This video is a tutorial on creating a paper microfluidic device through wax curing, droplet test, and choosing proper channels. Applications are demonstrated as well, including mixing and chemical sensors. Source from: 

Lo, Katey, Joseph Summers, Vladimir Bulovic, and Rajeev Ram. 6.S079 Nanomaker, Spring 2013. (MIT OpenCourseWare: Massachusetts Institute of Technology), http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-s079-nanomaker-spring-2013 (Accessed 18 Oct, 2014). License: Creative Commons BY-NC-SA