Duke eNable

Enabling the Future at Duke University

Welcome to Our Blog!

Hi Everyone,

Thanks for checking out our Duke e-Nable Blog. We’ll use this to keep you up to date on all the cool projects we’re working on. Check back often for new posts!

Featured post

Haiti Updates: August 13


Bonswa tout moun! (Hello everyone) Our travelers made it back to the states late Friday night after a tiring but successful trip to Haiti. Be on the lookout for a longer post soon with stories and pictures from Milot!!


Haiti Updates: August 7

Well, it’s time once again to pack up everything and head down to Haiti! It has been a little over a month since our last trip and we are ready to present Chris with his final device. We have packed many things including …

  • The complete arm
  • 3 spare sockets
  • 3 spare forearms
  • 1 spare gripper hand
  • Extra foam
  • Harnesses, straps, and extra material
  • A variety of tools including screwdrivers, calipers, and a protractor
  • A hairdryer
  • Paint and paintbrushes
  • 3D structure scanner
  • Camera and GoPro
  • Soccer ball
  • A partridge in a pear tree



Emily and Joel will arrive in Milot this afternoon and depart on Friday. This week, the goal is to fit the new arm, test its efficacy in different scenarios, and make final adjustments. We will also begin to plan for the next steps in our work with Chris.

You have to hand it to these strapping young students that they have a firm grasp on what will enable their success. (I will not apologize for this sentence)


Haiti Updates: August 1


After a rather eventful month, we have finished the new arm for Chris! The updated version is printed in skin-toned filament and makes use of the modifications we have been working on since the first trip.


On Monday, Emily and Joel will travel to Milot to meet with Chris again and test out the updated arm design. As the departure date approaches, we are working hard to print extra parts — some with larger dimensions — and acquire additional pieces of hardware and tools that could be useful during this trip.

Haiti Updates: July 25


Many hands make light work

As we approach the deadline for the second trip to Haiti, things are really starting to come together. The socket and forearm are just about done and only need some minor adjustments. Besides the overall fit of the socket, two of the major problems that we wanted to fix were the length and angle the arm. The length needed to be decreased and the angle needed to be brought more towards the body. After some adjustments to the location of the screw holes, we are pretty confident that these problems are solved. Moreover, we decided to add an additional screw hole to both pieces so that we have two options for the angle, depending on how the screws are placed. The two pictures below show these options.

The most recent modification involved adapting the location of the screw holes in order to embed the screw heads beneath the inner surface of the socket. This design will enhance the integrity of the connection and make the bottom of the socket more comfortable by moving the hardware out of the way. Once this is finalized, we are ready to print the final arm and various extra pieces in skin-colored filament.

Get a grip

The final hand is also just about completed. In order to further increase the grip capabilities of the hand some sticky grip material was added on the inside of the thumb. This should prevent larger objects from slipping once grabbed. The material we will be using for the final arm has arrived as well, and as a test we printed the final hand design out with it.

Buckle up kids

This week we solidified the design for the detachable piece between the harness and socket.The black webbing in a V-shape provides integrity to the apparatus by combining a high strength, durable material with a configuration that adequately distributes the weight of the arm. The bottom two straps will be adjustable using simple rectangular buckles, and the top two straps will be sewn onto the harness once we fit it to Chris.

Lastly, we adapted the design for the straps on the socket itself. In order to provide a user-friendly and effective fastening system, we decided to affix elastic straps to one side of the socket, with Velcro patches on the bottom that attach to the other side. In this way, we can still use the elastic to provide a compressive force that helps stabilize the socket, while allowing Chris to adjust the fit with his other hand.

Haiti Updates: July 18

Since returning from Haiti, we have been working on the individual pieces of the device to make specific modifications. Once these are finalized, we will reassemble the device and prepare for the next trip!

Put a sock (in) it

The laser scan was imported into the CAD software to allow for a virtual fitting. With this, the original socket was edited in order to better fit the arm. Some adjustments still have to be made to the socket, as the fit was tight in a few places when the foam was added to the interior wall. All in all, things are coming along well, and a finalized socket should be done within the week. Ensuring the forearm will be angled naturally will be the harder portion of the design.

Need a hand?

For the most part, the hand did not need any adjustments. One thing that we did want to change, however, was the shape of the thumb. The first thumb design was mostly straight and would tend to slip on larger curved objects, such as water bottles. To fix this problem we decided to rotate and curve the thumb so that it will wrap around objects more. We also plan to add grip to the inside of the thumb to further prevent slipping.

Sew it goes

The overall design of the harness succeeded in transferring the weight of the device from Chris’s arm to his back and shoulders. The main change we want to make is to connect the socket by straps with buckles, so that Chris can put the harness and socket on separately. This way it will give him the flexibility of wearing the harness underneath his shirt if he wants. Another slight variation to this version involves adjusting the angle at which the straps cross in the back. Shoutout to Iris for being our model!

The new version has been sewn together, and the next step will be finalizing the design for the detachable connection to the socket. Below are some of the options.

Casting call

Last week we used the plaster cast, made from wrapping plaster gauze around Chris’s residual limb, to make a replica of his arm. A mixture of Plaster of Paris and water was poured into the mold and allowed to dry; then the gauze cast was cut away to unveil the final result. While the surface is still rough from the texture of the gauze, the shape is consistent with the 3D scan of the arm, which we scaled and printed out. We can now use both models to test the fit of the socket.

First Haiti Trip Success

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!

Haiti Updates: July 4

Bonswa! Our travelers made it safely back to Durham this morning and are excited to share stories and footage from Milot. We accomplished a lot and have several plans to make improvements before the next trip. Stay tuned for a more in depth blog post within the next couple of days!

As a sneak preview, here is a group shot of Chris and the Renaldi family, whose hospitality and kindness truly made this trip special.


Haiti Updates: June 30 First Trip

After about two months of designing and building an arm, we are happy to report that the first trip to Haiti is underway. Emily and Gabriel, two of our founding members, are currently on their way to Milot with the arm that we have designed.


The main focus of this trip will be to fit the arm on Chris and test out the design. Their time there will be spent making sure the arm fits and is comfortable, following Chris around and take note of what he does on a daily basis, and making adjustments as they see fit. To help them accomplish these things they have brought several parts of different sizes, extra parts, hardware tools, a 3D scanner, and a plaster molding kit.


Upon their return they will hopefully be armed (pun fully intended) with the knowledge to make a completed device that we can deliver to Chris in August.

Haiti Updates: June 25

Today we assembled the first full prototype of Chris’s arm! We are currently working through a few adjustments to the design and will assemble an updated version tomorrow evening.

The biggest change we made recently is modifying the design of the socket. Now the inside of the socket is open, with elastic bands stretching across to hold the upper arm in place. Additional elastic bands attach the top of the socket to the shoulder harness, to transfer some of the load to the shoulders and back. On the socket we bring next weekend, we will sew the elastic on rather than pinning it.


The end of the socket is connected to the forearm by screws, and the forearm is connected to the gripper thumb hand with a bolt. We also tried to create a natural angle between the upper and lower parts of the arm, because we hope to keep this device as inconspicuous as possible once we print it in a skin-toned filament.

We are using strips of Dycem, a non-slip material, to enhance the gripping capability of the hand. This weekend, we will bring two versions of the terminal hand with and without the Dycem lining to test whether this modification is useful.


Over the next four days, we will assemble the updated version of the arm, print extra sockets and terminal hands, and further prepare for the trip. We will touch down in Milot in just FIVE days!!


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