Prosthetic limbs are somewhat of an engineering miracle. Allowing someone to replace a lost limb, and move it around is amazing. But many advancements are being made to make prosthetic arms even more realistic. The most interesting one, in my opinion, is a prosthetic arm that can be controlled by just your mind. The first person to get one of these advanced limbs, Johnny Matheny, lost his arm to cancer in 2005. Another cool advancement, is connecting the arm to the skeleton and connecting the nerves to it. This makes it seem more like an actual limb than a prosthetic.
To learn more about Johnny Matheny, check out this article.
https://futurism.com/mind-controlled-robotic-arm-johnny-matheny
This relates to engineering because its robotics and it helps people who have lost limbs.