These tiny flexible PCBs have a coil, transistors and a little LED on them – when in the range of an RFID or NFC reader (such as that in your phone) the coils pick up the electromagnetic energy emitted and use them to blink the LED for a cool cyberpunk effect – no batteries required! These are seriously cool wearable LEDs that light up when close to contact-less payment terminals, NFC smartphones, RFID card door locks, etc.
Note that these stickers do not actually act as an NFC/RFID tag, they don’t transmit any data back – they only blink the LED when in the presence of an RFID electro-magnetic field.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.