1. A Brief Introduction to Microfluidics

With the enormous developments in micro- and nanofabrication, a new research field for scientists and engineers called micro- or nanofluidics was opened. While printer cartridges from which an ink-jet nozzle can shoot picoliter volume droplets of ink onto a sheet of paper are still one of the most prevalent microfluidic devices, this book focuses on the pharmaceutical and biochemical applications of microfluidics. Picoliter (10⁻¹² L, equivalent to the volume within a cube of 10 μm edge length) droplets already appear very small, but are still large compared to functional entities in biology and chemistry. A picoliter water droplet consists of nearly 10¹³ molecules. In the same volume 10⁴ bacteria and approximately ten red blood cells would only fit. To design, build, and operate devices that can manipulate drugs, particles, and biological materials like proteins and cells in miniaturized fluid volumes can be considered as a central theme of microfluidics. Such devices also known as Lab-on-a-chip systems (LOC), bio-microelectromechanical systems (BioMEMS) or miniaturized total analysis systems (μTAS) allow us bridging the gap between volumes which are familiar in classical laboratories or pilot factories and the microscale volumes common in biology. They can be the key to automated drug formulation, fast screening, protein crystallization, drug delivery, microbiorectors, organ-on-chip, and many other applications.