Researchers have created an ultrasonic sensor that allows amputees to control each of their prosthetic fingers individually. It provides fine motor hand gestures that aren’t possible with current commercially available devices.
The amputee’s everyday prosthesis is similar to the majority of devices on the market. It’s controlled by electromyogram (EMG) sensors attached to his muscles. He switches the arm into various modes by pressing buttons on the arm. Each mode has two programmed moves, which are controlled by him either flexing or contracting his forearm muscles. For example, flexing allows his index finger and thumb to clamp together; contracting closes his fist.
The team attached an ultrasound probe to the arm. When he tries to move his amputated ring finger, the muscle movements differ from those seen when he tries to move any other digit. The team fed each unique movement into an algorithm that can quickly determine which finger he wants to move.
The ultrasound signals and machine learning can detect continuous and simultaneous movements of each finger, as well as how much force he intends to use.