All‐Printed Smart Label with Integrated Humidity Sensors and Power Supply

Sensing smart labels are an essential component of the Internet of Things (IoT) to provide identification and data. However, the widespread use of these labels into functional devices requires easy integration and power supply. Herein, a smart label is presented with integrated humidity sensor and printed battery. The smart label is composed by detection, communication, control, and energy subsystems. It is based on a screen printed RLC circuit and a printed humidity sensor with electrical linear response. The printed battery based on lithium iron phosphate as an active cathode material is fabricated with six single cells connected in series, leading to ≈100 mAh g −1 . The printed humidity sensor has a linear response with a sensitivity of 0.004/% relative humidity (RH). Thus, it demonstrates the development of fully printed smart labels, improving integration into a variety of applications.