Polymers have assumed the leading role as substrate materials for microfluidic devices in recent years. They offer a broad range of material parameters as well as material and surface chemical properties which enable microscopic design features that cannot be realised by any other class of materials. A similar range of fabrication technologies exist to generate microfluidic devices from these materials. This review will introduce the currently relevant microfabrication technologies such as replication methods like hot embossing, injection molding, microthermoforming and casting as well as photodefining methods like lithography and laser ablation for microfluidic systems and discuss academic and industrial considerations for their use. A section on back-end processing completes the overview.

A growing number of microsystem technology (MST) applications, particularly in the field of microfluidics with its applications in the life sciences, have a need for novel fabrication methods which account for substrates other than silicon or glass. We present in this paper an overview of existing polymer microfabrication technologies for microfluidic applications, namely replication methods such as hot embossing, injection molding and casting, and the technologies necessary to fabricate the molding masters. In addition, techniques such as laser ablation and layering techniques are examined. Methods for bonding and dicing of polymer materials, which are necessary for complete systems, are evaluated.

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The need for low-cost microfabrication technologies in modern life-sciences is described. The article compares the replication technologies, hot embossing and micro-injection moulding and gives an overview over the technologies used for fabrication of the replication masters. The back-end processes transforming the replicated plastic part into a complete microsystem are described. Some manufacturing issues of mass production are discussed.

A growing number of microsystem technology (MST) applications, particularly in the field of microfluidics with its applications in the life sciences, have a need for novel fabrication methods which account for substrates other than silicon or glass. We present in this paper an overview of existing polymer microfabrication technologies for microfluidic applications, namely replication methods such as hot embossing, injection molding and casting, and the technologies necessary to fabricate the molding masters. In addition, techniques such as laser ablation and layering techniques are examined. Methods for bonding and dicing of polymer materials, which are necessary for complete systems, are evaluated.

A microsystem integrating electrochemical detection for the simultaneous detection of protein markers of breast cancer is reported. The microfluidic platform was realized by high precision milling of polycarbonate sheets and features two well distinguishable sections: a detection zone incorporating the electrode arrays and the fluid storage part. The detection area is divided into separate microfluidic chambers addressing selected electrodes for the measurement of samples and calibrators. The fluidic storage part of the platform consists of five reservoirs to store the reagents and sample, which are interfaced by septa. These reservoirs have the appropriate volume to run a single assay per cartridge and are manually filled. The liquids from the reservoirs are actuated by applying a positive air pressure (i.e.via a programmable syringe pump) through the septa and are driven to the detection zone via two turning valves. The application of the realised platform in the individual and simultaneous electrochemical detection of proteic cancer markers with very low detection limits are demonstrated. The microsystem has also been validated using real patient serum samples and excellent correlation with ELISA results obtained.

Hematopoietic lymphoid tissue inducer (LTi) cells initiate lymph node (LN) and Peyer’s patch (PP) development during fetal life by inducing the differentiation of mesenchymal organizer cells. The growth factor signals underlying LTi cell development and LN and PP organogenesis remain poorly understood. LTi cells express the Il7r and the receptor tyrosine kinase Kit, whereas organizer cells express their cognate ligands. To determine the relative significance of Il7 and Kit signaling in LTi cell homeostasis and PP and LN development, we have analyzed mice deficient for Kit (KitW/Wv), Il7 (Il7−/−), or both (Il7−/− KitW/Wv). Unlike KitW/Wv and Il7−/− single mutants, Il7−/− KitW/Wv mice were almost devoid of LTi cells in their mesenteric LN anlage. This LTi deficiency was associated with a block in mesenchymal LN organizer cell generation and the absence of almost all LNs. In contrast, intestinal LTi cell numbers, PP organizer cell generation, and PP development were strongly affected by impaired Kit signaling, but were independent of Il7. Hence, Kit and Il7 act synergistically in LN organogenesis, whereas Kit signaling, but not Il7, critically regulates PP organogenesis and LTi cell numbers in the intestine. Consistent with these differential growth factor requirements for PP and LN development, PP organizer cells expressed higher Kitl and lower Il7 levels than did LN organizer cells. Collectively, these results demonstrate that Kit and Il7 differentially control PP and LN organogenesis through the local growth factor-driven regulation of LTi cell numbers.

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