Electronic Textiles & Soft Sensors Workshop Recap

Last Sunday’s Soft Sensors Workshop was a lot fun. We learned about several different kinds of materials and threads, various ways to make input devices for electronics, and even made a few of our own sensors.

On the left is a small fabric switch made during the class from three layers of fabric, with adhesive conductive fabric as the switch parts. On the right is being made a 4-position pressure switch in the shape of a flower.

Also, CRASH Space now has a sewing machine! Syuzi helped us acquire it. It’s a Bernini with a strong motor that’s good at sewing conducdtive threads (which are typically thicker than normal)

Some things we learned in the workshop:

General Fabric Hacking

• You need multimeters & alligator clips to hack the fabrics. Just wires and hook jumpers aren’t good enough to get good purchase on the fabric & thread.
• A good starter kit of wearable tech is : http://www.aniomagic.com/

Conductive Thread

• Thread is rated by its conductivity rating, often in ohms/foot.
• The more silver a thread has, the more conductive it is, making it a better wire
• Highly resistive thread can be used as resistors for LEDs, etc.
• For machine sewing, conductive thread goes in bottom bobbin, not on top spool. Otherwise it breaks or jams machine.
• When hand sewing, use single thread, not double, by way of a “bookbinder’s knot”
• Also when hand sewing, don’t do finish up with big knot at end, a small one will do
• Sparkfun 2-ply thread isn’t so good, it frays.

Fabrics

• Some conductive cloth is more conductive along one dimension. Test it out to see which way is which.
• Some fabrics can be etched like circuit boards
• Resistive fabric is pressure-sensitive, can be used as sensor
• Stretch/ Spandex-like conductive fabric changes resistivity slightly when stretched
• Tulle netting is useful as padding between conductive fabrics, acting like an insulator until pressed.