Stability of Ti₃C₂T_x MXene Electrode Arrays Under Different Sterilization Conditions

Recently, Ti₃C₂T<i>_x</i> MXene has attracted increasing interest for use in sensing and stimulation applications for monitoring electrophysiological activity in the body. The electrochemical properties of MXene-based electrode arrays have consistently demonstrated superior recording quality with increased signal to noise ratios (SNR) compared to clinically standard arrays. Further, the high capacitance of the MXene nanostructure paired with the large charge injection capacity (CIC) make these devices very desirable for high-quality, micron-scale recording and electrical stimulation. For MXene wearable and implantable devices to become clinically and commercially viable, however, they must be able to withstand routine sterilization procedures. Standard sterilization modalities used widely across the world include steam autoclave sterilization at 120 <b>°</b>C, Ethylene Oxide (EtO) gas, and hydrogen peroxide (H₂O₂) plasma. Here, we present a comprehensive analysis of the structural, functional, and electrical effects of these common sterilization protocols on thin-film spray-coated Ti₃C₂T<i>_x</i> neural microelectrode arrays as well as Ti₃C₂T<i>_x</i> infused ‘MXtrodes’. To confirm that bacteria could be effectively eradicated from the Ti₃C₂T<i>_x</i> MXene devices, <i>E. Coli</i> inoculated samples were first tested in each sterilization machine, and the resulting colony-forming units (CFU) were counted. Across all sterilization modalities, the bacterial colony units were below the threshold of detection which confirmed the devices could be effectively sterilized. Post-sterilization analysis reveals that for both autoclave and EtO sterilized devices, the crystalline structure, contact adhesion, and electrical properties remain unchanged. Furthermore, there were no changes in the XRD and Raman spectra for autoclave or EtO sterilized thin-films or MXtrodes. Finally, electrochemical impedance and conductivity were statistically unchanged, and SEM did not reveal any delamination or morphological changes to the devices. Hydrogen Peroxide plasma sterilization, however, resulted in severe damage of Ti₃C₂T<i>_x</i> MXene films as confirmed by SEM, XRD, and Raman. Further, plasma sterilization significantly increased the recoding impedance measurements and revealed a significant loss in conductivity. Ultimately, our findings indicate that EtO and Autoclave sterilization do not alter Ti₃C₂T<i>_x</i> MXene devices and should be considered for all future MXene wearables and invasive implants.