Research On Printable And Flexible Carbon-Based Strain Sensors

Flexible strain sensors have important application prospects in human motion monitoring and other fields.Although the performance of flexible sensors can be effectively improved through complex device structure design and cumbersome preparation processes,the difficulty in reducing production costs has seriously hindered their commercialization.Moreover,if the raw materials used in the production process are harmful,there is a potential threat to human health and the environment.To address the above two challenges,on the one hand,it is necessary to develop simple and large-scale manufacturing processes that can effectively reduce production costs,and on the other hand,the use of non-toxic and sustainable raw materials can reduce the harm to humans and the environment.Therefore,in this master’s thesis,based on the printing process,green solvent and carbon-based materials,two types of flexible strain sensors are prepared on different substrates.Their working performance and mechanism are explored from both macroscopic and microscopic perspectives,and they are applied in the field of human exercise and healthcare monitoring.These studies provide new ideas for large-scale,low-polluting manufacturing of flexible wearable electronics.The main contents are as follows:(1)The green solvent dihydrolevoglucosenone(Cyrene)was used to dissolve thermoplastic polyurethane(TPU)and disperse graphene to make conductive ink,and the graphene-TPU composite film was embedded in the polydimethylsiloxane(PDMS)matrix by stencil printing and transfer process.By adjusting the ratio between graphene and TPU,the optimized sensor has ultra-high sensitivity(gauge factor > 3905),broad sensing range(0-80 %)and good fatigue resistance(over 5000 working cycles).It can realize the in-situ monitoring application of joint bending angle and bicycle riding speed.(2)The green solvent Cyrene was used to dissolve TPU,disperse carbon nanotubes(CNTs)and graphene to make conductive ink,and the ink was printed on the elastic fabric substrate decorated with thermal transfer paper by stencil printing process to make graphene-CNTsTPU/fabric flexible strain sensor.The sensor has high sensitivity(gauge factor > 210),broad sensing range(0-112 %)and excellent response symmetry.The sensor is combined with an integrated wireless test transmission system to realize real-time electrical signal monitoring such as human motion,vocalization,pulse and ECG,which demonstrates the potential of the flexible fabric-based strain sensor for healthcare monitoring applications.This article includes 55 pictures,6 tables,and 103 references.