Research On Development And Soft Robot Application Of Flexible Wearable Strain Sensor Based On EGaIn

With the continuous progress of science and technology,liquid metal has been widely used in fields such as flexible electronics,biomedical treatment,and military detection due to its unique physical and chemical properties,making it an ideal material for fabricating flexible thin films.However,as the functional requirements of flexible electronic products continue to increase,some problems of flexible films,such as fatigue failure,susceptibility to thermal expansion,material aggregation,and complex processes,have gradually emerged.Therefore,how to successfully develop new flexible composite materials based on liquid metal that have good elasticity,strong conductivity,and high stability has attracted the attention of researchers.This project mainly focuses on Eutectic gallium indium（EGa In）,which has good conductivity and high fluidity,and is combined with a flexible material with good elastic deformation ability and biocompatibility.The aim is to create a new type of composite material that is stable,elastic,and mechanically robust,and can be used in wearable strain sensors and soft robots.The main work accomplished is as follows:A composite film of EGa In,multi-walled carbon nanotubes（MWCNTs）,and polydimethylsiloxane（PDMS）was prepared,and the mass ratio was optimized to explore its reliability.The experimental results showed that the EMP film exhibited excellent mechanical and electrical properties,including high conductivity(1.315×10^-2 S·cm^-1),tensile strength（120%）,contact angle（133.3°）,and low elastic modulus（1.2 MPa）.A low-cost,high-performance flexible stretchable strain sensor was developed based on EMP,and applied to correct sitting posture in adolescents.Based on the hardware and software design of the EMP sensor,a control system with high sensitivity and good stability was constructed,which can monitor the bending angle of the neck in real-time.When the forward or backward bending of the neck is greater than 20 degrees or 30 degrees,an alarm will be issued,which expands the practical application of low-cost wearable electronic devices.The shape,size,ratio,and preparation process of the PDMS,EGa In,and neodymium iron boron（Nd Fe B）magnetic composite film were analyzed in detail.Through testing and characterization of properties such as stress-strain,elastic modulus,tear energy,thermal stability,swelling degree,crosslinking density,and hysteresis loop,the PEN film obtained had high acid-base resistance,low elastic modulus（1.17 MPa）,low thermal expansion coefficient(2.473763118×10^-6 K^-1),optimal swelling degree（0.02446）,crosslinking density(1.52×10^-3mol/cm³),contact angle（113.5°）,and tear energy（7.36 KJ/m²）.A flexible PEN magnetic composite film was used as the substrate for the soft robot to improve the current problems of poor toughness and weak strength in the field of soft robots.By establishing a motion model,studying the magnetization method,testing the fatigue resistance,trajectory control,and exploring different substrate materials and single/double leg structures,it was found that the maximum speed of the PEN soft robot with a double-leg structure on paper can reach 48.3 mm/s,demonstrating good magnetic control sensitivity and motion stability.In summary,this project focuses on EGa In,which has excellent conductivity and flowability,to construct a conductive network by filling MWCNTs,and uses PDMS as a flexible substrate to prepare the EMP strain sensor,which can better fit dynamic changes of human skin and correct the sitting posture of adolescents by monitoring the bending of the neck.Nd Fe B was filled to enhance the magnetic performance,magnetic response,magnetic operability,durability,and stability of the flexible composite material PEN,thereby improving the actual speed,reliability,and lifespan of soft robots.The application research shows that EMP and PEN films effectively solve problems such as aggregation,poor mechanical properties,and low reliability of flexible composite materials.Based on EGa In flexible composite materials,this research is expected to bring new development opportunities and application prospects in wearable sensors,soft robots,and biomedical fields.