A soft button is or can be an interactive element used in clothing.
It can be used to switch something on. This something can be a gadget or a LED or an action of an ARDUINO. It is called soft because it is made of cloth or other pliable materials in contrast to a hard button or switch, for example a light switch.

Because you design the soft button yourself it can take all kind of shapes, from simple, like a circle or a square to imaginative like images of animals.

You can also make soft buttons in existing things, like a soft button in a pocket in your trousers, or inserting it into cushions.

You can make a soft button work when pushed slightly or only when really wrinched.

This instructable tells you how to make a button, which is on when you press, off when you do not . A button is not a swicth. A switch, having two states, on or off, can be made also, but needs more design in the sewing of the cloth, for instance with a flap and a few magnets.

Eventually when using a microcontroller, for instance an ARDUINO, you can make a button which serves a s a switch, but this instructable focusses first on the principle and making of the simple soft button.

This instructable will also give experiences and design tips. Of course you should experiment yourself. The soft button is an excellent field for experimenting and doing it yourself.

Step 1: Materials and Tools

For a simple soft button you need at least:

materials:
aluminium foil (from the supermarket)
some electrical wires,
soft material like foam, foam rubber, polystyreen
duct tape
cloth to cover your button

tools:
scissors or a cutter
sewing thread
no soldering yet!

more advanced, and more expensive:
you can replace the aluminium by conductive aluminum laminated fabric, see plugandwear.com
or by velostat
or by conductive thread,
you can replace the simple electric wire by a thinner wire, I prefer the thinnest possible in clothing

Step 2: Making the Conductive Surfaces

Aluminium foil is easliy damaged, therefore I use duct tape to reinforce it.
And at the same time the wire can be attached with the duck tape. The wire cannot be soldered to the aluminium foil.

Prepare the wire:
So use a pincer or a knive to get the copper of the wire visible, I usually mak the copper free for more than 2 centimeters for the side on the aluminium foil.

Put the long copper side on the aluminium foil and apply the duct tape evenly.
The side of the duck tape does not conduct anymore!

Make two of these reinforced and connected aluminum sides of about 5-10 centimeters in sides.

Step 3: Making of the Seperating Material

We have used foam rubber as a material to seperate the two conductive layers. Because we make a hole in this polystereen , the conductive layers which will be sandwiched around this middle layer can be made to touch, when you press on the three layers.

Thickness of the foam rubber: depends on the size of your button, usually for the smaller buttons 8 millimeters...

The hole in the foam rubber should be around the size of a dollar.
If you have cut out a bigger hole, you can add a support in the middle.

The relation size hole, material around the hole is important to consider:
if the hole is two small the user will not find the place where to press, if the hole is to big the two conductive layers might come together without being pressed.

Thicker foam can be used if you want to wrench the button instead of a gentle push.

Step 4: Sandwiching and Fastening

When you have prepared the conductive layers and the middle layer you can put them on top of each other. Remeber that the conductive sides need to be seeing each other through the hole.

Then you have to attach the layers using needle and thread, or glue.
The point is to get a surface which can touch on the conductive side, but does not stay like that, it has to regain it's shape if released. That is why you have to experiment how to attach the three layers.

Step 5: Testing

Testing is important before sewing it into cloth.

You can use a cheap multimeter for this, measuring the resistance, 0 when pressed, too big to measure when not pressed.

You can also use a cell battery of 3V and a LED to test. You can connect the wires without soldering. Be sure to connect the long leg of the LED to the + side of the battery.

Step 6: Sewing

After making and testing you can use your imagination to make whatever you want.

And really this last part is much more demanding then the functional part!

So now it is up to idea and design.

Some design considerations:
do you want to have a visible recognizable button (or not and hide it)?
what does the button do?

From these questions you can determine the shape and size of the button.

You can also use existing object to insert the sanswich in, for instance nice colorful cushions or teddy bears.

You can design the button differently, improvising with materials around. This is the subject of another instructable about a soft pouch.

Step 7: Examples

Here are some ideas for soft buttons.
You can make simple funny buttons with the prepared images you can iron on cloth. See the first image with the colorfull patches.
If you have a sewing machine, you can make your own designed and shaped soft buttons, we show two of our buttons in the images.
If there is a Fablab around or you have your own lasercutter then you can iron on you own shapes, see these dark blue soft buttons
We used these buttons in the project "connected garments".
http://www.contrechoc.com/garments/100330_pers_connected_garments_small.pdf

Once I tried to make the most soft button possible, using .very fluffy cloth, which you can see in the last button. This button was used in a Fablab project:
http://myfablab.wordpress.com/2009/12/01/gossip-attiny-44-project-description/

Also once I tried to design the most perfect soft button:
http://myfablab.wordpress.com/2010/06/06/the-perfect-soft-button/

more examples of our work can be seen at:
project in blogs on www.contrechoc.com exploring technical stuff
and design work at www.by-wire.net/