This communication describes the first paper-based microfluidic device that is capable of generating its own power when a sample is added to the device. The microfluidic device contains galvanic cells (that we term ''fluidic batteries'') integrated directly into the microfluidic channels, which provides a direct link between a power source and an analytical function within the device. This capability is demonstrated using an example device that simultaneously powers a surface-mount UV LED and conducts an on-chip fluorescence assay.