This interactive mat created with self-made conductive paint consists on a reaction game. When a LED lights up randomly, the players have to press the conductive field on the mat quickly, so the first who presses gets a point. This is indicated by another LED (different colour for each player) that lights up and a display counting the points and game rounds.

The conductive paint allows to create any kind of game, interactive drawings, clothing or even instruments, just by painting different patterns and coding with the Arduino. This can be very useful in the field of industrial design to make interactive prototypes.

Step 1: Materials Needed

- Piece of white cloth

- Black acrylic paint

- Graphite powder

- Brush

- Sponge

- Masking tape

- Arduino

- 3 different colours LEDs

- Two 1 megaohm resistors

Step 2: Make the Conductive Paint

Mix 2 teaspoons of graphite powder and 3.5 teaspoons of black acrylic paint in a bowl (depending on the quantity needed you can add more or less)

*You can choose any other colour paint, but it has to be taken into account that the graphite will make it greyish.

Step 3: Paint the Game Layout on the Cloth

For this kind of game what is needed is two shapes that will serve as "button", so when the player will touch it the circuit will be closed and the LED will light up.

1. Put the masking tape along the shape of the button that you want to do so it is easier and cleaner to paint.

Don't forget to draw also a line from the button till one side of the cloth where the cables will be connected and the Arduino and board placed.

2. Paint the surface either with a brush or a sponge and make sure that the whole area is covered with paint.

3. To go quicker, the paint can be dried with a hairdryer and then another layer of paint can be added (2 or 3 layers should be enough to ensure the correct working)

Step 4: Connect Cables to the Conductive Paint

Connect one cable to each of the line's edges (you can use tape to hold them properly). Paint on the tips and hold while drying up to ensure that the cables are making contact with the paint pattern on the cloth.

Step 5: Code the Game and Setup the Arduino Circuit

- Connect 3 LEDs to the board. 2 will be used as visualisation of which player is faster to press the "button", and the middle one will indicate when the button has to be pressed, lighting up randomly every round.

- Connect the two cables that are in contact with the cloth paint, making sure to use 1 megaohm resistor for each capacitive sensor.

- Code the game and upload to Arduino. You can download the code below and see the Arduino setup for this reaction game on the image. Be aware that you have to download the following libraries so the code works:

LCD

Capacitive Sensing

- Take into account that the "buttonValue" threshold should be adjusted depending on the paint layers. Try out printing the values when touching the buttons and set up the optimal value according to the sensitivity desired.