Self-powered pendulum and micro-force active sensors based on a ZnS nanogenerator

We demonstrated a nanogenerator as a pendulum and micro-force active sensor which is first made from zinc sulfur (ZnS) nanowires. The ZnS nanowires were synthesized on an Si substrate by a carbonthermal evaporation process at 1050 degrees C. The length and diameter of the ZnS nanowires are around 20-50 mu m and 50-100 nm, respectively. The X-ray diffraction (XRD) pattern shows that the ZnS has a wurtzite structure. The TEM image shows that the nanowires grew along the [ 0001] axis, which is in the spontaneous polarization direction. The ZnS nanowires can be packed into a nanogenerator either in-serial or in-parallel. Furthermore, on the basis of our theoretical calculations, which applied a compressive stress (1 x 10(6) N m(-2)) along the c-axis of ZnS nanowire, the corresponding output piezopotential can be reached of similar to 2 V. Because the output voltage and current of the ZnS nanogenerator are proportional to the momentum, it can detect various momentums from 0.077 N s to 0.177 N s. The latter can also be self-powered to trace a simple harmonic motion of a pendulum that is released from different heights or angles. The same device can therefore be used for pendulum and micro-force active sensors without applying an external power source.