| With the development of advanced technologies such as the Internet of Things,big data and artificial intelligence,tens of billions of distributed sensors are widely used in health monitoring,environmental monitoring,smart homes,smart transportation and infrastructure monitoring for achieving real-time control and obtaining useful information,it takes less energy to drive a single sensor,but it will generate a huge energy consumption to drivie tens of billions of sensors will.Sensors powered by wired means have problems such as redundant cables and electromagnetic interference,traditional battery-based sensors possess inherent drawbacks such as short life,limited capacity,regular charging,frequent replacement and high risk of environmental pollution,which cannot meet future sustainable and environmentally friendly energy needs.Therefore,it has become an inevitable trend to harvesting energy from the environment to achieve self-driven and sustainable operation of electronic devices.In 2012,Prof.Zhonglin Wang’s group firstly proposed a triboelectric nanogenerator(TENG)based on triboelectric effect and electrostatic induction,which had the advantages of light weight,many material options,easy fabrication and low cost,the technology has now been proven to convert most forms of mechanical energy in the surrounding environment into electrical output,which shows great potential in achieving self-driven and sustainable operation of electronic devices.However,in the process of industrialization and practicalization of TENG,it is still challenging to design and manufacture TENGs that can adapt to different application scenarios with high efficiency and excellent durability characteristics.It is one of the important ways to achieve excellent performance of TENGs in energy harvesting and sensing monitoring applications through rational structural design.Bionics provides new methods and ideas for various challenges faced in scientific innovation and technological research.Creatures have evolved over billions of years of existence,and their have long evolved into optimal combinations for their survival environments.To meet different needs,imitating and learning the structural characteristics of organisms will provide inspiration for the design of efficient TENG.In this paper,from the perspective of optimizing the structural design,with the objectives of improving the applicability of TENG,improving the output performance and stability of TENG,and designing high-efficiency sensors based on TENG,four efficient TENGs with unique structure and excellent performance are designed and manufactured based on the principle of triboelectrification and electrostatic induction phenomenon by imitating fish scale structure,imitating coaxial counter-rotating propeller structure,fish lateral line system and Archimedes helix structure.Based on the structural composition,theoretical model and working principle of TENGs,the intrinsic connection between the structures and their respective excellent performance was revealed,and the effects of the constituent elements and external excitation on the output performance of TENGs were tested separately,and finally the applicability of TENGs in energy harvesting and sensing monitoring was explored,with the following research highlights.(1)To address the problem that TENG based on special structure electrodes cannot harvest energy in a specific direction due to its strictly symmetric electrode structure.Inspired by the scale structure of the arapaima gigas,in this paper,a fish-scale imitation electrode structure is proposed,and by establishing a theoretical model of the current output characteristics of the electrode structure and its structural features,it was revealed that the problem that the TENG based on the special structure electrode cannot achieve omnidirectional energy harvesting was solved due to the periodic symmetric arrangement of the fish-scale imitation electrode structure and the curved shape of each side of the electrode.Based on this,this paper designed and manufactured a bionic TENG with fish scale imitation electrode structure to realized planar omnidirectional energy,rotational energy harvesting and rotational state monitoring.In terms of manufacturing method,the flexible circuit board manufacturing process is used to encapsulate the fish-scale electrode structure with polyethylene terephthalate film,which avoids direct friction between the electrode and the slider,and enhances the durability of TENG,making it curlable,foldable and adaptable,which can change its shape according to actual needs and can be applied to different scenarios.For example,in planar sliding mode,the bionic TENG can be used to collect the energy generated by the mouse sliding in the plane,and the electricity generated can light up dozens of LEDs at the same time.In rotation mode,the Bionic TENG can be used to collect energy generated by rotational motion to power other electronic devices.When the bionic TENG is used as a self-powered sensor for the monitoring of rotation status,the monitoring of rotation speed is achieved by the number of pulses output per unit time,the size of output current and the brightness of the LED.This work provided an effective strategy for dual-mode energy harvesting and self-driven rotation state monitoring.(2)To address the challenge that the mechanical motion in nature with low frequency,random and limited amplitude is converted into electrical energy,and to address the technical problem that sufficient friction between the directly contacted tribo-pair is necessary for generating more tribo-charges and higher output power density,but it can cause severe wear to the friction layer material.Inspired by the coaxial reversing propeller structure,firstly,a coaxial reversing unit was designed and the mechanism of efficient motion transfer of the coaxial reversing unit was revealed,it could transform the mechanical motion into the high speed relative rotational motion of the independent layer and the metal electrode,whicn realized efficient motion transfer and enabled the TENG to produce a large output.Secondly,a noncontact wheel-shaped TENG with soft and dense nylon fleece was designed and the underlying mechanism of TENG output performance and durability enhancement after the introduction of nylon fleece was revealed,the introduction of nylon fleece enabled the surface charge of the independent layer to be replenished in the soft-contact mode,which enhanced the output performance of the TENG,reduced material wear,and extended the service life of the TENG.Based on the above,a soft-contact TENG based on a coaxial reversal structure was designed and fabricated in this paper,and a solution was proposed to solve this challenge and technical contradiction.The test results showed that the total transferred charge and generated electronic energy of TENG with a coaxial counter-rotating unit was improved by more than 11 times and15 times compared with conventional devices.After the introduction of nylon fluff,the maximum output voltage,the maximum output current.and the maximum charge transfer of TENG were expanded to 3.86 times,3.79 times,and 3.75 times of the original one respectively.After 500,000 cycles,the maximum output voltage didn’t decay significantly.The TENG was successfully used to harvest energy generated by random body movements to power other electronic devices.This work provided an effective way for the efficient and stable collection of low-frequency,random and limited-amplitude mechanical motions in nature.(3)Developing self-actuated sensors that are waterproof,shape adaptive,sensitive to subtle mechanical shifts,and scalable is an important requirement for the next generation of wearable electronics.Inspired by the fish lateral line system,a bionic TENG consisting of a cylindrical porous silicone rubber with spiral silver-plated nylon fibers inside and a latex balloon with nylon fleece on the inner surface was designed in this paper to mimic the fish lateral line system,owing to the synergistic effect of the latex balloon,silicone rubber and spiral structure of silverplated nylon yarn,it was waterproof,shape adaptive and stretchable,which revealed that due to the synergistic effect of the porous structure of the silicone rubber surface and nylon fleece,a significant increase in surface area beyond the structural limit was achieved to enhance the output performance of the bionic TENG.Based on this,a fish-like lateral line system of TENG with waterproof,shape adaptive,stretchable and sensitive to fine mechanical displacement characteristics was successfully fabricated in this paper using electrostatic flocking process and sacrificial template method.The experimental results showed that the bionic TENG could adapt to any three-dimensional surface and various deformations,and withstand tensile strain of more than 140%.The maximum output voltage,output current,and transferred charge of the TENG with the porous and fleece structures were expanded by 3.92 times,3.43 times,and 3.31 times,respectively,compared to that without the structure.The TENG was successfully used for human respiratory status monitoring,realized the recognition of respiratory pattern,respiratory rate,respiratory speed and inhalation-expiration ratio,and transmitting information as a humancomputer interaction interface.This research work provided new advances in the development of efficient,wearable,and flexible sensing technologies with promising applications in areas such as respiratory motion monitoring,rehabilitation therapy,and virtual reality.(4)The rapid development of rehabilitative sports training,robotics and virtual reality technologies has stimulated a higher demand for joint rotation state monitoring.However,there is still a lack of cost,energy efficient and low-computational complexity solutions for this specific need.In this paper,from the perspective of structural design,an Archimedean spiral electrode was proposed and integrated with the radial array electrode to design a dual-mode TENG.By establishing a theoretical model of the voltage output characteristics of the dualmode TENG and its structural characteristics,the sensing mechanism of the dual-mode TENG for joint rotation state monitoring was revealed,the monitoring of joint rotation angle and rotation speed was achieved by calculating the number of pulses generated by the radial array electrodes,and the identification of joint rotation direction was achieved by the increasing and decreasing trend of the voltage signal output from the Archimedean spiral electrodes,the single structural design reduces the manufacturing complexity,and the simple sensing mechanism simplifies the signal processing algorithm.Based on this,a dual-mode TENG was fabricated in this paper by using a flexible circuit board manufacturing process and encapsulating the electrode structure with PET film.This TENG was integrated with a fixed bracket to achieve human joint rotation state monitoring and virtual robot joint motion control.This research work provided a cost-effective,energy-efficient and low-computational complexity solution for joint rotation state monitoring,which had a wide range of promising applications such as motion monitoring,robotics,rehabilitation therapy and virtual reality. |
PDF Full Text Request