Designed by medical research company Organvo in California, the mini-livers are just half a millimetre deep and four millimetres wide, Metro.co.uk reported.
The 3D printer builds up 20 layers of hepatocytes cells that are responsible for carrying out liver functions, and two major types of liver cell.
Additionally, the printer adds cells from the lining of a blood vessel, which allows the liver cells to receive nutrients and oxygen.
Keith Murphy, the firm's CEO, said that previously they were able to show that liver function was retained in their 3D liver for over five days.
But, now their tissues perform consistently for at least 40 days, a significant improvement over the average 48 hour performance of 2D cultures, Murphy added.
While research is in the early stages, scientists think that future versions could be used for transplants.