Introduction

In the agri-food sector, the viscosity parameter is particularly relevant, which differs considerably between edible vegetable oils according to their origin, cultivar, or use for food applications. Lab-on-a-Chip (LoC) is a fascinating technology for producing analytical systems at the microscale. In particular, microfluidic LoCs based on capillary forces provide a tool for the production of low-cost, easy-to-use, portable and accurate viscometers. The invention concerns a cheap, portable, easy to use and disposable capillary viscometer for monitoring the quality of oil “in the field” (for example, in restaurants or public places). It represents a valid alternative to expensive and less rapid traditional systems to limit anti-counterfeiting and validate the excellence of oil products.

Technical features

The set-up of the invention is composed of a PDMS (polydimethylsiloxane) microchannel equipped with an oleophobic coating and interfaced with an optical microscope and a computer for data analysis and processing. These two tools can be replaced by a smartphone equipped with a high resolution camera and appropriate software. The microfluidic viscometer allows the calculation of the viscosity values ​​of pure oils from the reprocessing of capillary dynamics data with an error of less than 1%. Each chip acquires a single capillary dynamics curve (even of less refined and therefore more turbid oils) in less than 100 s using 50 microliters of sample in a viscosity range of the order of 1-1000 cP, without the need for a reference sample. Furthermore, unlike commercial viscometers, it is also able to discriminate between pure oils and blends by performing an accurate fit of the capillary dynamics curve in a constant capillary pressure regime. In addition, the use of the viscometer to monitor the properties of mineral oil in industrial processes is being investigated.

Possible Applications

The microfluidic viscometer could be used for anti-counterfeiting of edible oils from:

• Anti-sophistication nuclei (NAS, ASL, …);
• Consumer associations (such as Coldiretti);
• Large retailers or producers of oils for checks along the supply chain.

Advantages

• Small, cheap and easy to use.
• Allows to discriminate pure oils from blended oils and their degree of use
• Analysis in real time;
• Portable for on field analysis;
• Uses very small volumes of fluid, without a reference sample.