The secret is a printing technique called Touchcode that uses special capacitive inks which are apparently still compatible with existing printer hardware. The ink is printed in a specific pattern on one end of the card that’s detected by the touchscreen as multiple simultaneous finger presses. And the arrangement of this pattern can be used to transmit data like a website URL. The capacitive ink is also printed on the other end of the card where it’s held, connecting it to the unique pattern so the whole thing basically serves as an extension of your fingers.
The technique is downright clever, and while Nukotoys is using it in a couple of sets of collectible trading cards that interact with games on the iPad, the other potential uses are pretty exciting. Imagine passing someone a business card they just press to their phone’s screen to store your contact info, or pressing a receipt to your tablet’s display to automatically initiate a payment.