What is a characteristic of myoelectric devices?

Myoelectric devices are characterized by their ability to utilize electrical signals generated by the muscles. These devices detect electrical impulses produced by muscle contractions and convert them into movements or actions, such as opening and closing a prosthetic limb. This characteristic allows for a more intuitive control compared to purely mechanical devices, as users can simply think about moving their muscles to operate the device.

While these devices do require some form of power to function, including batteries in most cases, the key distinguishing feature is their reliance on muscle-generated electrical signals for control. The other options do not accurately capture this unique aspect of myoelectric devices. For example, purely mechanical devices operate without any electrical assistance and do not involve muscle signals, while stating that they are powered by battery only or require external power sources does not highlight the fundamental characteristic that defines their operation.