These piezoelectric
parameters were related to the piezoelectric current. The single
ZnO nanowire generates a piezoelectric current of about 10−
100 pA, but these experiment samples (billions of ZnO
nanowires) only generate current around 100 nA. The touch
number between Pt metal and ZnO nanowire can be estimated
by the current density and output current, and then, the current
ratio and piezoelectric parameter reveal that ultralong ZnO
nanowires are around 103−105 wires.