Abstract
In situ bioprinting has emerged as a promising technology for tissue and organ engineering based on the precise positioning of living cells, growth factors, and biomaterials. Rather than traditional in vitro reconstruction and recapitulation of tissue or organ models, the in situ technology can directly print on specific anatomical positions in living bodies. The requirements for biological activity, function, and mechanical property in an in vivo setting are more complex. By combining progressive innovations of biomaterials, tissue engineering, and digitalization, especially robotics, in situ bioprinting has gained significant interest from the academia and industry, demonstrating its prospect for clinical studies. This article reviews the progress of in situ bioprinting, with an emphasis on robotic-assisted studies. The main modalities for in situ three-dimensional bioprinting, which include extrusion-based printing, inkjet printing, laser-based printing, and their derivatives, are briefly introduced. These modalities have been integrated with various custom-tailored printers (i.e., end effectors) mounted on robotic arms for dexterous and precision biofabrication. The typical prototypes based on various robot configurations, including Cartesian, articulated, and parallel mechanisms, for in situ bioprinting are discussed and compared. The conventional and most recent applications of robotic-assisted methods for in situ fabrication of tissue and organ models, including cartilage, bone, and skin, are also elucidated, followed by a discussion on the existing challenges in this field with their corresponding suggestions.