Mr. Boxberger, you are exploring a finger orthosis that is made using a 2.5D printing process and that might one day replace prefabricated, off-the-shelf orthoses. What makes your 2.5 D printing process so unique?
Lukas Boxberger: The term "2.5D" does not refer to the actual printing process but serves to illustrate the concept. In reality, we use a conventional 3D printer to make the orthosis. However, in this case, we only print several millimeters to build up the height of the orthosis, which means we don’t create a complex shape, but rather a strip. It is used to integrate the wires. To do this, we developed a special printer head at the Fraunhofer IWU. This process allows us to make orthoses of different sizes and devices for the finger, arm, or foot. The benefit here is that you can later mold the plastic.
How do you heat the plastic?
Boxberger: The plastic is heated via the integrated wire by using electrical current. The heat from the wire enables the plastic to reach the right temperature so you can mold it. You knead the plastic gently to shape it into the desired form.
Our printer head allows us to integrate wires into the plastic during the printing process. We can vary both the polymer and the wire depending on the required electrical function.
How warm does the plastic get?
Boxberger: The temperature our first prototypes reach is currently 60°C. However, we are working on a solution that facilitates moldability at 35 degrees Celsius and depends on the plastic you choose. The point of moldability is achieved very quickly as you only heat the finger orthosis for about 30 seconds. At this point it can be molded and becomes solid again after 30 seconds of cooling. This makes it possible to quickly readjust the orthosis during the treatment process should you need a different angel for the finger, for example. I can see this technique being used in the treatment of scoliosis as it pertains to the support corset suffers must wear. It would be a big advantage if you could make quick adjustments to the structure.
When it comes to further development, a great feature would be the option of using an orthosis on more than just one patient. For now, we haven’t factored in sterilization processes in the materials selection, though it would be interesting to take our research in this direction as well.