Microtensiometer water potential sensor for plants | FLORAPULSE

The FloraPulse microtensiometer is an innovative and proven MEMS (Micro-Electro-Mechanical System) sensor for continuous measurement of water potential in woody plant stems.

The nanoporous silicon membrane, with a pore diameter of approximately 2 nanometers, used in the sensor allows measurement of water potentials down to -35 bars!

After a simple installation (approximately 20 to 30 minutes), during which the microchip tensiometer is integrated into the woody tissue of the plant, the sensor provides water potential data measured directly and continuously. This sensor thus replaces manual on-site measurements using a pressure bomb, which are extremely lengthy, costly and unsafe (high-pressure instrument).

Compared to water potential determination by pressure chamber measurement (the most proven manual method to date), microtensiometers often provide more accurate and more comparable data, as they do not depend on the operator, unlike pressure bombs (results vary from one user to another).

The sensor is available with differential analog or digital SDI-12 output signal and can be used with appropriate data loggers. Thanks to its low energy consumption, it is perfectly suited for battery-powered IoT applications.

Delivered with microtensiometric probe and the tools necessary for installation, installation is simple and takes only 20 minutes thanks to an instructional video.

Available in 2 distinct versions:

• Analog probe: compatible with scientific data loggers
• SDI12 probe: compatible with any SDI12-compatible data logger

Technical specifications:

• Field of application: Continuous measurement of water potential in woody plants
• Suitable for stem diameters: Recommended for stem diameters > 5 cm
• Limitation/specificity: recommended for operation at temperatures between 5 and 50°C (caution, temperatures < 0°C may damage the sensor)
• Measurement range: 0 to -35 bars
• Resolution: Theoretically infinite, depending on the data logger used, for example: Campbell-Logger or Multi-Interface: < 0.1 bar
• Accuracy: greater than +/- 5% of measured value
• Data logger requirements and sensor output signal:

Analog sensor:

• Regulated, low-noise and switchable excitation voltage (1 to 5 V)
• 1 differential channel with measurement range of 0 to 32 mV per volt Vex (i.e., for a 1 V output up to 32 mV, and for a 2 V output up to 64 mV); If the expected water potential range is limited, the required electrical measurement range may also be limited (advice on request).
• Resolution: 12 bits in the corresponding measurement range of 0 to 32 mV per volt Vex
• Input impedance of analog channels: at least 1 MΩ

SDI-12 sensor:

• SDI-12 port: all Campbell loggers and our multi-interface meet the above requirements.

• Power supply: Vex (! regulated, low noise !) 1 to 5 VDC, max. excitation duration 50 ms. Negligible power consumption.
• Operating conditions: Temperature: 5 to 50°C, humidity: 0 to 100%
• Dimensions and weight: Sensor diameter: 12 mm, weight: 20 g (sensor only, without cable)
• Sensor cable length:
  • Analog sensor: 0.15 m + 3 m plug-in extension, extension possible up to 20 m
  • SDI-12 sensor: 0.15 m + 5 m plug-in extension, extension possible up to 60 m

Key advantages:

• Continuous real-time water potential data
• Can remain installed in the same tree for more than a year (limited in case of frost)
• Easy installation in less than 30 minutes
• Wind and rain resistant installation, designed for field measurements
• No more laborious, time-consuming and dangerous pressure bomb measurements
• Extremely low energy consumption, suitable for IoT applications
• Compatible with numerous data loggers (analog sensor with differential signal in mV or digital SDI-12 output)

Limitations:

• At very low water potentials (< -15 bar), cavitation may occur in the sensors.
• Exposure of sensors to temperatures below 0°C may cause defects.

Typical applications: grape, almond, pistachio, cherry, mango, apple, peach, plum, olive, prune