Characterisation analyses on silver nanoparticles grafted polyurethane as a potential material for electroencephalography electrodes.

Abstract

The development of dry electrodes for electrophysiological signal detection has rapidly increased in recent years to replace the use of wet electrodes. Researchers have explored different materials and designs in developing reliable and user-friendly dry electrodes. The utilization of organic-based material such as biocompatible synthetic polymer is necessary to produce a better skin interface for electrophysiological signal detection. Therefore, this study aims to surface modify the based-substrate of polyurethane (PU) by employing polydopamine (PDA) as a mediator layer to immobilize different concentrations (25, 50 and 100 mM AgNO3) of conductive silver nanoparticles (AgNPs) onto the PU surfaces. The chemical functionality and morphology analyses were performed on the samples using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscope/energy dispersive X-ray (SEM/EDX), respectively. The wettability contact angle instrument was then used to determine the wettability properties of the samples. The ATR-FTIR analysis indicated the existence of N–H group, C–O stretch, C–H, C=O and C–N bonds which belong to the chemical functionalities of PU/PDA. While the SEM/EDX results showed that the PU/PDA/50AgNPs contained the most optimal AgNPs distribution on the PU/PDA surfaces with less particle agglomeration. Other than that, the PU/PDA/50AgNPs exhibited better hydrophobicity by increasing the water contact angle of the PU/PDA from 82.96 ± 1.37° to 92.08 ± 1.98°. Therefore, the most desired physicochemical properties for the fabrication of EEG electrodes are possessed by the PU/PDA/50AgNPs due to identical chemical functionalities, desired morphology with a homogeneous dispersion of AgNPs and greater hydrophobicity.