A toolbox for microvalve-based bioprinting

Microvalve-based bioprinting (MBB) enables precise deposition of bioinks in the form of droplets through the controlled ejection of nanoliter-scale cylindrical ligaments. Despite its increasing use in tissue biofabrication, standardization criteria for assessing bioink printability remain limited. In this study, we present a quantitative printability toolbox for evaluating various bioinks, including fibrinogen, collagen type I, Matrigel, and alginate, in the context of MBB. We systematically analyzed how rheological properties and the contact angle influence ligament formation and droplet ejection. High-speed imaging captured ligament dynamics such as velocity and volume as well as droplet-substrate interactions. The role of Tween 20 (T20) surfactant was further investigated to reduce interfacial aggregation and improve droplet uniformity. Our results revealed viscosity and concentration thresholds specific to each bioink, enabling the construction of a comprehensive printability map correlating bioink properties with ligament stability and droplet printability. This framework provides a practical guide for bioink optimization in MBB towards reproducible fabrication of complex biological structures for biomedical applications.