The Calgary Arm is an ultra-low-cost upper-limb prosthesis designed to be assembled from widely available materials. It operates on the principle of a jamming gripper. If you have seen a vacuum packed bag of rice, ground coffee, etc, you have probably noticed that it remains hard until you puncture the package and let air in, at which point the contents can flow and the bag can easily be reshaped in your hands. This is because external air pressure tightly packs the individual grains together so they jam and can't slide past one another. When the vacuum is released, so is the jamming effect, and the grains can flow readily. A jamming gripper makes use of this principle when the outer layer (in this case a balloon) deforms to adjust to the shape of whatever it is pressed against, and then a vacuum is applied (in this case via a reversed bicycle pump), locking it into that shape. The object can then be picked up via a combination of mechanical interlocking (if the gripper actually partially wraps around it), friction, and suction (if there is a "suction cup" effect between the balloon and the surface of the object).

See the videos below for more information:

The Calgary Arm was created in the course of a 4th year Capstone Design Project in Mechanical (Biomedical) Engineering at the University of Calgary over the 2016/2017 academic year. The team is shown here at the 2017 Capstone Design Fair:

From left to right, Dr. Mark Ungrin, Tyler Anker, Shalese Baxandall, Peter Hillman, Amanda Mackey, Joel Neumann and Rohan Antony (photo courtesy of Michael Platt).

Numerous passers-by tested out the arm, and used it to sign their names on the tabletop, providing a large number of test cycles - so far, so good!

This project has media attention from a number of outlets, including the CBC online, CBC radio, CTV, CTV again, the Calgary Herald, and the Calgary Sun.

While the design project is now over, we will be continuing to refine the project as we look to validate the Calgary Arm in real world situations.

Update - on April 5th they made the Governor General's Twitter feed: https://twitter.com/GGDavidJohnston/status/849790392992006144. That's Joel in the upper right image (and also Doug Kondro, world famous chicken prostheticist from the lab in the lower right).

For more information contact Dr. Mark Ungrin at mark.ungrin@ucalgary.ca, the group as a whole at calgaryarm@gmail.com, or the individual students at: tyler.anker89@gmail.com, shalesebaxandall@gmail.com, peter.hillman94@gmail.com, amanda.r.mackey@gmail.com, joel.a.neumann@gmail.com, rohan.antony1994@gmail.com