Introduction: Needle-Felted Pressure Sensor

Create a pressure sensor using:

- Needle-felted wool

- Thin muslin

- Velostat

- Conductive thread

This sensor can be used an analog input for Arduino code.

Step 1: Prepare the Core Components

Component 1: A felted wool ball. This can be made using unwoven wool (I used Leicester wool), a felting needle, and a piece of foam. There are several tutorials specific to felting online. Here, we just have a basic ball.

Component 2: Two fabric swatches, each in an "+" shape. I used a thin muslin here.

Step 2: Add Conductive Thread to First Swatch

On one of the two swatches, sew a trace of conductive thread. I used stainless steel thread, and a couch stitch. Leave a few inches of extra thread at one end.

Step 3: Attach First Conductive Layer to Ball

Sew this first swatch onto the ball, with the conductive thread facing outward.

Step 4: Add the Second Conductive Layer

On the second swatch, create a new trace of conductive thread. This trace should be different than the first.

Not pictured here, but very important: cut a layer of velostat in the same "+" shape as the two conductive swatches. The velostat is a pressure-sensitive conductive sheet, and is essential to this sensor functioning.

You are going to wrap the second "+" swatch around the first one-- so that the conductive thread on each face each other. But! before attaching, make sure the velostat is sandwiched between the two.

Step 5:

Add a new, thin layer of wool around the sensor, and test the sensor before continuing.

If you are using Arduino, you can test the sensor using Arduino's analogRead(), for example in Open the console and make sure the values change as you expect when squeezing the ball.

Step 6: Have Fun With Shape and Color

This step is purely for aesthetics. I chose to add a bit more shape and color-- all using wool and felting needles.

Step 7: Play!

Hook your new pressure sensor up to some code, and play! As a deme, I use Processing and Arduino here so that my computer plays a sound effect when I squeeze the sensor hard enough.