Fabrication and development of mechanical metamaterials via additive manufacturing for biomedical applications: a review

Abstract In this review, we propose a comprehensive overview of additive manufacturing (AM) technologies and design possibilities in manufacturing metamaterials for various applications in the biomedical field, of which many are inspired by nature itself. It describes how new AM technologies (e.g. continuous liquid interface production and multiphoton polymerization, etc) and recent developments in more mature AM technologies (e.g. powder bed fusion, stereolithography, and extrusion-based bioprinting (EBB), etc) lead to more precise, efficient, and personalized biomedical components. EBB is a revolutionary topic creating intricate models with remarkable mechanical compatibility of metamaterials, for instance, stress elimination for tissue engineering and regenerative medicine, negative or zero Poisson’s ratio. By exploiting the designs of porous structures (e.g. truss, triply periodic minimal surface, plant/animal-inspired, and functionally graded lattices, etc), AM-made bioactive bone implants, artificial tissues, and organs are made for tissue replacement. The material palette of the AM metamaterials has high diversity nowadays, ranging from alloys and metals (e.g. cobalt–chromium alloys and titanium, etc) to polymers (e.g. biodegradable polycaprolactone and polymethyl methacrylate, etc), which could be even integrated within bioactive ceramics. These advancements are driving the progress of the biomedical field, improving human health and quality of life.