The NovoGen MMX Bioprinter

Step 1: Engineers load one syringe with a bio-ink (A) made up of spheroids that each contain tens of thousands of parenchymal liver cells and a second syringe with a bio-ink (B) containing non-parenchymal liver cells that bolster cellular development and a hydrogel that helps with extrusion.

Step 2: Software on a PC wired to the bioprinter instructs a stepper motor attached to the robotic arm to move and lower the pump head (C) with the second syringe, which begins printing a mold. The mold looks like three hexagons arranged in a honeycomb pattern.

Step 3: A matchbox-size triangulation sensor (D) sitting beside the printing surface tracks the tip of each syringe as it moves along the x-, y-, and z- axes. Based on this precise location data, the software determines where the first syringe should be positioned.

Step 4: The robotic arm lowers the pump head (E) with the first syringe, which fills the honeycomb with parenchymal cells.

Step 5: Engineers remove the well plate­ (F)—which contains up to 24 completed microtissues, each approximately 250 microns thick­—and place it in an incubator. There, the cells continue fusing to form the complex matrix of a liver tissue.

This article originally appeared in the August 2013 issue of Popular Science_. See more stories from the magazine here._