implexx sap flow sensor

sap flow & stem water content sensor


  • A calibrated, digital sap flow sensor for researchers and growers
  • Measure total tree sap flow and, with additional tree canopy information, you can also measure crop evapotranspiration (ETc)
  • Equidistant, 3-needle design that can be used with various heat pulse velocity methods
  • Flexible approach to how you measure heat velocity in woody stems
  • SDI-12 output to connect to ours or your data logging system
  • Internet access via ES-SYS telemetry systems and Sensori online platform
  • LoRaWAN and NB-IoT compatible
  • Simple sturdy design allows for this sensor to be used for long periods for time
  • Includes both pre-written programs for data loggers and software to quick data analysis and interpretation
  • Sensors are manufactured by Implexx Sense




low cost sensors to maximize research outcomes

The Implexx Sap Flow Sensors are low cost, highly accurate and reliable sensors for the measurement of sap flow, transpiration, and even stem water content, in plants.

The Implexx Sap Flow Sensors are ideally suited for scientific researchers interested in plant water use, physiology, or hydrology research. The sensors provide the greatest flexibility for scientists needing to undertake field work or research in the glasshouse.

Implexx Sap Flow Sensors utilise the SDI-12 output protocol which means it can connect to a range of data logger models and brands. The Implexx Sap Flow Sensor is currently used on loggers from the ES-SYS to Campbell Scientific to YDOC to DataTaker plus many LoRaWAN and NB-IoT systems.

The Implexx Sap Flow Sensor can be used as a stand-alone device or in combination with other environmental sensors such as evaporation, VPD, solar radiation, soil moisture, or water potential. Edaphic Scientific can supply data logging equipment for you, or we can assist you in connecting the sensors to your existing data logger network.

The Implexx Sap Flow Sensor is also unique in that stem water content can be measured simultaneously with sap flow or transpiration. Additional equipment is not required - stem water content can be measured with the same sensors that are measuring sap flow.


who is using the Implexx Sap Flow Sensor?

The Implexx Sap Flow Sensor is currently being used by researchers, students and growers in many research projects around the globe including NASA, USDA, US Forest Service, University of California, University of Florida, Georgia State University, Chinese Academy of Sciences, University of Chile, and many institutions throughout Europe including France, Germany, Sweden, Finland, Poland and Greece.

The Implexx Sap Flow Sensor was deployed in Biosphere 2, Arizona, USA, to measure the response of tropical rainforest trees to droughts.

Click here for a case study from world leading researchers at TU Braunschweig, Germany, who are utilising The Implexx Sap Flow Sensor in combination with drones and isotope analysis in the savanna woodlands of Costa Rica.

The Implexx Sap Flow Sensor is popular with many researchers and growers because it is calibrated, easy to install, and requires almost no ongoing maintenance.


heat pulse velocity sap flow sensors design

  • Number of needles: 3 - downstream and upstream temperature needles and middle heater element needle;
  • Needle Length: 30 mm
  • Distance between needles: Equidistant, 6 mm spacing
  • Number of thermistors: 4 - 2 downstream and 2 upstream thermistors
  • Position of thermistors: 10 mm and 20 mm from tip of needle (called inner and outer temp sensor positions, respectively)


Edaphic Scientific’s capabilities

At Edaphic Scientific we want to work with you from the start of your project through to its completion. We can provide:

  • Assistance with project and experimental design
  • Procurement of all monitoring equipment, including sensors, data loggers and data management software. Edaphic Scientific is a one-stop shop where we can source and find any necessary equipment for your project from our preferred suppliers or third party suppliers
  • Installation and training
  • On-going assistance with data interpretation and equipment maintenance
  • Data correction and analysis, including statistical analysis with the R-package
  • Report and publication preparation including tables, figures, graphs, and manuscript writing


advanced data collection and management solutions

Edaphic Scientific recognises the need for flexible and adaptable sensor and data logging solutions for experimental or environmental monitoring projects.

You can connect the HPV sap flow sensors to our data logging systems, or we can assist you in connecting the sap flow sensors to your existing system.

Data can be downloaded directly in the field from data loggers. Alternatively, data can be downloaded over the internet on your iPhone, iPad or desktop computer with the Sensori cloud-based, data management software solutions.

Edaphic Scientific provides sap flow sensors with individual loggers or whole-wystem solutions with a centrally located data logger and additional equipment such as weather stations, soil moisture, water potential, carbon and nutrient monitoring.

Data can be collected directly from logging units with a USB download cable or remotely, anywhere in the world, via the mobile phone network and an internet connection.


individual data loggers

Edaphic Scientific supplies a one-to-one sap flow sensor to data logger monitoring solution.

The Implexx Sap Flow Sensor is compatible with a variety of data logger models and brands. The Implexx Sap Flow Sensor can be supported by any data logger that is compatible with the SDI-12 protocol.

The ES-SYS-0 System provided by Edaphic Scientific is ideal for projects and installations where only one, or a few, sensors are required. The ES-SYS-0 consists of a low-cost data logger with a built-in modem. It can support one, or several, Implexx Sap Flow Sensors with the option to connect additional sensors such as soil moisture, air temperature, relative humidity or rain gauges.

The individual sap flow data loggers are ideal for:

  • Urban tree monitoring: where security and safety for equipment is paramount. The data logger and power supply can be installed high and out of reach, or installed in underground pits. The cable for the sap flow sensors can be any length and sensors can be installed on any part of the tree trunk. If the sap flow sensors were damaged or vandalised, they can be quickly and cheaply replaced as they are low cost sensors.
  • Remote tree monitoring: in remote locations, it may not be practical to have a single, centrally located data logging system with cables extended to various trees for sap flow monitoring. The individual sap flow data loggers are ideal in such projects.
  • Horticulture and Viticulture: growers often require to run machinery and undertake other management procedures without worrying about tripping, cutting or damaging cabling and monitoring equipment. With a individual sap flow data logger, it is possible to undertake precision plant water use measurements on individual trees or vines without the need for extensive cabling and power supplies.


whole-system monitoring solutions

Edaphic Scientific can supply multiple sap flow sensors all connected to a single, centrally located data logging system, with multiplexers, power supply and environmentally protective housing.

Additional parameters can be added to the system for the monitoring of meteorological variables, soil moisture and water potential 

Edaphic Scientific can supply a monitoring system that is completely pre-programmed, pre-configured and ready to be installed. We can also provide assistance with field installation and training of staff and students.



free software

The Implexx Sap Flow Sensor has a calibrated output for whole tree sap flow. However, many scientists and researchers want to view the raw data and analyse their own data. The Implexx Sap Flow Sensor also outputs all the raw data from a measurement cycle.

These raw data can be analysed by the researcher as required. Alternatively, a free Excel file is supplied with the sensors that uses published conventions to convert raw temperature data into heat velocity, sap flux density and sap flow.



sap flow sensor installation

Sap flow sensors are relatively easy to install in trees – particularly with some practice. Edaphic Scientific can provide training for you on correct approach to sap flow sensor installation.

Along with your sap flow sensors, we provide additional items for sensor installation including drill guide, drill bits and grafting wax.

IMPLEXX-SF-IK Installation Kit contains everything that is required to install the Implexx Sap Flow Sensor onto a tree including drill, drill guide, drill bits (pack of 10), straps, and grease.

IMPLEXX-SF-TP Kit contains additional items that are required to measure basic tree properties including trunk diameter, a stem borer for sapwood depth and sapwood fresh volume, a high precision balance to measure sapwood fresh weight and dry weight, and a set of calipers.

Below is a YouTube video demonstrating how to install the Implexx Sap Flow Sensor:





feature specification
Measurement Principle Heat Pulse Velocity | Dual Method Approach (DMA)
Measurement Range -200 +1000 cm/hr heat velocity
Accuracy ±0.01 cm/hr heat velocity
Resolution 0.001 cm/hr heat velocity
Needle Dimensions 30 x 1.3 mm
Position of Thermistors Outer: 10 mm; Inner: 20 mm
Distance Between Needles 6 mm
Epoxy Body Dimensions 40 x 16 mm
Needle Materials 316 marine grade stainless steel
Temperature Range -30 to +70 °C
Response time and Resolution 200 milliseconds
Heater Resistance 39 ohms (typical)
Power Input 12 VDC
Power Consumption Idle: 4 mA; Measure: 270 mA | Typical Measurement Cycle: 0.4 mAhr
Sensor Output SDI-12 (ver 1.4)
Cable Length 5m (standard) | 60m (maximum)
Warranty 1 year

manual & docs

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