A mechanical hand utilizing DARPA-developed neural technologies has become the first to allow a paralyzed patient to feel physical sensations through a prosthesis. The 28 year-old test subject was able to determine which mechanical finger was being touched whilst blindfolded, with total accuracy.
The identity of the patient has not been disclosed for privacy reasons, however a DARPA press release states that he was left paralyzed due to severe spinal injuries. In the past, test subjects have been able to manipulate prostheses via thought alone, but the technology had been a one-way street. An individual could send signals to the hand from the brain in order to control the prosthesis but received no tactile sensory data in return, making it difficult to direct precise movements.
The new study takes the science of prosthetic technology to a new level, allowing two-way communication between a mechanical hand and its user. The feat was accomplished by running wires connected to electrodes on the patient's sensory cortex (the part of the brain responsible for identifying tactile sensations) and motor cortex (the part that directs body movements) to the prosthesis.
The mechanical hand that interfaces with the DARPA tech was developed by the Applied Physics Laboratory at Johns Hopkins University. Torque sensors integrated into the device are able to detect when pressure is being applied to the prosthesis, converting force into electrical signals which are transmitted to, and interpreted by the subject's brain.
During laboratory testing, the patient was blindfolded while researchers touched each of the hand's bionic fingers. The patient described the sensation, stating that it was as if his own hand were being touched.
"At one point, instead of pressing one finger, the team decided to press two without telling him," comments program manager for DARPA's Revolutionizing Prosthetics program, Justin Sanchez. "He responded in jest asking whether somebody was trying to play a trick on him. That is when we knew that the feelings he was perceiving through the robotic hand were near-natural."
It is hoped that developments based on the technology could one day see amputees and those suffering from paralysis have access to mind control prostheses that allow individuals to feel once more.