Ultrahigh Cell Density 3D Bioprinting by Acoustic Fluids-mediated Stereolithography

Dense cell populations and their complex structures are the essentials of physiologically functional solid organs, but their biomimetic construction is challenging. Here, an ultrahigh cell density (UHCD) bioprinting system is presented for fabricating organ-analogous intricate architectures based on an acoustic fluids-mediated stereolithography (ASL) technique. The ASL can achieve cell aggregation on a prepolymerized solid-liquid interface with densities comparable to native tissues through focused surface acoustic waves-induced vortices. Meanwhile, the ASL-based UHCD bioprinting shows reduced light scattering in each ultrathin layer printing process, reaching cell densities of 1 billion cells mL^-1. Additionally, by incorporating an acoustic-assisted medium exchange system, the ASL facilitates the bioprinting of multicellular components in arbitrary architectures. Based on these features, ASL's capability in fabricating structure-mimetic liver tissue models with regenerative functionalities is demonstrated. It is believed that the ASL technique achieves breakthroughs in UHCD bioprinting, opening new avenues in the development of artificial tissue and organ engineering.