Two-dimensional paper networks (2DPNs) area new set of devices allow complex chemical processing in a very low-cost format. We have, for the last 5 years, been learning how to translate what we have learned about point-of-care diagnostic technologies in conventional microfluidics into the language of porous media. The wicking of fluids in porous materials (like paper, nitrocellulose membranes, etc.) allows us to discard pumps, which permits great savings in complexity and cost, and the potential to perform complex tests without any permanent instruments. However, there are many physical and chemical differences between open ducts and porous media. We have put a good deal of effort into understanding the performance and design rules of simple paper systems. Furthermore, application of reagents to the papers in liquid and dry form is central to device development, testing, and economical manufacture. Currently, the primary applications for this technology in our lab are highlysensitive multiplexed immunoassays and multiplexed isothermal nucleic acid amplification assays. All assays are designed with visible optical readout that can be captured and quantified using camera-equipped cellular phones.