Imagine being paralyzed or losing a limb. You would mourn the loss of your full mobility, knowing full well that a prosthetic replacement wouldn’t offer you the same ease of movement or sensitivity that your original limb did. Losing an arm would be particularly difficult as humans use their arms and hands for a large variety of tasks, such as: picking up objects, feeling the texture of surroundings, and communicating.
Prosthetic arms are thought of as having limited functionality; they allow a small range of motion and are not capable of reaction to external stimuli. In response to this problem, DARPA (Defense Advanced Research Projects Agency), the research branch of the U.S. military, launched a program called Revolutionizing Prosthetics in 2006. This program has made great advancements in upper limb prosthetics throughout the years, but their biggest breakthrough came in recent months.
DARPA researchers have been able to develop a prosthetic arm that can be controlled by the brain, similar to a biological arm. Doctors performed brain surgery on a paralyzed woman named Jan (last name not released) and implanted a small group of electrodes into her motor cortex. The signals picked up by the electrodes in Jan’s motor cortex were then processed in real time by a computer and sent to the prosthetic arm, making it move however Jan wished. This granted Jan a new large range of motion, and her movements were described as appearing natural.
The success of this surgery inspired researchers to try to take the process a step further: they had successfully designed a prosthetic to receive neurologic impulses, but could they design a prosthetic that could send sensory impulses back to the brain? DARPA researchers began study how to create a prosthetic arm that could transmit signals to the brain, and thereby relay the sensation of touch. Researchers worked on this problem for months, creating simulations and drafting ideas.
After all of their hard work, DARPA researchers have succeeded in their goal. On September 11th, 2015 DARPA announced that it had developed a prosthetic arm that could “feel” the things it touched. This feat was accomplished through a surgery similar to the one performed on Jan. This time, however, a tiny group of electrodes was placed in a paralyzed man’s, Nathan’s, sensory cortex, which, if the arm worked correctly, would receive sensory information from pressure sensors located on the prosthetic arm’s fingers. To test the effectiveness of their project, DARPA researchers blindfolded Nathan and then pressed on the pads of the prosthetic’s fingers. Nathan was able to correctly identify which finger the researchers were pressing on nearly every single time. To further test the arm’s abilities, researchers pressed on two of the fingers at the same time without telling Nathan. He was successfully able to identify both of the fingers. Project manager Justin Sanchez stated that that moment was “when we knew that the feelings he was perceiving through the robotic hand were near-natural.”
These incredible achievements and devices have the power to change amputees and paralyzed patients’ lives forever by granting them a greater and more natural range of motion and allow them to perform tasks that were once thought to be extremely challenging, if not impossible, without real limbs. DARPA’s new prosthetics would give users the ability to tell if they are touching an object and how hard they’re grasping it, and make performing everyday tasks much simplier. While DARPA is keeping quiet about the greater details of the project’s success, such as how sensitive the arm is to different types of surfaces, it is speculated that this technology could eventually be modified to give wearers the ability to sense texture and temperature. DARPA has made great strides in the field of upper body prosthetics, and it is exciting to see what they will develop in the future.