Research On Polyurethane-based Flexible Bioelectric Dry Electrodes

With the development of smart wearable technology,people are paying more and more attention to smart monitoring clothing.Flexible dry biopotential electrode is an important part of smart monitoring clothing.The flexible dry biopotential electrode can collect the physiological electrical signals of the human body,such as ECG signals and EEG signals.Disposable gel wet electrodes are often used to collect physiological electrical signals of the human body in clinical practice,but wet electrodes have problems such as gel drying that affects signal quality and easily leads to skin allergies.The flexible dry biopotential electrode does not use gel,which avoids the above problems and is suitable for long-term use.In this subject,based on thermoplastic polyurethane(TPU),two flexible dry biopotential electrode of different conductive materials have been fabricated using the template method.One is PPy/TPU flexible dry biopotential electrode,the other is Ag/TPU flexible dry biopotential electrode.During the production process,a micropillar array was generated on the surface of the flexible dry biopotential electrode by using the template method.The micro-pillar array can effectively reduce the relative slip between the electrode and the skin,thereby reducing motion artifacts and improving signal quality.The main research content and research conclusions are as follows:(1)The flexible TPU film with micropillar array on the surface was prepared by template method.The diameter of the micropillars was about 0.47 mm and the height was about 0.18 mm.The micropillar array on the surface was well formed and distributed uniformly.(2)The PPy/TPU flexible dry biopotential electrode(PPy/TPU-ME)with a micropillar array on the surface was prepared by in-situ polymerization of polypyrrole.The impedance measured on the skin surface was significantly lower than that of the planar electrode.Analyzing static and dynamic ECG signals,the signal quality of PPy/TPU-ME is better than that of planar electrodes.In the static state,the signal-to-noise ratio(SNR)of the planar electrode is 22.65 dB,while the PPy/TPU-ME is 25.22 dB.When it is dynamic,the signal-to-noise ratio of PPY/TPU-ME can reach 95.67%of that of the wet electrode,and its power spectral density(PSD)is 3.18×10^-6(m V)²Hz.(3)The Ag/TPU flexible dry biopotential electrode(Ag/TPU-ME)with micropillar array on the surface was prepared by the method of filling silver paste conductive material.And compared with the performance of PPy/TPU-ME and wet electrode.The impedance of the interface between Ag/TPU-ME and skin is always lower than that of PPy/TPU-ME,and the impedance is 0.57 M?and 1.97 M?respectively at 0.1 Hz.In the static state,the signal waveform of Ag/TPU-ME is similar to that of the wet electrode,the signal noise is small,and the SNR is 27.87 dB.When performing large-scale exercise(walking state),the signal-to-noise ratio can reach 20.05 dB,which is higher than PPY/TPU-ME,and its PSD is2.34×10^-6(m V)²Hz.Similar to W-E but lower than Ag/TPU-ME.