An autonomous and wireless pulse-amplitude modulated chlorophyll fluorometer
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Julian Reimer
Julian Reimer worked as a research assistant at the Laboratory for Electrical Instrumentation and Embedded Systems. His research interests include software engineering with focus on embedded systems and full stack application development.
Sebastian Stöcklin worked as a research associate at the Laboratory for Electrical Instrumentation and Embedded Systems. His research interests include adaptive low-power electronics, modeling of electromagnetic interfaces, and radio-frequency systems.
Laura M. Comella works as group leader for the department of Microsystems Engineering at the University of Freiburg. Core fields of her current research are sensor development and low power soft- and hardware solutions for medical applications and environmental sensing (in forest and agriculture).
Peter Woias is a full professor at the Department of Microsystems Engineering at the University of Freiburg. His research interests include microfluidics, chemical micro process engineering, optical, mechanical and dielectric sensors, energy harvesting and energy-autonomous embedded systems using piezoelectric, thermoelectric or photovoltaic generators.
Christiane Werner is a full professor at the Faculty of Environment and Natural Resources at the University of Freiburg. Her research interests include plant ecophysiology and ecosystem functioning, adaptations to climate change, stress ecophysiology, chlorophyll fluorescence, stable isotope and proton-transfer-mass spectrometry and laser spectroscopy.
Leonhard Reindl was full professor at the Department of Microsystems Engineering at the University of Freiburg until 2020. His research interests include wireless sensor systems, identification systems, energy harvesting systems, surface acoustic wave devices and materials as well as microwave communication systems.
Stefan J. Rupitsch is a full professor at the Department of Microsystems Engineering at the University of Freiburg. His research interests include electromechanical transducers, energy harvesting, embedded systems, ultrasonic imaging, localization and therapy, simulation-based material characterization, wireless sensors and noncontact measurements.
Abstract
Measuring chlorophyll fluorescence is an important tool in plant research, since it is a reliable non-invasive method for capturing photosynthetic efficiency of a plant and, hence, an indicator of plant stress/health. The principle of chlorophyll fluorometry is based on the optical illumination of a plant’s leaf at a certain wavelength, while simultaneously measuring the emitted fluorescence light intensity at a different optical wavelength. By relating the fluorescence light energy at small and large excitation power, conclusions on the efficiency of the photosystem and, therefore, on the plant’s photosynthesis capability can be drawn. Current mobile chlorophyll fluorometers are either (i) compact and energy efficient but limited in functionality and accuracy by omitting modulated measurement signals or (ii) sophisticated and precise with respect to the measurement, but with the drawback of extended weight, size, energy consumption and cost. This contribution presents a smaller, lighter and cheaper sensor device that can be built with sufficiently low energy consumption to be powered by energy harvesting while being light enough to be attached nearly anywhere such as tree branches. With a device cost below 250 €, the performance of the developed device is similar to more expensive commercial devices considering measurements of the relative variable fluorescence. Moreover, the sensor device provides a wireless interface in the European 868 MHz SRD band with up to 10 km of range in free space while just consuming 150 µW in receiving mode due to a custom duty cycling technique.
Zusammenfassung
Die messtechnische Erfassung der Chlorophyll-Fluoreszenz ist ein zentrales Werkzeug in der Pflanzenforschung, da es sich hierbei um ein nichtinvasives Messverfahren zur Ermittlung der Effizienz der Photosynthese handelt und damit ein Indikator des Zustands der Pflanze zur Verfügung steht. Die Chlorophyll-Fluoreszenz basiert auf der optischen Bestrahlung einer Pflanze bei einer bestimmten Wellenlänge und darauffolgender Auswertung des emittierten Fluoreszenzlicht bei einer anderen Wellenlänge. Mit Hilfe von unterschiedlichen Intensitäten der optischen Bestrahlung lässt sich darauf schließen, wie effizient eine Pflanze Photosynthese durchführen kann. Gegenwärtige transportable Chlorophyll-Fluorimeter sind entweder (i) kompakt und energieeffizient bei geringem Funktionsumfang und oftmals unzureichender Genauigkeit oder (ii) komplex aufgebaut und präzise bei hohem Gewicht und Energiebedarf sowie erheblichen Anschaffungskosten. In diesem Beitrag wird ein kleiner, leichter und kostengünstiger Fluorimeter-Sensor vorgestellt, der aufgrund seines geringen Energiebedarfs mit Energy-Harvesting-Komponenten betrieben und auch in Baumkronen angebracht werden kann. Obwohl die Bauteilkosten des entwickelten Sensors lediglich 250 € betragen, ist die Leistungsfähigkeit vergleichbar mit kommerziell erhältlichen und weit teureren Chlorophyll-Fluorimetern. Der vorgestellte Fluorimeter-Sensor verfügt zudem über eine drahtloses Kommunikationsmodul, mit dem im freien Raum Übertragungsentfernungen von 10 km bei einem Leistungsbedarf im Empfangsmodus von lediglich 150 µW erzielbar sind.
Funding statement: This research was supported by the Forschungsallianz Oberrhein zu den technischen Grundlagen der Nachhaltigkeit.
About the authors
Julian Reimer worked as a research assistant at the Laboratory for Electrical Instrumentation and Embedded Systems. His research interests include software engineering with focus on embedded systems and full stack application development.
Sebastian Stöcklin worked as a research associate at the Laboratory for Electrical Instrumentation and Embedded Systems. His research interests include adaptive low-power electronics, modeling of electromagnetic interfaces, and radio-frequency systems.
Laura M. Comella works as group leader for the department of Microsystems Engineering at the University of Freiburg. Core fields of her current research are sensor development and low power soft- and hardware solutions for medical applications and environmental sensing (in forest and agriculture).
Peter Woias is a full professor at the Department of Microsystems Engineering at the University of Freiburg. His research interests include microfluidics, chemical micro process engineering, optical, mechanical and dielectric sensors, energy harvesting and energy-autonomous embedded systems using piezoelectric, thermoelectric or photovoltaic generators.
Christiane Werner is a full professor at the Faculty of Environment and Natural Resources at the University of Freiburg. Her research interests include plant ecophysiology and ecosystem functioning, adaptations to climate change, stress ecophysiology, chlorophyll fluorescence, stable isotope and proton-transfer-mass spectrometry and laser spectroscopy.
Leonhard Reindl was full professor at the Department of Microsystems Engineering at the University of Freiburg until 2020. His research interests include wireless sensor systems, identification systems, energy harvesting systems, surface acoustic wave devices and materials as well as microwave communication systems.
Stefan J. Rupitsch is a full professor at the Department of Microsystems Engineering at the University of Freiburg. His research interests include electromechanical transducers, energy harvesting, embedded systems, ultrasonic imaging, localization and therapy, simulation-based material characterization, wireless sensors and noncontact measurements.
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© 2021 Walter de Gruyter GmbH, Berlin/Boston
Articles in the same Issue
- Frontmatter
- Beiträge
- The progress in development of the Planck-Balance 2 (PB2): A tabletop Kibble balance for the mass calibration of E2 class weights
- Faseroptische Kalibrierung von Positionssensoren für Planck-Waagen
- Quantenbasierte Sensorik zur Erfassung und Diskretisierung von Strömen für EMK-Wägesysteme
- An autonomous and wireless pulse-amplitude modulated chlorophyll fluorometer
- Strömungsfeldmessung der Kühlschmierstoffzufuhr an der Schleifscheibe
- Thermophysikalische Charakterisierung von Wärmedämmschichten
Articles in the same Issue
- Frontmatter
- Beiträge
- The progress in development of the Planck-Balance 2 (PB2): A tabletop Kibble balance for the mass calibration of E2 class weights
- Faseroptische Kalibrierung von Positionssensoren für Planck-Waagen
- Quantenbasierte Sensorik zur Erfassung und Diskretisierung von Strömen für EMK-Wägesysteme
- An autonomous and wireless pulse-amplitude modulated chlorophyll fluorometer
- Strömungsfeldmessung der Kühlschmierstoffzufuhr an der Schleifscheibe
- Thermophysikalische Charakterisierung von Wärmedämmschichten
