Development of a new type monitoring system of leaf surface temperature and humidity

Abstract

Abstract. In this study, a new type of leaf surface temperature and humidity wireless monitoring system was designed. The system is composed by several sensor nodes. The communication among the nodes is ZigBee. The node has three modules: wireless communication module, leaf temperature and humidity measurement module and battery power supply module. The temperature measurement module was made up with a new type high integration infrared contactless temperature measuring sensor A2TPMI334-L5.5OAA300. The sensor with integrated A2TPMI ASIC and 5.5mm lens optics with 5° field of view adapted to an object temperature range –20…+300°C , respectively. The output voltage of the sensor is sent to MCU after the filtering by the operational amplifier. The humidity sensor probe is made by Honeywell HIH-4000-003 humidity sensor. The HIH-4000 Series Humidity Sensors are designed specifically for high volume OEM users. The RH sensor is a laser trimmed, thermoset polymer capacitive sensing element with on-chip integrated signal conditioning.The two channels of voltage signal of the leaf temperature and humidity will be sent to PDA by wireless communication module which has already embedded in MCU. The MCU is JN5139, it satisfies the requirements of self-connecting network and low-power consumption in the field. According to the experiments of corn plants, the results showed that the temperature accuracy of the node reached 0.1℃ after calibration. The humidity accuracy of the node reached ±5%.The communication between nodes and PDA is stable.