable resistive pulse sensing (TRPS) uses the Coulter principle to detect, measure, and analyze particles at length scales ranging from tens of nanometers through to micrometers. The technology and its associated methods have advanced so that TRPS is regularly used as a characterization technique in peer-reviewed studies. This Perspective is concerned with opportunities to further develop TRPS, with a specific focus on improved measurement of size and charge for submicrometer particles. There is currently broad demand for increased rigor in such measurements. Particular points of interest include consistent use of statistics, development of accurate physical models, and realistic assessment of uncertainties associated with the usual measurement protocols. Highlights from recent studies involving TRPS are also reviewed. The technique is particularly popular in the burgeoning research field relating to extracellular vesicles, and the range of biologically relevant applications also includes liposomes, viruses, and on-bead assays.