Polymer Nanosheet Interfaced Bioelectrode for Skin‐Inert sEMG Measurement

Abstract

poly(ethylene glycol), poly(methacrylic acid), and polyacrylamide. [2] The strong adhesive of the electrode is required for good contact with the body surface, which is crucial to ensure signal transduction and high-quality performance. However, for acute measurements, especially for infants and people with sensitive skin, [3] the adhesiveness of the pre-gel electrode and direct contact between the pre-gel electrode and skin may cause discomfort and skin irritation at measurement sites. [4] In this regard, the hypoallergenic hydrogel electrode which has a different adhesive gel content was invented to overcome this problem. Nonetheless, the dry electrode fabricated on a rigid substrate was not sufficiency flexible to conform to human skin, leading to insufficient electrical performance.A free-standing polymeric ultrathin film (or nanosheet) is attractive to use for skin-contact application owing to its high adhesiveness and ultra-flexibility that allow the nanosheet to conform on various surfaces including skin [5] and internal organs [6][7][8] without additional glue or adhesive. The recent development of nanosheet technology involving fabrication with drugs, [5,8] fluorescent dyes, [9] conductive polymers, [10][11][12] and cells [13][14][15][16] has been applied to a variety of biomedical applications from surgical intervention to tissue engineering and health-care devices. [17] In our previous report, a conductive polymer nanosheet was fabricated for use in ultraconformable electrodes for bioelectrical signal monitoring. [10] However, with the conductive nanosheet itself, measurement limitations were observed for some flexible parts of the body such as wrists due to the instability of the mechanical robustness resulting from body motion and the electrode placement area, leading to poor measurement efficiency.To avoid such mechanical mismatch, in this study, elastomers were selected to fabricate the nanosheets because of their unique properties; they are elastic, flexible, or tough depending on the polymer morphology. One of the particularly attractive properties of elastomers is the glass transition temperature (T g ) at which the polymeric chains of the elastomer change from a glassy state to a rubbery state. In particular, elastomers have a brittle and rigid-like structure below T g and a loose and flexible structure above T g , which exhibit reversible properties under external force. On the basis of their mechanical properties, polystyrene-polybutadiene-polystyrene triblock copolymer (SBS)The interface between skin and electrodes plays a major role in the accuracy and efficiency of biopotential measurements. For reliable biosignal recording, stable and low-impedance contact is required between electrodes and the target tissue. Conventional wet electrodes (Ag/AgCl) are composed of metal electrodes with skin-adhesive hydrogel. However, for long-term measurement, direct contact between the pre-gel electrode and skin causes discomfort and skin irritation, especially for infants and people with sensitive skin b...

Three‐in‐One Portable Electronic Sensory System Based on Low‐Impedance Laser‐Induced Graphene On‐Skin Electrode Sensors for Electrophysiological Signal Monitoring

“…EEG signals were converted to FFT map through the Power Spectral Density in Matlab (version 2017a) (Figure 4). SNR was calculated according to literature, [ 49 ] $$\[ \begin{array}{*{20}{c}}{{\rm{SNR}}\left( {dB} \right) = 20{{\log }_{10}}\frac{{{A_{\rm{s}}}}}{{{A_{\rm{n}}}}}}\end{array} \]$$where A s is the highest signal peak and A n is the standard deviation (SD) of the background noise.…”

“…EEG signals were converted to FFT map through the Power Spectral Density in Matlab (version 2017a) (Figure 4). SNR was calculated according to literature, [49] dB A A…”