The New Multifluidics Tool Print Head for Multi-material Printing

During the RESTORE project, Brinter developed and tested their own technology of the microfluidic system for manipulating and printing various bio-ink combinations. The print head, capable of mixing multiple low-to-high viscosity bioink components (such as hydrogels, nanoparticles, crosslinkers, and cells) based on the modular configuration utilizing microfluidic chips, has been commercialized into a Multifluidics Tool (Figure 1) after the project finalization. The new print head offers a one-stop solution to manipulate, formulate and define how the extruded bio-ink or layer is composed (for example, in a coaxial or gradient manner).

Figure 1. Commercialized Multifluidics Tool combined with a triaxial needle.

Switching between bio-inks is traditionally done using multiple cartridges in different print heads, making switching relatively slow and tedious. However, a microfluidic chip can print with different bioinks concurrently or alternatingly. Material switching can be achieved without slowing the printing down by using a chip with multiple inlets and channels that converge into a single outlet (a multi-nozzle microfluidics chip). The Multifluidic Tool print head combined with a coaxial/triaxial nozzle can co-print materials from two or three syringes. Co-printing is especially handy when working with low-viscosity materials, such as alginate, that require curing catalysts or liquid crosslinking agents, such as calcium chloride. This technique is also extremely beneficial for creating core-shell structures and hollow tubes for vascular tissue engineering applications. It can also help reduce the shear stress on the cells using a protective sheath layer, resulting in high cell viability in the printed constructs.

Furthermore, in some cases, the mixing of materials is desired. Rather than pre-mixing solutions, our Multifluidics Tool print head can be combined with a custom-made passive mixer unit that can perform on-the-fly mixing of various bioink components (Figure 2). This will also enable 3D printing of different material gradients, including gradients of gel stiffness, the concentration of cells or immobilized additives such as bioactive nanoparticles, which is the degree of complexity needed to precisely reproduce anisotropic tissues, such as cartilage.

Figure 2. Multifluidics Tool printing using a two-valve manifold with a mixer and a custom three component mixing part for the print head.

For Brinter, this new multifluidic printing technology gives a lever in the challenging competitive landscape of the bioprinter market. It will enforce Brinter’s bioprinter’s modularity even more and enable applications that might otherwise be impossible to achieve, such as printing drug formulations with various release profiles in different layers of the printlet or gradient bioprinting, leading to improved tissue functionality and more accurate tissue models.