Fabrication and Experimental Assessment of a Soft Biomimetic Artificial Ventricle using Sheetlike Actuators

Abstract

Heart failure is a long-term condition affecting 63 million people worldwide [33]. While heart trans-plantation is considered the gold standard for treating this kind of end-stage heart failure, the severes hortage of donor organs necessitates the exploration of alternative therapies such as total artificial hearts and ventricular assist devices. However, the current total artificial hearts are flawed; their rigid surfaces can induce thrombosis, haemolysis and infection [2][6][18][31]. A soft biomimetic approach could theoretically mitigate these flaws by providing a pumping mechanism that more closely replicates the physiology of the native ventricle [28][32]. Therefore, this thesis aims to manufacture and experimentally assess a soft biomimetic artificial ventricle.Osouli et al. developed a novel ventricular model, which describes the left ventricular myocardium as aseries of smoothly twisting surfaces [28], which can be used for this purpose. To mimic the ventricular sheet-like myocardial model, a flat pneumatic artificial muscle (FPAM) is used as an actuator. This typeof actuator is soft, strong and can contract under a low pressure of 50 kPa. Following systematic evaluation of materials and fabrication processes, nylon-coated TPU combined with heat pressing yields themost consistent results. Isotonic and isometric characterisation confirms state-of-the-art performance,with the FPAM achieving a mean contraction of 20.2 % and a peak force of 95.5 N.The FPAM forms the structural foundation of the artificial myocardium. The 3D model proposed by Osouli et al. [28] is transformed into a 2D surface to facilitate FPAM integration. Key design optimisations include the quantity and width of the zero-volume air chambers (ZACs). After which, this sheet is formed back into the myo architecture proposed by Osouli et al. Biomimetic motion evaluation revealsa ventricular twist of 9.03° (native: 17.0°), wall thickening of 12.0% (native: 37.5%), and longitudinal contraction of 1.37% (native: 11.9%). Functional assessment yields an ejection fraction of 38.4% anda maximum pressure of 82.9 mmHg.The prototype exhibits sub optimal performance relative to the native ventricle, a discrepancy primarily attributable to the limited contractile capacity of the artificial myocardium, which constrains both biomimetic motion and ventricular performance. Nevertheless, this thesis provides the first demonstration that a sheet-like actuator-based artificial ventricle can simultaneously induce bio mimicry andventricularlike performance, establishing this approach as a promising foundation for future devices.