Engineering the Auricular Cartilage by Hydrogel‐ and Microgel‐Based 3D Bioprinted Constructs—An Update

ABSTRACT Auricular cartilage defects, resulting from congenital malformations such as microtia or acquired causes including trauma, infections, and tumor resection, significantly impair facial symmetry, auditory function, and psychosocial well‐being. Conventional reconstruction methods, such as autologous costal cartilage grafting and alloplastic implants, have limitations, including donor‐site morbidity, infection risk, calcification, immune rejection, and an inability to replicate the auricle's complex architecture and elastic biomechanics. To address these challenges, researchers have developed biomaterial‐based scaffolds that offer high tissue compatibility, precise shape fidelity, and minimally invasive delivery. In this regard, three‐dimensional (3D) bioprinting has emerged as a transformative technology, enabling the fabrication of patient‐specific constructs with controlled spatial deposition of biomaterials, bioactive molecules, and living cells, thereby facilitating the generation of functional auricular cartilage. This review presents the essential design criteria for bioinks tailored to auricular cartilage bioprinting, encompassing cell sourcing strategies, rheological properties and printability, bioactive factor incorporation, and mechanical performance. It then overviews recent advances in hydrogel‐ and microgel‐based bioinks for 3D and four‐dimensional (4D) bioprinting of patient‐specific auricular constructs, emphasizing natural, synthetic, and hybrid hydrogel systems. Finally, the review discusses current material and technological limitations and outlines prospective research directions to guide future studies and accelerate innovations in auricular cartilage regeneration.