In this paper, we report a simple and practical composite structure for a nanogenerator (NG). The composite design using two kinds of piezoelectric materials, zinc oxide and poly(vinylidene fluoride), requires no more system size and complexity than for a single material, but improves the power density and sensitivity of the NG significantly. With no need of an external power source or batteries, the composite NG can efficiently convert the vortex motion in the atmosphere into electricity. Based on the Karman vortex street principle, ambient wind-speed measurements with the NG are demonstrated. Due to the simple structure, high sensitivity and good environment-friendly properties, the NG as an active sensor should play an important role in wireless environmental monitoring networks.
