Our favorite electric textiles expert, [Leah Buechley], put together this machine embroidered LED matrix proof of concept. For the vertical rows, the top thread is conductive, while the thread on the underside (the bobbin) is not. For the horizontal rows, the the thread is swapped and the fabric acts as an insulator between the two layers of wiring. You can see a small brown bunch of thread next to each LED: this is the via to wiring on the backside of the fabric. The matrix is being controlled by a LilyPad Arduino. This is an interesting idea and has the potential to make prototyping wearable projects much faster. Here are two more pictures of the project.