The Preparation Of Elastic Electrodes And Their Application In Electromyography Sensors

Surface electromyography sensors(SEMG)are widely used in the fields of ergonomics,sports science,and medical research,and have attracted widespread attention and rapid development worldwide.However,current surface electromyography sensors have problems with strain interference,low conductivity,and poor skin-conformability of their electrodes.Hence,the efficient recognition of various exercise intensities becomes difficult,especially for the athletes to determine whether their muscle exercise is up to standard and for doctors to efficiently monitor the muscle recovery of patients.In the early stage of this paper,conductive gel/PDMS electrodes,silver+PDMS composite electrodes,and gallium indium tin liquid metal+PDMS composite electrodes were prepared using different conductive materials and structures,and their impedance and strain electrical stability were characterized.The resistance of the gel/PDMS electrode is small,which is equivalent to the commercial Ag/Ag Cl gel electrode,but the initial resistance of the gel elastic electrode is 2.31M?,the resistance is large,and the electrode resistance changes by 43% at 30% tensile strain.strain interference is large,and the dehydrated gel is not conducive to continuous use for a long time;the impedance of the silver+PDMS composite electrode is large,the initial resistance is 1.09?,and the conductivity is excellent,but the electrode resistance changes by 56.4% at 30% tensile strain,Strain interference is large;Gallium indium tin liquid metal+PDMS composite electrode has excellent conductivity,initial resistance is 16.52m?,and because liquid metal has almost no elastic modulus,a large amount of mixing has little effect on the elasticity of the electrode,and when stretched The liquid metal flows in the PDMS of the elastic substrate,which will not cause the conductive path to break,so the resistance changes only 1.91% when stretched at 30%,and the tensile stability is excellent,and PDMS in a liquid metal overflow surface,so that the liquid metal in direct contact with the skin,and electrode-skin impedance comparable to the commercial Ag/Ag Cl gel electrode.But because the liquid metal overflows the surface of the sample,it will cause the electrode to contaminate the skin.By summarizing the advantages and disadvantages of the elastic electrode in the previous experiments,a three-layer structure elastic surface electromyography electrode(PDMS/Ga In Sn+PDMS/silver-coated nickel+PDMS)was finally prepared.The bottom layer of the electrode is composed of conductive magnetic particles(silver-coated nickel powder)and PDMS.Under a vertical magnetic field,the silver-coated nickel powder forms a vertical conductive column in uncured PDMS.The bottom layer are insensitive to stretching strain,collect SEMG charge from human skin,and finally transfers it to processing circuit via intermediate layer(Ga In Sn+PDMS)to the back-end signal processing circuit,and the top PDMS package electrode plays the role of electrical protection.Our skin-friendly electrode exhibits high conductivity(0.237m?.cm and 1.635m?.cm resistivity in transverse and longitudinal directions),low electrode-skin impedance(47.23k? at 150Hz),excellent strain-insensitivity(10% change of electrode-skin impedance within 0-25% strain range),high fatigue resistance(? 1500 cycles)and good conformability with skin.During various exercise intensities,signal to noise ratio(SNR)of our electrode increased by 22.53 d B,which is 206% and 330% more than that of traditional Ag/Ag Cl and copper electrode,respectively.Efficient recognizing of exercise intensities by our electrode confirms its great application potential for the field of sports health.Efficient recognizing of exercise intensities by our electrode confirms its great application potential for the field of sports health and proves that due to strain insensitivity,the signal-to-noise ratio of the signal is retained,allowing the electromyography electrode to distinguish different exercise intensities,which makes Our electrodes are special candidates for human health monitoring in sports and medicine.