The most commonly used way to achieve micro-scale compartmentalization is through the use of microfluidic chips. Microfluidic chips contain accurately patterned features in the range of 0.1 μm - 1 mm, and thus offer highly precise spatial and temporal control of cellular microenvironment. The traditional microfabrication materials are silicon and glass, but the microfluidics community has increasingly adopted polymers such as poly(dimethylsiloxane) (PDMS) as the materials of choice [4]. Typical polymer microfabrication techniques include optical lithography, replication molding, injection molding and hot embossing. An example of an often-used polymer-based fabrication process is replica molding of PDMS [5] using masters created through epoxy polymer photoresist SU-8 photolithography, a micromanufacturing technique developed in the microelectronics industry. A recent trend is to utilize materials more familiar to biologists, such as agarose [6,7] or polystyrene [8] for microfabrication.
