No abstract

with smart devices, is driven by reliable power. With the continuous development of microelectromechanical systems and the Internet of Things (IoT), many small electronic devices, which require a sustainable, portable, distributed, wireless, and even implantable power source, are increasingly widely used in daily life and industrial monitoring environments. [1] However, traditional power supply solutions, which include electric cables and batteries, cannot fully satisfy their special demands. [2] Fortunately, mechanical energy, which is widely present in the environment, such as via wind and water flow, contains a large amount of easily accessible energy. [3] Regarding mechanical energy harvesting techniques, until now, four main energy conversion mechanisms are used: electromagnetic, [4] piezoelectric, [5] electrostatic, [6] and triboelectric. [7] In particular, triboelectric nanogenerators (TENGs), which were first described by Wang and coworkers in 2012 [8] and are based on the triboelectrification effect and electrostatic induction, are becoming the most important devices since they have many advantages, such as simple fabrication, light weight, low cost, high output voltage, and high durability, especially for human-related activities. Recently, Harvesting wind energy and water flow energy from the living environment to efficiently and conveniently power many small electric devices at home is becoming increasingly important for the development of the smart home system. Triboelectric nanogenerators (TENGs) are considered to be one of the most effective devices to harness various types of mechanical energy. Here, an easily assembled electromagnetic-triboelectric hybrid nanogenerator (EANG) driven by magnetic coupling is reported. The introduction of magnetic coupling makes it easy to package, maintain, and assemble a nanogenerator (NG), so its performance is very stable regardless of environmental variations. A sliding freestanding mode TENG and a rotary electromagnetic generator (EMG) are integrated to improve their output and broaden the frequency range of external energy. It is shown that the EANG can be conveniently integrated with a wind cup or water turbine and harvest fluid energy to power small electronic devices, such as a humidity sensor and temperature sensor. Moreover, a NG can be used as a self-powered flow sensor to monitor the flow rate of outdoor wind and tap water. These results can be used to help solve practical problems regarding energy supplying and sensing in a smart home, smart building, and smart city.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.

A self-powered microfluidic system based on a rotary triboelectric nanogenerator can realize moving, splitting, merging, mixing and chemical transporting of droplets.

Triboelectric nanogeneration is a burgeoning and promising technology for harvesting low-frequency mechanical energy from the environment, but the energy conversion efficiency and service life of the triboelectric nanogenerator (TENG) device are limited by the inevitable frictional resistance between the tribo-surfaces. Herein, we propose an electrostatic induction nanogenerator (EING) circulation network (EICN) by integrating an arbitrary number of EING units for harvesting low-frequency mechanical energy. Because of absolute conquering of the friction resistance between the tribo-surfaces, the average power density of the EING device in the EICN by the initial charge injection (from a TENG or a power supply) is more than a 15-fold enhancement compared with the previous swing-structured TENG. The EICN can recover to the stable and optimal electrical output state in 90 s without external charge injection, even if the external triggering interrupts for 40 min and then restarts, demonstrating the excellent application feasibility of this strategy. To display the practical application scenario for harvesting large-scale mechanical energy from the environment, a high-performance and ultralow-friction TENG is designed for the initial charge injection to the EICN. Moreover, portable electronic devices are powered successfully to realize the self-powered sensing and remote marine environmental monitoring when an EICN with three EINGs is triggered by the real water wave. This EICN strategy not only can harvest low-frequency swing type mechanical energy but also has the capacity of harvesting the rotational mechanical energy after reasonable structure modification, providing an excellent candidate for large-scale blue energy harvesting in practical applications.