Moisture electricity generation based self-powered humidity sensor for smart agriculture

With the rapid development of smart agriculture, it is of great significance to monitor soil moisture through humidity sensors to maintain suitable soil environmental conditions and improve crop yield and quality. This study reports a self-powered humidity sensor (SPHS) based on moisture electricity generation, which was designed by using a humidity-sensitive composite film composed of polystyrene sulfonic acid: polyvinyl alcohol doped LiCl as the electrolyte layer and combined with copper and aluminum electrodes. The SPHS easily adsorbs and diffuses water molecules in humid environment, and relies on the principles of ion diffusion and electrochemical reaction to realize the sensing of soil moisture, without the external power source, and with good reliability and durability. The SPHS can spontaneously generate current response over a relative humidity (RH) range of 33 %-91 %, with a current response of 2.6 mu A at 33 % RH and up to 76.1 mu A at 91 % RH, which provides excellent RH-current linear response characteristics (R2 = 0.988). SPHS can be successfully applied in the field of human wearable devices, such as integration into masks for human breathing monitoring, as well as having excellent application potential in contactless human-computer interfaces. By integrating smart sensing technology and IoT communication technology, a smart agricultural environment sensing system was built in conjunction with SPHS for in-situ monitoring of soil moisture, ambient temperature, and light intensity to achieve real-time monitoring of the farmland environment, which promotes the development of agricultural production in the direction of intelligence, efficiency, and sustainability.