Single-Probe Heat-Pulse Microsensor for Water Transportation Measurement in Plant Shoots

To increase the productivity of agricultural crops, a growth method based on the physiological information of plants is required. In recent years, there is an increased demand for methods of minimally invasively measuring physiological information from plants. In this study, we propose a novel single-probe heat-pulse microsensor for minimally invasive measurement of water transportation (sap flow velocity) in plant shoots based on the fundamental conduction–convection principles of heat transport. The proposed sensor comprises a resistance temperature detector and a filament heater on a probe. We verified the performance of the sensor using thermal analysis and fabricated a sensor using microelectromechanical system technology. Finally, we demonstrated the feasibility of minimally invasive measurement of water transportation (measurement range: approximately 0–4 mm/s) in plant shoots.