| With the rapid development of the Internet of Things(Io T),the number of sensors has increased dramatically.How to keep these sensors powered up and running smoothly has become a major challenge for Io T systems.Traditional wireless sensor nodes are mainly battery-powered,but the battery life is limited,and the management and maintenance of the battery will increase labor costs and interrupt system operation,while the chemical waste generated by the battery will also cause environmental pollution.Therefore,obtaining energy from the environment to supply power to the sensor,thereby forming a self-driving sensor,has attracted widespread attention.The Triboelectric Nanogenerator(TENG)converts mechanical energy into electricity based on the coupling of triboelectrification and electrostatic induction,and it has many advantages of high output and efficiency,low cost,simple structure,and easy manufacturing.These advantages have wide application prospects in the field of energy harvesting and selfpowered sensors.Wind energy is considered an inexhaustible and widely distributed renewable energy.It is of great practical significance to promote the research and development of highperformance wind energy TENG and their applications in the power supply nodes of the Internet of Things.In order to achieve the above goal,this thesis introduced the combination of flow-induced vibration principle with TENG principle,innovatively designed a flexible membrane flapping type TENG,and systematically studied the movement and power generation characteristics of this generator,and further applied it to wind energy harvesting and self-powered flow rate sensor.The main results achieved are as follows:(1)Based on the power generation principle of the TENG and flow-induced vibration,this thesis has designed a structure of the flapping membrane TENG,established the equivalent circuit model of this generator,and analyzed the membrane flapping characteristics and dynamics model.Analyzed and simulated the potential distribution of flexible films in different states by using COMSOL software.These theories and analysis results have provided the basic theory for the experimental design and analysis of the flapping membrane TENG.(2)In order to improve the efficiency of wind energy harvesting,this thesis has creatively designed a TENG device with a wind barrier structure.This type of generator includes multiTENG unit stacking.Each TENG unit consists of a polymer membrane,copper electrode and support structure.The dual-side ends fixed polymer membrane will vibrate under the influence of the wind,generating an electric current due to triboelectrification between the upper and lower electrodes.The charged membrane further drives the electrons to reciprocate between the external circuits,realizing the conversion of wind energy into electrical energy.This thesis systematically analyzed the effects of thin membrane materials,the TENG unit structure parameters and quantities,and wind speed conditions on the performance of the TENG wind barrier.The study found that the optimal size of a single TENG unit is 100 × 20 × 3 mm~3.With the parallel connection of the TENG units,the output voltage,circuit and power all increase linearly.When the number of TENG units increased to 66,the output current was 440μA,and the power output was 26 m W,which successfully realized the power supply for the temperature sensor and the LED lighting system.(3)The electrical signal output by the TENG also contains external motion information,so it can be used as a self-powered sensor.Based on the thin membrane flapping triboelectric nanogenerator,this thesis designs a self-powered gas flowmeter with low pressure loss.The sensor consists of a circular pipe,two copper electrodes fixed symmetrically,and a thin membrane placed on the middle plane.One side end of the membrane is fixed;the other side is free to vibrate inside the pipe.Under the effect of the gas flow,the thin membrane continuously oscillates between the two electrodes to achieve triboelectricity and electrostatic induction,which drives the electrons to reciprocate between the two electrodes through an external circuit,forming a periodic electrical signal.In this thesis,the influence of factors such as membrane material,size,and airflow conditions on the output electrical signal of the triboelectric nanogenerator had been systematically studied.The research results show that,compared with the amplitude of voltage and current,their frequency and the average gas velocity present a clear linear relationship,and are not affected by humidity.Therefore,this thesis selected the frequency of the electrical signal as the sensing parameter of the flow velocity and flow rate and established the relationship between the dimensionless frequency and the flow rate,that is,the relationship between the Strouhal number and the Reynolds number.In addition,compared with commercial vortex flowmeters,the self-powered flowmeter designed in this thesis reduces the pressure loss by 40-60%.Through theoretical and experimental systematic research,the proposed membrane flapping triboelectric nanogenerator in this thesis can not only be used for wind energy harvesting,but also the electrical signal generated by it can be used for the sensing parameters of flow velocity and flow rate,and then can be used for self-powered flow velocity and flow sensors.This expands the application range of triboelectric nanogenerators also provided a new idea for the power supply and self-powered wireless sensor nodes of the Internet of Things. |
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