At no point during my graduate studies – which focused on under-water robots – did I ever foresee a day when I’d be publishing papers about play dough. Nor did I ever anticipate that flour, sugar and salt would become crucial components of my engineering research. And little did I know that play dough would end up being my medium of choice for introducing kids, including my own, to electronics.
I had long been fascinated with unusual ways to create electrical circuits, such as painting with conductive paint or sewing circuits with metallic thread. The more I saw people painting or sewing circuits, the more I thought about how much fun it would be to sculpt circuits. When first-year en- gineering student Samuel Johnson ’12 mentioned his interest in using play dough while talking about summer research opportunities in 2009, it seemed like the perfect time to tackle this project.
Thanks to a grant from the UST Young Scholars program and funding from the 3M Foundation, Johnson accepted the challenge of developing a play dough recipe that would allow us to make our sculptures conduct well enough to add lights and motors.
Johnson and I set out to replace the wires and resistor with play dough. While we couldn’t find any examples of people building circuits with play dough, lights, motors and buzzers, we didn’t have to start completely from scratch. It turns out that physics teachers sometimes have their students measure the resistance of play dough as a lab activity, and researchers such as those at MIT’s Lifelong Kindergarten lab have used play dough as an input device.
Many of us are introduced to how electricity works by using a battery to light a small bulb in elementary school.
Similarly, one of the first circuits that many engineers are taught to build consists of a battery, a light-emitting diode (LED) and a resistor (to prevent the LED from having too much current flow through it). So, the first “squishy” circuit that we tried to create involved lighting an LED.
Armed with the knowledge that commercial play dough conducts electricity well enough to measure its resistance, we felt confident that we could come up with a recipe that was conductive enough to make our sculptures light up.
In my previous research projects I was used to consulting scientific journals and research papers. For this project, our resources had titles like 101 Activities for a Rainy Day. Johnson tried countless recipes, measuring the resulting dough to see how conductive it was. By mid-summer he had developed a salt- and flour-based recipe that would allow us to create working circuits.
When you look at the electrical wiring in your house, you’ll notice that it’s almost always covered with an insulator to prevent the formation of short circuits. Johnson and I wanted to be able to sculpt more complicated circuits, and we knew that would require a sculptable insulator.
Johnson returned to the kitchen we’d set up in our lab, and created a recipe that used sugar instead of salt, and deionized water instead of tap water (along with a few other modifications). As a result, he was able to create a salt-free dough that was significantly more resistant to the flow of electricity, and which allowed us to treat the play dough like an insulator. Now we were able to begin sculpting more interesting circuits.
We started sharing our recipes and techniques with local educators and were quite happy to start seeing Squishy Circuits used in Minnesota classrooms as a way to teach children about electricity and circuits. Even the University of St. Thomas Child Development Center preschool students began wowing us with their circuit- building skills when we’d visit them for Squishy Circuit play sessions. (It was always amusing to me to think that during those sessions there were likely much older electrical engi- neering students sitting elsewhere on campus working with circuits as we taught these 3- and 4-year-olds about short circuits and the joys of annoyingly loud piezoelectric buzzers!)
In 2011, I was given the opportunity to give a live demonstration of Squishy Circuits at the TED (Technology, Entertainment and Design) conference. When the TED organization posted a video of the talk, I was amazed at how quickly we began to hear from people around the world who were interested in creating their own Squishy Circuits.
One of the most rewarding aspects of this experience has been watching the Squishy Circuits’ user community share their own projects. Our hope was that by posting all of the instructions online people would bring the activity into their own homes and classrooms. We have not been disappointed.
On an almost daily basis we receive emails and Facebook posts from around the world telling us about Squishy Circuit projects and workshops. Some examples include:
Interactions with these users have led us to create new recipes and projects. For example, we found a group of French parents on Twitter discussing the difficulty of finding cream of tartar in rural France. We had a user in rural Japan point out the same difficulty. So Johnson went back to the kitchen and developed an alternate recipe that used lemon juice instead of the cream of tartar. Similarly, we have a gluten-free version of the recipe as some individuals are topically allergic to gluten.
Matthew Schmidtbauer ’12, an electrical engineering student who joined the Squishy Circuit project in 2011, also has developed a number of new projects, such as using Squishy Circuits to build a battery and light an LED.
In his interactions with parents and teachers, Schmidtbauer learned that many felt intimidated by having to individually gather all of the various electrical components. He realized that it would be beneficial for people to have the option of buying Squishy Circuit kits that would include the recommended electrical components – such as buzzers, motors, LEDs and battery packs. Matthew founded Squishy Circuits Store, LLC, which creates kits that he now ships to schools, families and “makerspaces” around the world.
When we first started this project, we assumed the activity would be best suited for an elementary or middle school classroom; however, over the last few years we have heard from (the parents of) users as young as two. We’ve even heard about Squishy Circuit nights for adults.
All of which brings me back to the joy of teaching people and helping them use that new knowledge to create things as whimsical as play dough circuits. I find that most people have a hard time not smiling when playing with play dough, and laughter tends to flow freely during Squishy Circuit events. But this play is serious. Beneath every squishy creature with glowing eyes is an understanding of concepts such as the directionality of LEDs and how electricity flows through a circuit. Most important is the sense of excitement that grows as these circuit builders realize that they made those lights glow and buzzers beep.
I’m not expecting play-dough-powered cars in my future, but I do expect that some of these young circuit sculptors will grow up to be tomorrow’s innovators and engineers.
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