A Pen That 3D Prints Bone Right Onto Patients

One of the greatest promises of 3-D printing is that we’ll one day be able to print organs on-demand. Need a new liver? There it is, at the push of a button.
 
Anticipating that future, scientists from the University of Wollongong in Australia have created the BioPen, a tool that lets physicians more or less draw new bones on people through 3-D printing. The pen is loaded with so-called "stem cell ink," a batch of human cells that can form new bone. Another second substance, a polymer, then seals the area so the stem cells can do their work in peace. You can see why this is promising: if someone loses parts of bone in an accident, a tool like this pen could apply a fix directly to the problem area.
 
We’ve seen 3-D printed bones before, actually, but this device could give a little more precision. It’s yet to undergo clinical testing, so it still may be a while before it hits the market, but if and when it does, it’ll have some company.