Robotic prosthetic arms and hands can make dramatic differences in the lives of those who use them. We’ve written about a range of upper limb prosthetics designed to assist people with specific needs including a robot hand that works with quadriplegics, a wheelchair-mounted robotic arm that enables greater independence for users, and soft hands for elderly caregiver robots.
Biomedical engineers from the University of Utah modified a prosthetic arm developed by DEKA Research & Development Corp. with a sense of touch. Originally funded by the Defense Advanced Research Projects Agency (DARPA), DEKA’s LUKE arm was approved by the FDA in 2014. DARPA supported LUKE (Life Under Kinetic Evolution) — one of Segway inventor Dean Kamen’s several brainchildren — to offer the option of returning to active duty to men and women who had lost limbs. Prior to the more recent Utah developments, the FDA approved the LUKE arm because of its ability to translate signals from a patient’s muscles into precise movements such as preparing meals, brushing teeth, and opening locks with keys. In sum, the Utah team started with a robotic arm and hand responsive to mind control.
The LUKE arm is constructed of metal parts and motors with a silicon skin over the hand. Richard A. Norman, a University of Utah bioengineer who worked on the original design, invented the array of microelectrodes and wires called the Utah Slanted Electrode Array that is implanted into nerves in the recipient’s forearm. The array transmits signals from the brain to an external computer that controls the arm and hand movements.
The Utah team leader, biomedical engineering associate professor Gregory Clark, used sensors in the LUKE hand to send signals back to the brain. The earlier technology sent feedback so the brain wouldn’t exert too much pressure while touching, holding, or turning. Clark and his group recreated the burst of impulses from nerves to the brain that occurs when the hand first touches something. The result? The LUKE arm’s hand now gives the patient a sense of touch. Clark described the new technology in an article published in Science Robotics.
Further work with the LUKE arm includes building a completely portable version without a connected external computer. Additional work is planned to augment the sensory capability with temperature and pain and to adapt the arm for use by people whose limb loss extends above the elbow.
