The Izon Exoid qNano comparison helps clarify the role of TRPS technology in nanoparticle analysis. Tunable Resistive Pulse Sensing occupies a specific position because it measures particles one by one through a nanopore and provides access to information that optical methods do not always deliver: charge.
When choosing between a TRPS system such as Exoid, the former qNano or another counting technology, laboratories therefore need to look beyond measurement quality alone. The real question concerns daily use: passage reliability, clogging risk, sample preparation, analysis throughput and the parameters that are actually required.
Understanding what TRPS provides
TRPS technology is based on the passage of individual particles through a calibrated opening. Each particle creates a current change, making it possible to obtain size, concentration and, under specific measurement conditions, zeta potential data.
Published specifications for Exoid state size and concentration measurement from 40 nm to 11 µm, as well as size measurement with zeta potential from 40 nm to 2000 nm. This range makes the technology relevant for laboratories working on small particles or closely related populations.
qNano was replaced by Exoid, with automated control of parameters that were previously adjusted manually, such as pressure, voltage and pore stretch. This development is intended to make operation more controlled, even though the principle remains based on the physical passage of particles through a nanopore.
Identifying when TRPS remains relevant
TRPS remains highly relevant when the laboratory needs access to charge per particle. This information may be essential for formulation, stability, surface modification or batch control studies.
The technology is also useful when the critical population lies between 40 and 80 nm. This range is difficult for some optical methods, especially technologies that do not efficiently detect below around 80 nm. For small exosome subpopulations or very fine biological particles, this threshold can be decisive.
Finally, TRPS can be appropriate when resolution matters more than speed. When closely related populations must be finely separated, electrical single-particle detection can provide a very detailed reading.
In these cases, looking for another technology does not always make sense. If charge, the 40 nm threshold or resolution are central to the requirement, TRPS remains difficult to replace.
Measuring the operational cost of the nanopore
The main point of caution with TRPS is its operation through a physical opening. The pore must be sufficiently adapted to particle size, but this constraint makes the method more sensitive to complex samples.
Polydisperse biological samples may contain larger particles, debris or aggregates that are poorly suited to the pore. These elements can disturb passage, cause clogging or lead to gradual measurement drift.
Proteins and lipoproteins can also foul the pore walls. The issue is not always immediately visible. A partially affected pore may continue to function, but with decreasing counts or a particle size distribution that shifts for instrumental reasons.
The buffer must also be considered. As the signal is based on ionic current, the sample must be in a conductive electrolyte. A poorly conductive buffer may require exchange, adding a preparation step and potentially promoting aggregation.
Comparing with methods without a nanopore
A method without a physical opening significantly changes the workflow. Interferometric microscopy, for example, measures particles in a static 5 to 10 µL droplet deposited on a slide. In this case, there is no pore, no capillary and no fluidic circuit crossed by particles.
This approach removes clogging risk. Larger particles, debris or aggregates do not block passage: they become visible elements in the image. The absence of a required electrolyte also makes it easier to work with different buffers.
An instrument such as Videodrop SC can provide particle concentration and a number distribution in less than one minute, without calibration and without settings to adjust. This simplicity may be useful for process monitoring, rapid controls or samples that are difficult to pass through a pore.
The limitation is clear: this approach does not measure charge and does not detect below approximately 80 nm.
Comparing available alternatives
| Platform | Principle | Published range | Charge | Fluorescence | Strength |
| Videodrop – Myriade Lab | ILM | Around 80-500 nm – 10^8-10^10 p/mL | No | No | Fast counting, process monitoring, low volume |
| NanoSight – Malvern Panalytical | NTA | 10-2000 nm – 10^6-10^9 p/mL | No | Yes | General sizing and counting |
| ZetaView – Particle Metrix | NTA | 10-1000 nm – 10^5-10^9 p/mL | Yes | Yes, up to 11 channels | Multiparametric analysis and colocalization |
| NanoAnalyzer – NanoFCM | Nano-flow cytometry | 40-1000 nm | No | Yes | Single-vesicle phenotyping |
| Virus Counter – Sartorius | Fluorescence-based counting | 5 x 10^5-1 x 10^9 p/mL | No | Required | Specific viral counting in complex matrices |
| Exoid – Izon | TRPS | 40 nm-11 µm | Yes | No | Resolution, charge and small particles |
This table shows that the choice depends on the priority parameter. TRPS remains relevant for charge, resolution and particles below 80 nm. Fast optical methods may be better suited to routine monitoring, but they do not address the same technical needs.
Choosing according to sample type
Sample behavior is decisive. A clean, well-prepared sample measured occasionally may be well suited to a TRPS approach. In this case, clogging risk is lower and data quality may justify the complexity of the method.
The situation changes with dirty, concentrated or heterogeneous biological samples. Debris, aggregates or oversized particles can make passage less stable. The laboratory must then spend more time on preparation, pore selection, dilutions and troubleshooting.
For samples intended for rapid monitoring, a pore-free technology may be more practical. It does not replace charge measurement, but it can quickly provide information on size and concentration when the detection range is compatible.
The right choice therefore depends on the real nature of the samples, not only on the technical datasheet.
Knowing when to keep Exoid or qNano
It may be preferable to keep a TRPS approach in several situations. If the particles of interest are between 40 and 80 nm, the lower threshold of the technology becomes a decisive advantage. If charge per particle is essential, TRPS addresses a need that label-free optical counters do not cover.
TRPS also remains relevant when the laboratory is looking for very good separation of closely related populations. In this case, resolution may matter more than throughput.
Finally, when samples are clean, volumes are modest and measurements are occasional, nanopore constraints may remain acceptable. The operational cost of TRPS becomes more problematic when failed passages, clogging or repeat runs become frequent.
The question is therefore not whether Exoid or qNano are outdated, but whether their advantages are actually being used.
Building a complementary organization
In many laboratories, the best solution is not to replace one technology completely with another. It may be more efficient to distribute use cases.
A fast optical method can be used for routine analysis, dirtier samples or process monitoring. TRPS can be reserved for measurements that truly require high resolution, analysis below 80 nm or charge measurement.
This organization avoids using a demanding technology for every analysis, while preserving its value when its specific capabilities are needed.
It also helps reduce repeat runs on difficult samples, organize workflows more effectively and reserve the most detailed instruments for questions that justify them.
Comparing Izon Exoid qNano according to real needs
The Izon Exoid qNano comparison should be built around laboratory use cases. If the main requirement concerns charge, particles between 40 and 80 nm or fine resolution, TRPS retains a strong position. If the priority is fast counting, simplicity, low volume or process monitoring, a nanopore-free approach may be more suitable.
Failed passages, repeat runs, preparation time, sample type and the parameters actually used in the results should all be analyzed. An instrument can produce very rich data, but become costly in daily use if a significant proportion of measurements is lost due to passage constraints.
An Izon Exoid qNano comparison should therefore not oppose technologies in theory. It should help identify the most coherent method according to samples, throughput, size thresholds and the expected level of information.
