High-performance piezoelectricity in monolayer semiconducting transition metal dichalcogenides is highly desirable for the development of nanosensors, piezotronics and photo-piezotransistors. Our experimental observation indicates that the conductivity of MoS 2 devices can be actively modulated by the piezoelectric charge polarization-induced built-in electric field under strain variation. In addition, a new type of MoS 2 strain/force sensor built using a monolayer MoS 2 triangle is also demonstrated. Our results provide evidence for strain-gating monolayer MoS 2 piezotronics, a promising avenue for achieving augmented functionalities in next-generation electronic and mechanical–electronic nanodevices.
LI, Peifeng; LIAO, Qingliang; YANG, Shize; BAI, Xuedong; HUANG, Yunhua; YAN, Xiaoqin; ZHANG, Zheng; LIU, Shuo; LIN, Pei; KANG, Zhuo and ZHANG, Yue.In situ transmission electron microscopy investigation on fatigue behavior of single ZnO wires under high-cycle strain[J]. Nano Letters, 2014, 14(2): 480–485.
The fatigue behavior of ZnO nanowires (NWs) and microwires was systematically investigated with in situ transmission electron microscopy electromechanical resonance method. The elastic modulus and mechanical quality factors of ZnO wires were obtained. No damage or failure was found in the intact ZnO wires after resonance for about 10 8 –10 9 cycles, while the damaged ZnO NW under electron beam (e-beam) irradiation fractured after resonance for seconds. The research results will provide a useful guide for designing, fabricating, and optimizing electromechanical nanodevices based on ZnO nanomaterials, as well as future applications.
A low-cost fabrication strategy to efficiently construct highly sensitive graphite-based strain sensors by pencil-trace drawn on flexible printing papers is reported. The strain sensors can be operated at only two batteries voltage of 3 V, and can be applied to variously monitoring microstructural changes and human motions with fast response/relaxation times of 110 ms, a high gauge factor (GF) of 536.6, and high stability >10 000 bending–unbending cycles. Through investigation of service behaviors of the sensors, it is found that the microcracks occur on the surface of the pencil-trace and have a major influence on the functions of the strain sensors. These performances of the strain sensor attain and even surpass the properties of recent strain sensing devices with subtle design of materials and device architectures.
A self-powered, single-electrode-based triboelectric sensor (TES) is reported to accurately detect the movement of a moving object/body in two dimensions. Based on the coupling of triboelectric effect and electrostatic induction, the movement of an object on the top surface of a polytetrafluoroethylene (PTFE) layer induces changes in the electrical potential of the patterned aluminum electrodes underneath. From the measurements of the output performance (open-circuit voltage and short-circuit current), the motion information about the object, such as trajectory, velocity, and acceleration is derived in conformity with the preset values. Moreover, the TES can detect motions of more than one objects moving at the same time. In addition, applications of the TES are demonstrated by using LED illuminations as real-time indicators to visualize the movement of a sliding object and the walking steps of a person.