A simple but practical method to convert the hydroenergy of microfluids into continuous electrical output is reported. Based on the principle of streaming potential/current, a micro fluidic generator (MFG) is demonstrated using patterned micropillar arrays as a quasiporous flow channel. The continuous electrical output makes this MFG particularly suitable as a power source in self-powered systems. Using the proposed MFG to power a single nanowire-based pH sensor, a self-powered fluid sensor system is demonstrated.