During my thesis commissioned by the Technical University in Delft I developed a body-powered hook prosthetic.
Upper limb amputees in developing countries don't always have access to suitable prosthetics. In this case exisiting body-powered hooks cannot be produced locally which is making them too expensive to purchase. 80% of the world's disabled people live in developing countries, so this needed to be changed.
Many upper-limb amputees do not have access to modern prosthetic hand devices and prefer to use a prothesis chosen for the purpose of carrying out tasks; a hook prosthetic based on the Hosmer Dorrance Canted Hook Model. This is a body powered hook which requires the patient to use body movements to pull the cable to open or close the device. A big advantage of the body-powered hook, compared to a prosthetic hand device, is that hooks are more resistant to hars work environments and unlike the hands, do not easily get damaged by water or dirt.
Taking in account a couple of conditions to fulfill the need of developing countries such as functionality at minimum cost, patient-specific and easy to repair, I started working on this project over a period of fourteen weeks.
By doing a lot of research and reading articles, I listed my requirements and preferences. I made a morphological map of four functional components and their solutions and created my first prototype out of piece of cardboard. Shortly afterwards, I further developed the first prototype in Solidworks and got it cut out by a steel laser cutting machine (this was predetermined). After some evaluation, changes were made and a second and third prototype were created. By twisting the sheet steel the two dimensional steel turned into a three dimensional design and this is obviously where it's name came from.
The two pieces of sheet steel were attached to eachother by a bolt, lock nut, two spring washers and a rubber band.
After testing, listing all the purchase prices and fabrication costs, this newly designed hook met almost all of its requirements and can be considered as a successful prototype.