Biological response of Ti-based intermetallic thin films, to be used as biopotential electrodes

Abstract

Biopotential electrodes are crucial in modern preventive medicine, being the primarily responsible for the high-resolution monitoring of the bioelectrical activity of in human body. In this work, flexible dry biopotential electrodes based on binary systems of Ti-Me (Me = Al, Cu, Ag, Au) thin films were developed for non-invasive physiological monitoring. These biopotential electrodes supported by polymeric bases aim to expand the applications of enhanced sensing in new opportunities, for better healthcare conditions. The Ti-Me thin films were prepared by DC magnetron sputtering without substrate heating. The use of a composed target (with different number of Me pellets) originated a wide range of chemical compositions and different thin film microstructures and physical responses. Working as bipotential electrodes, the Ti-Me thin films will be placed in direct contact with the skin and body fluids, which means that the materials selected need to be harmless and do not compromise the skin integrity. The interaction of the Ti-Me thin films with skin cell models (fibroblasts and keratinocytes) was assessed in vitro for each system, studying their cytotoxicity and evaluating the oxidative stress. No evidences of Ti release to the medium was observed. On the other hand, the metal leakage from the Ti-Me films increased with the Me atomic content, for the generality of the films. Some oxidative stress was observed, proportional to the amount of Me present in the thin film. However, no significant damage in cell viability was noticed, with exceptions of some compositions of Ti-Cu thin films.