Synthesis and characterization of Iron Nanowires for stretchable resorbable cardiac patch electrodes

Heart Failure (HF) is a life-threatening syndrome with a high prevalence of morbidity and mortality, poor functional capacity and quality of life. Currently, there are over 64 million individuals worldwide who are affected by this syndrome. Among the available treatment options, heart transplantation offers the most promising survival benefit. Nevertheless, the limited availability of grafts, graft dysfunction, long-term non-cardiac complications and the potential for immune rejection represent significant challenges. Heart donation after circulatory death (DCD) is not currently well-established due to the difficulty in assessing the condition of the graft. However, it is estimated to increase the number of available hearts for transplant by approximately 20%. The objective of this thesis project is to develop and characterise micro-electrodes for the measurement of cardiac electrical activity in a multiple sensing cardiac patch. It will assess the vitality of the donor’s heart before transplantation and in the weeks following surgery in order to increase the number of available grafts by DCD. The fabrication of micro-electrodes for a bioresorbable cardiac patch is dependent on three main requirements: a mechanical structure that supports the dynamics of a beating heart; proper biocompatibility and bioresorbability to interact with the heart without raising harmful responses or reactions; and proper sensing of the electrical heart stimulus to detect the cardiac action potential waveform (mV level). The primary objective of this project is to develop a biodegradable conductive composite material with a conductive filler of iron nanowires on a POMaC substrate. Firstly, the Fe NWs were synthesized via the magnetic field-assisted in situ reduction method, and their size and morphology were characterized using scanning electron microscopy (SEM). The POMaC substrate was also fabricated and its mechanical properties relative to the cross-linking of the polymer were studied using a stretching setup. Finally, the Fe NWs suspension was cast onto the substrate under the influence of a Halbach array, which had been designed and simulated. A variety of Fe NWs arrays were produced by orienting the magnet under the substrate in different ways. To assess the variation in sheet resistance of these samples, the Van der Pauw method was employed.