Detecting Soil Moisture Levels Using Battery-Free Wi-Fi Tag

TL;DR

This paper introduces SoilTAG, a low-cost, battery-free Wi-Fi-based soil moisture sensing system that achieves high accuracy over several meters, enhancing agricultural monitoring capabilities.

Contribution

It presents a novel chipless sensor design methodology and a passive Wi-Fi tag for precise, low-cost soil moisture detection at various distances.

Findings

Identifies soil moisture with 2% accuracy at 3m distance.

Achieves 5% moisture sensing resolution at 13m distance.

Demonstrates effective soil moisture detection in open field conditions.

Abstract

Soil sensing plays an important role in increasing agricultural output and protecting soil sites. Existing soil sensing methods failed to achieve both high accuracy and low cost. In this paper, we design and implement a high-accuracy and low cost chipless soil moisture sensing system called SoilTAG. We propose a general chipless sensor design methodology which can allow us to customize the signal feature for sensing soil moisture, instead of blindly capturing the disturbance law of the soil. Based on this principle, we design a battery-free passive tag which can respond to different soil-moisture. Further, we optimize hardware and algorithm design of SoilTAG to locate the passive tag and extract its reflection signal feature to identify soil-moisture using WiFi signals. Extensive experimental results reveal that it can identify 2% absolute soil water content with a sensing distance up to 3m in open field. When the sensing distance is up to 13 m, it can also achieve 5% absolute soil-moisture sensing resolution.