Corrosion-Resistant Capacitive Soil Moisture Sensor Module

Elevate your automated gardening or agricultural projects with our High-Durability Capacitive Soil Moisture Sensor. Unlike traditional resistive sensors that use exposed metal prongs prone to rapid oxidation, this module utilizes capacitive sensing technology to measure soil moisture levels without direct electrical contact with the soil.
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Precision Growth: Corrosion-Resistant Capacitive Soil Moisture Sensor

Elevate your automated gardening or agricultural projects with our High-Durability Capacitive Soil Moisture Sensor. Unlike traditional resistive sensors that use exposed metal prongs prone to rapid oxidation, this module utilizes capacitive sensing technology to measure soil moisture levels without direct electrical contact with the soil.

Key Features

  • Corrosion-Resistant Design: Built with high-quality materials that prevent the electrodes from rusting or degrading over time, significantly extending the sensor's lifespan in damp environments.

  • Capacitive Sensing Technology: Measures changes in capacitance caused by the dielectric permittivity of the soil. This means no DC current flows through your soil, preventing electrolysis and nutrient depletion around the probe.

  • Onboard Voltage Regulator: Supports a wide operating voltage range (3.3V to 5.5V), making it directly compatible with Arduino, Raspberry Pi, ESP32, and STM32 platforms.

  • Analog Output: Provides a simple linear analog voltage output, allowing for easy calibration and integration into your existing codebases.

Technical Specifications

FeatureSpecification
Operating Voltage3.3V ~ 5.5V DC
Output Voltage0 ~ 3.0V DC
InterfacePH2.0-3P (Analog)
Dimensions98mm x 23mm
TechnologyCapacitive (Non-resistive)

Why Choose Capacitive over Resistive?

Most entry-level sensors work on resistance, essentially "sacrificing" the metal on the probe to get a reading. After a few weeks, those sensors often fail due to heavy oxidation.

The Capacitive Advantage: By acting as a capacitor, the probe is coated in a protective layer. It "feels" the moisture through the insulation, ensuring your automated irrigation system stays reliable for seasons, not just weeks.

Ideal Applications

  • Smart Agriculture: Large-scale crop monitoring where sensor longevity is critical.

  • Indoor Gardening: Automated watering systems for houseplants or "smart" terrariums.

  • Environmental Research: Long-term soil data logging in various climates.

  • DIY Robotics: Perfect for students and hobbyists building their first IoT garden.

Quick Connection Guide

  1. VCC: Connect to 3.3V or 5V.

  2. GND: Connect to System Ground.

  3. AOUT: Connect to any Analog-to-Digital Converter (ADC) pin on your microcontroller.

 

What's in the box?

1 x Capacitive Soil Moisture Sensor Module

Resources

To use this capacitive soil moisture sensor with a Raspberry Pi Pico, you will need to utilize one of the Pico’s Analog-to-Digital Converter (ADC) pins. Since the Pico’s GPIO pins are digital-only by default, only specific pins (GP26, GP27, and GP28) can interpret the varying voltage signals from the sensor.

Wiring Connections

Connect the sensor to your Pico using the following pinout:

  • VCC (Sensor) to 3V3 (Pin 36) on the Pico.

  • GND (Sensor) to any GND pin (e.g., Pin 38) on the Pico.

  • AOUT (Sensor) to GP26 (Pin 31 / ADC0) on the Pico.

MicroPython Implementation

The Pico’s ADC converts the sensor's analog voltage (0V to 3.3V) into a digital value ranging from 0 to 65535. Because this is a capacitive sensor, the value will be higher when the soil is dry and lower when the soil is wet.

Python
import machine
import utime

# Initialize ADC on Pin 26
soil_sensor = machine.ADC(26)

# Calibration values (To be adjusted based on your specific sensor)
# Dip the sensor in water to find 'wet' and leave in air to find 'dry'
DRY_VALUE = 45000 
WET_VALUE = 18000

while True:
    # Read raw analog value
    raw_value = soil_sensor.read_u16()
    
    # Convert raw value to percentage
    # (High value = Dry, Low value = Wet)
    moisture_percent = (DRY_VALUE - raw_value) * 100 / (DRY_VALUE - WET_VALUE)
    
    # Constrain percentage between 0 and 100
    moisture_percent = max(0, min(100, moisture_percent))
    
    print(f"Raw Value: {raw_value} | Moisture: {moisture_percent:.1f}%")
    
    utime.sleep(1)

Calibration Tips

Since every sensor and soil type varies slightly, you should perform a manual calibration for accuracy:

  1. Dry Point: Hold the sensor in open air and record the raw_value. Update DRY_VALUE in the code.

  2. Wet Point: Submerge the sensor in a glass of water up to the maximum immersion line (do not submerge the electronics at the top) and record the raw_value. Update WET_VALUE.

Power Management

The sensor is rated for 3.3V to 5.5V. While the Pico’s 3.3V output is convenient and safe for the ADC pins, using the VBUS pin (5V) may provide a more stable signal if you are using long jumper wires, but you must ensure the sensor's output voltage does not exceed 3.3V to avoid damaging the Pico.

Are you planning to use this sensor for a simple automated watering system or a more complex data-logging project?

  • Availability: Out of Stock
  • Model: capacitive soil moisture
  • Brand: Generic2