Introduction: RFID Bracelet: Remote Control Doors

About: I'm all about Making and Mental Health. Reach out if you need a chat .

Getting through RFID key-card doors is a pain in the behind when your hands are full of books or files, and your key-card is in your pocket, or swinging free on a lanyard.

To address this problem, GeeDee86 let me have some redundant cards to play with, and I managed to turn the cards into bracelets.

Caveat: This technique should work on most cards with RFIDs embedded, but be aware that it is not acceptable to do it to some payment cards, such as the Oyster card you use to pay for your London commute. Check the ToS of your particular card, and look for clauses on mutilation.

Step 1: Materials and Tools

As well as the card*, you need:
  • Non-polar solvent, such as nail varnish remover, paint thinners, acetone or petrol.
  • Shallow  non-plastic tray or dish. 
  • Tools to prod and stir.  Wooden coffee stirrers, metal forceps or narrow-nosed pliers are ideal.
  • Non-metallic material to make a bracelet. I used a popsicle stick, but you could use papier mache, thin plywood, heavy fabric, scrap acrylic etc.
  • Superglue.
  • Tools appropriate to your materials
  • Glues or paints as required to finish the bracelet materials, if desired.

Safety: Most non-polar solvents can cause contact dermatitis, so I recommend using protective gloves and eye protection. You also need to ensure that you have plenty of ventilation, as the fumes are toxic and do odd things to your head, and the fumes of most solvents are highly flammable, so be aware of your personal fire precautions.

*I have no images of the cards before starting the project, in order to comply with Data Protection legislation.

Step 2: Soaking

Just what it sounds like.

Lay the card in the shallow tray, cover it with your solvent, and leave it to soak. I made a tray from aluminium cooking foil, and folded the sides over the top to prevent the volatile solvent (nail varnish remover) evaporating too quickly.

Prod and stir the cards as often as you like - you are trying to gently dissolve the plastic away from the fragile chip and wires of the actual RFID device.

After somewhere between a couple of hours and overnight, the card will delaminate, allowing you to gently peel them apart and lift out the copper coil and chip of the actual RFID device. The longer you leave it, the easier the peeling will be - I left my first one overnight, and the layers curled up and conveniently rolled themselves right off the coil.

Make sure you dispose of the contaminated solvent safely and responsibly. 

Step 3: Bracelet

While the card is soaking you can start on the bracelet.

I followed Canucksgirl's Instructable to turn a craft popsicle stick into a bracelet, quite forgetting that the colour of the stick would dissolve into the boiling water...

Step 4: Attach Antenna

Once the bracelet was cool and dry, it was time to attach the antenna. 

I teased it out into a fairly flat, fairly straight arrangement, and wrapped it around the outside ofthe bracelet, tacking it in place with  cyanoacrylate glue ("superglue", "crazy glue"), and then covering with a "varnish" of more superglue to keep the wires tidy and safe.

I could have glued the antenna to the inside of the bracelet, but I wanted to ensure a close contact with the key-code panel beside the doors, and the antenna might have been uncomfortable inside the bracelet. 

Step 5: Using the Bracelet

Once the bracelet was finished, I turned it back over to GeeDee86 for testing.  I'll let him comment on the functionality:

*Gareth, hit the "edit" button tothe rightgof the page, then type something interesting here.*

Step 6: A Package Arrives

GeeDee86 here...

A package arrived on my desk from Kiteman, inside; one RFID bracelet (undamaged!)

Step 7: Programming the Card

So, I have created a test person on my access control software... Jim Nasium, and assigned the bracelet to him.

Step 8: Found a Willing Volunteer

So, I enlisted the help of the friendly Caretaker (Janitor) type person, and a real door.

Step 9: Through the Looking Glass (uh... Door...)

To prove that it *really* did work... here's the Caretaker going through the unlocked door.

The only issue I can tell with this design, is you have to get the actual chip (rather than the coil) *very* close to the reader for it to detect it... maybe the coil of wire was damaged during manufacturing...

Edit from Kiteman: I think it was antenna shape - the original arrangement was a flat antenna to place against a flat detector, but now it is curved and over-lapping. I'll bear that in mind next time.

Now we wait for RFID Bracelet Mk II :)

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