Our first trip to Haiti was packed with challenges, uncertainties, and adventures. The hospitality and kindness we were met with was unparalleled, and it was exhilarating to get a glimpse of the potential impact of this arm.
Armed, but not dangerous
Things the TSA has a problem with: flammables, Galaxy Note phones, liquids, aerosols, sharps, — and the most dangerous item of them all — plaster mold… which had to be checked three different times in three different airports. Somehow, various sized hands and sockets and forearms placed in a suitcase between clothes didn’t warrant a second scan — that dubious honor was given to the water bottle in Gabriel’s backpack. (He’s really not that good at packing — on the way back he left the bug spray in his bag, needing the Haitian TSA to search the bag and throw the spray unceremoniously into plastic trash can filled with things travellers shouldn’t have packed in the first place.)
A new angle
The various sized sockets and forearms came in quite handy (heh…). The version of the socket based on the picture measurements was slightly too small. The upscaled version was better, but was still a little tight near the top and bottom of the socket. The bend between the socket and forearm ended up going away from Chris’s body, rather than towards it, which will necessitate changes in the design in the upcoming week. The straps for the socket have to be edited slightly to have them hold the arm better, especially near the end of the limb. The elbow of the prosthetic was in line with his elbow (whooo :D), though the forearm was too long (awww 😦 )
The harness succeeded in transferring some of the weight from the device to Chris’s back and shoulders. The main change we plan to make to the harness is making it detachable from the socket via buckle straps; this way the harness can be put on separately, underneath a shirt, and then connected to the socket. Similarly, we plan to change the the straps on the socket so that Chris can insert his limb into the socket from the side and close the straps around it, rather than sliding it in from the top.
It takes two to tango
And by tango we mean to use a laser scanner in order to take measurements. It’s a surprisingly intricate dance. One person holds the laser scanner, trying to keep the USB cable from getting too tangled or in the way of the infrared camera. The other person holds the laptop with the image from the camera visible to the person scanning, so that the one scanning can be sure the limb will is in view. And now begins the hard part, a crouched shuffle to the right and around Chris’s arm, which is raised up towards the ceiling while he lays on his side (surprisingly difficult when it comes to directions, especially with vire meaning “to turn” and rive meaning “to arrive” sounding so similar. In the end, Gabriel ended up laying down on the floor in demonstration, which resulted in a rare Chris smile that unfortunately was not captured on camera). We wonder what everyone else was thinking as we slowly moved around Chris, trying to avoid bumping into walls, chairs, or tripping over Chris’s legs while keeping the camera at the optimal distance for measurements. We didn’t have too much time to think about that though, focusing instead on making sure the scan was working, and feeling the the sweat slowly slide down our backs from the heat and the nervousness.
A gentle tug-of-war
A plaster cast was used to make a mold of the arm, so that we could take back a physical version of Chris’s arm. We will later fill it with plaster so that we can use it to test the sockets we print. It was not without its challenges though. Getting the cast onto Chris was the easy part…. removing it proved much more difficult. Chris’s arm is slightly wider near the end, so trying to remove the cast proved fruitless. In the end, we cut open the mold from the top to about half way down one side, and then put the mold back together using excess plaster. While the mold will not be perfect, it will allow us to verify the sizing of the socket with an approximation, and will work especially near the end of the limb, which is the hardest part of the socket to model well.
Sometimes the old ways are best… (because it’s always a good time to quote Bond)
We took manual measurements of the arm using a tape measurer and — because no true engineering student is too far from it — a pair of callipers for that extra (and slightly unnecessary) four digits of precision after the decimal. The measurements will serve as a means of verifying the current design and will serve for scaling the result of the laser scan.
Be on the lookout for another blog post soon where we will share our personal impressions of Haiti and the trip as a whole!