Fig. 13.

Microfluidic devices for 2-D or 3-D co-culture and transverse gradient generation. (a) Wong et al. show a device used for partitioning a mirofluidic channel using gels to enable tunable 3-D cell culture. Separation is achieved with laminar flow using a syringe pump. (Reprinted from [83] with permission from Elsevier, 2008.) (b) Puccinelli et al. achieve patterned 3-D culture using passive pumping. The red and green halves of the culture channel represent the separation of the two cell types via laminar flow. The outer media channels allow access to each cellular compartment via diffusion through the small diffusion channels and enable gradient generation. The pictures at the bottom demonstrate the ability to visualize the separation of the cell types despite the close contact between streams with the insert showing how pressure can be used to vary the widths of each region [84]. (Figures and captions adapted and reproduced by permission of The Royal Society of Chemistry, 2008.)