Publications

In recent years, the triboelectric nanogenerator (TENG) has attracted increasing attention because it not only converts various mechanical energy into electrical energy but also produces electrical signals as responses. On the basis of the TENG, a magnetic flap type difunctional sensor (MFTDS) has been developed to detect pneumatic flow and liquid level. Consisting of an outer magnetic flap, an inner magnetic float, and a conical cavity, its working mechanism and output characteristics were studied. The MFTDS detects pneumatic flows from 10 to 200 L/min with a flow resolution of 2 L/min. Compared with a commercial flow switch, the MFTDS results are in good agreement. Moreover, the MFTDS detects changes in liquid levels. The effects of liquid level height and flow rate on the performance of the MFTDS were measured and compared with a commercial liquid-level sensor. The results indicate that the output voltage of the MFTDS varies linearly with height but is independent of flow rate. The heights of liquid level from 30 to 130 mm were effectively detected. This work promotes the prospect for multifunctional triboelectric sensors.

A new facile strategy to maximize the charge density over 1000 μC m −2 for a high-output TENG is demonstrated by introducing new physics in contact electrification, i.e. ‘Electric-field-driven interfacial trapping of drifting triboelectric charges’.

Klare Präferenzen: Ein Hg2+-Sensor auf Basis des triboelektrischen Effekts nutzt Au-Nanopartikel (rot im Bild) zur Erhöhung der elektrischen Leistungsfähigkeit und als Erkennungselement. Für den selbstversorgenden Nanosensor sprechen ein einfacher Aufbau, geringe Kosten sowie eine hohe Selektivität und Empfindlichkeit. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Abstract In the new energy era, ocean wave energy is recognized as one of the most important clean and renewable energy sources. As an advanced energy technology, developing triboelectric nanogenerators (TENGs) to harvest ocean wave energy has become a promising research direction. However, for most of the current fully enclosed TENGs or liquid–solid TENGs, the industrialization is limited. In this work, a TENG with a new working scheme is proposed for water wave energy harvesting. Through designing the opposite dynamic electric‐double‐layers, the efficient conversion of water kinetic energy into electrical energy is achieved. Moreover, the TENG structure is extended to an array. Under irregular water waves, the TENG array exhibits desired output performance, with the stable output current of 60.0 µA, output voltage of 60.0 V, and average power density of 5.38 W m −3 . Finally, the TENG array is demonstrated to successfully power signal spotlights, the digital thermometer and the water quality detector. This study not only broadens the research ideas for TENGs, but also provides a new mechanism for the ocean wave energy exploitation, which is of great significance to the industrialization of TENGs and blue energy.

Utilizing magnetic field directly modulating/turning the charge carrier transport behavior of field-effect transistor (FET) at ambient conditions is an enormous challenge in the field of micro-nanoelectronics. Here, a new type of magnetic-induced-piezopotential gated field-effect-transistor (MIPG-FET) base on laminate composites is proposed, which consists of Terfenol-D, a ferroelectric single crystal (PMNPT), and MoS2 flake. When applying an external magnetic field to the MIPG-FET, the piezopotential of PMNPT triggered by magnetostriction of the Terfenol-D can serve as the gate voltage to effectively modulate/control the carrier transport process and the corresponding drain current at room temperature. Considering the two polarization states of PMNPT, the drain current is diminished from 9.56 to 2.9 µA in the Pup state under a magnetic field of 33 mT, and increases from 1.41 to 4.93 µA in the Pdown state under a magnetic field of 42 mT and at a drain voltage of 3 V. The current on/off ratios in these states are 330% and 432%, respectively. This work provides a novel noncontact coupling method among magnetism, piezoelectricity, and semiconductor properties, which may have extremely important applications in magnetic sensors, memory and logic devices, micro-electromechanical systems, and human-machine interfacing.

Contact-electrification is a universal effect for all existing materials, but it still lacks a quantitative materials database to systematically understand its scientific mechanisms. Using an established measurement method, this study quantifies the triboelectric charge densities of nearly 30 inorganic nonmetallic materials. From the matrix of their triboelectric charge densities and band structures, it is found that the triboelectric output is strongly related to the work functions of the materials. Our study verifies that contact-electrification is an electronic quantum transition effect under ambient conditions. The basic driving force for contact-electrification is that electrons seek to fill the lowest available states once two materials are forced to reach atomically close distance so that electron transitions are possible through strongly overlapping electron wave functions. We hope that the quantified series could serve as a textbook standard and a fundamental database for scientific research, practical manufacturing, and engineering.

Tunneling junction is used in many devices such as high-frequency oscillators, nonvolatile memories, and magnetic field sensors. In these devices, modulation on the barrier width and/or height is usually realized by electric field or magnetic field. Here, a new piezotronic tunneling junction (PTJ) principle, in which the quantum tunneling is controlled/tuned by externally applied mechanical stimuli, is proposed. In these metal/insulator/piezoelectric semiconductor PTJs, such as Pt/Al2 O3 /p-GaN, the height and the width of the tunneling barriers can be mechanically modulated via the piezotronic effect. The tunneling current characteristics of PTJs exhibit critical behavior as a function of external mechanical stimuli, which results in high sensitivity (≈5.59 mV MPa-1 ), giant switching (>105 ), and fast response (≈4.38 ms). Moreover, the mechanical controlling of tunneling transport in PTJs with various thickness of Al2 O3 is systematically investigated. The high performance observed with these metal/insulator/piezoelectric semiconductor PTJs suggest their great potential in electromechanical technology. This study not only demonstrates dynamic mechanical controlling of quantum tunneling, but also paves a way for adaptive interaction between quantum tunneling and mechanical stimuli, with potential applications in the field of ultrasensitive press sensor, human-machine interface, and artificial intelligence.

Hydrogels play a pivotal role in the realm of iontronics, contributing to the realization of futuristic human–machine interactions. The electric double layer (EDL) between the hydrogel and electrode provides an essential ionic–electronic coupling interface. While prior investigations primarily delved into elucidating the formation mechanism of the EDL, our study shifts the focus to showcasing the current generation through the mechanical modulation of the EDL at the hydrogel–metal interfaces. The dynamic EDL was constructed by the mechano-driven contact–separation process between the polyacrylamide (PAAm) hydrogel and Au. Influencing factors on the dynamic regulation of the EDL such as ion concentration, types of salt, contact–separation frequency, and deformation degree were investigated. Dehydration usually limits the practical applications of hydrogels, and it is a long-standing and difficult problem. However, it seemed to be able to slow the EDL formation process here, resulting in a sustained continuous direct current signal output. Such hydrogel iontronics could rectify the displacement electronic current of a triboelectric nanogenerator by the ionic current. The directional migration of ions could be further enhanced by using charge-collecting metals with different work functions, for example, Au and Al. It offers a paradigm to enable ionic rectification that could be seamlessly incorporated into electronic systems, ushering in a new era for efficient energy harvesting and biomimetic nervous systems.

We show that by controlling the growth conditions, the crossed networks of ZnO nanorods were grown on an MgO (001) substrate. The [0001] ZnO nanorods grow along the ⟨111⟩ directions of MgO substrate and form aligned arrays. This growth is a result of polar surface induced growth from both the MgO {111} and ZnO ± (0001). The crossed ZnO nanorod networks are a potential candidate for field emission, optoelectronics, ultrasensitive sensing, catalysts and filtering.