Measure Exosomes and Other Nanobiologicals With Tunable Resistive Pulse Sensing

Tunable Resistive Pulse Sensing (TRPS) is a single-particle measurement technique designed for measuring nanoparticles in the size range of 40 nm to 11 µm. TRPS measures individual particle size and zeta potential, or size and concentration, with a level of precision and accuracy not found in commonly used light scattering techniques that provide bulk estimates. TRPS is suited to a range of biological sample types containing colloidal particles, including exosomes/extracellular vesicles, virus-like particles, lipid nanoparticles, and other biopharmaceuticals. Now used in over 50 countries and included in over 1500 publications, TRPS brings in-depth insights into particle characteristics to a range of disciplines. Ensure accurate and precise characterisation of your sample with the TRPS measurement system: the Exoid.

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Charaterise With Precision and Accuracy

Measure individual exosomes, extracellullar vesicles and nanoparticles from 40 nm to 11 µm.

Simultaneously Measure Particle Size and Concentration

Obtain number-based size distribution plots, derived on a real particle-by-particle basis.

Measure the Zeta Potential of Individual Particles

Precisely measure the zeta potential and size of each particle in your sample.

Measure Individual Particles With Confidence

The precision, resolution and accuracy of size measurement in Tunable Resistive Pulse Sensing (TRPS) is unmatched by any other nanoparticle analysis technique. TRPS measures nanoparticles suspended in electrolytes on a particle-by-particle basis as they pass through a tunable nanopore. When particles pass through they momentarily disrupt the electrical current in the pore, which creates a blockade. The dimensions and frequency of these blockades are used to determine particle size, concentration and zeta potential. Every particle measured is compared to a set of NIST-traceable calibration particles of known size, which ensures accuracy and repeatability.

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Why Use Tunable Resistive Pulse Sensing?


Tunable Resistive Pulse Sensing (TRPS) is a true single-particle measurement technique that provides far greater resolution over ensemble techniques.


Reproducibility is enabled through the use of standardised NIST-traceable  calibration particles.


Automated data processing is achieved via a user-friendly data visualisation interface.


Unlike other techniques, TRPS measurements do not rely on prior knowledge of the optical properties of particles or the dispersant.


Parameters are adjusted to maximise the signal-to-noise ratio and are monitored during calibration and sample measurement to ensure high-quality data.

Figure 1.

NTA (top) and TRPS (bottom) particle size distribution of a quadrimodal sample, comprised of CPN100, CPN150, CPN200, CPN240 at a ratio of 1:1:1:1 with a total concentration of 10^10 particles/mL). TRPS offers high resolution of the four subpopulations, with baseline separation of data sets. NTA shows some resolution of subpopulations, but clear separation is not achieved.

Figure 2.

The Exoid is capable of measuring heterogenous samples over a wide size distribution, without the need for multiple measurements or adjustment of settings. Subpopulations can be identified with high resolution and accurately quantified individually.

Simultaneously Measure Size and Concentration

Using Tunable Resistive Pulse Sensing (TRPS), you can simultaneously measure particle size and concentration. As particles individually pass through a nanopore, a blockade is created. The magnitude of the blockade is directly proportional to particle size while the frequency of the blockades is used to determine concentration. TRPS can distinguish multiple subpopulations with high resolution, which is an important capability for fields working with polydisperse samples, such as extracellular vesicle (EV) research.

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Measure the Zeta Potential of Individual Particles

With Tunable Resistive Pulse Sensing (TRPS) you can measure particle size and zeta potential (or surface charge) simultaneously. TRPS measures each particle individually ensuring highly precise data collection, a powerful new approach for life sciences.

The single-particle approach used by TRPS makes it much more precise than ensemble approaches, such as PALS.

Learn more about zeta potential
Figure 3.

Comparison of TRPS (top) and PALS analysis (bottom) of bimodal charged samples of 380 nm low charged bare polystyrene particles and 400 nm highly charged carboxylated polystyrene particles. There is a huge discrepancy between both techniques. Whilst TRPS can resolve the two particle types perfectly (top) with zeta-potentials agreeing well with values from unmixed samples, PALS can only measure a solution-averaged zeta-potential value (bottom).

Tunable Resistive Pulse Sensing: Bringing Resolution to Particle Characterisation

TRPS is used in a wide range of applications including exosomes/extracellular vesicles, viruses and virus-like-particles, nanomedicine and other heterogenous nanoparticles. Select your field to read relevant publications and case studies.


A comprehensive measurement suite for nanosized drug products.

Extracellular Vesicles

Combine with qEV isolation for fast, easy and pure extracellular vesicle isolation. Accurate and dependable extracellular vesicle measurement down to 40nm.

Vaccine and Virus Formulation

Truly quantitative measurement of total viral titre.

The Exoid: Successor of the qNano Gold

The Exoid is Izon’s Tunable Resistive Pulse Sensing (TRPS) system. Unlike with the qNano Gold, where parameters were adjusted manually, pressure, voltage and pore stretch are adjusted directly from your Exoid-connected device. Significant hardware improvements reduce noise levels significantly over the qNano, meaning that smaller particles can be measured more reliably. The Exoid also has a clean user interface which provides guidance throughout the setup and measurement process.

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Skill Required for Insightful, Reliable Nanoparticle Measurements

Many physical characterisation methods on the market are rapid and require very little effort and skill. However, they do not have the resolving power required for complex samples containing particles of different sizes. Systematic, comparative studies have shown the low resolving capability of these techniques, and the relatively low repeatability compared to Tunable Resistive Pulse Sensing (TRPS). In contrast, TRPS provides precision via its single-particle nature combined with the use of calibration particles and active monitoring by the user. Even though proper sample preparation, skill, and effort are required for TRPS measurements – particularly for the measurement of particles at the lower end of the size range – it’s the only way forward if you want repeatable data on heterogenous samples containing small particles.


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