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.
Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.