Sap flux probes have been used to study sap velocity since the early
20th century and have progressively improved in accuracy and usability.
Advances are also being made in making these devices cheaper via
open-sourced projects; however, these solutions require extensive time
and skill to construct a reliable device. When our lab tried to
replicate Miner’s results, only two of the first ten probes built passed
rudimentary testing. We therefore redesigned the system in a PCB-based
design that simplifies construction, and presents opportunity for
automated mass manufacturability at a scale not possible with existing
designs. New designs for both the Thermal Dissipation Method (TDM) and
the Heat Ratio Method (HRM) techniques were tested. We present our
open-source designs for wireless sap flux probes that communicate over
2km using the LoRa protocol through canopy to an internet hub, where
data is logged in near-real-time and accessible online.