Wave energy is one of the most available energy sources in oceans. In this work, a design of high power density triboelectric nanogenerator (TENG) based on a tower structure is proposed for harvesting wave energy from arbitrary directions. Such tower-like TENG (T-TENG) consists of multiple units made of polytetrafluoroethylene balls and three-dimensional printed arc surface coated with melt adhesive reticulation nylon film. The power generation model coupled with the kinetic model for the T-TENG is proposed and discussed. The T-TENG can effectively convert arbitrary directional wave energy into electrical energy by utilizing charged balls rolling on an optimized arc surface due to ocean wave excitation. In addition, it is found that the power density of the present T-TENG increases linearly from 1.03 W/m3 to 10.6 W/m3 by increasing the units from 1 to 10 in one block. This supports that the power density of the T-TENG increases proportionally with the number of units connected in parallel without rectifiers due to its distinctive mechanism and structure. Therefore, the design of T-TENG provides an innovative and effective approach toward large-scale blue energy harvesting by connecting more blocks to form T-TENG networks.

IntroductionWith the rapid consumption of global energy, the utilization of new energy is of crucial importance for the development of society and the protection of the ecological environment. [1,2] Triboelectric nanogenerators can effectively collect low-frequency vibration energy and convert it into electrical energy. [3][4][5][6][7][8][9] These nanogenerators are a milestone in the development of new energy research. [9,10] Their discovery has provided new ideas for the collection of many forms of environmental energy, such as vibrational energy, wind energy, hydropower, and bioenergy. [11,12] A sound wave is a special form of mechanical vibration. [13] As a clean, abundant, and sustainable form of energy, sound waves are ubiquitously present in our surroundings, including various sounds from human activities, airport construction sites, and transportation. Unfortunately, most sound wave energy has been wasted because of its very low energy density and the lack of effective technologies for harvesting acoustic energy. [14,15] Energy harvesters operating on the basis of electromagnetic induction or the piezoelectric effect have been proposed to collect various types of vibrational energy, such as vehicle vibration and human movement. [16][17][18][19] However, their application has encountered severe difficulties in regard to acoustic wave energy. The mechanism of power generation using electromagnetic induction is that the conductor in the magnetic field cuts the magnetic induction line to generate induced currents. [20] However, due to the small acoustic energy density and the rapid change in sound pressure, effective cutting of the magnetic line under the action of an acoustic wave force is very difficult for conductors. [21,22] Therefore, using electromagnetic induction to collect acoustic wave energy remains a great challenge. In contrast, piezoelectric materials have good sensitivity to slight disturbances, and most of the previous studies regarding acoustic energy harvesting have concentrated on piezoelectric nanogenerators. [23] However, thus far, such nanogenerators have been limited by low electrical output performance and high structural complexity. [24] Therefore, an advanced acoustic energy harvester with high output performance and good practicability must be proposed soon.An acoustic wave is a type of energy that is clean and abundant but almost totally unused because of its very low density. This study investigates a novel dual-tube Helmholtz resonator-based triboelectric nanogenerator (HR-TENG) for highly efficient harvesting of acoustic energy. This HR-TENG is composed of a Helmholtz resonant cavity, a metal film with evenly distributed acoustic holes, and a dielectric soft film with one side ink-printed for electrode. Effects of resonant cavity structure, acoustic conditions, and film tension on the HR-TENG performance are investigated systematically. By coupling the mechanisms of triboelectric nanogenerator and acoustic propagation, a theoretical guideline is provided for improving energy out...

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The marine internet of things (MIoT), an increasingly important foundation for ocean development and protection, consists of a variety of marine distributed sensors under water. These sensors of the MIoT have always been highly dependent on batteries. To realize in situ power supply, a flexible seaweed-like triboelectric nanogenerator (S-TENG) capable of harvesting wave energy is proposed in this study. The flexible structure, designed with inspiration from the seaweed structure, processes extensive marine application scenarios. The bending and recovering of the S-TENG structure under wave excitations are converted to electricity. As the output performance increases with the number of parallel connected S-TENG units, an S-TENG system with multiple units could serve for floating buoys, coastal power stations, and even submerged devices. Through the demonstration experiments performed in this study, the flexible, low-cost S-TENG could become an effective approach to achieve a battery independent MIoT.

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The human–machine interface plays an important role in the diversified interactions between humans and machines, especially by swaping information exchange between human and machine operations. Considering the high wearable compatibility and self-powered capability, triboelectric-based interfaces have attracted increasing attention. Herein, this work developed a minimalist and stable interacting patch with the function of sensing and robot controlling based on triboelectric nanogenerator. This robust and wearable patch is composed of several flexible materials, namely polytetrafluoroethylene (PTFE), nylon, hydrogels electrode, and silicone rubber substrate. A signal-processing circuit was used in this patch to convert the sensor signal into a more stable signal (the deviation within 0.1 V), which provides a more effective method for sensing and robot control in a wireless way. Thus, the device can be used to control the movement of robots in real-time and exhibits a good stable performance. A specific algorithm was used in this patch to convert the 1D serial number into a 2D coordinate system, so that the click of the finger can be converted into a sliding track, so as to achieve the trajectory generation of a robot in a wireless way. It is believed that the device-based human–machine interaction with minimalist design has great potential in applications for contact perception, 2D control, robotics, and wearable electronics.

Flexible pressure sensors are widely applied in tactile perception, fingerprint recognition, medical monitoring, human–machine interfaces, and the Internet of Things. Among them, flexible capacitive pressure sensors have the advantages of low energy consumption, slight signal drift, and high response repeatability. However, current research on flexible capacitive pressure sensors focuses on optimizing the dielectric layer for improved sensitivity and pressure response range. Moreover, complicated and time-consuming fabrication methods are commonly applied to generate microstructure dielectric layers. Here, we propose a rapid and straightforward fabrication approach to prototyping flexible capacitive pressure sensors based on porous electrodes. Laser-induced graphene (LIG) is produced on both sides of the polyimide paper, resulting in paired compressible electrodes with 3D porous structures. When the elastic LIG electrodes are compressed, the effective electrode area, the relative distance between electrodes, and the dielectric property vary accordingly, thereby generating a sensitive pressure sensor in a relatively large working range (0–9.6 kPa). The sensitivity of the sensor is up to 7.71%/kPa−1, and it can detect pressure as small as 10 Pa. The simple and robust structure allows the sensor to produce quick and repeatable responses. Our pressure sensor exhibits broad potential in practical applications in health monitoring, given its outstanding comprehensive performance combined with its simple and quick fabrication method.

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