NFC-POWERED LED STICKER WITH INTEGRAL CAPACITOR

An LED sticker is disclosed that receives an NFC transmission from a nearby smartphone to energize LEDs in the sticker. A spiral (or loop) antenna is used in the sticker to generate power from the NFC transmission. The NFC signal is at 13.56 MHz, which is the resonant frequency of the NFC antenna circuit in the smartphone. The LED portion is formed by sandwiching pre-formed microscopic LEDs between two conductive layers to connect the LEDs in parallel. The conductive layers form a relatively large integral capacitor that is used to achieve the 13.56 MHz resonant frequency. So no additional capacitor is needed in the circuit to achieve a resonance of 13.56 MHz. This greatly reduces the design requirements of the antenna. The LED sticker may also contain an NFC tag having its own independent loop antenna and NFC chip. Various practical applications of the LED sticker are disclosed.