Effect of the deposition process on the stability of Ti<sub>3</sub>C<sub>2</sub>T<i> <sub>x</sub> </i> MXene films for bioelectronics
Sneha Shankar, Brendan B. Murphy, Nicolette Driscoll, Mikhail Shekhirev, Geetha Valurouthu, Kateryna Shevchuk, Mark Anayee, Francesca Cimino, Yury Gogotsi, Flavia Vitale
Abstract
Abstract Ti 3 C 2 T x MXene is emerging as the enabling material in a broad range of wearable and implantable medical technologies, thanks to its outstanding electrical, electrochemical, and optoelectronic properties, and its compatibility with high-throughput solution-based processing. While the prevalence of Ti 3 C 2 T x MXene in biomedical research, and in particular bioelectronics, has steadily increased, the long-term stability and degradation of Ti 3 C 2 T x MXene films have not yet been thoroughly investigated, limiting its use for chronic applications. Here, we investigate the stability of Ti 3 C 2 T x films and electrodes under environmental conditions that are relevant to medical and bioelectronic technologies: storage in ambient atmosphere (shelf-life), submersion in saline (akin to the in vivo environment), and storage in a desiccator (low-humidity). Furthermore, to evaluate the effect of the MXene deposition method and thickness on the film stability in the different conditions, we compare thin (25 nm), and thick (1.0 μ m) films and electrodes fabricated via spray-coating and blade-coating. Our findings indicate that film processing method and thickness play a significant role in determining the long-term performance of Ti 3 C 2 T x films and electrodes, with highly aligned, thick films from blade coating remarkably retaining their conductivity, electrochemical impedance, and morphological integrity even after 30 d in saline. Our extensive spectroscopic analysis reveals that the degradation of Ti 3 C 2 T x films in high-humidity environments is primarily driven by moisture intercalation, ingress, and film delamination, with evidence of only minimal to moderate oxidation.