Characterizing PDMS/MWCNTs and PDMS/GNP composites for biopotential sensing

This article focusses on preparation and mechanical testing of thin-polymer electrodes to efficiently measure the biomedical signals while providing a conformal skin-contact. The method to prepare thin electrode films using Polydimethylsiloxane (PDMS) with different Young's moduli has been described. The Young's modulus was evaluated for each film by conducting tension-relaxation tests. The PDMS electrodes were made conductive by mixing them with Multi-Walled Carbon Nano Tubes (MWCNTs) and Graphene Nano Powder (GNP) using an ultrasonic mixer. The current study addresses a novel approach of preparing PDMS based sensors by doping them with CNTs and GNPs and wetting them in N-N Dimethylformamide (DMF) prior to their dispersion in PDMS. This was done to avoid their clumping in PDMS and to ensure more uniform dispersion. The conductance of the PDMS/MWCNT and PDMS/GNP electrodes were measured using an impedance spectrometer and were compared with that of standard silver-silver chloride (Ag/AgCl) and dry silver (Ag) electrodes.