Arduino Experiments: Capacitive Sensor
Another week, another Arduino experiment.
My original idea was to start scavenging for interesting, vintage objects I could potentially repurpose and turn into my own hardware interface. It occurred to me that my favorite flea market at the Pasadena City College is happening this upcoming Sunday, so I thought I would wait and shift my focus to something different for this week.
Well, not so different. I wanted to find the simplest, most obvious item I could add interactivity too. And so I found myself starring at a blank piece of paper … How cool would it be if I could DRAW my own controller? A quick Google search and I realize that interactive paper projects are quite a thing!
Look at these amazing examples: http://blog.wan-ifra.org/2014/09/29/interactive-paper-combines-the-best-of-both-worlds
Coming from an art & graphic design background, I think this might well be my new obsession. But how does it work?
Well, it all comes down to the ability of the human body to act as a capacitor. When we touch a conductive object or material, we create a certain degree of capacitance, increasing the ability of the conductive object or material to store an electric charge.
Bare Conductive, for instance, sells electric paint and their own starter kit to create all kinds of paper electronics. Their ink conducts electricity, so you can basically paint wires or sensors directly into paper.
Their website got me really excited, but for a first trial, I needed to look for a cheaper way to understand capacitive sensors and how they work with Arduino.
And this brings me to my experiment of the week – turning a pencil drawing into a capacitive sensor.
In order to understand what I was doing, I read different tutorials and articles. But the one that really helped me move forward was this one here, which I recommend for all beginners alike.
The biggest challenge for me was to comprehend Arduino’s Capacitive Sensing Library. You can read more about the code in this page I just shared. If you watch the video below, my LED light blinks before I am anywhere near the graphite, which makes me think I have some grounding issues, maybe? I spent a while playing with the cutoff value (as in, a number that defines how high the sensor needs to read in order to trigger a touch.). To be honest, I haven’t quite figured out yet how to play with that code. I definitely need to dig deeper into it, and make sense of all the variables and values. Also, this code does not work with my Arduino Leonardo. Something I need to investigate.
I’m looking forward to experimenting with electric paint, but for now I think I might stick to graphite until I’m confident enough to venture further into the wonderful world of paper electronics.