Various techniques could be applied to create this kind of "stroke sensor" such as knitting or crocheting loop stitch or rug knotting techniques. This Instructable shows how to stitch conductive 117/17ply silver plated nylon thread and a more resistive 66 Yarn 22+3ply 110 PET thread into neoprene in order to create a "stroke sensor". The rubberiness of the neoprene creates enough friction so that the threads will not come loose when stroking. Meaning you don't have to knot each individual hair. It is important to use these particular threads as thicker conductive threads tend to curl when repeatedly stroked and thus don't work for the stroke sensing anymore.
The publication DIY Wearable Technology also contains information on this sensor and can be downloaded from:
HOW TO GET WHAT YOU WANT:
Loop stitch technique post >> www.kobakant.at/DIY/
Stroke sensor post >> www.kobakant.at/DIY/
Step 1: Materials and Tools
* Conductive thread- Silver Plated Nylon thread, 117/17 2ply
* Resistive thread - 66 Yarn 22+3ply 110 PET
both from LessEMF: lessemf.com/fabric.html
* Stretch conductive fabric
* Fusible interfacing
* 1.5 mm thick neoprene with polyester jersey laminated to either side from SedoChemicals: www.sedochemicals.de
* LilyPad sewable LED
* Sewable coin cell holder
both from Sparkfun: www.sparkfun.com/commerce/product_info.php
* 3V coin cell
- Sewing needle
Step 2: Material preparations
Step 3: Thread needle, stitch, cut
Start by stitching through from the front side of the neoprene where the conductive fabric is adhered to the back. Make sure the thread goes all the way through the neoprene and makes contact with the conductive fabric before coming out the front again. Then cut all four threads to roughly equal lengths - depending on sensor design - about 2-3cm.
Repeat this over and over again until both conductive fabric strips have "hairs" connected to them. See photos.
Now thread the resistive thread the same way and repeat the same technique over again but this time fill the surface area in between the two conductive thread/fabric strips. See photos.
When you are finished with this, your sensor is finished, in order to see results continue with step three. or simple use alligator clips, an LED or a multimeter or an analog to digital converter to read sensor values.
Step 4: Complete circuit
End of one of the conductive fabric strips -- to -- Negative LED lead
Positive LED lead -- to -- Positive battery holder lead
Negative battery holder lead -- to -- End of the other conductive fabric strip
Now when you stroke the sensor you will see how the LED lights up brighter the greater the surface you stroke and the harder you stroke.