Description
A Master of Science thesis in Biomedical Engineering by Kashif Rast Baz Khan entitled, “Mxene-Based Implantable and Flexible Electrodes for Neuromuscular Monitoring”, submitted in June 2023. Thesis advisors are Dr. Amani Al Othman, Dr. Hasan Al Nashash, and Dr. Muhammad Al Sayah. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).
Abstract
Biocompatible and long lasting bioelectrodes have advanced neural sensing and muscle stimulation research in recent years. Previously, bioelectrodes constructed from metals suffered from mechanical and immunological limitations that resulted in extremely high electrochemical resistances that would interfere with the neural-electrode bridge. They also had the problem of causing an immunologic response in the body due to mechanical mismatch and they lacked the flexibility. This shifted research to the development of soft, flexible electrodes that had low electrochemical resistances. In this thesis proposal we investigated the possibility of developing novel, flexible, implantable bioelectrodes based on Mxenes / Polydimethylsiloxane (PDMS) / Glycerol composite. MXenes possess the advantage of having metallic ultra-conductive transition metals consisting of large groups of carbides, nitrides, or carbonitrides, while PDMS has inherent biostability and biocompatibility. Various MXene-based electrodes compositions (15% and 20% Mxene content) were prepared and evaluated for their potential in neural sensing. The samples were subjected to a series of characterization techniques such as Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), mechanical, long-term stability, biocompatibility biosignal sensing from the skin. The experimental results showed that the Compositions exhibited promising bulk impedances of 280 Ω and 111 Ω, conductivities of 0.462 mS/cm and 1.533 mS/cm. The CV testing revealed promising electrochemical stability of the compositions and the charge storage capacities were 0.665 mC/cm2 and 1.99 mC/cm2. Through mechanical testing the Young’s moduli were found to be 2.61 MPa and 2.18 MPa respectively. The composite samples have elongated by 139% and 144% respectively. The long-term stability test was done via PBS immersion of samples for over 8 weeks. The results exhibited a reduction in the impedances for the prepared samples in general. CV revealed the electrochemical stability with an increase in CSC. ECG and EMG testing showed excellent results when compared with commercial electrodes, hence, promising potential for flexible biosignal sensing applications.