Redefining 3D Bioprinting: Vertical Bio-Ink Deposition for Improved Biofabrication

Abstract

A novel approach to Extrusion-based 3D printing named Vertical Pillar Extrusion (VPE) is proposed, wherein living cells are deposited vertically into a supportive substrate, diverging from the established horizontal deposition method. Traditional substrate-based 3D bio-printing methodologies primarily employ horizontal layering techniques. This innovative, low-cost technique entails the utilisation of a needle-equipped nozzle, minimising substrate disturbance by abstaining from horizontal movements within the medium. Bio-Ink injection occurs exclusively from the top, while extrusion is initiated upon needle retraction from the substrate. Extrusion during retraction mitigates the sheer stresses for the living component of the bio-inks. Various bio-ink nozzle types (tapered and straight) will be analysed to identify the optimal nozzle configuration that maximises the survival rate of the living components within the bio-ink. We aim to utilise this printing technique for bio-inks derived from algae and bacteria and for printing a bio-ink containing dissolved chitosan onto a substrate with an acetylating agent to fabricate 3D-printed chitin structures. The efficacy of this 3D printing technique is analysed via Computational Fluid Dynamics (CFD) simulations to predict the behaviour and interaction of the bio-ink with the substrate. Experimental validation of the results will be conducted to ensure the accuracy and reliability of the technique's practical applicability. The proposed methodology involves coding a new g-code generator, predicated on Digital Light Processing (DLP) slicer shutter images dictating the voxel locations for material deposition. We anticipate that this pioneering 3D printing technique will yield substantial enhancements in the precision of bio-ink deposition for the fabrication of 3D-printed engineered living materials