Grating-structured Triboelectric Nanogenerator Based Self-powred Acceleration Sensor

Acceleration sensors have a wide range of applications in earthquake early warning,human motion recognition,and vehicle motion sensing,etc.Based on their physical principle,traditional commercial acceleration sensors can be classified as capacitive,piezoresistive and piezoelectric acceleration sensors.However,capacitive and piezoresistive acceleration sensors require additional external power supply to work,while piezoelectric acceleration sensors are self-powered but have a small signal output.These characteristics of acceleration sensors limit their application in internet of things.In this paper,we propose a grating-structured freestanding triboelectric nanogenerator(GF-TENG).Real-time sensing of acceleration is achieved,and the fully assembled device enables sensing of vehicle motion and collision warning.The main research of the thesis is as follows.(1)In order to achieve real-time sensing of acceleration,the GF-TENG,which consists of a slider with one set of parallel electrodes and a stator with two sets of parallel electrodes,is fabricated.The slider slides on the stator and utilizes coupling effect of triboelectrification and electrostatic induction to generate a large self-powered AC voltage signal.By analyzing the number and trend of the voltage signal peak intervals,the values of displacement,velocity and acceleration can be obtained,the minimum resolution for displacement is 0.4 mm.After simulation and experimental optimization of the electrode width and electrode gap,the GF-TENG could even sense acceleration on a scale down to 0.8mm,and the time-varying acceleration can be well sensed.In addition,although its signal output magnitude varies with humidity,its waveform does not change and thus does not affect its sensing capability.(2)In order to extend the acceleration sensing range,the GF-TENG is combined with springs to form a grating-structured freestanding TENG based acceleration sensor.It is possible to obtain the desired acceleration sensing range by adjusting the spring constant and the mass of the mass,for example 4-45 m/s~2.For the acceleration sensor,two important parameters need to be sensed:acceleration direction and acceleration magnitude.The direction of acceleration is obtained by connecting two springs with the mass as a switch for sensing the voltage signal.For different directions of acceleration,the voltage signals appear in different channels,thus achieving the distinction of acceleration directions.Since the response time is logarithmically related to the magnitude of acceleration.Therefore,the magnitude of acceleration can be calculated from the response time of the acceleration sensor.(3)To demonstrate the capability of the acceleration sensor being applied in practice,it is installed on a model car for experiments.The acceleration sensor is able to sense the motion of the model car.As the response time is able to meet the requirements of the vehicle restraint system,the acceleration sensor has also proven to be able to open the airbag in time to protect the passengers in the event of a collision.This work broadens the application scenario of TENG-based self-powered sensors and provides new idea for the fabrication of self-powered acceleration sensors.In future research,the accuracy of acceleration sensing could be improved after the circuit fabrication process is improved.The dimension of acceleration sensors could be expanded to be applied in robotics,human motion recognition,etc.