Particle Counter for Ultra High Resolution Analysis

Given how the ‘Coulter Counter' has become such a standard and valuable piece of laboratory equipment, it is interesting how few researchers really understand the principle on which it operates.

When one considers the sophistication and power of instruments such as the Beckman Multisizer 3 particle counter, represented in the UK by Meritics, this is rather a shame. The ‘Coulter Principle', also known as the Electrical Sensing Zone Method, relies on the principle that particles, such as cells, moving in an electric field themselves cause a disturbance in that field.

As Mr. Wallace Coulter, to his eternal credit, realised, the magnitude of said disturbance is related to the size of the particle, a property that is exploited to the full in the Multisizer 3 particle counters. This instrument provides a very real parameter of the particle, its volume, and at very high resolution; diameter measurements actually range from a mightily impressive 400 nm to 1200 µm.

The Multisizer 3 will in fact provide cell number, volume, mass and surface area size distributions in a single measurement. This appraisal of course being unaffected by properties such as particle shape, colour, composition or refractive index and thus small changes of size distribution, such as those caused by aggregations and dissolutions, can be easily detected

The use of digital pulse processing (DPP) also enables more particle parameters to be measured allowing for greater characterisation. In fact the Multisizer 3's ability to detect cell volume and size change even if they happen over seconds makes it an important instrument with applications in many areas of cell growth study: cell cycle, cell death, compensation for osmotic stress, pathogenesis and phagocytosis.

Use of the Overlay function which allows for visualisation and comparison of cell populations with different sizes is a valuable feature. Of course the uses of the Multisizer 3 particle counter extend far beyond the Life Sciences to Industrial and Quality Control applications like Hydraulic Fluid and Lubricant characterisation.

With these sorts of specifications, perhaps in future we won't talk about the laboratory Coulter Counter anymore; we will just call it the Multisizer 3.

Date added: 2015-05-25 11:52:40