New device measures viscosity of ketchup and cosmetics

A device that can measure and predict how liquids flow under different conditions will ensure consumer products -- from make-up to ketchup -- are of the right consistency. The technology developed at the University of Sheffield enables engineers to monitor, in real time, how the viscous components (rheology) of liquids change during a production process, making it easier, quicker and cheaper to control the properties of the liquid.

The research is a joint project between the University's Department of Chemical and Biological Engineering and the School of Mathematics and Statistics. A paper describing the innovation is published Oct. 24, 2011 in the journal Measurement Science and Technology.

Dr Julia Rees from the University's Department of Applied Mathematics, who co-authored the study, said: "Companies that make liquid products need to know how the liquids will behave in different circumstances because these different behaviours can affect the texture, the taste or even the smell of a product."

The viscosity of most liquids changes under different conditions and designers often use complicated mathematical equations to determine what these changes might be.

The team from Sheffield has now developed a way of predicting these changes using a non-invasive sensor system that the liquid simply flows through. The sensor feeds information back through an electronic device that calculates a range of likely behaviours.

Dr Rees, from the Department of Applied Mathematics, explains: "Measuring the individual components of a liquid's viscosity is called rheometry. We can produce equations to measure a liquid's total viscosity, but the rheology of most liquids is very complicated. Instead, we look at properties in a liquid that we can measure easily, and then apply maths to calculate the viscosity. The sensor device we have developed will be able to make these calculations for companies using a straightforward testing process."

Companies developing new products will be able to incorporate the device into their development process, meaning there will no longer be a need for `grab samples' to be taken away for expensive laboratory testing, providing cost and efficiency savings.

The device can be made to any scale and can even be etched onto a microchip, with channels about the width of a human hair. This will be useful for testing where only small samples of fluid are available, for example in biological samples.

Dr Rees' team have developed a laboratory prototype of the system and are currently working to refine the technology and develop a design prototype.

Will Zimmerman, Professor of Biochemical Dynamical Systems in the Department of Chemical and Biological Engineering at the University of Sheffield, worked on the project alongside Dr Rees. He says: "Because the microrheometer works in real time, materials, time and energy will not be wasted when processing flaws are detected. Conservation is one of the best ways to 'green' industrial processing with greater efficiency. Ben Franklin's maxim, 'waste not, want not' is just as true today."

Source: University of Sheffield