Squishy Circuits Materials and Instructions Prepared by Rock City Robots www.RockCityRobots.com For additional ideas: http://courseweb.stthomas.edu/apthomas
/SquishyCircuits/index.htm To make a “squishy circuit,” you will need some conductive dough (recipe provided), some insulating dough (recipe to the right), several LEDs, a 9 v. battery clip, and a battery. You can use everyday, purchased play dough for the conductive dough. Most play dough has a lot of salt in it, and the salt is what conducts the electrical current. The insulating dough is made with sugar instead, and sugars do not conduct the electricity as well. Children can use the play dough to construct simple sculptures that will conduct the electricity, or complicated patterns. As they gain more experience, you can add buzzers and motors, using the same basic principles. Insulating Dough You only need just a few, basic ingredients to make your own. 1 1/2 cup Flour
1/2 cup Sugar
3 Tbsp. Vegetable Oil
Up to 1/2 cup Deionized
(or Distilled) Water
(Regular tap water can be
used, but the resistance of
the dough will be lower.)
Mix the first three
ingredients in a bowl; add
water, 1 tbsp. at a time, and
knead until it reaches the
desired consistency. Store
in an airtight container or
plastic bag. When stored,
condensation may form;
just knead moisture in
again. Dough should keep
for several weeks.
1
2
Make Your Own Conductive Dough 1 cup Water 1 1/2 cups Flour
1/4 cup Salt
3 Tbsp. Cream of Tartar*
1 Tbsp. Vegetable Oil
Food Coloring (optional)
*9Tbsp. of Lemon Juice may be Substituted
Learning the basics of electricity Electricity flows in a loop called a circuit. The circuit starts and stops with the battery (power source), and flows through the wires, the conductive dough, and electrical components, such as LEDs and motors. Attach the battery to the battery clip. Electricity is lazy; it likes to take the easy path, or the path of least resistance. It is easier for the electricity to flow through the dough than through the LED, so if the dough sections are touching, the electricity will not flow through the LED at all. If this happens, the light will not glow. This is called a short circuit. Make two sections of play dough, the shape is not important. Keep your dough pieces separate, either by leaving space, or by using insulated dough (see recipe) to separate the conductive dough sections. Insulators do not allow electricity to flow through them, which forces the current to go through the LED. Put the black wire from the battery pack into one section of dough. Put the red wire into the other section of dough. Remember, do not let the dough sections touch. Make sure your LED light is placed in the dough correctly. The LED has two leads coming out of the bottom. The longer lead goes to the dough with the positive (red) wire, the shorter goes to the dough with the negative (black) wire. Your LED should be glowing! Experiment with different shapes and configurations. Do not directly connect the LED to the battery. Mix water, 1 cup of flour, salt,
cream of tartar, vegetable oil, and
food coloring (if desired) in a
medium sized pot. Cook over
medium heat, stirring
continuously. The mixture will
begin to boil and get chunky.
Keep stirring until the mixture
forms a ball in the center of the
pot. Once the ball forms, place
the ball on a lightly floured
surface, and allow to cool for a
couple of minutes. Slowly knead
the remaining flour into the ball
until it has reached a desired
consistency. Store in an airtight
container or a plastic bag.
Condensations may form during
storage, but just knead the dough
again when ready to use. Dough
should be good for several
weeks, if stored properly.