“The Third Thumb is a 3D-printed thumb extension for your hand, controlled by your feet,” Clode told Digital Trends. “The Third Thumb investigates the relationship between the body and prosthetic technology in new ways. It is part tool, part experience, and part self-expression; a model by which we better understand human response to artificial extensions.”
The thumb’s 3D parts are connected using a Bowden cable system, similar to a bike brake, that is made of Teflon tubing and wire. “3D printing is the perfect medium for this project, as it enables quick prototyping, customized designs for various hand sizes, and one-off production,” Clode said.
The prosthesis’ motors are controlled via two pressure sensors retrofitted into the wearer’s shoes and receives its instructions via Bluetooth. Clode said she chose foot control for the project because she was inspired by the already strong connection between our hands and feet in various well-established products — such as driving a car, using a sewing machine, or playing the piano. The pressure sensors are designed to give plenty of control over the thumb, with one sensor controlling the flexion and extension, and the other controlling the thumb’s adduction and abduction. The results combine to create the kind of dynamic movement we would expect from, well, a regular thumb.
“The Third Thumb still needs more motor development before it could be commercialized,” Clode said. “The battery and motors are always the challenge with small wearables. I think it is a really unique product though, and it would be really interesting to develop it to that stage. The goal for the Third Thumb is to create a catalyst for society to consider human extension, framed in an approachable, accessible design. Success would be a widespread social engagement with The Third Thumb — from a jewelry designer to a falcon handler to a tattoo artist to a toddler. The more people who experience it, the better.”