Integrated microfluidic systems

Using unique physical phenomena at the microscale, such as laminar flow, mixing by diffusion, relative increase of the efficiency of heat exchange, surface tension and friction due to the increase of surface-to-volume ratio by downscaling, research in the field of microfluidic devices, aims at miniaturization of (bio)chemical apparatus for high-throughput analyses. Microchannel networks as core components of microfluidic devices are fabricated on various materials, such as silicon, glass, polymers, metals, etc., using microfabrication techniques adopted from the semiconductor industry and microelectromechanical systems (MEMS) technology, enabling integration of the components capable of performing various operations in microchannel networks. This chapter describes examples of diverse integrated microfluidic devices that incorporate functional components such as heaters for reaction temperature control, micropumps for liquid transportation, air vent structures for pneumatic manipulation of small volume droplets, optical fibers with aspherical lens structures for fluorescence detection, and electrochemical sensors for monitoring of glucose consumption during cell culture. The focus of this review is these integrated components and systems that realize useful functionalities for biochemical analyses.