MIMICKING THE DYNAMIC AND STATIC ECM: DESIGNING DOUBLE NETWORK HYDROGEL BIOINKS

Abstract

The aim of this work is to design a robotic bioprinting platform able to fabricate a three-dimensional structure onto irregular surfaces. Regarding the limitations of in-vitro bioprinting approach, widely used in scaffold-based tissue-engineering (handling difficulty , risk of contamination, shape not matching the defect), this bioprinter allows a direct dispensing (i.e. in-situ bioprinting) of biological material onto and into the damaged site [1-2]. The robotic platform was developed starting from the open source BCN3D-MOVEO robot [3-4]. The hardware was rebuilt to control the robot using LinuxCNC [5], the original end-effector was substituted by a syringe pump module, and joints were equipped with optical en-coders. A path planning algorithm that automatically projects any generic printing pattern on an irregular surface, was developed in Matlab. For each point, the normal direction is calculated to successively constrain the end-effector orientation (always perpendicular to the surface). An inverse kinematic algorithm calculates joint angles for each position of the end-effector and a gcode file is then exported to LinuxCNC. Resolution and repeatability were estimated and preliminary in-situ bioprinting tests were carried out extruding a hydrogel onto various substrates. The possibility of dispensing material onto irregular surfaces opens the way to a number of possibilities in the field of tissue-engineering. In this context, in-situ bioprinting could become a reality in the near future especially for the easiest accessible organs such as skin. Having a ''collaborative'' bioprinter, capable of assisting the surgeon during the operating phase, will allow a more precise intervention and will minimize human errors.