A lot of foods, drugs, and personal care products are emulsion-based. In general, emulsions are dispersions of two (or more) immiscible liquids. It is assumed that the mean droplet size and size distribution of an emulsion are important factors to control product properties, like shelf life and texture. Monodisperse, small-sized emulsion droplets are preferred by industry. Although it is possible to produce relatively monodisperse emulsions on small scale, industry is still struggling to obtain the same on a larger scale. This results from the nature of traditional emulsification techniques like stirring and homogenization. Another disadvantage of these conventional techniques is the inefficient use of energy: a lot of energy is lost in heating up the emulsified product, therewith causing heat damage to the product. Micro technology could be a solution to control emulsification conditions and heating up during emulsification due to the small scale of this technique. Therefore, the prerequisites for monodisperse, small droplet formation can be met with micro technology. Moreover, micro devices are very suitable to investigate the droplet formation mechanism in detail.Droplet formation at a T-shaped junction
Uniform droplets formed in a microchannel device. (Click on picture for a movie)
Given the arguments of the introduction, it is obvious that various Dutch industrial sectors are interested in obtaining uniform, small-sized emulsions at mild process conditions (in other words at room temperature, atmospheric pressure and with a low energy input). On lab scale micro channels are used to produce uniform, small-sized emulsion droplets. However, the production rates of such micro channels are going to be limited unless they can be placed in parallel. On larger scale, various other devices are used, but as mentioned these do not obtain small and uniform drops. The aim of this project is to combine the best of (these) two worlds: one in which droplet size and size distribution is well defined and one in which production rates are sufficient for industry. The main challenge will be to develop a (new) production method, which not only works on a lab scale, but can also be scaled up to meet industrial demands. The project will focus on droplet formation mechanism and the influence of interfacial tension in the process. In experiments droplet formation in micro devices will be visualised using a high-speed camera. Subsequently, extensive computer modelling will be used to investigate droplet break-up mechanisms in (more) detail as well as to design a production set-up.
Our set-up; A light microscope connected to a high-speed cameraAcknowledgements
This project is part of the national research initiative MicroNed.