Design, Performance And Application Of 3D Printed Carbon-based Flexible Sensors

Flexible strain sensors have received more and more attention from researchers due to their advantages such as thinness,bendable,flexible and wearable.A large number of flexible strain sensors are used in wearable devices,robot perception,medical rehabilitation,physiological signs monitoring,etc.In the field.At present,the main problems in the research of flexible strain sensors are high cost,complex technology,and difficult mass production.These problems severely limit the application of flexible strain sensors in reality.Under the existing material system,through the structural design of the sensing unit,the sensitivity and measurement range of the sensor can be significantly improved.At the same time,combined with the rapid prototyping characteristics of 3D printing technology,mass production of flexible sensors under this structure can be realized.Therefore,this paper proposes a porous carbon-based flexible strain sensor based on a 3D printing process,and conducts systematic research from the aspects of sensing characteristics,design principles and application scenarios.The specific work of this paper is as follows:(1)Through the analysis of the conductive mechanism and piezoresistive effect of carbon-based composites,combined with common carbon-based material systems,this paper selects flexible materials polydimethylsiloxane(PDMS)and nano-scale carbon black(CB)The composite conductive polymer CB/PDMS is used as the sensing material.The mechanical properties,electrical conductivity and piezoresistive properties of carbon-based composite materials at different ratios of 1:15,1:16,1:17,1:18,1:19,1:20 are studied,and the best is determined Concentration ratio of CB/PDMS.(2)The mechanical and electrical equivalent models of the flexible strain sensing unit were constructed,the relationship between the two was analyzed,and the advantages of the internal porous structure design were determined.Aiming at the two different strain forms of tension and compression,the porous structure design of the flexible strain sensor sensing unit is carried out.Finally,according to the simulation results,the optimal porous structure sensing unit under different strain forms is determined.(3)Set up a direct writing process 3D printing device to prepare sensing units with different structures under tensile and compressive strains.The performance test results show that,compared with the sensor unit prepared by the injection molding process,the shear thinning characteristic of the direct-write process during the extrusion of the nozzle is helpful to the arrangement of the conductive channels in the composite material,plus the design of porous structure can greatly improve the performance of the sensing unit.(4)According to the two different strain forms of tension and compression,explore the application of sports behavior monitoring and medical health monitoring.In sports behavior monitoring,the electronic skin prepared in this paper can measure the bending angle of finger joints.For medical health monitoring,compared with commercial piezoresistive film sensors,the prepared porous flexible pressure sensor has improved sensing performance in terms of sensitivity and measurement range.