(1) Through-wafer fluid interconnects allow the various components of a fluidic system to be built on both sides of a wafer rather than on just a single side. This physical separation can lead to flexibility in fabrication and the realization of high-density, complex systems. In most existing microfluidic systems, jluidic components (e.g., channels and reaction chambers) and elect!-omechranical components (e.g., valves, pumps, electrodes, mixers) tend to reside in one common plane, which ultimately requires that complex systems consume a large chip area. (2) By using fluid interconnects, two streams of fluid can cross over one another by diverting one stream to a different physical plane and returning that stream at a different location on the original plane. Analogous to using air-bridges in integrated circuits, this fluid jumper could simplify the design of complex fluid systems that may otherwise require crowded channel routing.