No, not all products require a 510k, but all devices getting a 510k are a medical devices. If the device is something non-invasive, and simple such as that of a band aid, it would be classified as a class I device. Most class I, and few class II devices require 510k’s. However, these devices are still subject to certain more general controls. To answer your other question, a device is typically defined as something created for a specific use, and because a band-aid is used to help a person when injured, it falls into the category of a medical device.