Sinterit and 3D designer create exoskeleton arm for children with spinal muscular atrophy

The exoskeleton arm

Poland-based Sinterit—a manufacturer of selective laser sintering (SLS) desktop 3D printers—and Bartłomiej Gaczorek, a 3D designer from the computer software company Crystal Cave, have collaborated to create an exoskeleton arm for children with spinal muscular atrophy (SMA).

SMA is a genetic neuromuscular disease that restricts leg, arm and hand movement, leaving sufferers dependent on specialized mobility support devices. Sinterit and Gaczorek used the Sinterit Lisa SLS desktop 3D printer to produce parts for an exoskeleton arm that allows children with the condition to draw, play and express themselves.  

The idea came from the mother of a three-year-old boy with SMA who approached Gaczorek after hearing of his 3D printing design expertise. Her son had already tried several low-budget devices incorporating 3D printed parts, but they had been inadequate.

Gaczorek considered these previous attempts to be ‘great examples of engineering’ but in need of ‘some improvements’. Specifically, it occurred to him that SLS might be the best choice of 3D printing technology—rather than the previously used fused deposition modeling (FDM) or stereolithography (SLA)—on account of its:

  • ability to create complex internal structures;
  • excellent precision;
  • freedom of form; and
  • use of strong yet lightweight non-toxic materials.

These attributes proved vitally important for producing both the prototypes and bespoke, end-use parts of the exoskeleton.

The designer used Autodesk’s Fusion 360 CAD/CAM software to design the exoskeleton arm. The software allowed for complex movement analysis and shape optimization.

The collaboration between Gaczorek and Sinterit began at the prototyping stage. After several prototyping trials, the Sinterit Lisa was used to create end-use parts for the arm that once assembled, ‘function perfectly’.

The combined use of Fusion 360 and Sinterit Lisa is said to have allowed for design, testing, development and production of the arm in an exceptionally short timeframe. The production process especially needed to be as fast and hands-free as possible to minimize the amount of time children spend unable to use their arms.    

Gaczorek consulted the parents of children with SMA, doctors and physiotherapists throughout the process, ensuring the prioritization of comfort, first and foremost, as well as durability and a fun, sleek appearance.

‘I decided to print [the] main elements [using] SLS technology because it is able to print complex internal structures,’ explained Gaczorek. ‘A very important factor for me is also the comfort of [the] user, which is much better with SLS and SLA than with FDM technology. The cost of [SLS printing with the] Sinterit Lisa is already very low compared to other industrial machines and the quality is perfect, that’s why I chose that printer.’

Gaczorek and Sinterit have now been asked to produce exoskeletons for three more children with SMA.