Paper Circuit

Introduction

Have you ever made a painting or drawing that included lights, like light from the sun, or from the windows of a house at night? Do you think it would be fun if those light sources could actually light up? That is what paper circuits allow you to do—build real lights directly into your drawings or paintings, like the one in Figure 1.

Figure 1. An example of a paper circuit that includes real lights in the centers of the flowers.An electrical circuit is a loop where electricity can flow. A basic circuit requires a battery, which stores electricity (other types of circuits can get electricity from other places, like a wall outlet). The battery must be connected to a light with materials that let electricity flow easily (kind of like water flowing easily through a pipe). These materials are called conductors (materials that do not let electricity flow easily are called insulators). Figure 2 shows a diagram of a basic circuit.

Figure 2. A diagram of a basic circuit. Electricity is supplied by the battery. It flows in a loop through the conductor (which, in this figure, is a wire), to the light, and then back to the battery.

Conductors for most circuits (like the wires for the lights in your house, or inside a computer) are made out of copper wire, because copper is a very good conductor. However, there are many different options for conductive materials in paper circuits, as shown in Figure 3.

Figure 3. The conductive materials you might test in this project. From top to bottom: artist's graphite pencil, #2 pencil, conductive ink, electric paint, copper tape, and aluminum foil.

There are also different types of batteries, as shown in Figure 4. You might be familiar with AA or AAA batteries, commonly used in toys and electronic devices.Coin cell batteries—the type found in watches—are tiny, flat, and lightweight. 9 volt batteries are bigger and heavier, but have a higher voltage, which is how hard the battery "pushes" on the electricity (the coin cell batteries in this project are only 3 volts [V]). A higher voltage can "push" electricity through a less conductive material, whereas a low voltage requires a very conductive material in order to push a lot of electricity through.

Figure 4. A 9 V battery (left) and a coin cell battery (right). In this project, you will test each of the conductive materials shown in Figure 3 with the batteries in Figure 4, to light up a tiny light called an LED (which stands for light-emitting diode). Which materials do you think will work with which battery? What combination do you think will be the "best" overall for an art project? Read the Questions and Bibliography sections to get started making your hypothesis.

Terms and Concepts

• Circuit
• Conductor
• Insulator
• Battery
• Coin cell battery
• 9 volt (V) battery
• Voltage
• Light-emitting diode (LED)

Questions

• What are some different materials that can be used as conductors in paper circuits?
• What are some examples of paper circuit projects? Hint: Do an internet search for "paper circuit" and look at some of the projects that come up.
• Look closely at the example paper circuit projects you find.
  • What type of conductive material do they use?
  • What type of battery do they use?
• Do a search to see what types of materials usually make "good" conductors, and what types are poor conductors.

Materials and Equipment

The following materials are available from SparkFun Electronics:

• 5 mm copper tape, SparkFun Electronics part # PRT-10561
• Electric paint pen, SparkFun Electronics part # COM-11521
• Conductive ink pen, SparkFun Electronics part # COM-13254
• 9 volt battery, SparkFun Electronics part # PRT-10218
• 2032 coin cell battery, SparkFun Electronics part # PRT-00338
• Alligator clip test leads, SparkFun Electronics part # PRT-12978
  • Note: These are sold as a 10-pack, but you only need 2 for this project.
• Pack of assorted LEDs, SparkFun Electronics part # COM-12062
  • Note: You only need a few LEDs for this project, but you can use additional ones for your artwork.

The following materials are available from home or an art supply store:

• Artist's graphite pencil(s) and/or #2 pencils, an art supply store.
  • Note: Pencils are labeled with letters and numbers that indicate a hardness scale. For example, #2 pencils might also have the letters "HB" on them. The pack of graphite pencils listed above contains 2B, 4B, and 6B pencils. To learn more about the pencil hardness scale, If you buy multiple pencils with different hardness ratings, you can test all of them.
• Aluminum foil
• Printer paper or construction paper (at least 6 sheets)
• Scotch® tape
• Metric ruler
• Scissors
• Thin paintbrush
• Drawing or painting materials of your choice (markers, colored pencils, crayons, etcetera)
• Newspaper to protect your work surface
• Lab notebook