Sap flow, IoT, LoRa WAN, NB-IoT, WiFi and modem devices


Industry and scientists are increasingly turning towards the Internet of Things (IoT) for sap flow monitoring and research. Yet, not all sap flow sensors are created equally and just about all commercially available sensors are unsuitable for IoT devices.

The Implexx Sap Flow Sensor from Implexx Sense is the only commercially available sap flow sensor that is widely suitable for many IoT devices from LoRa WAN to NB-IoT to modems and WiFi.

The Implexx Sap Flow Sensor is the only suitable sap flow sensor because it meets all the critical criteria required by IoT devices. These criteria include:

- digital output such as SDI-12 protocol;

- low power requirements;

- easy to install and maintain; and

- outputs are small data packets and easy to understand.


The Implexx Sap Flow Sensorhas a digital, SDI-12 output

Most sap flow sensors are analog sensors. The analog models require complex wiring and programming, data loggers, and usually additional multiplexers.

The Implexx Sap Flow Sensor, in contrast, is a 3-wire digital sensor utilising the SDI-12 protocol.

Many The Implexx Sap Flow Sensors can potentially connect to a small or compact LoRa WAN, NB-IoT or WiFi device.


low power requirements

Sap flow sensors contain a heating element which often require substantial power support. For example, the thermal dissipation probes (TDP), also known as Granier probes, as well as stem heat balance, or Dynagage, sensors, require continuous heating and therefore large battery packs and solar panels. This configuration is unsuitable for IoT devices which typically operate off small batteries and solar panels.

The Implexx Sap Flow Sensor is a heat pulse device that only requires the heater element to turn on for 3 seconds, or less, during a measurement cycle. This can occur once every 10 minutes or, to conserve power, less frequently such as once per hour. A small battery can potentially power a Implexx Sap Flow Sensor for many weeks without charge.


easy to install and maintain

The Implexx Sap Flow Sensor is a relatively easy sensor to install into a tree. An installation kit is provided by Implexx Sense including a drill, drill guide and drill bits. With these tools, a Implexx Sap Flow Sensor sensor can be installed in less than 5 minutes.

Once installed, The Implexx Sap Flow Sensor typically does not require any regular maintenance. It is recommended that the sensor is reinstalled approximately every 12 months to minimise localised wounding to plant tissue.


small data packets

Many IoT devices, such as LoRa WAN, NB-IoT and WiFi enabled devices, operate on the transmission of small data packets over long distances. Several sap flow sensors, however, require relatively large data packets to be transmitted sometimes at high frequency.

The Implexx Sap Flow Sensor is entirely flexible and can be configured to send the smallest data packet possible. The main output from the Implexx Sap Flow Sensor is calibrated total tree sap flow (litres per hour). For many applications and projects, particularly for industry, this single output is all that is required.

Scientists and researchers, however, often require more data to check for sensor efficacy or additional parameters including sapwood temperature, sapwood water content, or sapwood thermal properties.

The Implexx Sap Flow Sensor can output a total of 33 parameters, per measurement cycle, for a comprehensive characterisation of tree water use and physiology. If a researcher requires this level of detail, then it may be possible to custom configure a LoRa WAN or NB-IoT device. Alternatively, a data logger with a modem and SIM card may be required.