Implexx Sap Flow Sensor - Accurate Measurement of Plant Water Use
What is the Implexx Sap Flow Sensor?
The Implexx Sap Flow Sensor measures sap flux density and stem water content on any plant with a stem diameter greater than 1cm.
The Implexx Sap Flow Sensor is a high-precision heat pulse sensor designed to measure the full range of sap flow in plants, including reverse, low, and extremely high flow rates. It provides over 30 plant physiological measurements in a single device, including stem water content, enabling accurate monitoring of plant water use and transpiration in research and field conditions.
Key Takeaways
- Measures full sap flow range, including reverse (negative) flow
- Simultaneous measurements of sap flux density and stem water content
- Outputs 30+ physiological parameters in real time
- Uses multi-depth sensing (2–5 points) for improved accuracy
- Compatible with SDI-12 data loggers and IoT systems
- Designed for long-term field deployment (5+ years)
- Used globally by researchers, universities, and scientific organisations
What is a Sap Flow Sensor?
A sap flow sensor measures the movement of water through a plant's stem. This data is used to quantify:
- Transpiration and evapotranspiration
- Plant water use strategies, such as anisohydric and isohydric behaviour
- Plant stress responses, including drought, temperature, and salinity
- Environmental and ecological interactions
What Makes the Implexx Sap Flow Sensor Unique?
Full-Range Sap Flow Measurement
The Implexx Sap Flow Sensor measures the entire observable range of sap flow in plants from reverse (hydraulic redistribution), slow and extremely fast.
The sensor measures the entire sap flow spectrum, including:
- Reverse flow (negative values)
- Very slow flow
- Extremely high flow rates
This eliminates the need for multiple sensor types.
Multi-Depth Measurement
The sensor measures sap flow at multiple radial depths within the stem:
- 2-depth configuration (smaller stems)
- Up to 5-depth configuration (larger trees)
This improves whole-tree water use estimation.
Multi-Parameter Output
In addition to sap flow, the sensor outputs over 30 parameters, including:
- Heat velocity
- Stem temperature
- Thermal diffusivity
- Water content indicators
This enables deeper plant physiological analysis.
Long-Term Stability
The system is designed for:
- Multi-year deployments
- Minimal recalibration
- Stable measurements under field conditions
How Does the Sensor Work?
The Implexx Sap Flow Sensor uses a heat pulse method:
- A controlled heat pulse is applied to the stem
- Temperature sensors measure heat movement through the wood
- Heat velocity is calculated
- Sap flow is derived from heat transport dynamics
This method allows accurate measurement across varying flow conditions.
Available Models
The Implexx Sap Flow Sensor measures sap flux density and stem water content across the radial profile of xylem in plants.
IX-SF30 (30 mm probe length)
- Measures at 2 depths
- Suitable for small trees and saplings
- Ideal for controlled experiments and young plants
IX-SF60 (60 mm probe length)
- Measures at up to 5 depths
- Suitable for mature trees
- Provides more detailed radial flow profiles
Applications
The Implexx Sap Flow Sensor is used in:
- Plant physiology research
- Irrigation scheduling and optimisation
- Forestry and ecosystem monitoring
- Climate and hydrology studies
- Agricultural water management
Technical Specifications
| Feature | Specification |
|---|---|
| Measurement Range | -1000 to >1000 cm/hr (heat velocity) | -200 to >200 cm3/cm2/hr (sap flux density) |
| Measurement Accuracy | ±0.1 cm/hr |
| Resolution | 0.001 cm/hr |
| Needle Dimensions | IX-SF30: 30 x 1.8 mm | IX-SF60: 60 x 1.8 mm |
| Position of Thermistors | IX-SF30: 10 and 20 mm from white body | IX-SF60: 10, 20, 30, 40 and 50 mm from white body |
| Distance Between Needles | 8 mm |
| Epoxy Body Dimensions | 40 x 16 mm |
| Probe Materials | 316 marine grade stainless steel |
| Temperature Range | -20 to +70 °C |
| Thermistor Response Time | 200 milliseconds |
| Measurement Cycle Time | 124 seconds |
| Power Input | 12 VDC |
| Power Consumption | IX-SF30: Idle: 4 mA; Measurement Cycle: 0.4 mAhr | IX-SF60: Idle: 4 mA; Measurement Cycle: 0.7 mAhr |
| Sensor Output | SDI-12 (ver. 1.4) |
| Cable Length | 5 m (standard) | 60 m (maximum) |
Frequently Asked Questions
How accurate is the Implexx Sap Flow Sensor?
The sensor provides high-precision measurements across a wide range of flow conditions due to its heat pulse method and multi-depth sensing.
Can it measure reverse sap flow?
Yes. The sensor measures negative flow, which is critical for understanding plant water dynamics.
What data systems is it compatible with?
It supports SDI-12 communication and integrates with most environmental data loggers and monitoring systems.
Is it suitable for long-term field use?
Yes. The sensor is designed for multi-year deployments with stable performance.
Validation and Use
The Implexx Sap Flow Sensor has been used by:
- Research institutions (e.g., CSIRO, USDA)
- Universities (e.g., University of California, University of Arizona, University of Georgia, University of Florida)
- Government organisations
- International scientific programs
It has been deployed across a wide range of environments and study types.