OK, so you’ve entered into the world of NFC and you have an understanding that these nifty little stickers can do amazing things but you’ve been wondering to yourself, how are NFC tags powered? If they can send data, do they need a battery or power supply?
Technically NFC tags don’t have their own power supply – they use something called electromagnetic induction to get power from your device, similar to the way wireless charging devices work. Let’s delve into this a little deeper.
Getting power via electromagnetic induction
When you tap your phone against an NFC tag, your phone actually ‘powers’ the NFC tag. NFC tags are usually called ‘passive tags’ for this reason. They don’t have a power supply and therefore are limited in how much information they can send and receive and can only transfer data to an active device as there’s no processing power in the tag itself.
If you look at the back or insides of any NFC tag or sticker, you will notice little coils of wire. These are an important part of the electromagnetic induction process that happens when you tap your phone against an NFC tag.
Whilst you may not be familiar with the science behind electromagnetic induction (discovered by Michael Faraday in the 1830’s) you will be familiar with current technology that uses the same principle such as:
- Induction cooktops
- Guitar pickups
- Graphics tablets
- Wind up or mechanically powered torches
- Wireless charging stations
- Power transformers (there’s one on most streets in Australia!)
- Induction motors (you have one in your ceiling fan)
So as you can see, even though the term electromagnetic induction may seem very sciency and you would think it’s not common, chances are you’re already using it without even knowing it!
Now we can get incredibly technical about this technology and bore you for hours with mathematical equations and technical jargon, or you can watch this great nine minute crash course on induction that will give you a really good overview about how NFC tags (and many other devices) get their power through electromagnetic induction.