Skywalker Legacy : building a moving prosthetic hand

By Kiran Kumar

A team of undergraduate students in the Biomedical Engineering Society at UC San Diego is undertaking an out-of-this-galaxy challenge: designing, building and testing a low-cost prosthetic hand that can be controlled seamlessly by the user’s own mind. The goal for the project, called Skywalker Legacy, is to enable simple procedures involved in day-to-day life — including moving individual fingers, holding and moving objects — for those who use prosthetics. 

Students in the Biomedical Engineering
Society's Skywalker Legacy project.

To build this non-invasive prosthetic, there are a number of challenges the team of students will need to address, including mechanical and software challenges. Darin Tsui, a bioengineering undergraduate student, illustrated how the team’s model would mechanically imitate a hand’s physiology. At the bottom of a hand, there are muscle nerves. Stimulating the muscle nerve pulls at the joint to move a finger. 

“To mimic this, we’re using linear actuators as the muscle nerves, and the hinges act as joints to move the fingers,” said Tsui. 

The flexibility of the selected material, likely resin, would impact whether hinges are necessary, or if a wire from the linear actuators to the fingertip would suffice. 

An early prototype of one 
of the prosthetic fingers
the students plan to develop.

Additionally, there are a number of software challenges which Skywalker Legacy will face. Charlie Anderson, a bioinformatics student, said getting individual digit control is going to be quite difficult. In order to detect messenger signals from the body, they will be using non-invasive surface electrodes strategically placed on each relevant muscle group in the subject’s forearm. This is a well established method referred to as electromyography. These signals will have to be delivered to the linear actuators, acting as the muscle nerves for the hand. Since these signals are taken non-invasively, they are very general. To translate these signals, Anderson and his team will use a machine learning program which will output a digit number that corresponds to a specific finger. Then, the hardware team will translate this output to stimulate the linear actuator of the particular finger.

Jay Chen, a bioengineering student and the project co-chair, said he has a lot of confidence in this team. He explained that the project name, Skywalker Legacy, originated from the majority of the team being self-proclaimed Star Wars nerds. He knew that this had to be a tribute to the Skywalkers as, “two out of three of them have lost an arm.”

The team hopes to have a functioning prototype by May or June, when they will conduct functionality tests. They hope that next year, they can expand on the project and further the Skywalker Legacy project.