Microfluidics is an evolving scientific field with immense commercial potential: analytical applications, such as biochemical assay development, biochemical analysis and biosensors as well as chemical synthesis applications essentially require microfluidics for sample handling, treatment or readout. A number of techniques are available to create microfluidic structures today. On industrial scale replication techniques such as injection molding are the gold standard whereas academic research mostly focuses on replication by casting of soft elastomers such as polydimethylsiloxane (PDMS). Both of these techniques require the creation of a replication master thus creating the microfluidic structure only in the second process step—they can therefore be termed two-(or multi-)step manufacturing techniques. However, very often the number of pieces to be created of one specific microfluidic design is low, sometimes even as low as one. This raises the question if two-step manufacturing is an appropriate choice, particularly if short concept-to-chip times are required. In this case one-step manufacturing techniques that allow the direct creation of microfluidic structures from digital three-dimensional models are preferable. For these processes the number of parts per design is low (sometimes as low as one), but quick adaptation is possible by simply changing digital data. Suitable techniques include, among others, maskless or mask based stereolithography, fused deposition molding and 3D printing. This work intends to discuss the potential and application examples of such processes with a detailed view on applicable materials. It will also point out the advantages and the disadvantages of the respective technique. Furthermore this paper also includes a discussion about non-conventional manufacturing equipment and community projects that can be used in the production of microfluidic devices.

Glass is increasingly desired as a material for manufacturing complex microscopic geometries, from the micro-optics in compact consumer products to microfluidic systems for chemical synthesis and biological analyses. As the size, geometric, surface roughness, and mechanical strength requirements of glass evolve, conventional processing methods are challenged. We introduce microscale computed axial lithography (micro-CAL) of fused silica components, by tomographically illuminating a photopolymer-silica nanocomposite that is then sintered. We fabricated three-dimensional microfluidics with internal diameters of 150 micrometers, free-form micro-optical elements with a surface roughness of 6 nanometers, and complex high-strength trusses and lattice structures with minimum feature sizes of 50 micrometers. As a high-speed, layer-free digital light manufacturing process, micro-CAL can process nanocomposites with high solids content and high geometric freedom, enabling new device structures and applications.

Fused silica glass is the preferred material for applications which require long-term chemical and mechanical stability as well as excellent optical properties. The manufacturing of complex hollow microstructures within transparent fused silica glass is of particular interest for, among others, the miniaturization of chemical synthesis towards more versatile, configurable and environmentally friendly flow-through chemistry as well as high-quality optical waveguides or capillaries. However, microstructuring of such complex three-dimensional structures in glass has proven evasive due to its high thermal and chemical stability as well as mechanical hardness. Here we present an approach for the generation of hollow microstructures in fused silica glass with high precision and freedom of three-dimensional designs. The process combines the concept of sacrificial template replication with a room-temperature molding process for fused silica glass. The fabricated glass chips are versatile tools for, among other, the advance of miniaturization in chemical synthesis on chip.