A recent development, inspired by nature, is the use of ‘artificial cilia’ to create pumping and/or mixing in microfluidic devices. Cilia are small hairs that can be found in biology and are used for (fluid) actuation and sensing. Microscopic actuators resembling cilia, actuated to move under the influence of various stimuli such as electrostatic field, magnetic field, and even light, have been developed by a number of groups and shown to be capable of generating flow and mixing in microfluidic environments. The research on artificial cilia started about a decade ago and is rapidly expanding. In addition to being relevant for potential application in lab-on-a-chip devices, the work on artificial cilia forms a beautiful example of how a biol...