Microfluidics and Formulation Emulsions and complex colloidal systems

In 1960, Richard Feynman (Nobel Prize in Physics 1965) published an article following a pioneering conference entitled "There's Plenty of Room at the Bottom", predicting a great revolution in miniaturization technologies. Although this miniaturization had already begun in the 40s with the invention of the transistor, advances in the field were restricted to electronics. Feynman imagined new fields of application and the development of manufacturing processes for miniaturized devices, inspired in particular by complex biological systems. Feynman's ideas began to take shape in the late 70s, with research into the development of inkjet printing and the appearance of the first microelectromechanical system (MEMS) in 1984. MEMS are micrometer-sized electromechanical devices that function as sensors and/or actuators. The development of techniques for the realization of these microsystems paved the way, in the early 90s, for the manipulation of fluids on this scale and the birth of microfluidics.

Microfluidics is a fast-growing science concerned with the behavior of fluids flowing through micrometer-sized channels. The idea of developing a "laboratory on a chip" has numerous applications, particularly in biochemistry and medical analysis, but also in fine chemistry. The formation of homogeneous droplets and the control of mass and momentum transfer at this scale have led scientists to take an interest in various applications, such as encapsulation, the production of micro- or nanoparticles and fibers, and organic synthesis using toxic reagents (with radically reduced volumes to be used), among others.

The microfluidics market is estimated to be worth $28 billion by 2023. Numerous start-ups, often linked to university research groups in the field, have emerged. With the development of microfluidics, both to understand fundamental phenomena (science) and to envisage new applications (technology), many challenges still lie ahead, e.g. the use of low-cost, high-performance materials to make certain devices accessible, or the large-scale production of complex colloidal systems.

After a brief review of the generalities (physical quantities, chip manufacture) and applications of microfluidics, the formulation of emulsions (direct, reverse, multiple and Pickering) as well as microcapsules, microgels and vesicles is detailed in this article.

As is customary in the industry, unless otherwise indicated, the percentages quoted are by volume.