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A PCB Based Sap Flux Sensor for Increased Manufacturability and Lower Cost
  • +5
  • Brett Stoddard,
  • Jonathan Fookes,
  • DongJun Lee,
  • Will Richardson,
  • Cara Walter,
  • Chet Udell,
  • Steven Good,
  • John S Selker
Brett Stoddard
Department of Electrical & Computer Engineering, Oregon State University

Corresponding Author:stoddardbrett@gmail.com

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Jonathan Fookes
Department of Electrical & Computer Engineering, Oregon State University
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DongJun Lee
Department of Electrical & Computer Engineering, Oregon State University
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Will Richardson
Department of Biological & Ecological Engineering, Oregon State University
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Cara Walter
Department of Biological & Ecological Engineering, Oregon State University
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Chet Udell
Department of Biological & Ecological Engineering, Oregon State University
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Steven Good
Department of Biological & Ecological Engineering, Oregon State University
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John S Selker
Department of Biological & Ecological Engineering, Oregon State University
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Abstract

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.