Research On Flexible Bioelectric Dry Electrodes Based On Microstructure Arrays

The electrolytes of wet electrodes are easy to dry and the surface impedance of dry electrodes and skin is large,and conventional microneedle electrodes are complex to fabricate.In this work,we applied barb array imitating Xanthium to fabricate dry bioelectric electrode.First,the polymer and thermoplastic resin were injected into barb arrays,and then the silver layer was plated on the array through silver mirror reaction.Last,the Ag/Ag Cl barb electrode was prepared by chlorination experiment.The index of soft friction coefficient between electrodes and skin was creatively put forward,and the latitudinal friction coefficient of barb array achieved 1.0465,which can effectively reduce the slip between electrodes and skin during dynamic measurement.The performance of dry bioelectric electrode was improved by chlorination.And the properties of wet electrode,plate electrode and barb electrode were compared:the barb electrode owned the best performance.The electrode-skin impedance was lower than that of the wet electrode.At10Hz,the impedance of the barb electrode was 33.91k?,which was approximately 1/6 of that of the wet electrode.During static ECG measurement,the performance of barb electrode and wet electrode was comparable.During dynamic ECG measurement,the ECG signals measured by wet electrodes and plate electrodes were seriously distorted,while the barb electrodes can still collect ECG signals stably,showing unique advantages at dynamic state.When swing arm at 90°,the signal-to-noise ratio can reach 36.33 d B and the power spectral density was 2.36×10^-6 m V²/Hz.When the magnitude of the resistance caused by skin deformation was between 5.58×10⁶ and 1.74×10⁷?,the dry bioelectric electrode imitating Xanthium can collect ECG signals equivalent to the static state.Therefore,the proposed barb electrode imitating Xanthium can effectively solve the dynamic noise problem of bioelectric signals,and was suitable for long-term dynamic measurement.In addition,polypyrrole conductive polymers are widely used in supercapacitors and heating fabrics,but have not been used to dry bioelectric electrode.In this paper,polypyrrole was used as conductive material to make dry bioelectric electrode,and the ECG signal was successfully collected.The barb array firstly was modified by dopamine,then carried out in situ polymerization,and coated lastly with high conductivity Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)(PEDOT:PSS),the electrode can achieve the best ECG signal acquisition effect.The power spectral density of the ECG collected during the swing arm of 90°can achieve 2.62×10^-7(m V²/Hz).