US Patent 10360419 Interactive systems and methods with tracking devices

A wearable device includes a radio-frequency identification (RFID) tag having a memory that stores identification information. The wearable device also has a power harvesting circuit configured to harness power from electromagnetic radiation. Further, the wearable device has a sensor coupled to the power harvesting circuit and configured to utilize the power to monitor a condition of the wearable device. Even further, the wearable device has a microcontroller coupled to the sensor and configured to write data indicative of the condition to the memory of the RFID tag, wherein the RFID tag is configured to transmit the identification information and the data in response to receipt of the electromagnetic radiation from an RFID reader.