conductive felt, je t’aime

I’m going to be making the majority of my soft cyborg’s nose out of conductive felt so that it’s one big force sensor. I started to play around with making conductive felt using bronze wool and merino wool. I found a Canadian supplier to order bronze wool from; it’s pricey ($9/3 pads) but it cards way better than steel wool and is much easier on the hands.

Initially I just played around with carding and felting the bronze and merino wools together. I used too much bronze wool and there was no resistance. I was much more meticulous the second time around. An Instructables tutorial on making conductive felt suggested using a 2:5 ratio, bronze wool to fleece. I went with 8g of bronze wool and 20g of merino wool. (The tutorial also said that this conductive fleece could be spun—something I will have to explore further at a later date.)

Materials & Equipment

  1. merino wool
  2. fine bronze wool
  3. scale (I used a digital scale the second time around)
  4. hand carders (i.e. cat brushes–the bronze wool will wreck real carders)
  5. felting needles and tools (optional but they make felting much faster)
  6. a piece of foam (for felting on)

materials & equipment

Conductive Fleece

The bronze wool needed to be teased apart a bit but aside from that, it blended easily with the wool fibres.

Bad Conductive Felt

While my first attempt at making conductive felt was a flop, I did figure out that the felt works better when it is loosely felted. I got a bit of variation in my reading with the thicker section of the felt rectangle. The ball’s reading did not change at all.

electric scale

Good Conductive Felt

Less bronze wool in this batch. I might even try a little less. The flat circle provided consistent variation in its resistance level when touched. The ball was a bit trickier, sometimes there was resistance, sometimes there wasn’t. Also, the ball’s resistance reading changed depending on how densely the fleece was felted. Structurally I need my soft cyborg’s nose to be able to be squeezed repetitively, however if it is too dense I won’t get a resistance reading. So I’ll try less bronze wool next.

Circuit

I used a simple force sensor circuit to test the resistance of the conductive felt. Here’s the code:

/*
AnalogReadSerial
Reads an analog input on pin 0, prints the result to the serial monitor

This example code is in the public domain.
*/

void setup() {
Serial.begin(9600);
}

void loop() {
int sensorValue = analogRead(A0);
Serial.println(sensorValue, DEC);
}

carded conductive fleece

carded conductive fleece (detail)

good conductive felt

soft circuit

1 comment to conductive felt, je t’aime

  • Looks great! Glad to see you’re exploring this process. A multimeter might be a handy tool to have around so you can keep notes on the resistance range of each of these sensors.

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