RFID cards are becoming a fairly common way to purchase goods, but they're already widely used to pay fares on buses, trains, subways, and trolleys across various cities. TAP cards are quick and reliable, but it can be a real pain to remember to bring them with you, especially if you weren't planning on using public transportation that day.
Luckily, an intrepid tinkerer at Adafruit has managed to find a way to embed an RFID card into her phone, something you're far less likely to leave at home.
It's a little more elaborate than just cutting your card to size and sticking it in your device, but it's not a terribly difficult process. Unlike cutting the chip out, you're going one step further and dissolving the entire card, which leaves both the RFID chip and antenna intact. The video instructions are below, but if you'd like to follow along with it, check out the steps following.
To do this, you're going to dissolve the card in acetone. Acetone is a naturally occurring substance (although it is also artificially produced) that is used in the making of certain plastics, fibers, drugs, and chemicals. However, in this instance, we're going to be using it to melt down some plastic. Acetone is not particularly dangerous, but it can cause irritation and nausea if touched or ingested, so as you would when handling any chemical, take care.
To begin, place the card in the container that we will be pouring the acetone into. A glass or metal vessel is preferable, as the acetone may dissolve certain plastics.
Fill the container with acetone until the card is submerged, then cover it to help prevent evaporation.
Once the plastic has dissolved enough, go through the pieces until you find the RFID antenna. The antenna is shiny and made of enamel-coated wire. It does not have to stay in the "card" shape to work properly, but be careful not to break it.
Remove the back plate of your phone. There needs to be space in between the antenna and any metal objects in the phone in order for the reader to scan it correctly. To accomplish this, tape the antenna to a piece of paper, then continue taping over it until you have built up a thin layer. Then, lay the antenna over the contents of the phone.
Replace the back plate and give your new phone-card a try.
If it does not work, experiment with how many layers of tape you are using and the placement on the antenna within the phone.