Self-adhesive and biocompatible dry electrodes with conformal contact to skin for epidermal electrophysiology

Long-term biopotential monitoring requires high-performance biocompatible wearable dry electrodes. But currently, it is challenging to establish a form-preserving fit with the skin, resulting in high interface impedance and motion artifacts. This research aims to present an innovative solution using an all-green organic dry electrode that eliminates the aforementioned challenges. The dry electrode is prepared by introducing biocompatible maltitol into the chosen conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate). Thanks to the secondary doping and plasticizer effect of maltitol, the dry electrode exhibits good stretchability (62%), strong self-adhesion (0.46 N/cm), high conductivity (102 S/cm), and low Young's modulus (7 MPa). It can always form a conformal contact with the skin even during body movements. Together with good electrical properties, the electrode enables a lower skin contact impedance compared to the current standard Ag/AgCl gel electrode. Consequently, the application of this dry electrode in bioelectrical signal measurement (electromyography, electrocardiography, electroencephalography) and long-term biopotential monitoring was successfully demonstrated.