Data Tag Cards
Using conductive ink to invisibly link physical paper with digital data
I ordered a pot of electric paint from Bare Conductive because I was fascinated by the idea that I could just paint my own circuits. Originally, I wanted to use it on business cards to make an LED flash or something.
While I was playing with the viscous liquid, I discovered that conductive ink can be used to simulate fingers on a capacitive touch screen.
Because apparently there's a startup for everything, I then found out about TouchBase who raised $30.000 to produce and sell you conductive ink business cards.
I decided to do my own take on the technology and add a second, digital dimension to my business cards as well.
How it works
On the back of the cards, I painted rectangles on a four by four grid. The rectangles are connected with thin lines of conductive ink. It is important that the circuit touches your hand at some point.
When a person touches the card he connects the circuit to ground. When pressed onto a capacitive touchscreen, the phone recognizes the bigger rectangles as fingers touching the screen.
In order to identify individual cards, I am making use of an artificial neural network.
Patterns are not calculated from the touch position on the screen, but from the relations between the individual touches. This way, it doesn't matter where or in which direction the card is places on the screen, which makes for a more robust detection.
It's interesting that the ink circuits don't have to be on the papers surface in order to be recognized. The codes could also be printed between two layers of paper, creating an invisible alternative to barcodes or QR codes.
There are less limitations compared to the aforementioned technologies because you don't need a scanner and scanning software. However, it still doesn't feel like a thing that would work on a bigger scale.
It's interesting how my paper cards or any other object equipped with conductive ink data codes get a second, digital dimensions. More information can be associated with a piece of paper than just the words or pictures on its surface.
Also, because the codes can only be read using a smartphone, the cards can also draw data from the device. Using the iPhone sensors like GPS, a piece of paper suddenly gets an exact geolocation. This opens the door for a whole range of calculations and speculations about the objects environment.