Introduction: Embodying Chemistry: Paint an Interactive Dance Pad
Explore chemistry concepts while making a mobile, interactive dance pad using conductive paint and a capacitive touch-based microcontroller. You will learn about the chemical properties of conductive paint and understand how the paint is used to make a circuit (that is painted on the dance pad).
To begin watch this video about artist Thomas "Detour" Evans who embeds painted circuits in his work:
In the video, the painting becomes part of the live performance because each painted sensor represents a rubber pad on an MPC drum machine. To make this work, Evans collaborated with Bare Conductive, the company that makes Electric Paint and the Touch Board, a microcontroller with 12 capacitive touch and proximity electrodes, that can be used to turn any material or surface into a sensor.
You can try this on your own. In this example, Electric Paint and the Touch Board (on paper) is used with GarageBand software:
Supplies
Conductive paint (ex. Electric Paint)
Pencil
Paper
Cardboard or card stock (for dance pad)
Alligator clips (optional)
Micro-USB cable
Laptop computer with Arduino IDE installed
Speaker or headphones
Step 1: Chemical and Electrical Properties of Paint
Research the chemical properties of paint such as pigments, polymers, and additives. Conductive paint is a paint that is electrically conductive, meaning it conducts electricity. It consists of a conductive pigment, for example, silver, copper, nickel, or various forms of carbon, either suspended as particles or dissolved in a solution. Graphite, which contains carbon atoms, is a very good conductor of electricity. See how electricity moves through graphite:
Electric Paint uses a combination of carbon black and graphite in a water-soluble solution to make a conductive water-based paint.
Step 2: Painting the Circuit
Use a pencil to sketch out a custom circuit design on paper first, making sure to include the leads or lines that will be connected to the Touch Board electrodes. Use a paintbrush to paint (with conductive or Electric paint) the circuit design on stiff board that is big enough to dance on. For example, dance students (as part of a chemistry project) painted a design that was inspired by the "covalent" structure of graphite.
Each carbon atom is joined to three other carbon atoms by covalent bonds. The carbon atoms form layers and free (delocalized) electrons move between the layers, so graphite can conduct electricity.
Note: Leave space on the painted dance pad for the Touch Board to be attached and connected later.
Step 3: Cold Solder the MIDI Bridges on the Touch Board
The Touch Board has a MP3 decoder chip, which is capable of playing multiple music samples simultaneously. The leftmost solder bridge connects a digital pin on the microcontroller to a MIDI pin on the decoder chip. The right solder bridge connects another digital pin and puts the chip into real-time MIDI mode.
To use the Touch Board’s real-time MIDI Mode, you have to make some physical changes to the board. Electric Paint can be used to cold solder components called bridges. Connect the solder bridges by adding a tiny blob of the paint across the gap between the exposed gold pads.
Once the paint is fully dry (20-30 minutes) you can move on to the next step.
Step 4: Upload Code to the Touch Board
In order for the dance pad to be interactive you have to upload code to the Touch Board. Plug the device into your laptop computer via a micro-USB cable and plug in your headphones or speaker. Make sure that the power switch on the board is turned on. To set up the Touch Board for use with Arduino software follow these steps.
Open the Arduino IDE and open the MIDI Piano sketch from your Sketchbook. You will find it under File > Sketchbook > Touch Board Examples > Midi_Piano. Ensure that Touch Board is selected under Tools > Board and that the correct serial (CU) port is selected under Tools > Port.
With all of the correct settings selected, click File > Upload to upload the code.
The RX and TX LEDs will flash on the Touch Board and the Arduino IDE should say “Done uploading.”
While the device is still connected you can test if it's working by connecting your headphones to the audio jack on the Touch Board.
Step 5: Connect the Touch Board to the Dance Pad
Now that we have the code on the Touch Board, we can go ahead and connect the (now dry) pad to the device. You can either do this using an alligator clip cable, or by cold soldering with a small blob of Electric Paint to connect the sensors directly to the leads on the painted circuit (dance pad).
Note: It is easier to remove alligator clips if you want to make changes. If cold soldering, wait until all of the connections are fully dry (at least 30 minutes).
It doesn’t matter which sensor you connect the painted leads to, provided that there is a file named appropriately to the sensor on the microSD card.
For example, TRACK000.mp3 if you are connecting to electrode 0.
For more details on naming the tracks and uploading your own sounds to the microSD card click here.
Step 6: Try It Out
When you have uploaded the code, take a speaker or headphones, and connect it to the Touch Board. Try dancing on the pad with your bare feet, you should hear a sound when your foot touches a painted line or shape.
Move the Touch Board (and laptop or power source) out of the way. In this example (see photo), the dancer's movement simulates the movement of the free electrons in the diagram for carbon (graphite).
You can also use the MIDI code to trigger other media such as video clips:
This work is made possible by support from STAR, a Biogen Foundation Initiative. The team at Lesley supporting this initiative includes faculty and staff in the Lesley STEAM Learning Lab, Science in Education, the Center for Mathematics Achievement, and other related Lesley University departments and programs.