A handheld bioprinter for multi-material printing of complex constructs.

In situ bioprinting, also known as the process of depositing bioinks at the defect site, has emerged as a promising strategy for the repair and restoration of large tissues. This technology accomplishes these goals through the site-specific delivery of pro-healing structures. However, realising the full potential of this technology requires the ability to print multiple materials for simultaneous or sequential dispensing of a variety of drugs and cells for better tissue biomimicry. In this article, we describe a portable and modular bioprinter that is capable of depositing a variety of bioinks while allowing for precise control over their physicochemical properties. Using stereolithography (SLA) 3D printing, we construct microfluidic printheads with complex fluid circuitries that allow for the deposition of multi-component fibers with sophisticated cross-sectional geometries and material compositions. In addition, the modular design of this platform makes it possible to print a wide variety of bioinks, such as those that can be chemically or photo-crosslinked, as well as nano-composite inks with shear-thinning and self-healing properties. The versatility of this technology for biomedical applications is demonstrated by printing constructs for co-delivery of various drugs or cells at the same time, as well as generating implanted biosensors. Overall, this method not only has a significant potential for site-specific and in situ tissue printing, but it also has the potential to have applications in traditional ex vivo bioprinting for automated and high throughput tissue engineering.