Research On Flexible Mechanics Sensors Using On Wearable Devices

In recent years,with the development of wearable devices,flexible mechanical sensors for wearable devices have been receiving increasing attention.The novel flexible pressure sensors and strain sensors are fabricated based on nanomaterials.The flexible strain and pressure sensors can be directly attached to the surface of the human body or the wearable device to monitore human health and exercise parameters,and the flexible strain sensor and pressure sensor gradually become a new point of consumption growth.In this paper,we fabricate high-performance flexible strain sensors and pressure sensors which can be used in flexible wearable devices.Firstly,we fabricate the reduced graphene oxide(rGO)and the microscopic characteristics of rGO are analyzed by scanning electron microscopy(SEM)and Raman spectroscopy.As the sensing material of the flexible strain sensor and pressure sensor,the performance of rGO directly determines the performance of the flexible strain sensor and pressure sensor.In this paper,the rGO is fabrication by laser scribing and thermal reduction method,and the microstructure of rGO is characterized by SEM and Raman spectroscopy.The laser scribing and the thermal reduction method for fabricating the rGO is simple with low cost,which can reduce the fabrication cost of the flexible strain and pressure sensor.Nextly,we fabricate a flexible strain sensor for wearable devices.The flexible strain sensor with the gague factor(GF)up to 402 is fabricated,then the strain sensor is are characterized by SEM and Raman spectroscopy,experimental results show that the strain sensor achieves high performance with high GF and large strain range.Then strain sensor is optimizated by novel structure and novel material,the strain sensor with higher GF and larger strain range is fabricated.Then a theoretical model is developed to explain the relationship between the strain and the relative resistance change.In order to analyze the mechanism concretely,a simulation model is built by using the finite element method(FEM),which agrees the experimental results well.Finally,some applications of the strain sensor for wearable devices are developed.Finally,we fabricate a flexible pressure sensor for wearable devices.The flexible pressure sensor based on the honeycomb-like graphene network(HGN)is fabricated with high sensitivity up to 3.54 %/kPa and large pressure range,then the pressure sensor is characterized by SEM and Raman spectroscopy.A simulation model is built based on the microstructure of HGN to explain the relationship between the pressure and the relative resistance change by using the FEM,which agrees the experimental results well.Finally,some applications of the pressure sensor for wearable devices is developed.