Gravity: Analog Resistive Soil Moisture Sensor for Arduino / Raspberry Pi

The Gravity Analog Resistive Soil Moisture Sensor provides a simple way to measure soil water content using two conductive probes. Designed for short-term indoor plant monitoring and educational experiments, it is an accessible choice for students, educators, and makers building basic IoT systems.

Resistive moisture detection method

The module passes electrical current between two probes to gauge the resistance of the surrounding soil. Moist soil conducts electricity more readily with lower resistance, whereas dry soil exhibits higher resistance.

Immersion gold probe finish

The contact probes use an Electroless Nickel Immersion Gold (ENIG) surface finish. This treatment protects the underlying nickel from oxidation and maintains flat, untreated contact surfaces for consistent conductivity.

Plug-and-play Gravity interface

Equipped with a standard Gravity analog interface, the board connects directly to Arduino IO expansion shields. Its 3.3V to 5V operating range also ensures compatibility with Raspberry Pi, Intel Edison, Joule, and Curie platforms.

Operating ratings and dimensions

The sensor operates at 3.3V or 5V with a working current of 35mA, outputting an analog signal between 0V and 4.2V. The board measures 60 x 20 x 5mm and includes an analog sensor cable with colour-coded power, ground, and signal wires.

Project suitability and usage guidance

This resistive sensor is intended for short-term indoor setups and budget-friendly educational labs. When placed in continuously damp or highly humid soil, resistive probe surfaces may erode within days, in which case a capacitive sensor is recommended.

Downloads & documentation

• Product wiki (DFRobot)