Controlling needle insertion inside hydrogel structures to generate vascularized tissue engineered constructs

AbstractVascularization is a critical limitation for the translation of tissue engineered constructs. However, automated, direct fabrication of hollow, vascular-like channels inside tissue-like gel substances remains a challenge for manufacturing science. A proposed method is to employ a robotic-arm controlled 3D printer to navigate user-defined needle tips within the gel materials. In this work, a simulation model for the needle-gel contact process is developed and experimentally validated, to generate hollow channel inside gels. Optimization of navigation forces is performed to predict the amount of insertion force and deflection. It has been found that needle navigation depends on parameters such as geometrical shape of needle tip, variation in speed and gel properties. Insertion force was found to increase with increase in needle speed while large needle diameters were found to generate large insertion forces. On the other hand, needle deflection was found to decrease with increase in the needle diameter as well as velocity of the insertion. Moreover, due to the non-isometric shape, a bevel-shaped needle tip showed larger deflection than conical needle tip. It is concluded that the developed model can simulate needle navigation process in different gel material and thus, lays the foundation for further development of manufacturing modality for fabrication of hollow channels in tissue engineered constructs. This may also find application for fabrication of sub-surface, enclosed microfluidic channels.