Research Of Micro-nano Energy Harvesting Technology Based On Biodegradable Materials And Its Applications

In the past decades,the fast development of micro/nano manufacturing technology has pushed electronic products into an era of miniaturization,intelligence and high level integration,and micro/nano electronic devices and systems have proliferated.In addition,the introduction and innovation of flexible electronic materials endow electronic products with laminating,elastic and even stretchable characteristics,making wearable electronic devices possible.With the rise of the Internet of Things(Io T),Artificial Intelligence(AI)and other intelligent application,wearable devices have gained extensive attention in the past decade.Now wearable devices are pervasive in many aspects of human daily life,such as intelligent healthcare,portable communication and mobile entertainment,etc.However,the burgeoning wearable devices and systems pose new challenges to energy supply.It requires a reliable,sustainable,autonomous self-powered and green power supply method.In this case,the nanogenerator has emerged as a device to convert various energy efficiently from the environment and the human body into electrical energy.The micro/nano acquisition technology has become one of the most attractive new energy acquisition technology by the researchers' innovating mechanism,optimizing structures and introducing various materials,which provides a viable solution for the energy supply of flexible wearable devices.However,the extensive use of artificial polymer materials and toxic metal materials prevents the current nanogenerators technology from becoming a truly wearable and nontoxic energy source for the human body.In these circumstances,with the introduction of biodegradable materials,this dissertation discusses the feasibility of the biodegradable nanogenerator through structural optimization design,mechanism theory simulation and electrical test analysis.Furthermore,through piezoelectric,triboelectric,and hybrid mechanism,some new high-performance wearable nanogenerators using natural lignocellulose and biodegradable silicone rubber are proposed,which implement new applications in the self-driving intelligent microsystem.The dissertation is divided into four aspects:First,piezoelectric nanogenerator(PENG)with biodegradable materials are studied based on the piezoelectric effect.In terms of material composition and performance improvement of biodegradable PENG,this study uses barium titanate nanoparticles as piezoelectric functional materials and used biodegradable silicone rubber and natural lignocellulose as substrate materials.At the same time,the effect of different mass fractions between the piezoelectric functional material and substrate materials on the electrical properties of the manufactured device is discussed.The results show that the optimal doping concentration of barium titanate nanoparticles in biodegradable silicone rubber and natural lignocellulose are 25 wt% and 10 wt%,respectively.Afterwards,a high-performance biodegradable PENG is obtained through optimizing polarization parameters.This dissertation opens a new path for biodegradable PENG with simple fabrication processes and large-scale production.Two types of biodegradable PENG with excellent output performance are successfully designed and fabricated,which are biodegradable silicone rubber piezoelectric nanogenerator and natural lignocellulose piezoelectric nanogenerator.Both types of PENG prototypes have been verified in the dissertation.Next,triboelectric nanogenerator(TENG)with biodegradable materials are studied based on the principles of triboelectric micro/nano energy collection.The dissertation focuses on the relationship between structural characteristics and device performance of biodegradable TENG,and then investigates the influence of electrode structure on the performance of biodegradable TENG.According to the parasitic capacitance effect,the electrode miniaturization structure TENG is proposed and designed.When the electrode size is reduced to 1/3 of the size of the friction interface,the electrical output is stable while the light transmittance of the device increases and the signal crosstalk reduces.Therefore,it provides a new idea for the biodegradable TENG to be used in the field of optics and human-machine interaction.Based on the asymmetric pairing of ions model and the ion migration capability model,the dissertation proposes a prototype of a single-layer triboelectric nanogenerator using natural lignocellulose,which gives a practical strategy for the application of biodegradable TENG in integrated microsystems.Then,biodegradable composite nanogenerators are studied based on the piezoelectric and triboelectric coupling effect.In the experiment,the main components of the nanogenerator are still the biodegradable silicone rubber and natural lignocellulose.Around performance optimization issues of the electrical output performance of biodegradable nanogenerator,through the analysis of different nanogenerator mechanisms and the structure's coupling,the dissertation focuses on the research into the relation between the output performances of the integration of piezoelectric nanogenerator and triboelectric nanogenerator and the total output.The dissertation provides a good way of enhancing the output power of biodegradable nanogenerator.Finally,the existing problems of biodegradable nanogenerators in practical applications and the solutions of the technical bottlenecks of solving the problems are discussed.According to the weakening of the triboelectric effect in a humid environment,through the induction of the coupling mechanism of electrostatic induction and ion conduction,as well as the design of a dedicated matching circuit,this dissertation provides a solution for the instability of power in a complex humid environment.In the aspect of the irregular low-frequency output signal of the active sensor,single-channel signal processing systems and multi-channel signal processing systems are designed to solve the insufficient accuracy of the biodegradable nanogenerator as an active sensor.In the meantime,a reconfigurable experiment and a biodegradable experiment are carried out on the biodegradable PENG to verify the reusability and degradability of the biodegradable nanogenerator and provide an effective solution of the bottleneck problems of biocompatibility and pollution-free development of micro/nano energy devices in wearable/implantable application scenarios.In conclusion,the dissertation has established various physical models on the basis of studying techniques and applications of biodegradable nanogenerators.The material selection,structural design,processing technic and performance optimization of the devices are realized through theoretical analysis.As a result,a number of the prototypes of biodegradable nanogenerators have been designed and fabricated.Biodegradable nanogenerators have achieved a variety of structural innovations and electrical output improvements.Besides,a special matching circuit and two kinds of signal processing systems are used to realize practical applications.