Liquids play an important role both in society and in many technologies. Although the viscosity, optical absorption, and scattering properties of chocolate make this particular liquid unsuitable for application in optics, the use of other fluids has resulted in fluidic micro-optics developing into an innovative new discipline. The use of fluids for optics is not new; macro-optical examples include rotating pools of mercury used as reflecting telescope mirrors (Borra, 1982), and we have already seen micro-optical examples in the previous chapters.

Fluidic micro-optics, for which the term optofluidics has attained common usage, is based on the combination of microfluidics and micro-optics, and has evolved in the last decade. Microfluidics, as we mentioned in Chapter 12, is a branch of microsystems engineering that employs microfabricated fluidic channels, micropumps, and microvalves to realize complete fluidic systems (Srinivasan et al., 2004; Kedzierski et al., 2009). Many microfluidic systems have been developed for biochemical analysis, in which optical components already play a role; laser diodes, LEDs, photodetectors, and other micro-optical devices have been integrated with fluidic structures to yield micro-total-analysis (so called μTAS) systems.

Optofluidics, however, concerns the use of fluidic effects and systems for the realization of the optical component itself (Psaltis et al., 2006; Monat et al., 2007).