Preparation Of Ordered Microstructured Carbon Thin Films And Self-driven Microfluidic Power Generation

With the development of society,energy is more and more important for people's production and life.The continuous advancement of science and technology enables people to obtain energy from the environment in a variety of ways,providing a variety of solutions to the energy crisis.Abundant water resources in the natural environment make the interface between solids and liquids ubiquitous.It has been observed long ago that electrical signals are generated when solid-liquid interfaces interact,but these electrical signals are relatively weak,making them difficult to apply.In recent years,with the rapid development of micro-nano technology,people have found new solid-liquid interface interactions in carbon substrates such as carbon nanotubes and graphene to produce strong electrical effects,such as: humidity power generation,fluid flow power generation,Droplet movement power generation,etc.,is expected to become a new energy supply method.However,these new power generation methods often require external driving devices,or special environmental conditions such as high humidity and high liquid ion concentration differences.Therefore,how to realize the "pumpless" power generation and improve the environmental adaptability remains to be further studied.Studies have shown that ordered micro/nano structures can provide strong capillary forces and can achieve self-drive of liquids.In this paper,inspired by the ordered parallel groove structure of rice leaves and the ordered through-hole structure of large trees,a bionic ordered structure,namely a parallel groove structure and an ordered porous graphene carbon film structure,was prepared by the directional icetemplate method.Sequential porous structure has low flow resistance,high capillary force,and can achieve rapid self-drive of microfluids.Then carbon materials are introduced to realize microfluid self-driven power generation,and the reasons for microfluid power generation are further analyzed.The influencing factors were discussed and analyzed,such as the influence of the porous structure,the influence of the geometric size,and the influence of the concentration of the ion solution,etc.,in order to obtain the best voltage output.The main research contents of this article are as follows:(1)Compare the main methods for preparing porous structures and analyze the advantages and disadvantages of various methods.From the perspective of mechanics,the process of freeze casting by the ice template method is analyzed,and the effects of freezing speed,system concentration and temperature on the porous structure of freeze casting are described.The experiments explore the preparation of ordered porous blocks,the preparation of ordered porous films,and the preparation of ordered parallel trench structures.The porous structure was characterized by scanning electron microscopy.(2)From the perspective of bionics,the parallel groove structure of rice leaf was designed,and the ordered parallel groove structure film was prepared by the directional ice template freeze casting method.The capillary force of the ordered groove microstructure can realize the rapid self-driving of the liquid,which provides the conditions for the "pumpless" of microfluidic power generation.Firstly,the output voltage of the ordered parallel-trench structured carbon film is studied.Compared with a flat carbon film without trenches,the ordered-structure film has a higher output voltage.Secondly,the structure size of the trench,the geometric size of the film,and the influence of different electrolyte solution concentrations on the output voltage were explored to obtain the optimal output voltage conditions.Finally,the maximum output power is obtained by connecting different external loads in series,and multiple films can be connected in series to obtain higher voltage output.(3)A undirectional ice template freeze-casting method is used to prepare a simulated wood oriented porous structure from a graphene oxide solution,and an ordered porous graphene film is prepared by experimental methods such as hot pressing and reduction.The micro-nano directional through holes in the film can provide strong capillary forces and achieve self-driving of the liquid.Compared with the disordered porous film structure prepared by the ordinary freeze casting method,the oriented porous film structure can achieve higher voltage output.Higher voltage output can be achieved by connecting multiple porous films in series.Utilizing the self-driven power generation characteristics of the ordered porous film,a sweat power bracelet is designed and manufactured to experimentally simulate the power generation performance of the human body when sweating a small amount and sweating a large amount,which provides microfluid power generation in wearable devices New ideas.In summary,from the perspective of bionics,this paper uses the fast,efficient,and environmentally-friendly directional ice template method to prepare ordered structures to achieve rapid self-driving of liquids;the introduction of appropriate material systems enables microfluidic self-driven power generation.Because the prepared ordered porous structure has the characteristics of larger solid-liquid contact area,small flow resistance and stable structure,a higher stable voltage is obtained.Design and prepare sweat power bracelet to collect human sweat energy.This research provides new ideas for the application of microfluidic power generation in wearable devices.