Squishy Circuits

 Conductive & Insulated Dough for Soft Circuits

Looking for something fun and educational? Then look no further! If you did not know, off-the-shelf Play-Doh is conductive! You can model with it and hook up a battery pack into it and make circuits! You will need a non-conductive dough to pair with it like a plasticine modeling clay that lacks the salt content.

As this is a Makerspace, and we’re all about making, here is a recipe for making both doughs at home! Whether or not you do make circuits or just make it to model, is up to you!

This will need the use of a stove or heating element. If you’re not an adult following along, please ask an adult to assist you for everyone’s safety!

What You Will Need:

Conductive Dough:

Electronics:

How to Make:

Make sure you use separate bowls, or thoroughly clean between making each dough to minimize contamination. Food coloring is optional, but I believe color makes things more interesting. You can also use it to indicate which dough is which as well, which helps! You can either mix it in with the ingredients in the beginning, or work it into the dough once it is out of the pot. Store the dough in a zip top bag or air tight container for future use.

For Conductive Dough:

Mix your ingredients into a pot. It is suggested you mix your dry ingredients (flour, salt, cream of tartar) first, then add your wet ones (water oil, lemon juice, food coloring).

 Set the heat to medium on your stove. Continue to stir until a dough ball forms.  If uncolored, it should have a light yellowish color to it, similar to sugar cookie dough.  Remove from the pot when it has the preferred dough consistency and set on some parchment paper or silicone sheet to cool.

When it is still warm, but cool enough to touch, Knead in extra flour if needed.

Knead in the food coloring if you have not added it into the pot before cooking. If you are kneading the food coloring in, use disposable food gloves to keep your hands from getting dyed as well!

Store the dough in a zip top bag or air tight container for future use.

For Insulating Dough:

Mix the flour, sugar, and vegetable oil in a bowl. Add in the food coloring now if you don’t intend to knead it in.

 Slowly add in the water little by little as you knead the mixture or it may become too sticky and difficult to use. 

Continue to knead until it acquires the preferred dough texture. Knead in extra flour if needed. It should be a little bit sticky and have the consistency similar to pizza dough.

Using disposable gloves, knead in food coloring, if you have not added it into the mixture prior. 

Note: I’ve made it twice to make sure, but it will be sticky no matter what, and when handling gets warmed up and gets a tad more stickier. You may want to keep some flour on hand or use wax/parchment paper when in use to keep it from sticking on things you don’t want it to. You may also want to lightly line your bag/container with some flour in storage to help you take it out next use. This also will not last long– in about 3 weeks after making this it had mold!

You may also want to mix the food coloring in first for this dough instead of kneading the color in, due to its stickiness.

If you don’t use food coloring and need to tell the difference, the conductive dough is more solid like cookie dough, the insulated dough is sticky and more akin to pizza dough. 

Making the Circuit:

What you make is as limited as your imagination! However, there are some rules.

Circuits are circular—you need to make sure your power and ground and everything in it is all set up right. For that, you will always need two parts of conductive dough. One conductive part will be hooked up to the power (+) end of the battery, and the other conductive part for ground (-), with one part of the insulating dough in between to keep the circuit from shorting.

You may want to instinctively put your ground in the insulated dough– but it creates too much resistance and your LED may not glow!

When putting in your LEDS, make sure the anode and cathode are on the right side of the conductive dough. The anode is the longer leg of the LED, and that goes into the conductive dough (the purple one in my picture), the shorter leg goes in the insulated dough (the red dough).

For more information check out our Physical Computing guide.

 You could show resistance by adding a resistor, dimming your LED.

I also noted while making the circuits that this dough is softer than the store bought kind and may need a few tries to get the jumper cable near the LED in the dough. 

When you’re done you can try and separate the sculpture for storage, or let it dry out. However, once it is dry, it will no longer be conductive. I also suggest not returning the already mixed dough to their respective containers if you’re concerned about cross contamination.  If either dough dries out, you can rehydrate it by mixing in a little water and working it back into the dough.

But How Does it Work?

For more information about electricity and circuits, please check out our Physical Computing Page!

It’s all about the salt! Salt is a compound of Sodium (Na) and Chlorine (Cl). Water breaks down the salt compound and creates Ions that are freely and easily. Ions are particles that carry an electric charge due to gaining or losing electrons, the subatomic particle responsible for electricity and electromagnetism.  The sodium ion loses an electron and becomes positively-charged; the chlorine ion gains an electron and becomes negatively-charged.  (Electricity needs both in order to work!)

And if you want to add some more words to your vocabulary, salt is an electrolyte, a substance that creates a conductive fluid or gel by being dissolved in a medium.  Salt water is an electrolyte solution. (In case you’re wondering at this moment, yes, electrolyte replacements like Pedialyte and sports drinks like Gatorade are conductive as well!)

The cream of tartar (potassium bitartate) is a compound of potassium, carbon, hydrogen, and oxygen which produces ions when dissolved in water and the lemon juice is an kind of electrolyte solution, which is conductive in itself! (Like potatoes, you can use lemons to make an electrochemical battery.)

On the other end, table sugar (monosaccharide) is a compound of hydrogen, oxygen, and carbon. They share some of their electrons instead of losing or gaining them, which is known as a covalent bond.  Because there’s no loss of electrons when dissolved in water, the molecule stays the same. No ions, no electricity! Likewise, the distilled or deionized water removes any potential salts and minerals in water that would make the water a conductive solution to help keep the dough as nonconductive as possible.

You can purchase distilled water in most grocery stores, or make it from home using your tap water and some pots. Since tap water can contain minerals and salt, it needs to be purified for use.

In short, mixing salt and the cream of tartar/lemon juice in the dough makes it conductive, adding the sugar and distilled water makes the insulated dough non-conductive.

More Info:

Show us what you made! Send it to bmcc.makerspace@gmail.com or reach us at bmcc.makerspace on Instagram (or use the the #bmccmakerspace tag) to be highlighted on our page!