Data storage by any means usually requires an electric driving power for writing or reading. A novel approach for self-powered, triboelectrification-enabled data storage (TEDS) is presented. Data are incorporated into a set of metal-based surface patterns. As a probe slides across the patterned surface, triboelectrification between the scanning probe and the patterns produces alternatively varying voltage signal in quasi-square wave. The trough and crest of the quasi-square wave signal are coded as binary bits of "0" and "1," respectively, while the time span of the trough and the crest is associated with the number of bits. The storage of letters and sentences is demonstrated through either square-shaped or disc-shaped surface patterns. Based on experimental data and numerical calculation, the theoretically predicted maximum data storage density could reach as high as 38.2 Gbit in-2. Demonstration of real-time data retrieval is realized with the assistance of software interface. For the TEDS reported in this work, the measured voltage signal is self-generated as a result of triboelectrification without the reliance on an external power source. This feature brings about not only low power consumption but also a much more simplified structure. Therefore, this work paves a new path to a unique approach of high-density data storage that may have widespread applications.
Hybrid consensus problems among a group of continuous-time high-order agents with directed communication topology are investigated by a time delay approach, where each agent obtains the communication information from its neighboring agents only at discrete-time instants. Firstly, based on both the continuous-time state information of each agent and the discrete-time communication information with time-varying sampling interval of its neighboring agents, a hybrid discrete/continuous consensus protocol is designed. Secondly, hybrid consensus problems are transformed into simultaneous stabilization problems of multiple sampled control subsystems with low dimensions by the state space decomposition approach. Thirdly, by using the time delay approach and linear matrix inequality (LMI) theory, sufficient conditions for hybrid consensus and consensualization are presented, where four LMI constraints are only included. It should be pointed out that the hybrid consensus for high-order swarm systems depends on the gain matrices, the spectra property of the Laplacian matrix, and the maximum sampling interval. Moreover, the consensus function is determined when swarm systems achieve hybrid consensus. Finally, numerical examples are given to illustrate the effectiveness of the theoretical results.
Bending of polar-surface-dominated (PSD) nanobelts of ZnO can be explained by one of two processes: electrostatic neutralization of the dipole moment via deformation (called an electrostatic polar charge model) or imbalances between surface tensions via surface-termination induced stresses. This article presents experimental data on the structural features of nanorings and nanobows formed by bending single-crystal, PSD ZnO nanobelts. Our data exclusively support the electrostatic polar charge model as the dominant mechanism for bending.
A one-step hydrofluoric-acid-free hydrothermal-etching technique is demonstrated for the preparation of porous silicon with vertical holes. This method demonstrates a “green” chemical approach for etching a silicon wafer or the preparation of bismuth-silicon nanostructures without toxic acid or applying an external voltage. By controlling the heating temperature (<180°C) and time, nanoscale vertically holed porous silicon has been created. A formation mechanism has been proposed on the basis of experimental observations.
Abstract A new approach which is compatible with many of the existing procedures for the analysis of DNA species in gel electrophoresis is being demonstrated. It takes advantage of fluorescence photobleaching in order to create a sharp boundary between the stained and the (partially) photobleached DNA. By arbitrarily creating a stained DNA band of narrower width, the sensitivity to detect (averaged) DNA band movements has been increased. This feature permits measurements of time‐dependent electrophoretic mobility over very short time periods. The approach can be used to shorten the running time of gel electrophoresis experiment and to increase the resolution because of the sharper boundary and narrower band width. With faster running time, diffusion of both DNA and dye in the gel also becomes less serious. Movement of fluorescence pattern after photobleaching also permits measurements of localized motions when the gel pores are small in comparison with DNA sizes. Experiments demonstrating some aspects of the proposed technique, as well as the anticipated limitations, are presented and discussed.
We have developed a simple and economic technique for synthesis of one-dimensional nanobelt structures of semiconductive oxides such as ZnO, SnO 2 , In 2 O 3 , CdO, Ga 2 O 3 and PbO 2 . The as-synthesized oxide nanobelts are pure, structurally uniform, single crystalline and most of them free from dislocations; they have a rectangular-like cross-section with typical widths of 30–300 nanometers, width-to-thickness ratios of 5–10 and lengths of up to a few millimeters. The belt-like morphology appears to be a unique and common structural characteristic for the family of semiconducting oxides with cations of different valence states and materials of distinct crystallographic structures. The nanobelts are structurally and morphologically controlled and they are intrinsic semiconductors, providing a new system after carbon nanotubes for a systematic understanding on dimensionally confined transport phenomena in functional oxides. They are also ideal building blocks for fabrication of nanoscale devices based on the integrity of individual nanobelts.
Triboelectric nanogenerator (TENG) technology based on contact electrification and electrostatic induction is an emerging new mechanical energy harvesting technology with numerous advantages. The current area power density of TENGs has reached 313W/m2 and their volume energy density has reached 490kW/m3. In this review, we systematically analyzed the theoretical system of triboelectric nanogenerators. Starting from the physics of TENGs, we thoroughly discussed their fundamental working principle and simulation method. Then the intrinsic output characteristics, load characteristics, and optimization strategy is in-depth discussed. TENGs have inherent capacitive behavior and their governing equation is their V–Q–x relationship. There are two capacitance formed between the tribo-charged dielectric surface and the two metal electrodes, respectively. The ratio of these two capacitances changes with the position of this dielectric surface, inducing electrons to transfer between the metal electrodes under short circuit conditions. This is the core working mechanism of triboelectric generators and different TENG fundamental modes can be classified based on the changing behavior of these two capacitances. Their first-order lumped-parameter equivalent circuit model is a voltage source in series with a capacitor. Their resistive load characteristics have a “three-working-region” behavior because of the impedance match mechanism. Besides, when TENGs are utilized to charge a capacitor with a bridge rectifier in multiple motion cycles, it is equivalent to utilizing a constant DC voltage source with an internal resistance to charge. The optimization techniques for all TENG fundamental modes are also discussed in detail. The theoretical system reviewed in this work provides a theoretical basis of TENGs and can be utilized as a guideline for TENG designers to continue improving TENG output performance.
