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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Marine mammals relying on tactile perception for hunting are able to achieve a remarkably high prey capture rate without visual or acoustic perception. Here, a self-powered triboelectric palm-like tactile sensor (TPTS) is designed to build a tactile perceptual system for underwater vehicles. It is enabled by a three-dimensional structure that mimics the leathery, granular texture in the palms of sea otters, whose inner neural architecture provides additional clues indicating the importance of tactile information. With the assistance of palm structure and triboelectric nanogenerator technology, the proposed TPTS has the ability to detect and distinguish normal and shear external load in real-time and approximate the external stimulation area, especially not affected by the touch frequency, that is, it can maintain stable performance under high-frequency contact. The results show that the TPTS is a promising tool for integration into grippers mounted on underwater vehicles to complete numerous underwater tasks.

remains a challenge, especially the perception of ocean waves motion. [1][2][3][4] Ocean wave sensing devices based on additional complex mechanical and hydraulic structures typically transform the multidirectional wave motion into linear reciprocation or rotation of these structures to generate electric signals. However, some such devices are restrained by several drawbacks, including lower accuracy and robustness and expensive maintenance costs. Furthermore, impeller-type sensors increase the risk of collision between marine animals, [5] remote radar sensors impact the lives of marine animals due to the generation of a strong electromagnetic field, [6] and the laying of large sensing equipment generates noises and disturbances to marine animals [7] and changes hydrodynamic conditions. Conventional signal processing strategies have been demonstrated to possibly provide insufficient information to estimate ocean wave cues, resulting in difficulty to meet the requirements of high accuracy (error range in the order of 1 m). [8,9] Moreover, most of these ocean wave sensors need an external power supply, and the high cost of power supply limits their development. Therefore, novel ocean wave sensing techniques are still an open research topic.The design of efficient ocean wave sensors for monitoring the marine environment and revealing dynamic changes has been a major challenge. In this study, a self-powered bionic coral wave sensor (BCWS) based on a triboelectric nanogenerator is proposed. The BCWS captures wave data, which are useful for marine engineering construction, marine resource development, and marine disaster warning. It is mainly composed of triboelectric perceiving units (60 mm in length, 10 mm in width, and 1.5 mm in thickness) encapsulated in coral tentacles, a fixation mechanism, a buoyancy tray, and a counterweight mechanism. With the help of its bio-inspired structural design, the BCWS effectively improves the signal response time and sensitivity in the 3D perception of wave information. In particular, the coral tentacles stimulated by a load cause contact-separation between fluorinated ethylene propylene and conductive ink electrodes, thereby generating electric signals. This analysis of the experimental data reveals that the BCWS perceives wave height, wave frequency, wave period, and wave direction with millimeter accuracy. To demonstrate the applicability and stability of the BCWS, several of its potential functions are illustrated, including controlling light emitting diodes, perceiving wave information in the ocean, and assisting overboard rescue. The results show that the BCWS provides an intelligent solution for modern marine monitoring.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/admt.202101098.

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