Studty Of The Construction And Performance Of Grapefruit Peel Carbon Aerogel Based Flexible Pressure Sensor

Due to its simple construction,high flexibility and excellent portability,pie-zoresistive flexible pressure sensors offer enormous potential in the fields of health monitoring,electronic skin and wearable device.People’s expectations of pressure sensor sensing performance,substrate materials,and other related met-rics are rising in tandem with science and technology’s rapid advancements.To achieve the widespread application of pressure sensors human health monitoring field,the following three problems must be solved:Firstly,the cost of conductive materials（such as graphene,carbon nanotubes,and metal nanomaterials）is high and not renewable;Secondly,the mechanical properties of the flexible substrate material are poor robust and the compatibility with human skin is not satisfactory,which will severely restricted the sensitivity and detection of the sensor;Thirdly,the method of constructing 3D structures to improve pressure sensing perfor-mance is complicated and time-consuming.As a means of addressing these issues,this paper adopts the biomass material grapefruit peel carbon aerogel with envi-ronmentally friendly preparation,low-cost and wide-source as the conductive ma-terial and takes full advantage of the natural three-dimensional porous structure of Grapefruit Peel carbon aerogel（C-GPA）;Polydimethylsiloxane（PDMS）as well as Polydopamine-Aminated Lignin-polyacrylamide（PDA-AL-PAM）hydro-gels with high elastic modulus and good compatibility with human skin were se-lected as elastic substrates.Ultimately,flexible pressure sensing materials with high sensitivity,low cost and broad detection range were prepared by in situ polymerization and free radical reaction respectively and assembled into flexible pressure sensors.The development of novel pressure sensors and the high-value exploitation of grapefruit peel will be made possible by these new technologies and concepts.The following are the most important findings:（1）C-GPA with excellent electrical conductivity was prepared by a simple but effective hydrothermal treatment followed by a high-temperature carboniza-tion process.The circumstances of hydrothermal and carbonization treatments on the morphology and pore size of carbon aerogels were investigated in order to produce the optimum products.The carbonization temperature has also been in-vestigated in relation to the degree of graphitization and electrical conductivity.The experimental results showed that C-GPA can retain its 3D interconnected network structure following hydrothermal and carbonization treatment,the poros-ity was as high as 93%,and the pore size was mainly distributed in 70μm.As the carbonization temperature increased from 600℃to 800℃,the degree of graph-itization of C-GPA increased（I_D/I_G decreased from 0.89 to 0.68）,and the electri-cal conductivity was significantly enhanced（conductivity increased from 0.0458s/m to 38.2 s/m）.（2）The super-elastic PDMS/C-GPA pressure sensing material was prepared by vacuum impregnation method which use PDMS as the base material and C-GPA as the conductive material.The results indicated that the prepared pressure sensing material had ultra-high conductivity（1.47 s/m）,excellent fatigue re-sistance（50%strain,10000 cycles）,extremely wide detection range（0-800 k Pa）,ultra-high sensitivity(63.4 k Pa^-1),short response time（20 ms）,and promising prospects for application in the field of human health monitoring.（3）The PDA-AL prepolymer was generated by the oxidative polymerisation of DA introduced by AL and then the PDA-AL-PAM hydrogel solution was pre-pared by mixing the PDA-AL prepolymer with AM.The prepared hydrogel solu-tion was infused into C-GPA and then the multifunctional composite hydrogel（PDA-AL-PAM/C-GPA hydrogel）was prepared by free radical polymerization reaction.The results demonstrated that the hydrogel had well electrical conduc-tivity（1.9 s/m）,strong adhesion（36 k Pa）,good biocompatibility,significant an-tibacterial effect（2.3 cm）and high sensitivity(170 k Pa^-1),making it suitable for direct adherence to human skin for the monitoring of small human movements.