Battery-free Display Tag The use of smaller 2.0 inch E-ink screen and further system optimization make the display tag can be powered and updated by a NFC enabled cell-phone. No large energy stor
age media, like battery or super capacitor rather than 300 µF capacitor is used to buffer enough energy to update the image in run time. Because, the cell-phone is continuously sending dummy data to power the tag even after the the image transmission, therefore the board can keep collecting more energy while E-ink is updating. The updating process of E-ink is also heavily duty-cycled to avoid system brown out.