Moisture sensor, measurement method and use

Abstract

The present invention relates generally to moisture sensors, in particular to moisture sensors using Time Domain Reflectometry (TDR). In particular, the present invention relates to a sensor device which is charged using wireless power transfer and subsequently performs a moisture measurement using Time Domain Reflectometry. The present invention also provides a measurement method using such a sensor device as well as a use or application method employing such a sensor device.

Description

Technical Field

[0001] This invention generally relates to moisture sensors, and more particularly to moisture sensors using time-domain reflectometry (TDR). Specifically, the invention relates to a sensor device that is charged using wireless power transmission and subsequently performs moisture measurement using time-domain reflectometry. The invention also provides measurement methods using such a sensor device, as well as uses or applications of such a sensor device. Background Technology

[0002] Measuring the moisture content of samples (preferably solid samples, more preferably soil) is an important aspect in many fields, such as geology, engineering, architecture, biology, and agriculture. For example, in agriculture, managing plant growth while facing increasingly limited water resources due to climate change is a significant issue. This necessitates continuous monitoring of soil moisture. The term "soil" refers to a generally loose layer of minerals and / or organic matter on or near the surface of a planet, influenced by physical, chemical, and / or biological processes, typically containing liquids, gases, biota, and providing support for plants. It serves as the substrate for plant growth, providing nutrients, water, and anchorage support for plant roots.

[0003] Methods for monitoring moisture content can be categorized into direct and indirect methods. Direct methods measure the water content of a sample by removing moisture through evaporation or chemical reactions. Examples of direct methods include gravimetric analysis and the calcium carbide method. Indirect methods measure properties of a sample that vary with water content, such as dielectric constant, conductivity, or light reflectance. Examples of indirect methods include time-domain reflectometry (TDR), time-domain transmission (TDT), conductivity methods, and near-infrared optics.

[0004] The principle of time-domain reflectometry (TDR) is based on the relationship between the dielectric constant of a sample and its water content. A TDR sensor emits one or more high-frequency electromagnetic pulses through a waveguide and measures the time delay between the incident and reflected electromagnetic pulses. These waveguides typically consist of pairs of stainless steel rods inserted into the sample. The significant difference between the dielectric constant of water (approximately 80) and that of other materials (ranging from 2 to 7) causes the pulse travel time, which depends on the volumetric water content.

[0005] US17,012,365 describes the use of a TDR to measure volumetric water content, but does not address the power supply requirements of the TDR sensor. Several methods exist for powering a TDR sensor: wired connection (e.g., WO 2004074781). Figure 1 and Figure 2 And US9,696,292 Figures 1 to 3The setup shown in A) may be impractical in an agricultural environment because these wired connections could hinder the movement of plant pots in a greenhouse, especially when conveyor belts are used. Similarly, TDR sensors powered by bulky batteries suffer from stability issues that could cause moving plant pots to tip over, and their ability to capture plant images is limited by battery size. Furthermore, battery use results in high maintenance costs associated with regular replacements.

[0006] Alternatively, TDR sensors may be wirelessly powered. Fonsêca et al. developed a passive RFID soil moisture sensor using time-domain transmissivity (TDT) (N. Fonseca, R. Freire, G. Fontgalland, B. Arruda, and S. Tedjini, “A Fully Passive UHF RFID Soil Moisture Time-Domain Transmissometry Based Sensor,” 3rd International Symposium on Instrumentation Systems, Circuits and Transducers (INSCIT), Bento Gonçalves, Brazil, 2018, pp. 1–6). This paper points out that measurement is achieved by simultaneously sampling the injected and propagated signals to determine the propagation delay time. However, this method is unsuitable for TDR measurements because electromagnetic radiation can introduce unwanted noise and interference into the TDR system, distorting the reflected signal and increasing the complexity of distinguishing the desired reflection from external noise, potentially compromising measurement accuracy and reliability. Furthermore, as noted in the study by Sun et al. (Sun and GD Young, “A Cost-Effective Soil Moisture Instrument Based on Time-Domain Transmission Measurement”, 2001), for example, TDT performs poorly under saline clay conditions.

[0007] Therefore, the present invention aims to provide a sensor that mitigates or eliminates one or more of the aforementioned disadvantages of the prior art. Summary of the Invention

[0008] This invention provides a sensor device, which includes:

[0009] The antenna is used to receive electromagnetic radiation;

[0010] A capacitor configured to store power received from the antenna;

[0011] A threshold activation element electrically connected to the capacitor compares the stored power with a predefined threshold, which is sufficient to generate time domain reflectance (TDR) sensor data.

[0012] A detection element, used to detect power outages, and

[0013] A TDR sensor is used to generate TDR sensor data when the threshold activation element signals that the power stored in the capacitor exceeds the predefined threshold, and the detection element signals that the antenna has stopped receiving electromagnetic radiation.

[0014] This invention provides a method for operating a sensor device, the method comprising the following steps:

[0015] i) Provide sensor devices.

[0016] ii) Powering the sensor device via electromagnetic radiation from the emitter.

[0017] iii) Determine whether the sensor device is adequately powered for TDR measurement, and whether electromagnetic radiation emission to the device has been interrupted, and

[0018] iv) If both conditions of step iii) are met, perform a TDR measurement to generate TDR sensor data.

[0019] This invention provides a method for operating a sensor device, the method comprising the following steps:

[0020] i) Provide sensor devices.

[0021] ii) Powering the sensor device via electromagnetic radiation from the emitter.

[0022] iii) Determine whether the sensor device is adequately powered for TDR measurement.

[0023] iv) When the condition in step iii) is met, prevent further power supply to the sensor device via electromagnetic radiation, and

[0024] v) Perform TDR measurements to generate TDR sensor data.

[0025] This invention provides an automated greenhouse, which includes...

[0026] - A container, preferably a container for containing one or more plants, the container comprising a solid material and a sensor device for determining the moisture content of the solid material.

[0027] -Emitter, and

[0028] -Recorder,

[0029] It further includes a transmission device for carrying the antenna of the sensor device in the container to the power transmission distance of the transmitter and the signal exchange distance to the recorder. Attached Figure Description

[0030] Figure 1 An example of a sensor device (100) for performing time-domain reflectometry (TDR) measurements on solid materials is shown.

[0031] Figure 2 An example of a sensor device (200) for performing time-domain reflectometry (TDR) measurements on solid materials is shown, the sensor device including an integrated circuit (210).

[0032] Figure 3 An example of a sensor device (300) for performing time-domain reflectometry (TDR) measurements on solid materials is shown, the sensor device including a transmitter (310).

[0033] Figure 4 An example of a sensor device (400) for performing time-domain reflectometry (TDR) measurements on solid materials is shown, the sensor device including an integrated circuit (210) and a transmitter (310).

[0034] Figure 5 An example of how to operate a sensor device is shown.

[0035] Figure 6 An example of a sensor device operation method is shown, in which further power is prevented from being supplied to the sensor device via electromagnetic radiation.

[0036] Figure 7 An example of how a sensor device operates is shown, in which measurement data is recorded. Detailed Implementation

[0037] like Figure 1 As shown, the present invention relates to a sensor device (100) comprising the following elements: an antenna (110), a capacitor (120), a threshold activation element (130), a detection element (140), and a TDR sensor (150).

[0038] An antenna (110) is a transducer that converts electric current into electromagnetic waves and vice versa. The antenna can transmit and receive electromagnetic fields, preferably radio waves and / or microwaves.

[0039] The capacitor (120) is electrically connected to the antenna (110) and is configured to store power received from the antenna (110). Therefore, the capacitor (120) is charged using the power received via the antenna (110).

[0040] A threshold activation element (130) is electrically connected to a capacitor (120) and is configured to compare the stored electrical current with a predefined threshold. The threshold activation element (130) is configured such that the predefined threshold is sufficient to generate time-domain reflectometry (TDR) sensor data. The threshold activation element (130) can be a comparator. The threshold activation element (130) can be a digital comparator, an analog comparator, a transistor switch, or a microcontroller with an analog-to-digital converter (ADC).

[0041] A detection element (140) is configured to detect the cessation of electromagnetic radiation reception. The detection element (140) may be a comparator that activates the TDR sensor (150) after the power stored in the capacitor (120) drops below a predefined threshold due to the cessation of electromagnetic radiation reception. The detection element (140) may be an analog comparator or a digital comparator. The detection element (140) may be a transistor switch. The detection element (140) may be a relay. The detection element (140) may be a voltmeter with an integrated comparator, providing feedback on voltage levels. The detection element (140) may be an ammeter with an integrated comparator, providing feedback on current. The detection element (140) may be a microcontroller with an analog-to-digital (ADC) converter.

[0042] The TDR sensor (150) is configured to generate TDR sensor data. The TDR sensor (150) generates TDR sensor data when the threshold activation element (130) signals that the power stored in the capacitor (120) exceeds a predefined threshold, and the detection element (140) signals that the antenna (110) has stopped receiving electromagnetic radiation. In other words, the sensor device (100) begins measurement after the capacitor (120) is fully charged and the antenna (110) no longer receives any electromagnetic radiation to charge the capacitor (120). Therefore, when the TDR sensor (150) is inserted into a solid sample, preferably a soil sample, the TDR sensor (150) is able to sense the moisture therein. The TDR sensor (150) of the sensor device (100) preferably includes at least two rods: a reference rod and at least one measuring rod. Alternatively, it is preferred that the TDR sensor (150) contains only one reference rod but includes multiple measuring rods. Preferably, all measuring rods are coated with an electrically insulating material, while the reference rod is not coated. Preferably, the multiple measuring rods have different lengths, which allows for the measurement of moisture as a function of depth when the rods are inserted into a solid material (e.g., soil).

[0043] The sensor device (100) of the present invention offers many advantages over the prior art: the sensor device (100) allows the generation of TDR sensor data without the need for wires. In particular, the sensor device (100) of the present invention can operate without power cables and batteries. Therefore, the sensor device (100) can monitor soil moisture in farmland without the need for power cables. In greenhouses, there is no need for power cables or batteries that would obstruct the view of plants growing in pots including the sensor device (100) of the present invention. This design allows for continuous monitoring and imaging of plants without the need to remove the sensor device (100). In addition, the sensor device (100) minimizes disturbances to the TDR sensor (150) from electromagnetic radiation emitted by external sources (such as emitters (500)) that could introduce unwanted noise and interference into the TDR system. Such interference can distort reflected signals and make it difficult to distinguish desired reflections from external noise, thereby impairing the accuracy and reliability of measurements.

[0044] The sensor device (100) preferably includes a temperature sensor for measuring the temperature of a solid material. This temperature sensor is electrically connected to a threshold activation element (130) so that temperature sensor data is generated only when the electrical charge stored in the capacitor (120) exceeds a predetermined threshold. Preferably, the temperature of the solid material is used to calibrate the TDR measurement. The sensor device (100) of the present invention can perform this TDR sensor data calibration internally based on a stored mathematical function or by interpolation using a lookup table.

[0045] In one embodiment, the sensor device (200) includes an integrated circuit (210), such as Figure 2As shown. The term "integrated circuit" refers to a compact electronic device that contains multiple interconnected electronic components (such as transistors, capacitors, resistors, and diodes) on a single chip or substrate. These components are arranged and interconnected in a manner that allows the integrated circuit to perform specific electronic functions (such as processing, storage, and communication). The term "integrated circuit" also includes a microcontroller, which is an application-specific integrated circuit that combines a central processing unit (CPU), memory, and input / output (I / O) peripherals on a single chip. The integrated circuit (210) is electrically connected to a threshold activation element (130) such that the integrated circuit (210) or the microcontroller is powered only when sufficient power is stored in the capacitor (120). The integrated circuit (210) or the microcontroller is also connected to a sensing element (140) and a TDR sensor (150). Preferably, the integrated circuit (210) stores TDR sensor data from the TDR sensor (150) and / or temperature data from the temperature sensor. Preferably, if the sensor device (200) includes multiple measuring bars, after each TDR measurement, the integrated circuit (210) stores an indicator in its internal memory that identifies the bar to be used by the TDR sensor (150) for the next TDR measurement.

[0046] In another embodiment, the sensor device (300) includes a transmitter (310), such as Figure 3 As shown. The transmitter (310) is configured to generate a digital data signal, and wherein an antenna (110) is electrically connected to the transmitter (310) to transmit the digital data signal. In one embodiment, the transmitter (310) converts a signal generated by a TDR sensor (150) and / or a temperature sensor into a digital data signal, and the antenna (110) is configured to transmit the digital data signal (410). The digital data signal may include TDR sensor data that has been corrected using temperature data. Preferably, the transmitter (310) is electrically connected to the temperature sensor. The sensor device (300) of the present invention may transmit the digital data signal (410) based on uncorrected TDR sensor data and temperature sensor data. The TDR sensor data may be corrected at the recorder side upon receiving the digital data signal (410) which includes both uncorrected TDR sensor data and temperature sensor data; such correction may preferably be performed by using a mathematical function fitted to pre-recorded temperature calibration data, or by interpolation in a lookup table of pre-recorded temperature calibration data. Preferably, the sensor device (300) of the present invention transmits both uncorrected TDR sensor data and temperature sensor data without performing temperature correction. In this way, the amount of energy consumed by the sensor device (300) in performing moisture content measurement and transmitting measurement data is minimized.

[0047] In another embodiment, the transmitter (310) is configured to generate a blocking signal (620), which is emitted by the antenna (110) once a predefined threshold of the threshold activation element (130) is reached. The purpose of the blocking signal (620) is to stop the electromagnetic radiation emission of the transmitter (500), thereby preventing the antenna (110) from receiving any additional electromagnetic radiation from the transmitter (500). Preferably, the blocking signal can be used as a feedback mechanism for the transmitter, whereby its internal system can interpret the received signal as a command to stop emission.

[0048] In another embodiment, the sensor device (400) includes both an integrated circuit (210) and a transmitter (310). The integrated circuit (210) processes data collected from the TDR sensor (150) and / or the temperature sensor. The transmitter (310) generates digital data signals for transmission. This configuration allows the device to efficiently transmit both TDR sensor data and / or temperature data to external systems, such as a recorder (700), for analysis.

[0049] Preferably, the TDR sensor (150) includes a time-to-digital converter (TDC). The TDC is used to accurately measure the time delay between a start signal and a stop signal and converts this time delay into a digital output. The TDC can measure the time delay between the start and stop signals of the reflected pulse of the TDR sensor (150) at high resolution, thus providing accurate measurements. The use of a TDC offers the advantage of easy integration into the sensor device (100), which in turn contributes to the miniaturization of the TDR sensor (150). In addition, the miniaturization of the TDR sensor (150) allows it to be integrated into plant pots in a greenhouse. This integration allows for imaging of plants in the pots without any obstruction from the sensor device (100).

[0050] Preferably, the transmitter (310) of the sensor device (300) includes an RFID chip or an NFC chip. The sensor device (300) with an RFID chip or an NFC chip is used as a tag or label to identify the solid material being measured.

[0051] Figure 5The diagram illustrates an example of a sensor device operation method for measuring sensor signals. A transmitter (500) emits electromagnetic radiation (510) towards a sensor device (100), and the antenna (110) of the sensor device (100) converts the electromagnetic radiation into an electric current, which charges a capacitor (120) if the transmitter (500) is within the power transfer range of the antenna (110). This process is referred to as wireless power transfer (520). Wireless power transfer (520) is the process of transmitting energy between a transmitter (500) and one or more receivers (such as the sensor device (100)) via electromagnetic radiation. During the charging state (530), the capacitor (120) accumulates electrical energy until a predefined threshold of a threshold activation element (130) is reached. Once this predefined threshold is reached, the threshold activation element (130) activates a detection element (140). When the capacitor (120) is no longer being charged, it indicates that the transmitter (500) has stopped emitting electromagnetic radiation, thus allowing the sensor device (100) to enter a discharging state (540). If the detection element (140) detects a power interruption (which is indicated by the capacitor (120) no longer being charged due to the emitter (500) ceasing its electromagnetic radiation emission), the detection element activates (550) the TDR sensor (150) to generate TDR sensor data (560).

[0052] Figure 6The diagram illustrates an example of a sensor device operation method for measuring sensor signals, where further power supply to the sensor device (300) via electromagnetic radiation is blocked. A transmitter (500) emits electromagnetic radiation (510) to the sensor device (300), and the antenna (110) of the sensor device (300) converts the electromagnetic radiation into an electric current, which charges a capacitor (120) if the transmitter (500) is within the power transfer range of the antenna (110). This process is referred to as wireless power transfer (520). During the charging state (530), the capacitor (120) accumulates electrical energy until a predefined threshold of a threshold activation element (130) is reached. Once this predefined threshold is reached, the threshold activation element (130) activates the transmitter (310) and the detection element (140). The transmitter (310) generates a blocking signal (620) emitted by the antenna (110). The purpose of the blocking signal (620) is to stop the electromagnetic radiation emission of the transmitter (500), thereby preventing the antenna (110) from receiving any additional electromagnetic radiation from the transmitter (500). When the capacitor (120) is no longer charged, it indicates that the transmitter (500) has stopped emitting electromagnetic radiation, thereby causing the sensor device (300) to enter a discharge state (540). If the detection element (140) detects a power interruption (indicated by the capacitor (120) no longer being charged due to the transmitter (500) ceasing its electromagnetic radiation emission), the detection element activates (550) the TDR sensor (150) to generate TDR sensor data (560). Preferably, the transmitter (310) converts the signals generated by the TDR sensor (150) and / or the temperature sensor into digital data signals, and the antenna (110) is configured to emit digital data signals (410).

[0053] Figure 7An example of a sensor device operation method is shown, in which measurement data is recorded. A transmitter (500) emits electromagnetic radiation (510) to a sensor device (300), and the antenna (110) of the sensor device (300) converts the electromagnetic radiation into an electric current, which charges a capacitor (120) if the transmitter (500) is within the power transfer range of the antenna (110). This process is referred to as wireless power transfer (520). During the charging state (530), the capacitor (120) accumulates electrical energy until a predefined threshold of a threshold activation element (130) is reached. Once this predefined threshold is reached, the threshold activation element (130) activates the transmitter (310) and the detection element (140). The transmitter (310) generates a blocking signal (620) emitted by the antenna (110). The purpose of this blocking signal (620) is to stop the electromagnetic radiation emission of the transmitter (500), thereby preventing the antenna (110) from receiving any additional electromagnetic radiation from the transmitter (500). When the capacitor (120) is no longer charged, it indicates that the emitter (500) has stopped emitting electromagnetic radiation, thus causing the sensor device (300) to enter a discharge state (540). If the detection element (140) detects a power interruption (indicated by the capacitor (120) no longer being charged due to the emitter (500) ceasing its electromagnetic radiation emission), the detection element activates (550) the TDR sensor (150) to generate TDR sensor data (560). The transmitter (310) converts the signals generated by the TDR sensor (150) and / or the temperature sensor into digital data signals, and the antenna (110) is configured to emit digital data signals (710). The antenna (110) of the sensor device (300) emits digital data signals (710), which can be received by the recorder (700). Preferably, the reader (800) is used both to perform wireless power transmission (520) to charge the sensor device (300) and to receive digital data signals emitted by the sensor device (300). Examples of readers are RFID readers or NFC readers.

[0054] In another embodiment, the sensor device is equipped with a timer programmed to enter a low-power state once the sensor device is fully charged and to initiate TDR measurements only after a set delay. This configuration allows the transmitter and device to be positioned close together for wireless power transmission during a predetermined period, which is the period during which the device is charged to enable TDR measurements. Once the transmitter (500) is no longer in range, the sensor device will perform TDR measurements after a specified delay, thereby preventing the antenna (110) from receiving any additional electromagnetic radiation from the transmitter (500) during the TDR measurement. Preferably, a conveyor belt transports the transmitter and / or device from one location to another. The conveyor may include various components such as belts, rollers, chains, or other elements that facilitate the movement of the transported items.

[0055] Additionally, the present invention provides a method for monitoring the moisture content of solid material in a container, preferably a container for holding one or more plants. The term "container" herein refers to a vessel capable of holding, storing, or transporting solid material. Containers can have various shapes, sizes, and configurations, and can be constructed from various materials. Thus, the container comprises solid material and the sensor device (300) of the present invention, wherein the rod of the sensor device (300) is inserted into the solid material. Preferably, the container comprising the solid material and the sensor device (300) is transported within the electrically transmittable range of the transmitter (500), and vice versa. Preferably, a conveyor belt transports the container or transmitter (500) from one location to another. The conveyor may include various components, such as belts, rollers, chains, or other elements that facilitate the movement of the transported items. The conveyor may be driven by a motor or other device and may include sensors or a control system to regulate its operation. Subsequently, once the transmitter (500) and the sensor device (300) are within power-transmittable range, the sensor device (300) is charged by the electromagnetic radiation emitted by the transmitter (500) and performs TDR measurements as previously described. A recorder (700) records the digital data signal (710) emitted by the sensor device (300), and the computing node compares this data with previously recorded data. Preferably, a reader (800), such as an RFID reader or an NFC reader, is used, which acts as both the transmitter (500) and the recorder (700). The recorder (700) is connected to the computing node, which is configured to compare the TDR sensor data obtained through the sensor signal with the TDR sensor data obtained through the previously recorded signal. Preferably, the sensor device (300) includes an RFID chip or an NFC chip to identify solid materials in the container.

[0056] This method provides an automated solution for monitoring the moisture content of solid materials in containers, particularly in containers used to hold plants within automated greenhouses. By using sensor devices (300) integrated with readers (800) (such as RFID or NFC readers), the system can accurately and efficiently monitor the moisture content of the solid materials, thus providing valuable data for optimal plant growth and yield. Particularly preferred is that the automated greenhouse includes a watering station configured with a computing node. The computing node monitors the moisture content of the solid materials in the plant pots and determines whether the plant pots need watering based on TDR sensor data.

[0057] The present invention also provides an automated greenhouse. The automated greenhouse according to the invention is a greenhouse equipped with a device for automatically monitoring plants growing in individual containers. Typically, a container will contain a growth substrate (preferably soil) and one or more plants growing on that growth substrate. Automated greenhouses typically use sensors, timers, and computerized control systems to monitor and adjust conditions based on specific plant requirements. The automated greenhouse of the present invention includes a container and a sensor device (300) according to the invention, the container comprising a solid material and, preferably, one or more plants growing on that solid material. Furthermore, the automated greenhouse includes a recorder (700). As described above, in the operation of the automated greenhouse, an emitter (500) emits electromagnetic radiation to a container located within an electrically transmittable range, the container including the sensor device (300) of the present invention. The moisture content of the solid material is measured by the sensor device (300) of the present invention as described above, and a corresponding digital data signal (710) is transmitted to the recorder (700). Preferably, the reader (800) is used both to perform wireless power transmission (520) to charge the sensor device (300) and to receive digital data signals (710) emitted by the sensor device (300). Examples of readers are RFID readers or NFC readers.

[0058] Preferably, the automated greenhouse of the present invention includes a watering station and a computing node, wherein the watering station is used to irrigate the containers when the computing node determines, based on sensor data received from the recorder (700), that the solid material needs watering. Therefore, the present invention facilitates reliable watering of plants in an automated greenhouse with minimal obstruction to visual inspection of the plants growing in the containers therein, and with minimal energy consumption. Preferably, the reader (800) is used both to perform wireless power transmission (520) to charge the sensor device (300) and to receive digital data signals (710) emitted by the sensor device (300). Examples of readers are RFID readers or NFC readers.

[0059] The following examples are intended to illustrate this disclosure and not to be limiting.

[0060] Example 1 is a sensor device, which includes:

[0061] The antenna is used to receive electromagnetic radiation.

[0062] A capacitor, configured to store the power received from the antenna.

[0063] A threshold activation element electrically connected to the capacitor compares the stored power with a predefined threshold, which is sufficient to generate time domain reflectance (TDR) sensor data.

[0064] A detection element, used to detect power outages, and

[0065] A TDR sensor is used to generate TDR sensor data when the threshold activation element signals that the power stored in the capacitor exceeds the predefined threshold, and the detection element signals that the antenna has stopped receiving electromagnetic radiation.

[0066] Example 2 is a sensor device as described in Example 1, further comprising an integrated circuit including both the threshold activation element and the detection element.

[0067] Example 3 is a sensor device as described in any one of Examples 1 or 2, further comprising a temperature sensor electrically connected to the threshold activation element.

[0068] Example 4 is a sensor device as described in any one of Examples 1 to 3, wherein the TDR sensor further includes a time-to-digital converter (TDC).

[0069] Example 5 is a sensor device as described in any one of Examples 1 to 4, further comprising a transmitter configured to generate a digital data signal, wherein the antenna is electrically connected to the transmitter to transmit the digital data signal.

[0070] Example 6 is a sensor device as described in Example 5, further comprising an integrated RFID chip or NFC chip, wherein the digital data signal emitted by the device includes an ID signal based on a unique identifier of the RFID chip or NFC chip.

[0071] Example 7 is a method for operating a sensor device, which includes the following steps:

[0072] i) Provide a sensor device as described in any one of Examples 1 to 6,

[0073] ii) Powering the sensor device via electromagnetic radiation from the emitter.

[0074] iii) Determine whether the sensor device is adequately powered for TDR measurement, and whether electromagnetic radiation emission to the device has been interrupted, and

[0075] iv) If both conditions of step iii) are met, perform a TDR measurement to generate TDR sensor data.

[0076] Example 8 is a method for operating a sensor device, which includes the following steps:

[0077] i) Provide a sensor device as described in any one of Embodiments 5 or 6,

[0078] ii) Powering the sensor device via electromagnetic radiation from the emitter.

[0079] iii) Determine whether the sensor device is adequately powered for TDR measurement.

[0080] iv) When the condition in step iii) is met, prevent further power supply to the sensor device via electromagnetic radiation, and

[0081] v) Perform TDR measurements to generate TDR sensor data.

[0082] Example 9 is a sensor device operation method as described in Example 8, further comprising the following steps:

[0083] The transmitter emits a digital data signal based on the measurement data.

[0084] The recorder records the digital data signal emitted by the transmitter.

[0085] The measurement data obtained through this digital data signal is compared with the measurement data obtained through previously recorded digital data signals from the same sensor device.

[0086] Example 10 is a method of operating a sensor device as described in any one of Examples 7 to 9, wherein the TDR sensor of the sensor device is inserted into a soil sample in a container, which is preferably a container for holding one or more plants.

[0087] Example 11 is an automated greenhouse, which includes

[0088] - A container, preferably a container for containing one or more plants, comprising a solid material and a sensor device, as described in any one of Examples 5 or 6, for determining the moisture content of the solid material.

[0089] -Emitter, and

[0090] -Recorder,

[0091] It further includes a transmission device for carrying the antenna of the sensor device in the container to the power transmission distance of the transmitter and the signal exchange distance to the recorder.

[0092] Example 12 is an automated greenhouse as described in Example 11, including a watering station and a computing node, wherein the watering station is used to irrigate the container when the computing node determines that the solid material needs watering based on sensor data received from the recorder.

Claims

1. A sensor device, the sensor device comprising: The antenna is used to receive electromagnetic radiation. A capacitor, configured to store the power received from the antenna. A threshold activation element electrically connected to the capacitor compares the stored power with a predefined threshold, which is sufficient to generate time domain reflectance (TDR) sensor data. A detection element, used to detect power outages, and A sensor is used to generate TDR sensor data when the threshold activation element signals that the power stored in the capacitor exceeds the predefined threshold, and the detection element signals that the antenna has stopped receiving electromagnetic radiation.

2. The sensor device according to claim 1, further comprising an integrated circuit including both the threshold activation element and the detection element.

3. The sensor device according to any one of claims 1 to 2, further comprising a temperature sensor electrically connected to the threshold activation element.

4. The sensor device according to any one of claims 1 to 3, wherein, The TDR sensor further includes a time-to-digital converter (TDC).

5. The sensor device according to any one of claims 1 to 4, further comprising a transmitter configured to generate a digital data signal, wherein, The antenna is electrically connected to the transmitter to emit the digital data signal.

6. The sensor device according to claim 5, further comprising an integrated RFID chip or NFC chip, wherein, The digital data signals emitted by the device include ID signals based on the unique identifier of the RFID chip or NFC chip.

7. A method for operating a sensor device, the method comprising the following steps: i) Provide a sensor device as described in any one of claims 1 to 6, ii) Powering the sensor device via electromagnetic radiation from the emitter. iii) Determine whether the sensor device is adequately powered for TDR measurement, and whether electromagnetic radiation emission to the device has been interrupted, and iv) If both conditions of step iii) are met, perform a TDR measurement to generate TDR sensor data.

8. A method for operating a sensor device, the method comprising the following steps i) Provide a sensor device as described in any one of claims 5 to 6, ii) Powering the sensor device via electromagnetic radiation from the emitter. iii) Determine whether the sensor device is adequately powered for TDR measurement. iv) When the condition in step iii) is met, prevent further power supply to the sensor device via electromagnetic radiation, and v) Perform TDR measurements to generate TDR sensor data.

9. The method of claim 8, further comprising the following steps: The transmitter emits a digital data signal based on the measurement data. The recorder records the digital data signal emitted by the transmitter. The measurement data obtained through this digital data signal is compared with the measurement data obtained through previously recorded digital data signals from the same sensor device.

10. The method according to any one of claims 7 to 9, wherein, The sensor of the sensor device is inserted into a soil sample in a container, which is preferably a container for holding one or more plants.

11. An automated greenhouse, comprising - A container, preferably a container for containing one or more plants, the container comprising a solid material and a sensor device for determining the moisture content of the solid material as described in any one of claims 5 to 6. -Emitter, and -Recorder, It further includes a transmission device for carrying the antenna of the sensor device in the container to the power transmission distance of the transmitter and the signal exchange distance to the recorder.

12. The automated greenhouse according to claim 11, comprising a watering station and a computing node, wherein, When the computing node determines that the solid material needs watering based on sensor data received from the recorder, it uses the watering station to irrigate the container.

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