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Sculpting Circuits

By Samuel Johnson and AnnMarie Thomas Illustrations by Julian Honoré/p4rse.com

You will need

For conductive dough:

1c water

1½c flour

¼c salt

3Tbsp cream of tartar

1Tbsp vegetable oil

Food coloring (optional)

Assorted LEDs

4 AA batteries in a battery holder

Low-current DC motors

For insulating dough:

1½c flour

½c sugar

3Tbsp vegetable oil

1tsp granulated alum

½c distilled or deionized water (check lab supply stores)

Making play-dough creatures is fun, but making them with light-up eyes and moving parts is even more enjoyable. We thought it would be better still if we could make the circuitry out of the dough itself!

Most play dough is already conductive, but we needed a way to insulate the conductive dough. We came up with a sugar-based dough that works well as an insulator. It’s pliable and resistant to blending with the conductive dough.

Rainy day and fidgety kids? Whip up both types of dough, gather some LEDs and batteries, and create your own menagerie of squishy circuit creations. Add a motor or two for sculptures with moving parts. Feeling adventurous? Play with the salt content of the recipes to vary their conductivity.

1. Make the conductive dough.

Reserve ½c flour, and mix the remaining ingredients in a medium-sized pot. Cook over medium heat, stirring continuously. The mixture will begin to boil and get chunky. Keep stirring until a ball forms in the center of the pot. Once a ball forms, turn off the heat and remove the dough to a lightly floured surface.

Slowly knead the remaining flour into the ball until you’ve reached the desired consistency.

Store dough in an airtight container or plastic bag. In the bag, water from the dough will create condensation. This is normal. Just knead the dough after removing it from the bag, and it will be as good as new. Stored properly, it should keep for several weeks. If it dries out, just add a little more deionized water and knead it with some flour.

2. Make the insulating dough.

Mix the dry ingredients and oil in a pot or large bowl. Mix in 1Tbsp of deionized water and knead; repeat until the mixture becomes moist and dough-like.

Remove the mixture from the pot or bowl, and slowly knead flour into it until it attains a firm consistency. You should use almost the entire ½c of flour.

Photograph by Samuel Johnson

3. Make squishy circuits.

Insert the 2 leads from the battery pack into 2 pieces of conductive dough, separated by a lump of insulating dough (we recommend using food coloring to differentiate the doughs).

Insert an LED so its anode (long lead) is in the positive battery lump, and its cathode (short lead) is in the negative battery lump. It will light up! end-graphic

Samuel Johnson is from Blaine, MN, and is an engineering student at the University of St. Thomas. AnnMarie Thomas is an engineering professor at the same university, and codirector of the Center for Pre-Collegiate Engineering Education.

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