Behind the Scenes: A Fun Demo with Cushions and Infrared Cameras
Introduction
Wheelchair users have been telling us that our 3D-printed cushions are a breakthrough in a number of ways, but especially in ventilation and heat management. We were curious, so we did a little in-house demo to see how different wheelchair cushions handle heat after someone sits on them. No lab coats, no published papers—just curiosity, a thermal camera, and one hot plastic butt.
Setup
We designed and 3D-printed a butt-shaped container out of UMA 90. The butt geometry was spec’ed to ISO 16840, with some “thighs” added for a more realistic impression profile, and also for added stability. The inside of the butt is hollow and water-tight, so we can fill it with hot water.
We filled our printed butt with hot water (140°F / 60°C) and set it on each cushion for one minute (emptying and refilling with new water for each cushion). The volume of the hot water used, as well as the time the hot butt was placed on the cushion, was the same between the cushions.
What We Observed
Using an infrared camera, we can see the temperature profile of the cushions before, during, and after the hot water-filled butt was placed on each cushion. It’s immediately apparent that the heat signature of the 3D-printed cushion is not only far smaller but also has far lower peak temperatures.
What was Interesting
It was interesting to see how differently each material handled heat. The open cellular structure of the printed cushion is almost entirely exposed to air, and our demo showed that it simply does not allow heat to be trapped and built up. For a person who has to sit on a cushion for long periods of time, this heat buildup is not only uncomfortable, but it also induces sweat buildup and can eventually lead to painful and problematic pressure sores.
Heat dissipation isn’t the only factor in comfort, but for people sitting for long periods, it could be a helpful lens to consider. This demo helped us think differently about material performance—plus, it gave us an excuse to 3D print a butt, and how often do you get to do that?