Here’s a design that has been making the rounds on the internet lately. Dezeen points out Dani Clode at the Royal College of Art, who created a “third thumb” to add to human dexterity. Clode calls it “part tool, part experience, and part self-expression.” From a design standpoint, it’s a 3D-printed prosthetic controlled using a pressure sensor on the bottom of the user’s shoe. A Bluetooth signal is sent to a motor on the wrist, which controls the thumb by pulling a plastic filament.
Clode told Dezeen she chose to put the pressure sensor on the foot because it mimics existing hand-foot behaviors such as driving a car or operating a sewing machine.