Looks like thread, but it’s actually coax
The “piece of thread” being cradled in the picture is actually a micro-miniature coax cable from New England Wire Technologies. The typical application is to send back video from cameras on the end of catheters in hard-to-view areas of the human body, but the light weight of the cable makes it a candidate for aerial uses as well. The super-small coax has a 0.0009-in. diameter and uses a spiral shield. Officially, the center conductor is 42 gage and the spiral 50 gage. New England Wire is a custom cable manufacturer.