Improved accuracy and precision of bioprinting through progressive cavity pump-controlled extrusion

3D bioprinting has seen a tremendous growth in recent years in a variety of fields such as tissue engineering, drug testing and regenerative medicine, which has led researchers and manufacturers to continuously advance and develop novel bioprinting techniques and materials. Although new bioprinting methods are emerging (e.g. contactless and volumetric bioprinting), micro-extrusion bioprinting remains the most widely used method. Micro-extrusion bioprinting, however, is still largely dependent on the conventional pneumatic extrusion process, which relies heavily on homogenous biomaterial inks and bioinks to maintain a constant material flow rate. Augmenting the functionality of the bioink with the addition of nanoparticles, cells or biopolymers can induce inhomogeneities resulting in uneven material flow during printing and/or clogging of the nozzle, leading to defects in the printed construct. In this work, we evaluated a novel extrusion technique based on a miniaturized progressive cavity pump (PCP) which allows precise control over the volumetric flow rate by positive displacement. We compared the accuracy and precision of this system to the pneumatic extrusion system and tested both systems for their effect on cell viability after extrusion. The PCP achieved a significantly higher accuracy and precision compared to the pneumatic system, while maintaining good viability. These improvements were independent of the bioink composition, printing speed or nozzle size. This study demonstrates the merit of precise extrusion-process control in bioprinting by PCPs and investigates their influence on process-induced cell damage. PCPs are a promising tool for bioprinting and could help provide standardized and validated bioprinted constructs while leaving the researcher more freedom in the design of the bioinks.