There are many applications where an embedded load or strain sensor has been used to provide what is called “structural health monitoring” or SHM of the component. Often these are special fiber optic filaments called FOBG (fiber optic Bragg gratings) that can contain hundreds of discrete stain sensors along the fiber length. Each of the sensors’ locations are known in the part and each can be individually interrogated, so that the strain field inside the part can be fully described. These FOBG filaments can be molded into a composite part, a plastic part or even a metal part (with Ultrasonic Additive Manufacturing or UAM). In fact, you reported on this in your 17 Oct 2019 post “Fabrisonic’s Smart Metal 3D Print Build Plate”.
Point is, while embedded sensors are not frequently seen in AM, they have been done before. And the FOBG technology has quite a few advantages (as a sensor) vs. the carbon fiber sensor approach described here. Not saying the CF sensor is not newsworthy, it is. But for folks interested ion embedded sensors, there are also more established methods that offer some advantages from a sensor perspective.