Nearly two years ago, Chmielewski underwent a 10-hour brain surgery at the Johns Hopkins Hospital in Baltimore as part of a clinical trial — originally spearheaded by the Defense Advanced Research Projects Agency, and leveraging advanced prosthetic limbs developed by the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland – to allow participants to control assistive devices, and enable perception of physical stimuli (touching the limbs) using neurosignals from the brain. Surgeons implanted six electrode arrays into both sides of his brain, and within months he was able to demonstrate, for the first time, simultaneous control of two of the prosthetic limbs through a brain-machine interface developed by APL.