| With the advance of science and technology,the application scenarios of robots have extended from the industrial field to special fields such as medical rehabilitation,field exploration and man-machine collaboration,which puts forward requirements for its compliance and environmental adaptability.The appearance of soft robot provides a new way to meet this requirement.Different from the hard robot driven by the motordrive system,the soft robot is driven by artificial muscles,which can produce response deformation under the external incentive,and provide power for the soft robot in its muscle-like distributed drive way.Therefore,the development of high-performance artificial muscles is of great significance to the development of soft robots.Ionic polymer-metal composite(IPMC)is an electroactive artificial muscle that can be bent and deformed by ion migration.It is composed of an ion exchange membrane and a surface electrode in the middle.It has the advantages of simple structure,light weight,good compliance,no noise,and low driving voltage.It has good application prospects in soft robots,MEMS,flexible electronics and other fields.However,the traditional IPMC with precious metal electrode has insufficient actuation performance and is difficult to operate in air for a long time,which limits its practical application to a certain extent.Therefore,how to balance the improvement of actuation performance and durability has become one of the bottlenecks to be solved urgently in the development of high-performance IPMC artificial muscles.In view of the above shortcomings,this paper takes the IPMC artificial muscle as the research object,studies its influence on the actuation performance through the design of the electrode interface and electrode surface,and analyzes the failure mechanism of the IPMC;and takes this as the starting point to optimize the design of the IPMC material system,and develops a new type of flexible electrode and IPMC with high stability and long-term efficiency.Then,through the modification of the base film,the actuation speed of the IPMC is further improved and its actuation performance is enhanced,and a high-performance IPMC artificial muscle with large deformation,fast response and high durability is developed.Finally,taking advantage of the excellent electrical actuation characteristics of the developed IPMC,intelligent flexible drive devices suitable for different scenarios are designed,and the integration of materials,structures and functions is realized,and its practical application in different functions is explored.This paper mainly carried out the following research work:(1)Directional texture was introduced into the electrode interface to study its effect on the actuation performance of IPMC and its anisotropy.Directional fringe microstructures were constructed on the surface of Nafion film using sandpaper,and the influence of this interface texture with highly uniform orientation on the actuation performance of IPMC was studied.It was found that the interface texture could increase the interface between the electrode and the substrate film,and improve the capacitance performance of IPMC;in addition,the actuation performance of four kinds of interfacial textured IPMC was studied.It was found that different texture angles had different degrees of gain for IPMC,and showed a sequence of M90 > M45 > M0 > MN in terms of actuation displacement and blocking force.This is due to the difference in the bending stiffness of IPMC in the transverse direction and the uneven stress distribution caused by the anisotropy of the texture.(2)The effect of Au electrode coating on the actuation performance of IPMC was analyzed,and the failure mechanism of metal electrode IPMC was studied and revealed.Using ion sputtering method,Au electrode layer was deposited on the Pt electrode layer of IPMC to form a high-quality Pt/Au composite electrode.The effect on the actuation performance of IPMC was studied,and the failure mechanism of IPMC was analyzed.Through observation and characterization,it was found that there are a large number of cracks on the surface of the electroless plated Pt electrode that affect its conductivity and IPMC actuation performance,and the deposition of the Au electrode can repair these cracks in situ,thus forming a high-quality communication surface on the defective electrode,which is conducive to the rapid transfer of charge and the establishment of a stable electric field,and can also reduce the loss of the working medium;the Pt/Au composite electrode exhibits a larger actuation displacement and nearly twice the effective actuation life.Through comparison,it is found that the factors that make it difficult for IPMC to operate for a long time are mainly the function of the electrode conducting electrons and the loss of the working medium in the natural volatilization and actuation state.(3)A long-lasting IPMC based on biomass porous carbon flexible electrode was designed and fabricated,and its durability was proven after testing.Based on the analysis of IPMC failure mechanism,following the principle of low resistance and high capacitance,a cost-effective new flexible electrode is designed and prepared,that is,a three-dimensional network electrode composed of rice husk-based porous carbon and PEDOT: PSS from a wide range of sources is used to provide a structural basis for the transfer of electrons and the further diffusion of ions,and an ionic liquid is used as a stable working medium;BPC/PP IPMC is fabricated by layer assembly method and compared with the control group.It is found that it is higher than capacitance,lower contact resistance,higher ionic conductivity,and better actuation displacement;most importantly,BPC/PP IPMC with a new flexible electrode and a stable working medium can continue to swing for 550,000 cycles,showing very good durability.(4)The construction method of high-efficiency ion channels in IPMC is proposed,which realizes the superior performance of both large deformation and fast response.On the basis of the soft porous carbon electrode,the functionalized metal-organic framework MOF material with ordered porous structure is used to modify the Nafion base membrane,that is,to open up high-efficiency ion channels in the Nafion base membrane to promote the migration and diffusion of internal cations;the introduction of MOF increases the specific capacitance and ionic conductivity of IPMC,and the efficient transmission of ions in the base membrane further improves the actuation performance and deformation speed of MOF-IPMC,which is conducive to realizing the superior performance of IPMC integrating large deformation and fast response.(5)Based on IPMC,a series of soft robots and soft actuation devices with different functions have been developed,and the IPMC has been tested and verified to have good repeatability and applicability.Using the decent actuation characteristics of IPMC,soft robots such as inchworm-like bionic crawling robot,flexible finger and flexible actuation devices such as flexible robotic arm and logic circuit switch are designed and manufactured.IPMC can effectively perform self-actuation and load actuation,and can realize the simulation of animal behavior and interaction with target objects,showing the characteristics of high repeatability and good applicability.In this paper,the influence of the morphological structure of the electrode interface and surface on the actuation performance of IPMC and the failure mechanism of the precious metal electrode IPMC were analyzed.The material system was gradually optimized,and a new type of IPMC artificial muscle was fabricated by layer-by-layer assembly.After a number of tests,the structure-activity relationship between the porous carbon electrodes,MOF-modified base membrane and the actuation deformation of IPMC was studied.On the basis of the above work,the research and development of soft devices based on IPMC was carried out.This word provided a new idea and approach for the manufacture and application of a new generation of low-cost,highenergy-efficient IPMC artificial muscles. |
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