Development and characterization of novel flexible cellulose electrodes for electrophysiological monitoring

Flexible and biocompatible electrodes are crucial components in developing future wearable and implantable biomedical devices. In this work, a novel composite bioelectrode from cellulose, supported by polydimethylsiloxane (PDMS), and glycerol were developed. Cellulose, an abundant and biodegradable biopolymer, provides the conductivity, while PDMS provides the support and the mechanical elasticity. All together, they provide elasticity and skin-conformability. Glycerol was added in this work as it also acts as an ionic conductor and a plasticizer, thus, improving interfacial charge transfer and electrode hydration stability. The composite was fabricated by an easy polymerization and curing process. The morphological, electrochemical, and mechanical characteristics of the fabricated electrode were evaluated. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) showed low impedance, high conductivity, and stability. The electrochemical characteristics demonstrated the lowest bulk resistance of 0.658 kΩ, a conductivity of 0.0193 S m^-1 and a charge storage capacity of 4.626 mC m^-2. The ductile properties for the samples showed a low elastic Young modulus of 10.3 ± 5.4 kPa. Electroencephalograph (ECG) signal was recorded at a considerable good quality with SNR of 33.31 dB. Thus, the cellulose-PDMS-glycerol electrode material appears to offer a highly promising, green platform for the development of soft bioelectronics to be employed in real-time physiological signal monitoring.