NFC_temp is a passive RFID tag at its core with some special features added. The parts that make it work are an ATTiny1626 microcrontroller, TMP117 0.1 °C accuracy thermometer and the RF430CL330H dynamic RFID IC in conjuction with a self designed 13.56 MHz antenna. When approached by a RFID reader some of the energy from the magnetic field is siphoned and stored in a capacitor to power the microcontroller for just long enough to read the thermometer and write the result to the dynamic RFID tag. The tag is then read by the reader (most likely a phone) and the temperature with 0.1 °C accuracy (in range -20 °C - 50 °C, total range -55 °C - 150 °C) is then displayed as a text based RFID tag. The device is about 18 mm x 40 mm in size and fits perfectly on a regular keychain.