The Malvern Correlator: The world’s first commercial laser-based, particle-size analyzer
On the 20th December 1977 (40 years ago) the Royal Radar and Signals Establishment (RRSE) and Malvern Instruments received the coveted MacRobert Award for the development of the Malvern Correlator. This was fundamental to the development of Photon Correlation Spectroscopy (PCS) and the evolution of the Zetasizer product line. The MacRobert award is the UK’s longest-running and most prestigious national prize for engineering innovation. Other past winners include engineers behind innovations such as the Pegasus jet engine, catalytic converters, the roof of the Millennium Dome and intelligent prosthetic limbs.
The concept for the Malvern Correlator originated from work carried out in the mid to late 1960’s at RSRE, Malvern on the fundamental properties of light. Roy Pike with his colleague Eric Jakeman conceived an idea relating to the temporal correlation of photon events, the aim being to create a novel type of ultra-high resolution spectroscopy. Other members of the team at that time included electronics engineer Robin Jones and Chris Oliver who helped build the first experimental system.
With the assistance of the National Research Development Council (NDRC) the technology was patented and a manufacturing license agreed with Steve Trudgill, the founder of Malvern Instruments (then Precision Engineering Systems) in February 1971. The first Malvern correlator (right) appeared on the market 9 months later and had applications in the following areas:
- Aeronautics: For plotting aerodynamic flow fields in aero-engine development
- Marine engineering: Measurement of velocity and turbulence fields around ship models
- Fuel and gas: Assessing the performance of burners from the velocity and turbulence levels of reactive gases
- Medical: Study of blood flow in the retina, which can be used to diagnose diseases and defects
The key application, as it turned out, was the ability to measure the size distribution of particles in suspension or macromolecules in solution by measuring the diffusion coefficient of the scattering entities. In fact, in 1970 the research team published a paper in Nature, titled “Determination of Diffusion Coefficients of Haemocyanin at Low Concentration by Intensity Fluctuation Spectroscopy of Scattered Laser Light”.
For particle sizing the electronics had to be paired up with a laser-scattering goniometer, such as that shown opposite, and in such a configuration the Malvern Correlator became the world’s first commercial laser-based, particle size analyzer.
Since then the technique of Photon Correlation Spectroscopy (PCS), more commonly known as Dynamic Light Scattering (DLS), has continued to evolve with Malvern’s first integrated measurement system, the Autosizer, appearing on the market in the late 1970s. The subsequent development of Electrophoretic Light Scattering (ELS) by Malvern in the early 1980s resulted in the first integrated size and zeta potential measurement system, the Zetasizer 2.
The latest iteration of the Zetasizer series, the Zetasizer Nano (right), employs the basic principles proposed by Roy Pike and his colleagues 50 years ago, but utilizing the latest advances in microprocessor technology, hardware and software capabilities to greatly improve measurement quality, versatility, robustness, and ease of use.
Quoting the MacRobert Award Evaluation Committee who were responsible for choosing the award recipients: “The Malvern Correlator provides an outstanding example of the way in which advanced scientific principles can be allied to the latest technological developments to provide equipment of practical and commercial value”. Without the foresight, knowledge and innovation provided by Roy Pike and his team, and the commercial acumen of Steve Trudgill, it is unlikely that Malvern Instruments would have made such a global impact in the field of analytical instrumentation. We therefore ‘take our hats off’ to all of the 1977 Macrobert Awardees for this important contribution to science, engineering and indeed the success of Malvern Instruments.
Related posts:
- Derek Stephen Trudgill, founder of Malvern Instruments
- Analytical and Scientific Instrument Heritage certification
- R. Pike, “The Malvern Correlator: Case Study in Development” Phys. Technol.10,104-109 (1979)
- R. Pike, “Lasers, photon statistics, photon-correlation spectroscopy and subsequent applications” J. Eur. Opt. Soc.-Rapid 5:10047S (2010)
- “Major Engineering Award for Malvern Research Team” The Radio and Electronic Engineer, Vol. 48, 146-148 (1978)