Research On Elastic Circuit Printing Technology For Flexible Electronics Applications

Flexible electronic technology is a popular research topic in consumer electronics at home and abroad.Functional flexible materials are the core of flexible electronic technology,but the conductive material system based on traditional rigid materials can not meet the requirements of tensile bending strain,so it is difficult to be applied in flexible electronic technology.In order to solve this problem,people have carried out research work on composite elastic conductor materials.With this kind of composite material,combined with advanced flexible printing technology,the traditional electronic circuit can be flexible and integrated into flexible wearable applications,so as to further promote the development of interdisciplinary fields such as human-computer interaction,optical display,medical and health.In this thesis,the applications of flexible wearable electronics were focused on.Taking composite elastic conductor as the research object,the dispensing direct writing technology was taken as the technological mean to carry out this research work.The electrical and mechanical properties of the composite elastic conductor at different proportions and their wearable application in finger motion perception were explored.The specific research works include the following aspects:(1)Preparation and properties of composite elastic conductor.An elastic conductor material composed of polyurethane flexible polymer with silver micron conductive filler and its preparation process were proposed.The composite elastic conductor material was characterized by Raman spectroscopy,scanning electron microscope imaging(SEM),energy dispersive spectroscopy(EDS),and the conductive mechanism of the material was explored and verified.The mechanical and electrical properties of the composite under stress and strain were tested,and the tensile limit and elastic modulus of the composite under different proportions were analyzed.A shear lap experiment was conducted to test the bonding strength of the composite elastic conductor and explore the effect of annealing process on the bonding strength.This part provides the material preparation basis for the next step of the elastic circuit printing technology research.(2)Research on elastic circuits printing technology based on composite elastic conductor.Considering the fluid mechanics properties of the composite elastic conductors,using glue direct writing technique to pattern processing,the process parameters’ influence on machining accuracy and resistivity were explored,such as pressure,direct writing,the needle diameter,substrate,printing speed,thus the processing technological parameters suitable for this kind of composite material were obtained.On this basis,the common parts of flexible circuit such as wire,electrode and variable resistance were printed.A flexible hybrid electronic circuit was printed by combining flexible and rigid devices.A flexible array LED display circuit and a flexible electro-optic signal sensing circuit were prepared.This part lays a technological foundation for the fabrication of flexible sensor parts discussed in the next chapter.(3)Application research of direct writing flexible devices based on dispensing.Based on the prepared composite elastic conductor,strain sensors were printed by dispensing direct writing process.The performance of the sensor under different curing processes was tested,and the response time and dynamic response performance of the sensor under different strains were compared.The sensors were transplanted to the glove to realize the human knuckle bending motion sensing and then a sensing system which can control the optical signal was designed.Using the combination of hardware and software,a human-computer interactive wireless sensing mouse was designed to realize the function of drawing patterns on the interactive interface.The heating performance of the patch heater prepared by the dispensing direct writing technology was studied,and the heating temperature of the patch was controlled under different voltages.This part realizes the application of composite elastic conductor in wearable devices,which is expected to be further applied in complex fields like human-computer interaction,medical and health.