NFC Technology: How ‘Tap to Pay’ Works

You hold your credit card near the reader. The card has no battery. It is a piece of plastic. Yet, it wakes up, talks to the reader, encrypts a transaction, and goes back to sleep. This is Near Field Communication (NFC).

Power from Thin Air

Electronics need power. The card reader contains a coil of wire generating a Magnetic Field. The card also contains a coil of wire.

• Induction: When the card enters the field, the magnet induces electricity in the card’s coil.
• The card “Steals” power from the reader to wake up its tiny chip.

The Conversation

Once awake, the card talks by “Loading” the field. It turns a resistor on and off. The reader “feels” the magnetic field get harder and easier to push (like pushing a swing). This creates a binary signal (1s and 0s). We use this tech for AprilTags visually, but warehouses use RFID (Long range NFC) to count boxes without opening them.