# Research Progress in Fluid Energy Collection Based on Friction Nanogenerators
## 1 Introduction  
The evolution of energy streaks across the sky has been lighting up the dawn of technological development. The price of chemical energy has gradually deviated from the ideal acceptable range, energy usage has increased sharply every day, and collecting environmental energy has been favored by researchers. It is also extremely difficult to build and maintain a certain amount of power plants in countries and regions with high construction costs, high site selection requirements, large maintenance and labor needs, backward living standards, or complex geographical environments [1, 2, 3, 4]. Entering the 21 st century, the Internet of Things has achieved milestone development. Whether it is medical health, daily life peripherals, or even industrial production and transportation, there are a large number of sensors, and the power gap is only increasing. The distinctive feature of this type of power demand is that it is not physically located and spreads across various spaces. Assuming battery power is used, the pollution to the environment will be immeasurable. Frequent replacement of batteries is likely to result in uncontrollable front-end and post-production costs and maintenance costs. In order to solve these problems, a large number of green energy supply devices have been developed, such as solar photoelectric converters [5, 6], wind turbines [7], thermoelectric generators [8, 9], fuel cells, etc. Solar converters require a large initial investment, occupy a large area, and have slow cost recovery. Wind turbines are similar to the former, but more attention should be paid to safety and noise issues. Throughout human history, the triboelectric effect has been seen as a detrimental occurrence in science and technology. Uncontrolled high-voltage static electricity consumes energy and increases the danger of electromagnetic interference andelectronic component failure. It must be minimized, if not completely protected. There are several motion modes, including heave, rotation, and vibration, while gathering fluid kinetic energy. These energies have high entropy, low frequency, and chaos. In the long river of human exploration of science and technology, the frictional electrification effect has long been regarded as a negative phenomenon. Uncontrolled high-voltage static electricity not only carries the risk of electromagnetic interference and breakdown of electronic components but also wastes energy, which needs to be reduced or even shielded as much as possible. In terms of fluid kinetic energy collection, there are motion modes such as vibration, oscillation, and rotation, which are characterized by disorder, low frequency, and high entropy. If these unnecessary high entropy fluid energies are collected using Faraday electromagnetic induction generators (EMGs) based on the law of electromagnetic induction, some EMGs need to operate under certain high-frequency motion, and some also need to exhibit certain motion trends, such as the certainty of rotation direction. Relatively speaking, the high entropy characteristics of the fluid capacity collection can lead to a significant waste of inexhaustible low-frequency vibration energy, including wave energy and wind energy. In 2012, [PERSON]'s team proposed a conversion device that utilizes the electrostatic effect, triboelectric nanogenerators [10]. In terms of cost, since the human energy revolution entered the era of electrification, most of the sources of electricity obtained by humans have come from electromagnetic induction generators (EMGs). EMG is equipped with a large number of iron cores and copper coils inside, which is costly. Unlike EMG, nanogenerators use a large amount of polymer materials, which are easy to obtain and have low manufacturing costs. In the operation of multiple single-unit parallel networking, multiple nanofriction generators can be assembled into a large-scale power storage network through specific control and energy storage circuits.