Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/416—Systems

Definitions

• the present invention relates to an transpiration measurement sensor, an transpiration measurement device, and an transpiration measurement method.
• Plant growth depends heavily on the rate and amount of water vapor (which can also be expressed as moisture) released from leaves, etc., that is, the rate and amount of transpiration. For this reason, accurate measurement of the rate and amount of transpiration from plants is extremely important for the advancement of agriculture, including thorough growth management and quality control of crops. For example, if the amount of transpiration from plants in a greenhouse could be accurately measured and the measured value could be used to monitor the amount of transpiration, it would be possible to control the amount of irrigation water, humidity conditions, etc. in greenhouse cultivation. Also, in order to increase the sugar content of fruits and vegetables, there is a cultivation method in which the amount of water given during the growth stage is controlled to a level that does not cause the crop to wither, thereby causing water stress. In this case as well, if the amount of transpiration could be accurately measured, it would be possible to achieve both high sugar content and a secure harvest.
• Patent Document 1 a method for determining the amount of transpiration using a humidity sensor has been considered, and devices for evaluating the amount of transpiration from a single leaf and from a single plant surrounded by a cover are commercially available.
• no method or device for evaluating the macroscopic amount of transpiration from the entire greenhouse has been found.
• a method has been proposed in which the saturation deficit (the difference between the saturated value of absolute humidity and the measured value) in a greenhouse is used as a guide for the amount of transpiration, but this method has the problem that it cannot estimate the amount of transpiration in a high humidity environment of 100% or more, i.e., above the condition where condensation occurs.
• JP 2014-215215 A International Publication No. 2016/013544
• the problem that this invention aims to solve is to provide a sensor and device that can easily measure the transpiration rate and amount from a state where almost no transpiration occurs, to a state where the relative humidity reaches 100%, and even exceeds 100% and becomes supersaturated, causing a large amount of droplets to form or a large amount of water to be released, as well as a measurement method using these.
• (Configuration 1) An evaporation measurement sensor having a structure in which a first thin wire electrode made of a material containing at least one of a first metal and carbon and a second thin wire electrode made of a material containing a second metal different from the first metal are alternately arranged in at least a portion of a region on a substrate having at least an insulating surface.
• a transpiration measuring device for measuring transpiration from an object to be measured, comprising: a sensor having a structure in which a first thin wire electrode made of a material containing at least one of a first metal and carbon and a second thin wire electrode made of a material containing a second metal different from the first metal are alternately arranged in at least a portion of a substrate, at least the surface of which is insulating; and a signal processing device for measuring the current flowing between the first thin wire electrode and the second thin wire electrode.
• a sensor having a structure in which a first thin wire electrode made of a material containing at least one of a first metal and carbon and a second thin wire electrode made of a material containing a second metal different from the first metal are alternately arranged in at least a portion of a substrate, at least the surface of which is insulating; and a signal processing device for measuring the current flowing between the first thin wire electrode and the second thin wire electrode.
• a sensor having a structure in which a first thin wire electrode made of a
• the transpiration measuring device according to claim 2 or 3, wherein a distance between the first thin wire electrode and the second thin wire electrode is constant in the region.
• (Configuration 5) The transpiration measuring device according to claim 4, wherein the interval is 100 nm or more and 10 ⁇ m or less.
• (Configuration 6) 6. The transpiration measuring device of any one of configurations 2 to 5, wherein the first metal is selected from the group consisting of gold, platinum, silver, titanium, and alloys thereof.
• (Configuration 7) The transpiration measuring device according to any one of configurations 2 to 6, wherein the material containing the second metal is selected from the group consisting of silver, copper, iron, zinc, nickel, cobalt, aluminum, tin, chromium, molybdenum, manganese, magnesium, and alloys thereof.
• Configuration 8) At least one of the first thin line electrodes and the second thin line electrodes is provided in a plurality of wires, The transpiration measuring device according to any one of configurations 2 to 7, wherein the first thin wire electrode and the second thin wire electrode extend from opposite directions toward each other, so that they run parallel to each other.
• (Configuration 9) 9. The transpiration measuring device according to any one of configurations 2 to 8, wherein the object to be measured is a plant.
• (Configuration 10) 9. An transpiration measuring method for measuring at least one of an amount of transpiration and an transpiration rate from an object to be measured, using the transpiration measuring device according to any one of configurations 2 to 8.
• (Configuration 11) Providing a humidity sensor and a galvanic current sensing droplet sensor; a step of placing the humidity sensor in an experimental environment with a relative humidity of 100% or less and acquiring output data from the humidity sensor under a plurality of conditions with different humidity and temperature to measure a change in the relative humidity of the experimental environment; calculating an absolute humidity from the relative humidity and the temperature; acquiring teacher data consisting of data on the rate of change of the amount of water vapor in the experimental environment based on the data on the change of the absolute humidity; placing the droplet sensor in a measurement environment and acquiring output data of the droplet sensor in the measurement environment; A step of comparing the teacher data with the output data of the droplet sensor to obtain a correlation; calculating a conversion coefficient ⁇ for converting the output value P of the liquid drop sensor into a rate
• the present invention provides a sensor and device that can easily measure the transpiration rate and amount from a state where almost no transpiration occurs, to a state where the relative humidity reaches 100%, and even exceeds 100% and becomes supersaturated, causing a large amount of droplets to form or a large amount of water to be released, as well as a transpiration measurement method using the same.
• the transpiration measurement method of the present invention has the characteristic of being able to measure the amount of transpiration from a local situation such as within a colony of plants (for example, crops in a greenhouse) to a macro situation such as the entire greenhouse.
• the unit of the transpiration rate measured by the present invention is [g/ m3 ], and as this unit indicates, the local transpiration rate [g] within a specific community, etc., can be calculated by multiplying it by the volume [ m3 ] of the local space around the sensor.
• the macroscopic transpiration rate [g] of the entire greenhouse can be calculated by multiplying the transpiration rate [g/ m3 ] obtained from one sensor by the volume [ m3 ] of the entire greenhouse, or by virtually dividing the greenhouse into several compartments, multiplying the transpiration rate [g/ m3 ] obtained from sensors installed in the compartments by the volume [ m3 ] of each compartment, and then summing up the values obtained for all the compartments.
• FIG. 1A and 1B are diagrams showing an outline of the configuration of an evaporative measurement device of the present invention, in which (a) is a plan view and (b) is a cross-sectional view taken along the line A-A' of the droplet sensor portion.
• 3A to 3C are diagrams illustrating the operating principle of the droplet sensor unit of the transpiration measuring device of the present invention.
• FIG. 2 is a flowchart showing the transpiration measurement method of the present invention.
• 1A to 1D are diagrams illustrating the transpiration measurement method of the present invention.
• FIG. 13 is a measurement example according to an embodiment, showing the change in bubbler temperature [° C.] over time.
• FIG. 11 is a diagram showing a measurement example according to an embodiment, illustrating the environmental temperature [° C.] and the relative humidity [% RH] on the sensor surface.
• This is a measurement example according to the embodiment, and shows the measurement results of the current value [pA] by two types of droplet sensors with different thin-wire electrode spacings processed as a digital signal, and the resistance value [ ⁇ ] of the thin-wire electrodes.
• FIG. 5D is a measurement example according to the embodiment, showing analog signal data (raw data) before the measurement result of the current value shown in FIG. 5C is obtained.
• 13A and 13B are photographs showing a measurement example according to the embodiment, in which transpiration measurement is carried out in a greenhouse.
• the transpiration measuring device 101 of the present invention is a device equipped with a droplet sensor unit 10 and a sensor signal processing and analysis unit 14 .
• the transpiration measuring device 101 of the present invention is characterized in that it uses a galvanic current detection type droplet sensor 10, which will be described later, as a sensor for measuring transpiration.
• the droplet sensor 10 is a sensor that detects droplets formed between a first thin-wire electrode and a second thin-wire electrode by sensing the current flowing between the first thin-wire electrode and the second thin-wire electrode.
• the present inventor discovered that there is a correlation between the size and number of droplets detected by the droplet sensor 10 and the amount of transpiration, and invented the present invention.
• the droplet sensor 10 shows a tendency for the frequency of sensor response to increase with an increase in the amount of transpiration, and can detect an increase in the size and number of droplets even in a supersaturated state where the relative humidity exceeds 100%, so that it is suitable for use as a sensor (a sensor for measuring transpiration) constituting the droplet sensor unit 10 of the transpiration measuring device 101 of the present invention. Therefore, as shown in the examples, the transpiration measuring device 101 including the droplet sensor 10 can measure the transpiration rate and amount of transpiration even in a supersaturated state where the relative humidity exceeds 100%, and satisfies the performance required for plant growth and quality control and advanced agriculture.
• the second feature of the transpiration measuring device 101 of the present invention is that, in linking the output value (output current value) of the droplet sensor 10 to the amount of transpiration (transpiration rate), a conversion coefficient is calculated by comparing the amount of water vapor in an experimental environment with a relative humidity of 100% or less, which is calculated from the absolute humidity calculated from the relative humidity and environmental temperature.
• a conversion coefficient is calculated by comparing the amount of water vapor in an experimental environment with a relative humidity of 100% or less, which is calculated from the absolute humidity calculated from the relative humidity and environmental temperature.
• the present inventor devised a method for calculating the amount of transpiration or the transpiration rate of a target plant from the micro (local) sensor response in a real environment by evaluating the correlation between the amount of water vapor in the environment obtained in a specified experimental environment and the macro (average) sensor response and calculating a conversion coefficient, thereby completing the present invention.
• the droplet sensor 10 is able to detect an increase in the size and number of droplets even under such supersaturated conditions, and extrapolation is performed by estimating a value that nominally exceeds 100% (including condensation). This ensures that the amount of evaporation is measured with precision and accuracy over a wide range.
• the transpiration measuring device 101 may be an integrated measuring device having the droplet sensor unit 10 and the sensor signal processing and analysis unit 14, in which the droplet sensor unit 10 and the sensor signal processing and analysis unit 14 are electrically connected by a signal line 16, or may be a separate measuring device separated into a sensor device having the droplet sensor unit 10 and a signal processing device having the signal processing and analysis unit 14.
• wireless is intended as a means for transmitting an output signal from the droplet sensor unit 10 to the signal processing and analysis unit 14, but media such as SSD (Solid State Drive) and memory cards may be used instead of wireless.
• the integrated type has the advantage that the device is easy to handle, while the separate type has the advantage that when multiple sensors are used, the signal processing unit and analysis unit can be shared, which is efficient and makes it possible to reduce the price of the entire device.
• the liquid drop sensor unit (liquid drop sensor) 10 is made up of a galvanic current detection type liquid drop sensor.
• the galvanic current detection type droplet sensor is a sensor in which a first thin wire electrode 12 made of metal A and a second thin wire electrode 13 made of metal B are arranged side by side on the surface 11 of a substrate 11 sub, and when a conductive droplet such as a water droplet touches the first thin wire electrode 12 and the second thin wire electrode 13 across the first thin wire electrode 12 and the second thin wire electrode 13, the sensor detects the galvanic current flowing between the two thin wire electrodes to detect the presence or generation of the droplet.
• a galvanic current detection type droplet sensor is disclosed, for example, in Patent Document 2.
• the surface 11 of the substrate 11 sub is made of an insulating material.
• the substrate 11 sub include a silicon oxide film substrate on silicon, a substrate made of synthetic quartz or glass, a plastic substrate made of polycarbonate, and a metal insulating substrate on which an oxide film or an organic insulating film is formed on a metal plate such as aluminum.
• the metals A and B constituting the first thin wire electrode 12 and the second thin wire electrode 13 are different metals from each other, and each may be a single metal or an alloy. Either metal A or metal B may be carbon, a metal carbide, or an alloy carbide.
• the distance d (see FIG. 1(b)) between the first thin-wire electrode 12 and the second thin-wire electrode 13 is constant.
• a constant distance d improves the stability and sensitivity of droplet detection, and therefore improves the stability and sensitivity of the measurement of evaporation by the evaporation measuring device 101.
• the distance d is preferably 100 nm or more and 10 ⁇ m or less, and more preferably 500 nm or more and 10 ⁇ m or less. When the distance d is within this range, it is easy to ensure the stability of droplet detection, and therefore it is possible to make the measurement of evaporation by the evaporation measuring device 101 more stable.
• the first thin wire electrode 12 and the second thin wire electrode 13 are made of a material selected from the group consisting of metal, alloy, metal carbide, alloy carbide, and carbon, and are selected so as to have different electrochemical potentials.
• the material containing the first metal constituting the first fine wire electrode 12 may be a material selected from the group consisting of gold (Au), platinum (Pt), silver (Ag), titanium (Ti) and alloys thereof.
• carbon (C) may be used instead of a metal, or a metal carbide or alloy carbide may be used.
• Examples of materials containing the second metal that constitute the second thin-wire electrode 13 include materials selected from the group consisting of silver (Ag), copper (Cu), iron (Fe), zinc (Zn), nickel (Ni), cobalt (Co), aluminum (Al), tin (Sn), chromium (Cr), molybdenum (Mo), manganese (Mn), magnesium (Mg), and alloys thereof.
• At least one of the first thin-line electrode 12 and the second thin-line electrode 13 is preferably provided in multiples, and the first thin-line electrode 12 and the second thin-line electrode 13 extend from opposite directions toward each other, so that they run parallel to each other. This increases the packing density (element density) of the sensor device, and improves the sensitivity, reliability, and stability of droplet detection.
• the electrodes (current collectors) of the droplet sensor unit 10 are composed of a first electrode 32 electrically connected to the first thin-line electrode 12 and a second electrode 33 electrically connected to the second thin-line electrode 13.
• the metal (material) constituting the first thin-line electrode 12 is different from the metal (material) of the second thin-line electrode 13.
• the first thin-line electrode 12 and the first electrode 32, and the second thin-line electrode 13 and the second electrode 33 are each composed of the same material.
• the first electrode 32 and the second electrode 33 are composed of the same material. From the latter viewpoint, it is preferable to use aluminum, which has low electrical resistance and can be kept relatively low cost, as the first electrode 32 and the second electrode 33.
• the droplet sensor unit 10 is electrically connected to the sensor signal processing and analysis unit 14 via a signal line 16 (see FIG. 1(a)).
• the sensor signal processing and analysis unit 14 has at least two functional units, a current value measurement unit 41 and a current value determination and analysis unit 42, and the current value measurement unit 41 and the current value determination and analysis unit 42 are electrically connected by a signal line 43.
• the current value measuring unit 41 measures the value of the galvanic current flowing between the first thin-wire electrode 12 and the second thin-wire electrode 13.
• the measurement method may be to use an ammeter that directly measures the galvanic current, or to amplify the galvanic current with an amplifier.
• the former method of directly measuring the current is simple and can be manufactured at low cost, while the latter method of using an amplifier is suitable for improving measurement accuracy.
• Representative amplifier methods include the charge amplifier method and the analog amplifier method.
• the analog amplifier method is a method in which the signal from one channel is phase-inverted and then the difference with the signal from the other channel is taken, and is particularly preferred because it is possible to increase the S/N ratio by 10 times or more while keeping costs down.
• the current value determination and analysis unit 42 has the following functions. - an input function for each signal, which is an output signal from the droplet sensor unit 10, a droplet detection/measurement signal, a relative humidity measurement signal from the humidity sensor, and an environmental temperature measurement signal at the installation location of the droplet sensor 10; a function of calculating absolute humidity from the relative humidity measurement signal and the environmental temperature measurement signal; - determining the time change ⁇ H of the absolute humidity, where the time change ⁇ H of the absolute humidity obtained corresponds to the rate of change of the amount of water vapor in the environment; A function for determining the time change ⁇ W of the output signal of the droplet sensor 10; A function of calculating a conversion coefficient ⁇ for converting the time change ⁇ W of the output signal of the liquid drop sensor 10 into a rate of change ⁇ H of the amount of water vapor in the environment from the time change ⁇ H of the absolute humidity relative to the time change ⁇ W of the output signal of the liquid drop sensor 10; A conversion coefficient storage function for storing and saving a list of environmental
• the current value determination and analysis unit 42 includes an input section for a signal line 43 from the current value measurement unit 41, an input section for a signal line 44 from a humidity sensor (not shown), an input section for a signal line 45 from an optional temperature sensor (not shown), and an output section for an output line 46.
• the arrows pointing to the current value determination and analysis unit 42 represent the input section
• the arrows pointing out from the current value determination and analysis unit 42 represent the output section.
• the means for transmitting each signal may be wireless instead of a signal line, and each signal may be in the form of either analog or digital.
• the current value determination and analysis unit 42 specifically consists of computing function devices such as a CPU (Central Processing Unit), an MPU (Micro Processing Unit) and a microcomputer, memories such as DRAM, SRAM and Flash memory, and storage such as SSD, Flash memory and HDD.
• a PC can be used as the current value determination and analysis unit 42.
• the transpiration rate is directly measured by the transpiration measuring device 101 of the present invention.
• the amount of transpiration can be calculated by performing time integration on the measured transpiration rate value ⁇ V(t) at each measurement time t.
• a humidity sensor and a galvanic current detection type droplet sensor 10 are prepared (step S11).
• the humidity sensor is a sensor that measures at least the relative humidity, and is not particularly limited. There is no problem in using a commercially available relative humidity sensor.
• the humidity sensor also has a function of measuring temperature.
• a temperature sensor may be prepared separately from the humidity sensor.
• the humidity sensor is placed in an experimental environment with a relative humidity of 100% or less, and output data from the humidity sensor is obtained under multiple conditions with different humidity and temperature, to measure the change in relative humidity in the experimental environment (step S12, FIG. 4(a)).
• the experimental environment is not particularly limited as long as it is an environment with a relative humidity of 100% or less and in which output data from the humidity sensor can be obtained under multiple conditions with different humidity and temperature. Examples include a room (in a laboratory) or a space (in an experimental box) having a certain volume. Alternatively, if the measurement environment described later is inside a house (for example, inside an agricultural house), the experimental environment may be inside the house or a space simulating the environment inside the house.
• FIG. 4(a) shows a schematic example of how the environmental temperature (air temperature) [°C] and relative humidity [% RH] change with time t. Note that the measurement time interval can be set to any value.
• the absolute humidity is calculated from the relative humidity and the temperature (step S13).
• the absolute humidity may be calculated by calculating the saturated water vapor pressure according to a general conversion method, multiplying it by the relative humidity to obtain the actual water vapor partial pressure, and then applying this value to a physical formula.
• the saturated water vapor pressure and the water vapor partial pressure can be calculated, for example, using the following formulas.
• FIG. 4(b) shows a schematic example of how absolute humidity [g/ m3 ] changes with time t, and indicates that the amount of change in absolute humidity per unit time [g/ m3 /min] is the rate of change in the amount of water vapor in the experimental environment.
• the droplet sensor 10 is placed in the measurement environment and output data of the droplet sensor 10 in the measurement environment is obtained (step S15, FIG. 4(c)).
• the measurement environment is intended to be an environment in which an object (measurement target) for which transpiration is to be measured exists or is to exist, and is typically an environment in which a target plant is growing or is to be grown.
• the measurement environment is inside a greenhouse, and more specifically, inside an agricultural greenhouse.
• FIG. 4(c) shows a schematic example of how the output value (sensor value [A]) of the droplet sensor 10 changes with time t, and indicates that the amount of change in the sensor value per unit time [A/min] can be obtained.
• a method for determining correlation can be one selected from the group consisting of regression analysis, t-test, and z-test.
• regression analysis can be extended to multivariate analysis, and the t-test is suitable for use when the population variance is unknown, while the z-test is suitable for use when the population variance is known.
• FIG. 4(d) is a schematic example of a graph obtained by using the amount of change in the sensor value per unit time (time change in the sensor value [A/min]) shown in FIG. 4(c) as the horizontal axis and the amount of change in the absolute humidity per unit time (rate of change in the amount of water vapor in the environment [g/ m3 /min]) shown in FIG. 4(b) as the vertical axis, and the slope of this graph [g/ m3 /A] indicates that it is the conversion coefficient ⁇ mentioned above.
• the above-mentioned graph may be an approximate straight line (regression line).
• the droplet sensor 10 is placed in the measurement target environment of the object to be measured to obtain the output P measure of the droplet sensor 10 (step S18).
• the measurement target environment is intended to be the environment in which the object to be measured (i.e., the object to be measured for transpiration) exists, and is typically the environment in which the target plant is grown.
• the measurement target environment may mean a space narrower than the above measurement environment.
• the measurement environment is inside a house (inside an agricultural house), whereas the measurement target environment may be a part of the object to be measured (e.g., a leaf of a plant or a crop), or a certain space including the part.
• the measurement target environment is preferably a space including a part of the object to be measured where transpiration is likely to occur, and by placing the droplet sensor 10 in such a measurement target environment, the transpiration amount or transpiration rate of the object to be measured (a plant or a crop) can be calculated from the sensor response obtained in a micro (local) space such as around several leaves or one leaf.
• the evaporation measurement method of the present invention continuously measures the evaporation rate S measure using the droplet sensor 10 in the measurement environment of the object to be measured for a period of time equal to or longer than a predetermined specified time t, and time-integrates the measured evaporation rate S measure over the specified time t to calculate the evaporation amount V [g/ m3 ] at the specified time t.
• the transpiration measurement method of the present invention uses a humidity sensor to obtain training data in an experimental environment with a relative humidity of 100% or less, analyzes whether there is a correlation between the training data and data obtained using the droplet sensor 10 in the measurement environment, determines a conversion coefficient ⁇ using the output data of the droplet sensor 10 for which a correlation has been found, and calculates the transpiration rate of the object being measured from the output of the droplet sensor 10 in the measurement environment of the object being measured.
• the transpiration measurement method of the present invention has a step of confirming the high degree of correlation between the training data and the data obtained using the droplet sensor 10, it has the characteristic of being highly accurate, precise, and stable in measurements, and further capable of measuring the transpiration rate and amount even in supersaturated environments with a relative humidity of more than 100%, making it a very effective method for plant growth and quality control and for the sophistication and efficiency of agriculture.
• the transpiration measurement method of the present invention is a local measurement method capable of measuring transpiration based on the detection of minute droplets by the droplet sensor 10, and has the characteristic of high spatial resolution. Due to this characteristic, the transpiration measurement method of the present invention is suitable for monitoring transpiration in a situation where a colony area where multiple transpiration bodies that emit water vapor are clustered and a blank area where no transpiration bodies are present, as is often seen in greenhouse cultivation, and the space formed by the colony area and the blank area forms an enclosed space isolated from the outside air.
• the conversion coefficient ⁇ obtained by performing steps S11 to S17 in the greenhouse as the measurement environment can be used in subsequent measurements in the same greenhouse.
• the measurement environment of the object to be measured a greenhouse in this example
• steps S11 to S17 have already been performed in the previous measurement
• the output P measure of the droplet sensor 10 placed in the measurement environment is obtained (step S18)
• the transpiration rate S measure of the object to be measured is obtained using the above formula (1) (step S19), thereby simplifying the measurement of the transpiration amount of the object to be measured.
• the conversion coefficient ⁇ may be calculated by performing steps S11 to S17 every time a measurement is performed, and in this case, it is expected that more precise cultivation management will be possible. Furthermore, assuming cultivation in a number of greenhouses installed in a particular farmland (which may be read as a district or region in a broader sense), for example, it may be possible to set a reference value for the conversion coefficient according to the volume of the farmland (district or region) and/or greenhouse by performing the above steps S11 to S17 on each greenhouse as a measurement environment and performing statistical analysis on the conversion coefficient ⁇ obtained.
• step S18 it may be possible to further simplify the measurement of the amount of evaporation of the object to be measured by considering that steps S11 to S17 have already been performed in the first measurement in a certain greenhouse, determining the output P measure of the liquid droplet sensor 10 placed in that greenhouse (measurement target environment) (step S18), and determining the evaporation rate S measure of the object to be measured using the above-mentioned reference value as the value of ⁇ in the above formula (1) (step S19).
• Example 1 In the first embodiment, a prototype of an evaporation measuring device 101 was produced using the droplet sensor 10 and a PC as the sensor and the current value determination and analysis unit 42, and a verification experiment was carried out on the concept of the above-mentioned evaporation rate measurement.
• the prototype droplet sensor 10 is a galvanic current detection sensor in which a first thin wire electrode 12 and a second thin wire electrode 13 are formed on a substrate 11 sub whose surface is made of silica.
• the first thin wire electrode 12 is made of gold (Au), has a line width of 2 ⁇ m, a thickness of 150 nm, and has 165 electrodes.
• the second thin wire electrode 13 is made of aluminum (Al), has a line width of 2 ⁇ m, a thickness of 150 nm, and has 165 electrodes.
• the distance d between the first thin wire electrode 12 and the second thin wire electrode 13 is constant, and a plurality of electrodes of 500 nm (0.5 ⁇ m) and 10 ⁇ m were fabricated.
• a current measuring device (current value measuring unit 41) is connected to the droplet sensor 10 via a cable or wirelessly, and the output of the current measuring device is sent to a PC via a signal line 43 or wirelessly.
• the current measuring device is homemade (custom-made), and a ThinkPad L570 (manufactured by Lenovo) was used as the PC.
• the measurement procedure is as follows. First, a temperature and humidity sensor and the above-mentioned droplet sensor 10 of the galvanic current detection type were prepared (step S11 in FIG. 3). Here, as the temperature and humidity sensor, E+E Elektronik/EE23 was used. In addition, a cooling vapor saturation type bubbler me-40DPRT (manufactured by Micro Equipment Co., Ltd. and other companies) was placed in an experiment box (a closed space with a capacity of 50 mL), a thermocouple thermometer was installed in the saturation tank, and the above-mentioned temperature and humidity sensor and droplet sensor 10 were placed in this experiment box.
• the output signals from each sensor were configured to be sent to the PC by wire in the case of analog signals, and were configured to be sent to the PC by wireless in the case of digital signals.
• the output signal of the droplet sensor 10 was configured to be sent from the current measuring device via the above-mentioned analog amplifier type amplifier. In addition, it was configured to be able to monitor the surface temperature of the droplet sensor 10 (the temperature of the surface 11 of the substrate 11 sub ).
• the bubbler was operated and the time change in relative humidity in the experimental box (experimental environment with a relative humidity of 100% or less) was measured with a temperature and humidity sensor (step S12).
• step S13 the absolute humidity was calculated from the relative humidity and the temperature (step S13), and then, based on the obtained change data of the absolute humidity, teacher data consisting of change rate data of the amount of water vapor in the experimental environment was obtained (step S14).
• the temperature in step S13 is the measurement result of the temperature (change over time) in the experimental box by the temperature and humidity sensor.
• step S15 the same experimental environment was used as the measurement environment, and output data of the droplet sensor 10 was obtained (step S15).
• step S16 the teacher data was compared with the output data of the droplet sensor 10, and correlation was determined by t-test (step S16). As a result, t>+2.0 was obtained, which indicates that the correlation is 95% or higher, and it was confirmed that a high correlation was obtained.
• Figures 5A to 5D Examples of measurement data are shown in Figures 5A to 5D.
• Figure 5A shows the change in bubbler temperature [°C] over time
• Figure 5B shows the environmental temperature (temperature inside the experimental box) [°C] and the relative humidity [%RH] on the sensor surface
• Figure 5C shows the measurement results of the current value [pA] from two types of droplet sensors 10 with different fine-wire electrode spacing processed as digital signals and the resistance value [ ⁇ ] of the fine-wire electrodes
• Figure 5D shows the analog signal data (raw data) before the measurement results of the current value shown in Figure 5C were obtained. These data were obtained by measuring while changing the bubbler conditions every 1200 seconds.
• the bubbler temperature is the temperature of the saturation tank constituting the bubbler
• the water vapor partial pressure Pb [hPa] of the air in the tank is determined by determining the temperature of the saturation tank, which is assumed to be equal to the saturated water vapor pressure [hPa].
• the saturated water vapor pressure P T [hPa] at T [°C] is theoretically determined, and the relative humidity [% RH] is calculated as Pb [hPa]/P T [hPa] x 100.
• the bubbler conditions i.e., the temperature of the saturation tank
• the relative humidity [% RH] on the sensor surface was calculated by calculating the water vapor partial pressure P E [hPa] of the experimental environment from the relative humidity and environmental temperature measurements taken by the temperature and humidity sensor, and determining the saturated water vapor pressure P S [hPa] on the sensor surface from the surface temperature T S [°C] of the droplet sensor 10, as P E [hPa]/P S [hPa] x 100.
• the measurement environment is the same as the experimental environment, that is, inside an experimental box, but even if the measurement environment is, for example, inside a greenhouse, the conversion coefficient ⁇ can be calculated according to the above procedure.
• the volume of the local space surrounding the droplet sensor 10 it is possible to determine the local amount of transpiration, such as within a specific community in which the droplet sensor 10 is installed.
• the macroscopic amount of transpiration such as for an entire greenhouse, can be determined by multiplying the amount of transpiration obtained from one droplet sensor 10 by the volume of the entire greenhouse, or by virtually dividing the greenhouse into several compartments, multiplying the amount of transpiration obtained from a droplet sensor 10 installed in each compartment by the volume of each compartment, and then adding up the values obtained for all compartments.
• a conversion coefficient ⁇ was calculated to convert the output value P of the droplet sensor 10 into the rate of change S of the amount of water vapor in the measurement environment (step S17).
• the conversion coefficient ⁇ was 0.55-0.68 for each sensor (average value for all sensors: 0.67).
• the greenhouse is approximately 50m x 40m x 3.5m in size and is used to grow cucumbers.
• the plants are grown in colonies of 15 rows, with an aisle approximately 1m wide between the colonies.
• the present invention makes it possible to easily measure the transpiration rate and amount from plants over a wide dynamic range, from a state where almost no transpiration occurs to a state where a large amount of droplets are generated or water is released in a supersaturated environment with a relative humidity of over 100%. Since the transpiration rate and amount are directly linked to plant growth and sugar accumulation, applying the method of the present invention to agriculture is expected to increase yields and improve the tastiness of the harvested products.

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• 2024
  • 2024-10-28 WO PCT/JP2024/038255 patent/WO2025094861A1/ja active Pending
  • 2024-10-28 JP JP2025554753A patent/JPWO2025094861A1/ja active Pending

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