A structure similar to a field effect transistor with two isolated top electrodes comprising the source and drain and a lower substrate electrode as the gate was used for the dielectrophoresis-based assembly of zinc oxide nanowires. The results reveal that the assembly of nanowires is significantly affected by the gap distance between the two top electrodes as well as the magnitude and frequency of the applied electric field. Gate assisted assemblies using direct current and alternating current dielectrophoresis were also investigated and determined to improve the assembly effect of nanowires.

In this paper, we present a nanoelectromechanical oscillator with a single semiconducting zinc oxide nanowire (ZnO) doubly clamped and suspended on two metal electrodes by which the piezoelectric property on the growth of the ZnO nanowire along the c-axis, [0001], is characterized by the resonant frequency shift of the oscillator. We report that the resonance of the nanowire oscillator can be detected in ambient air and the effective piezoelectric coefficient on the growth of a ZnO nanowire along the c-axis, [0001], is significantly larger than that of bulk (0001) ZnO.

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A new type of hot-wire flow-rate sensor (HWFS) with a sensing element made of a macro-sized carbon nanotube (CNT) strand is presented in this study. An effective way to improve repeatability of the CNT flow-rate sensor by coating a layer of Al2O3 on the CNT surface is proposed. Experimental results show that due to the large surface-to-volume ratio and thin coated Al2O3 layer, the CNT flow-rate sensor has higher sensitivity and faster response than a conventional platinum (Pt) HWFS. It is also demonstrated that the covered CNT flow-rate sensor has better repeatability than its bare counterpart due to insulation from the surrounding environment. The proposed CNT flow-rate sensor shows application potential for high-sensitivity measurement of flow rate.

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