The emerging concept of thread-based microfluidics has shown great promise for application to inexpensive disease detection and environmental monitoring. To allow the creation of more sophisticated and functional thread-based sensor designs, the ability to better control and understand the flow of fluids in the devices is required. To meet this end, various mechanisms for controlling the flow of reagents and samples in thread-based microfluidic devices are investigated in this study. A study of fluid penetration in single threads and in twined threads provides greater practical understanding of fluid velocity and ultimate penetration for the design of devices. "Switches" which control when or where flow can occur, or allow the mixing of multiple fluids, have been successfully prototyped from multifilament threads, plastic films, and household adhesive. This advancement allows the fabrication of more functional sensory devices which can incorporate more complex detection chemistries, while maintaining low production cost and simplicity of construction.