application to other, non-analysis, lab processes. Hence the term "lab-on-a-chip" was introduced. Although the application of LOCs is still novel and modest, a growing interest of companies and applied research groups is observed in different fields such as chemical analysis, environmental monitoring, medical diagnostics and cellomics, but also in synthetic chemistry such as rapid screening and microreactors for pharmaceutics. Besides further application developments, research in LOC systems is expected to extend towards downscaling of fluid handling structures as well, by using nanotechnology. Sub-micrometre and nano-sized channels, DNA labyrinths, single cell detection and analysis, and nano-sensors, might become feasible, allowing new ways of interaction with biological species and large molecules. Many books have been written that cover various aspects of these devices, including the fluid transport, system properties, sensing techniques, and bioanalytical applications. Chip materials and fabrication technologies The basis for most LOC fabrication processes is photolithography. Initially most processes were in silicon, as these well-developed technologies were directly derived from semiconductor fabrication. Because of demands for e.g. specific optical characteristics, bio- or chemical compatibility, lower production costs and faster prototyping, new processes have been developed such as glass, ceramics and metal etching, deposition and bonding, polydimethylsiloxane (PDMS) processing (e.g., soft lithography), Off-stoichiometry thiol-ene polymers (OSTEmer) processing, thick-film- and stereolithography-based 3D printing as well as fast replication methods via electroplating, injection molding and embossing. The demand for cheap and easy LOC prototyping resulted in a simple methodology for the fabrication of PDMS microfluidic devices: ESCARGOT (Embedded SCAffold RemovinG Open Technology). This technique allows for the creation of microfluidic channels, in a single block of PDMS, via a dissolvable scaffold (made by e.g. 3D printing). Furthermore, the LOC field more and more exceeds the borders between lithography-based microsystem technology, nanotechnology and precision engineering. Printing is considered as a well-established yet maturing method for rapid prototyping in chip fabrication. The development of LOC devices using printed circuit board (PCB) substrates is an interesting alternative due to these differentiating characteristics: commercially available substrates with integrated electronics, sensors and actuators; disposable devices at low cost, and very high potential of commercialization. These devices are known as Lab-on-PCBs (LOPs). The following are some of the advantages of PCB technology: a) PCB-based circuit design offers great flexibility and can be tailored to specific demands. b) PCB technology enables the integration of electronic and sensing modules on the same platform, reducing device size while maintaining accuracy of detection.