Research And Sensing Application Of Natural Biofilm Tribopositive Material Based-triboelectric Nanogenerator

With the rapid development and changes of technology and economic society,the demand for flexible,portable and wearable electronic devices has increased sharply.The triboelectric nanogenerator（TENG）,which combines energy collection and sensing,has become a research hotspot in the scientific community since it was invented in 2012.Based on the coupling effect of continuous friction electrification and electrostatic induction,Maxwell’s displacement current and surface polarization changes as the principles and basic theories,TENG provides a solution for decentralized energy supply and self-powered sensing.However,most of the existing friction material sequence lists are synthetic polymers,which are not biocompatible and reproducible,and their use is limited.The deepening of the concept of sustainable development has made natural organisms and their derivative materials began to be widely used in various fields.Their wide sources,rich natural functional groups,and easy processing are expected to become a part of the new generation of high-performance and environmentally friendly TENG.And TENG’s advantages as a clean energy source with simple and safe preparation are also expanded.However,the current research on the triboelectric properties of biomaterials is still limited.Therefore,the effective development and application of natural tribopositive materials is very necessary.Because the output power density of TENG has a quadratic correlation with its surface charge density,the surface charge generation and accumulation capabilities of natural tribopositive materials can be further optimized through structural optimization or material composite or other methods,and then the output performance can be improved.This topic starts with the less researched tribopositive materials,Firstly,Zein（Zein）,which is easy to form a film and can be spun in natural protein materials,was selected as the base material,and the electrical output performance was further improved through different surface microstructure construction processes;In addition,sodium alginate（SA）,one of the natural polysaccharides with more adhesion advantages,was also used as the friction substrate to prepare a composite friction film directly on the conductive fabric to further improve the triboelectric performance of the bio-based tribopositive film and simplify the process.And then suitable structure was chosen to assemble TENG to test its output performance and perform sensing applications.The specific research contents and results are as follows:（1）The smooth film（Zein-P）,rough porous film（Zein-SP）,fiber film with columnar structure（Zein-ES）and fiber film with flat ribbon structure（Zein-AC）were compared by casting and electrostatic spinning as tribopositive materizal for TENG,respectively,to explore the influence of different surface microstructures on the output electrical performance of TENG.The research results indicate that compared with the Zein-P,The surface roughness and porous structure of Zein-SP makes the open-circuit voltage（Voc）,short-circuit current（Isc）and transferred charge（Qsc）increased by 150%,67%,and 100%,respectively,while the electrospun fiber membrane increases the open circuit voltage by more than 8 times.Among them,the V_oc、I_sc、Q_sc of the Zein-AC,under the condition of 2.3 Hz,6 N force and 2 cm×2 cm contact area,approximately 2 times that of Zein-ES.Subsequently,a series of output performance tests of Zein-AC film-based TENG with the best output performance and hand motion sensing applications were carried out.It can sense different force methods and different degrees of bending,and can be used as a sensor.（2）SG and SA/Al₂O₃ composite fabric-based tribopositive materials were prepared on conductive fabrics with SA polysaccharides as matrix materials and polar small molecule glycerin and Al₂O₃ nanoparticles as modified additives,and the dielectric constants were significantly improved.The electrical output performance of composite fabric-based TENG with 4%glycerol incorporation and 0.1%Al₂O₃ dispersion concentration are the best.On this basis,SG/Al₂O₃（SA/glycerin/nano Al₂O₃ hybrid system）composite fabric-based TENG was prepared to explore the influence of synergy on the electrical output performance of TENG.Compared with SA-TENG,SG/Al₂O₃-TENG has an increase of 525%,800%and 200%in V_oc、I_sc、Q_sc,respectively.,and compared with SG-TENG by 22%,45%,and 29%respectively,while basically the same as SA/Al₂O₃-TENG.Besides,the flexibility of the film and the fastness of bonding with the conductive fabric have been improved,combining the advantages of the two fillers.And the air-tight TENG was designed and prepared to reduce the influence of the external environment on the output.In the end,the SG/Al₂O₃composite fabric was used as a tribopositive material,and sensor application of human hand and neck has verified its great application potential in the field of human health monitoring and sound signal conversion sensing.