Energy Harvesters And Self-powered Sensors Based On Triboelectric Effect

In the past decades,the Internet of Things(Io Ts)technology has been an important part of the current information technology and widely applied in health monitoring,environmental protection,infrastructure monitoring and etc.However,the rapid development of Io Ts technology may be shadowed by the traditional unsustainable power units for huge numbers of various sensors distributed in environment.A possible solution is to make each device self-powered by harvesting energy from the environment.This idea was first proposed by Prof.Zhonglin Wang in 2006.Later,Prof.Wang invents the“Triboelectric Nanogenerator(TENG)”in 2012.With the advantages of simple-preparation,low-cost and high-efficiency,TENG shows huge potential in harvesting low-frequency mechanical energy and realizing self-powered Io Ts technology.Based on the triboelectric effect,this thesis develops a series of basic application research about high-performance TENG and self-powered sensors by preparing triboelectric electrode materials,designing device structure,utilizing new processing technology,and coupling other effects.The main contents of this thesis are as follows:(1)Aiming at the problem of the random and arbitrary-direction wind energy harvesting,we design a flexible,transparent,lawn-structured triboelectric nanogenerator.The systematic optimization of device size,spacing,materials,and arrayed design significantly improves output current and power density of TENG.The output performance at different wind speeds and directions demonstrates that the lawn-structured TENG can effectively harvest wind energy with ultra-wide wind speed range and arbitrary direction.The hydrophobic surface of electrode material endows TENG excellent self-cleaning performance and enhanced environmental stability.If ten-level arrayed TENG is piled onto a common house roof with an area of 300 m~2,the expected output will hypothetically reach 7.11 k W(power)and 23.7 W/m~2(power density).Thus,this work provides a simple,low-cost,and high-performance approach for wind energy harvester filed.(2)The commercialization of TENG need continuously improve the output performance.In the thesis,a simple,low-cost and multifunctional TENG is presented based on the porous micro-nickel foam(PMNF)for harvesting the natural vibration energy.With the surface modification of PMNF toward the positive polarity,the PMNF based TENG outputs an open-circuit voltage up to 187.8 V and a short-circuit current of 71.9μΑwith the peak power density of 3.7 W/m~2at the resonance frequency of 13.9 Hz by harvesting vibration energy.Besides,through optimizing the device size and weight,the PMNF based TENG can harvest the ultra-wide-range vibration energy.This work supplied an effect approach to harvest the vibration energy from highways,railways,and tunnels in remote mountain areas.(3)To meet the new power-supplying requirements of flexible wearable electronics for the shape and multi-function,the printed multimaterial matrix for multilevel mechanical-responsive TENG with on-demand reconfiguration of shape is reported.Multimaterial structures with location-specific properties,such as tensile modulus,failure stress,and glass transition temperature for controlled deformation,crack propagation path,and sequential shape memory,are directly printed.The printed multimaterial structure with sequential deformation behavior is used to fabricate a multilevel-TENG(m TENG)device for multiple level mechanical energy harvesters and sensors.This work provides a new approach to customize and functionalize of TENG devices for functional wearable electronics as energy harvester and sensors.(4)To solve the eco-unfriendly problem of polymer electrode materials of TENG,a cellulose II aerogel-based TENG is fabricated as mechanical energy harvester and self-powered sensor.The cellulose II aerogels were fabricated in a dissolution-regeneration process via a green solvent of inorganic molten salt hydrate.The as-fabricated cellulose II aerogel exhibited an interconnected open-pore 3D network structure,higher degree of flexibility,high porosity,and high surface area of 221.3 m~2/g.Given its architectural merits,the cellulose II aerogel-based TENG presented an excellent mechanical response sensitivity and high electrical performance output.Blending with other natural polysaccharides,i.e.,chitosan and alginic acid,we synthesized composite cellulose II aerogels with introduced electron-donating and electron-withdrawing groups,which significantly enhanced the output performance of the cellulose II aerogel-based TENG.The combination of cellulose II aerogel and TENG led to a high performance and eco-friendly energy harvesting and self-powered system.(5)The era of the Io Ts has challenged the traditional interacting sensors,urgently need new sensors featured as self-powered,multi-interaction and high sensitivity.In this thesis,a self-powered artificial skin based on triboelectrification-induced electroluminescence(TIEL)effect was fabricated.Based on optical signal,this artificial skin not only can real-time detect various mechanical stimuli such as pressure,strain and shear stress,but also map their distribution.The visualized surface promotes two bionic applications:mechanically drived visible light communication systems and wearable gesture recognition gloves.This new-type optical signal based artificial skin for the first time realizes multi-kind force sensing and visual interaction in a self-powered way,avoid static noise in life and is suitable for large-scale production.(6)Displacement and velocity sensors have ubiquitous applications in the industrial and scientific fields.However,the existing technologies have to make a trade-off among resolution,working distance and complexity.In this thesis,a self-powered,highly sensitive,optical motion sensing(OMS)matrix based on triboelectrification-induced electroluminescence(TIEL)effect is designed.During the motion process,the displacement and velocity can be detected in real time by monitoring the optical signals generated by the sensing matrix itself.The self-powered OMS matrix can detect the multiple speed ranges from10μm/s to 4000μm/s,exhibiting excellent linear response sensitivity.In the measurement of 10 cm long stepping displacement,the real-time average velocity deviation is less than 2%and the displacement deviation is less than 4%.Moreover,this self-powered OMS matrix is also applicable for the rotational speed monitoring.This motion sensing matrix based on TIEL effect presents many significant advantages such as self-powered technology,high sensitivity,simple preparation process,large dynamic detection range and anti-electromagnetic interference.It has great potential in automation,manufacturing,process control,portable equipment,Io Ts and other fields.