ICT International

Advancing soil, plant and environmental decision making

Quick Start Guide for the Heat Deformation Sap Flux Meter (HFD)

Technical Specifications


  • Standalone system with integrated logger and battery


  • Logging:
    • Stand-alone logging
    • MicroSD expandable memory
    • 4GB MicroSD Removable Storage Card (capacity: 10+ years data storage)
    • Wireless connectivity and data transfer
    • Simple conversion and scripting
    • Flexible sensor calibration, look-up tables, and user scripts
    • 24-Bit resolution
    • IP65 rated water proof enclosure
    • Free Windows and Mac utility configuration software
    • Optional wireless logging


  • Power management:
    • Field: solar power and 12V battery
    • Lab: mains power supply
    • Internal Lithium-Polymer battery
    • Internal voltage regulation
    • Optical isolation lightning protection


Instrument Logging
Resolution 0.00001V—24-Bit
Accuracy 0.001V
Minimum Logging Interval 1 second
Delayed Start Suspend Logging, Customised Intervals
Sampling Frequency 10Hz
Communications USB, Wireless Radio Frequency 2.4 GHz
Data Storage MicroSD Card, SD, SDHC & SDXC Compatible (FAT32 format)
Software Compatibility Windows Vista, 7, 8, 8.1 and Mac
Data Compatibility FAT32 compatible for direct exchange of SD card with any Windows PC or Mac
Data File Format Comma Separated Values (CSV) for compatibility with all software programs
Memory Capacity Up to 16GB, 4GB microSD card included.
Operating Conditions
Temperature Range -40°C to +80°C
R/H Range 0-100%
Upgradable User Upgradeable firmware using USB boot strap loader function


Internal Battery Specifications
4.8Ah Lithium Polymer, 4.20 Volts fully charged
External Power Requirements
Bus Power 8-30 Volts DC, non-polarised, current draw is 340mA maximum at 17 volts per logger
USB Power 5 Volts DC
Internal Charge Rate
Bus Power 60mA – 700mA Variable internal charge rate, maximum charge rate of 700mA active when the external voltage rises above 16 Volts DC
USB Power 100mA fixed charge rate
Internal Power Management
Fully Charged Battery 4.20 Volts
Low Power Mode 3.60 Volts – Instrument ceases to take measurements
Discharged Battery 2.90 Volts – Instrument automatically switches off at and below this voltage when no external power connected.
Battery Life varies
  • With a recommended power source connected, operation can be continuous.


HFD8 Sap Flow Needles Installed
Downloads Available
References for HFD

Balugani, E. (2021). Partitioning of subsurface evaporation in water limited environments [University of Twente]. https://doi.org/10.3990/1.9789036552127
Balugani, E., Lubczynski, M. W., Reyes-Acosta, L., van der Tol, C., Frances, A. P., & Metselaar, K. (2017). Groundwater and unsaturated zone evaporation and transpiration in a semi-arid open woodland. Journal of Hydrology, 547, 54–66.
Dattola, A., Vonella, V., Olivadese, T., Pullia, F. M., Zappia, R., & Gullo, G. (2023). The Evaluation of the Water Consumption and the Productive Parameters of a Table Grapevine, Cardinal Cultivar, Grafted onto Two Rootstocks. Agriculture, 13(11), 2101. https://doi.org/10.3390/agriculture13112101
David, T. S., David, J. S., Pinto, C. A., Cermak, J., Nadezhdin, V., & Nadezhdina, N. (2012). Hydraulic connectivity from roots to branches depicted through sap flow: analysis on a Quercus suber tree. Functional Plant Biology, 39(2), 103–115. https://doi.org/10.1071/FP11185
Eliades, M., Bruggeman, A., Djuma, H., & Lubczynski, M. W. (2018). Tree Water Dynamics in a Semi-Arid, Pinus brutia Forest. Water, 10(8), 1039. https://doi.org/10.3390/w10081039
Eliades, M., Bruggeman, A., Lubczynski, M. W., Christou, A., Camera, C., & Djuma, H. (2018). The water balance components of Mediterranean pine trees on a steep mountain slope during two hydrologically contrasting years. Journal of Hydrology, 562, 712–724. https://doi.org/10.1016/j.jhydrol.2018.05.048
Fan, J., Guyot, A., Ostergaard, K. T., & Lockington, D. A. (2018). Effects of earlywood and latewood on sap flux density-based transpiration estimates in conifers. Agricultural and Forest Meteorology, 249, 264–274. https://doi.org/10.1016/j.agrformet.2017.11.006
Guyot, A., Ostergaard, K. T., Fan, J., Santini, N. S., & Lockington, D. A. (2015). Xylem hydraulic properties in subtropical coniferous trees influence radial patterns of sap flow: implications for whole tree transpiration estimates using sap flow sensors. Trees, 29(4), 961–972. https://doi.org/10.1007/s00468-014-1144-5
Link, R. M., Fuchs, S., Arias Aguilar, D., Leuschner, C., Castillo Ugalde, M., Valverde Otarola, J. C., & Schuldt, B. (2020). Tree height predicts the shape of radial sap flow profiles of Costa-Rican tropical dry forest tree species. Agricultural and Forest Meteorology, 287, 107913. https://doi.org/10.1016/j.agrformet.2020.107913
Nadezhdina, N., Vandegehuchte, M. W., & Steppe, K. (2012). Sap flux density measurements based on the heat field deformation method. Trees, 26(5), 1439–1448. https://doi.org/10.1007/s00468-012-0718-3
Van de Wal, B. A. E., Guyot, A., Lovelock, C. E., Lockington, D. A., & Steppe, K. (2015). Influence of temporospatial variation in sap flux density on estimates of whole-tree water use in Avicennia marina. Trees, 29(1), 215–222. https://doi.org/10.1007/s00468-014-1105-z

HFD CIS and Sap Flow Tool Software

Combined Instrument Software (CIS) requires additional Microsoft software installed, as well as driver for the USB Comm Port.


CIS and Instrument Installation Instruction:

  1. Ensure the SFM1 is not connected to the computer.
  2. Install the “CDM v2.12.28 WHQL: Certified” Virtual Com Port Driver found here: https://ftdichip.com/wp-content/uploads/2021/08/CDM212364_Setup.zip
  3. Download and install (For Windows 10 AMD/Intel) the “Microsoft Visual C++ 2010 Redistributable Package. This is available from the Microsoft download page: https://www.microsoft.com/en-au/download/details.aspx?id=26999
  4. Download and Install both the vcredist_x86.exe and vcredist_x64.exe packages from the pop up screen.
  5. Install the ICT Combined Instrument Software:
    1. Select “No” to warning about completely removing existing installations and all of its components.
    2. Select “Next”
    3. Change the install location from “\ICT International\ICT Instrument\” to “\ICT International\ICT Instrument\
    4. Select “Install”
    5. Untick “Run ICT Instrument” to prevent opening the application whilst changing the shortcut name (see below)
    6. Select “Finish”
  6. On the Desktop of your PC, change the file name of “ICT Instrument” to “ICT CIS”
  7. Open this shortcut, and confirm on the left of the software that it displays “”


SFT Sap Flow Tool Software Download:


Please download the Sap Flow Tool Software following this link – please note, purchase of license and physical dongle are required