Wireless Sensor For Plant Monitoring

A low-cost wireless sensor for plants. Real-time data on plant health, innovative agriculture, better monitoring than expensive methods… Could this be the future of farming?

Researchers from the Graduate School of Life Sciences and the Department of Electronic Engineering at Tohoku University have developed a low-cost wireless plant sensor, priced at “a few tens of dollars,” featuring an M5Stack M5Stamp-Pico. This sensor could provide more effective agricultural monitoring than existing methods.

Researchers highlighted that smart agriculture is a significant time-saver. Farmers often need more time to check every plant manually, and this sensor provides precise, real-time readings. It enables them to respond to areas where plants are experiencing high-stress levels.

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Traditional monitoring methods may work well for some purposes, but they are challenging to operate and quite expensive, according to Kaori Kohzuma, the study’s first and co-corresponding author. The team sought a new solution to address the challenge of continuously monitoring small changes. The resulting affordable sensor provides a promising tool for accurately monitoring plant health and stress through leaf colour and light reflection data. Its low cost allows for deploying multiple sensors across various locations, enabling simultaneous monitoring in many spots through a network.

The research team developed a two-part sensor mainly using off-the-shelf components. The sensor head, attached to the underside of leaves to avoid blocking sunlight, is based on the DFRobot Gravity OSRAM AS7341 11-channel visible light sensor. It is connected to an M5Stack M5Stamp-Pico ESP32-PICO-D4 microcontroller board, programmed with the Arduino IDE through a custom carrier board. The system is housed in 3D-printed cases, sealed with silicone sealant for weather protection, and powered by CR2 lithium batteries, which last over a month of monitoring.

Despite its low cost of “a few tens of dollars,” the sensor system performed well compared to a much more expensive commercial spectrometer. In field tests, the sensors monitored a birch tree’s chlorophyll levels and response to sunlight intensity over time.