By using high-resistance zipper switch, this sensor gives analog values instead of “ON/OFF”.instead of , you can make a slider (potentiometer) with zippers. Unlike
Resistive thread 66 Yarn 22+3ply 110 PET (4k ohm/20cm) is stitched on one side of the zipper using sewing machine. The thread is used as a top thread on the machine. To achieve the good connection to the zipper head, I had to go over the stitch many times with sewing machine.
The Lame Life Saver stitch is applied on the other side of the zipper. the end of the both stitches are connected to conductive fabric where you measure the resistance between.
As you move the zipper head, the distance from measuring point and the connection point on resistive thread stitch changes just like potentiometer sliders.
Joo Youn Paek posted a really nice report of her construction of an analog zipper sensor using resistors sewn in series with multiple contacts back to the zipper:
She used this technique in the Zipper Orchestra project: