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An important particle characterisation technique, resistive pulse sensing is a high-throughput method used to measure the size and quantity of particles in an electrolyte solution.

The Coulter Principle
Resistive pulse sensing is based upon the Coulter Principle, which states that the particles pulled through a hole with an electric current produce a change in impedance that is proportional to the volume of the particle.

The Coulter principle was developed by Wallace H Coulter in the 1940s, and the term is now used to reference an electric field being used to count and size dilute suspensions of particles in conductive liquids.

The principle is successful as it relies on the fact that a particle moving within an electric field causes a disturbance that is measurable. The size of the particle is proportional to the size of the disturbance.For the desired measurement particles must be suspended in a conducting liquid and the electrical field needs to be contained to surround the particles.

There are various considerations that need to be made when using the resistive pulse sensing technique to ensure you obtain the most accurate measurements. Anomalies can occur if the sample concentration is too high, so dilute samples are required.

Resistive Pulse Sensing Applications
One of the major application areas for resistive pulse sensing is the medical industry, and the ability to count and size particles is of great use to them.

The technique is often used in haematology applications, as it can be used to successfully characterise human bloody cells. Resistive pulse sensing can aid in the diagnosis of various diseases, as it is a standard method to determine red blood cell and white blood cell counts.

The method can also be used to count a wide range of other cells, including fat cells, plant cell aggregates, stem cell embryoid bodies, and bacteria.

Resistive Pulse Sensing from Lawson Scientific
Lawson Scientific has a well equipped laboratory to offer a wide range of particle characterisation analysis including using the resistive pulse sensing technique.

The nSC1 high-resolution nanoparticle size analyser from Spectradyne uses the resistive pulse sensing technique to perform rapid quantitative measurement of nanoparticles to determine their size.

The instrument is capable of measuring individual particles to create particle size distributions with quantitative concentration information. Particles from 40 nm to 2000 nm can be measured.

The nSC1 can also be used for virus studies, nanomedicine, extracellular vesicle analysis, and protein aggregation studies.

The Multisizer 4e Coulter Counter from Beckman Coulter is extremely versatile and accurate. The digital pulse processing technology within it provides ultra-high resolution, multichannel analysis which is unachievable with other technologies. The instrument can be used in various applications including marine biology, cell biology, quality control, and microbiology.

If you would like more information about the sample analysis Lawson Scientific Ltd can offer, please contact us