Silver-plated stretchable elastomeric electrodes for electrotherapy applications

The present study aimed to develop wearable, electrically conductive hygienic electrodes and their use for Transcutaneous Electrical Nerve Stimulation (TENS) application. The development of electrodes was done in two stages. Firstly, the dispersion of conductive activated carbon particles was done into flexible elastomer followed by its silver electroplating. The Orthogonal Array Testing (OATS) technique was used to optimize the silver-plating recipe. The Fourier transform infrared spectroscopy (FTIR) analysis confirmed the impact of activated carbon by increase in intensity of stretching bands. To improve electrode properties in response to various human body movements, resistivity changes due to stretching and repeated extension were tested on conductive elastomers. Increasing the extension degree allowed a very minute change in electrical resistivity. Therefore, the resistivity can be considered almost constant within the 0-60 % stretch range. While, a notable increase in electrical resistivity was observed after 70 % of stretch. However, the resistivity of elastomers remained stable even after repetitive extension (for over 100 cycles). Conversely, no significant change in resistivity was observed over time when subjected to a constant current. Furthermore, to minimize the effect of skin electrode resistivity during electrotherapy, the range of different pressure was applied over the surface of electrodes. Minimum value of resistivity about 1 Ω.mm was obtained at 6 N/cm ² of applied pressure. Additionally, hygienic properties, such as antiviral, antibacterial and antifungal were examined using different pathogens to assess the impact of the deposited silver particles. In the end, the durability of electrodes against washing and rubbing was confirmed. The potential applications of prepared electrodes are in the field of electrostimulation and electrotherapy etc.