Self-calibrating humidity sensor
By setting a reference capacitor and a humidity-sensing capacitor in the humidity sensor, and evaporating water vapor by heating the humidity-sensitive material layer of the humidity-sensing capacitor, automatic calibration is achieved, solving the temperature drift problem caused by polymer materials and improving the accuracy of humidity measurement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGZHOU AOSONG ELECTRONIC CO LTD
- Filing Date
- 2022-09-29
- Publication Date
- 2026-06-02
AI Technical Summary
Existing humidity sensors suffer from significant errors in humidity measurement due to the temperature drift characteristics of polymer materials, especially in high-humidity environments where aging becomes more pronounced.
The device employs a self-calibrating humidity sensor structure, which includes a reference capacitor and a humidity-sensing capacitor. By heating the humidity-sensitive material layer on the humidity-sensing capacitor to evaporate water vapor, the capacitance value of the humidity-sensing capacitor is calibrated. The value is then compared with the reference capacitor to achieve automatic calibration.
It effectively avoids or reduces measurement errors caused by the temperature drift characteristics of humidity-sensitive materials, thus improving the accuracy of humidity measurement.
Smart Images
Figure CN115575464B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sensor technology, and more particularly to a humidity sensor; more specifically, this invention relates to a self-calibrating humidity sensor. Background Technology
[0002] Humidity sensors are commonly used humidity sensing devices in production and daily life. They are widely used in indoor humidity measurement, smart homes, white goods, agriculture, and other fields, playing a significant role. Most common humidity sensors are based on the capacitive principle. This is because capacitive humidity sensors have many advantages, such as ease of fabrication using CMOS technology, strong compatibility, good linearity, and a wide humidity range (e.g., from 0-100% RH).
[0003] Capacitive humidity sensors use polymer materials as humidity-sensitive materials and place them on a humidity-sensitive capacitor. When the humidity of the surrounding environment changes, the water vapor content attached to the humidity-sensitive material changes, thus causing a change in the capacitance of the humidity-sensitive capacitor. This change in capacitance is used to measure the humidity of the surrounding environment.
[0004] However, humidity sensors using polymer materials suffer from temperature drift. Due to the inherent properties of polymers, water vapor will inevitably form chemically adsorbed molecules on the material, which are difficult to desorb from the polymer surface, thus causing drift. This drift is especially pronounced in high-humidity environments, where the long chains of the polymer expand spatially, making the humidity drift even more significant. In other words, after prolonged use, the polymer material itself ages, leading to data output drift, or a shift in the zero point. Humidity sensor specifications typically include a drift rate parameter, such as 2% / year. This temperature drift phenomenon can cause significant errors in the humidity measurement values obtained by humidity sensors. Summary of the Invention
[0005] The purpose of this invention is to provide a self-calibrating humidity sensor to solve the problems existing in the prior art and avoid or reduce the technical defects of humidity measurement accuracy deterioration caused by temperature drift.
[0006] To achieve the above-mentioned objectives of this invention, the present invention adopts the following technical solution:
[0007] A self-calibrating humidity sensor, comprising:
[0008] The substrate, a first insulating layer coated on the substrate, a heating device disposed on the first insulating layer, a second insulating layer coated on the heating device and separated from the first insulating layer, a reference capacitor disposed on the second insulating layer, and a moisture-sensitive capacitor disposed on the second insulating layer and simultaneously disposed above the heating device; the moisture-sensitive capacitor includes an interdigitated capacitor disposed on the second insulating layer and a moisture-sensitive material layer covering the interdigitated capacitor.
[0009] Preferably, the system further includes: a data acquisition unit communicatively connected to the reference capacitor and the humidity sensing capacitor, used to acquire the corresponding capacitance values of the reference capacitor and the humidity sensing capacitor; and an analysis and processing unit communicatively connected to the data acquisition unit and the heating device, used to compare the two capacitance values acquired by the data acquisition unit and, when the comparison results are different, control the heating device to heat the humidity sensing capacitor for a predetermined period of time, and, after the heating process for the predetermined period of time is completed, continue to execute the steps of acquiring the corresponding capacitance values of the reference capacitor and the humidity sensing capacitor and the steps of comparing the two capacitance values acquired by the data acquisition unit.
[0010] Preferably, the substrate is a silicon-based substrate. More preferably, both the first insulating layer and the second insulating layer are silicon dioxide insulating films with a thickness of 100-400 nm. This thickness of silicon dioxide insulating film can improve insulation performance, especially electrical insulation performance under high temperature and high heat conditions.
[0011] Preferably, the reference capacitor includes: a linear positive arm, a set of positive interdigitated fingers evenly spaced on the linear positive arm, a linear negative arm parallel to the linear positive arm, a set of negative interdigitated fingers evenly spaced on the linear negative arm, a positive terminal at one linear end of the linear positive arm, and a negative terminal at one linear end of the linear negative arm.
[0012] More preferably, the interdigitated capacitor includes: a linear positive arm, a set of positive interdigitated fingers evenly spaced on the linear positive arm, a linear negative arm parallel to the linear positive arm, a set of negative interdigitated fingers evenly spaced on the linear negative arm, a positive terminal at one linear end of the linear positive arm, and a negative terminal at one linear end of the linear negative arm.
[0013] Preferably, the heating device includes a positive electrode, a negative electrode, and a circuitous heating loop electrically connected between them. More preferably, one of the positive and negative electrodes is a tantalum electrode, and the other is a platinum electrode, with the tantalum electrode having a thickness of 0.01-0.5 micrometers and the platinum electrode having a thickness of 0.1-0.5 micrometers. Electrodes of this material and thickness provide better conductivity and stability. Preferably, the humidity-sensitive material layer is a polyimide material layer with a thickness of 1-5 micrometers.
[0014] Preferably, the self-calibrating humidity sensor further includes an output module, which is communicatively connected to the analysis and processing unit, for outputting the comparison result to the user when the comparison results of the two capacitance values are the same.
[0015] This invention also provides a self-calibration method for a self-calibrating humidity sensor, comprising the following steps:
[0016] Step S101: Obtain the two capacitance values corresponding to the reference capacitor and the humidity sensing capacitor;
[0017] Step S102: Determine whether the two capacitor values are the same. If they are different, proceed with steps S103, S101, and S102 in sequence. If they are the same, proceed with step S104.
[0018] Step S103: Heat the moisture-sensing capacitor for a predetermined period of time; and
[0019] Step S104: Output the comparison result of the two capacitors with the same value.
[0020] Compared with the prior art, the advantages of the present invention are as follows:
[0021] In the self-calibrating humidity sensor structure, module, and self-calibration method provided by this invention, two capacitors are set on the self-calibrating humidity sensor, one of which is a reference capacitor and the other is a humidity-sensitive capacitor. By heating the humidity-sensitive material layer on the humidity-sensitive capacitor, the water vapor adsorbed in the humidity-sensitive material layer evaporates, thereby restoring the capacitance value of the humidity-sensitive capacitor to the initial value of the dehumidified state. Furthermore, by comparing it with the reference capacitor on which no humidity-sensitive material layer is set, the parameter value of the humidity-sensitive capacitor is calibrated, thus realizing the automatic calibration of the humidity sensor, improving the accuracy of humidity measurement, and avoiding or reducing the measurement error caused by the temperature drift characteristics of the humidity-sensitive material.
[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description
[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:
[0024] Figure 1 This is a layered cross-sectional view of the self-calibrating humidity sensor of the present invention, showing the physical structure of several different structural components of the sensor, such as the reference capacitor, the humidity-sensing capacitor, and the heating device.
[0025] Figure 2 for Figure 1 The diagram shows a detailed structural diagram of the reference capacitor and the humidity-sensing capacitor of the self-calibrating humidity sensor.
[0026] Figure 3 for Figure 1 The diagram shows a detailed structural diagram of the heating device for the self-calibrating humidity sensor.
[0027] Figure 4 A flowchart illustrating the workflow of the self-calibrating humidity sensor of the present invention is provided.
[0028] Figure 5 A flowchart illustrating the self-calibration method of the self-calibration humidity sensor of the present invention is shown. Detailed Implementation
[0029] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as limiting the present invention.
[0030] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or components, nor does it exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connection or wireless coupling. The term “and / or” as used herein includes all or any unit and all combinations of one or more associated listed items.
[0031] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.
[0032] This invention provides a self-calibrating humidity sensor, which uses two capacitors on the sensor: a reference capacitor and a humidity-sensitive capacitor. By heating the moisture-sensitive material layer on the humidity-sensitive capacitor, the water vapor adsorbed in the layer evaporates, causing the capacitance value of the humidity-sensitive capacitor to return to its initial value in a dry state. By comparing this value with the reference capacitor, which does not have a moisture-sensitive material layer, the parameter value of the humidity-sensitive capacitor is calibrated. This achieves automatic calibration of the humidity sensor, improves the accuracy of humidity measurement, and avoids or reduces measurement errors caused by the temperature drift characteristics of the moisture-sensitive material.
[0033] In a typical embodiment of the present invention, combined with Figures 1 to 5 A self-calibrating humidity sensor 100 includes: a substrate 10, a first insulating layer 20 coated on the substrate 10, a heating device 30 disposed on the first insulating layer 20, a second insulating layer 40 coated on the heating device 30 and spaced apart from the first insulating layer 20, and a reference capacitor 70 disposed on the second insulating layer 40 (reference). Figure 2 The device 30 includes an interdigitated capacitor 52 disposed on the second insulating layer 40 and a moisture-sensitive material layer 54 covering the interdigitated capacitor 52; the heating device 30 is disposed below the interdigitated capacitor 52 to heat and dehumidify the moisture-sensitive material layer 54.
[0034] Figure 4 A functional block diagram illustrating the self-calibration of the self-calibrating humidity sensor of the present invention is shown. For example... Figure 4 As shown, the self-calibrating humidity sensor further includes:
[0035] The data acquisition unit 80 is communicatively connected to the reference capacitor 70 and the humidity sensing capacitor 50, and is used to acquire the corresponding capacitance values of the reference capacitor 70 and the humidity sensing capacitor 50.
[0036] An analysis and processing unit 90, communicatively connected to both the data acquisition unit 80 and the heating device 30, compares two capacitance values acquired by the data acquisition unit 80. If the comparison results differ, it controls the heating device 30 to heat the humidity-sensitive capacitor 50 for a predetermined period. After the heating process for the predetermined period ends, it continues the process of determining the comparison result.
[0037] The output module 200, which is communicatively connected to the analysis and processing unit 90, is used to output the comparison result to the user when the comparison results of the two capacitance values are the same.
[0038] This invention also provides a self-calibration method for a self-calibrating humidity sensor, such as... Figure 5 As shown, it includes the following steps:
[0039] Step S101: Obtain the two capacitance values corresponding to the reference capacitor and the humidity sensing capacitor;
[0040] Step S102: Determine whether the two capacitor values are the same. If they are different, proceed with steps S103, S101, and S102 in sequence. If they are the same, proceed with step S104.
[0041] Step S103: Heat the moisture-sensing capacitor for a predetermined period of time; and
[0042] Step S104: Output the comparison result of the two capacitors with the same value.
[0043] It is important to note that during the execution of the above steps, the executing entity or recipient corresponds to the above functional modules. In other words, the above steps are executed or implemented through the above functional units or modules, which will not be elaborated further here.
[0044] In the self-calibrating humidity sensor structure, module, and self-calibration method provided by this invention, two capacitors are set on the self-calibrating humidity sensor, one of which is a reference capacitor and the other is a humidity-sensitive capacitor. By heating the humidity-sensitive material layer on the humidity-sensitive capacitor, the water vapor adsorbed in the humidity-sensitive material layer evaporates, thereby restoring the capacitance value of the humidity-sensitive capacitor to the initial value of the dehumidified state. Furthermore, by comparing it with the reference capacitor on which no humidity-sensitive material layer is set, the parameter value of the humidity-sensitive capacitor is calibrated, thus realizing the automatic calibration of the humidity sensor, improving the accuracy of humidity measurement, and avoiding or reducing the measurement error caused by the temperature drift characteristics of the humidity-sensitive material.
[0045] Preferably, the substrate 10 is a silicon-based substrate. More preferably, both the first insulating layer 20 and the second insulating layer 40 are silicon dioxide insulating films with a thickness of 100-400 nm. This thickness of silicon dioxide insulating film can improve insulation performance, especially electrical insulation performance under high temperature and heat conditions. Furthermore, the purpose of the two insulating layers is to electrically isolate the heating device 30 from the substrate 10 and the humidity-sensitive capacitor 50, so as to prevent external moisture from falling onto the heating device 30, which could cause a short circuit in the internal circuit of the heating device 30 and burn it out. This would prevent the heating device 30 from heating and dehumidifying the moisture-sensitive material layer 54 on the humidity-sensitive capacitor 50, ultimately affecting the humidity measurement accuracy of the entire self-calibrating humidity sensor 100 and causing a large temperature drift phenomenon.
[0046] More preferably, refer to Figure 2 The reference capacitor 70 includes: a linear positive arm 71, a set of positive interdigitated fingers 712 evenly spaced on the linear positive arm 71, a linear negative arm 72 parallel to the linear positive arm 71, a set of negative interdigitated fingers 722 evenly spaced on the linear negative arm 72, a positive terminal 73 at one linear end of the linear positive arm 71, and a negative terminal 74 at one linear end of the linear negative arm 72.
[0047] The interdigitated capacitor 52 includes: a linear positive arm 51, a set of positive interdigitated fingers 512 evenly spaced on the linear positive arm 51, a linear negative arm 53 parallel to the linear positive arm 51, a set of negative interdigitated fingers 532 evenly spaced on the linear negative arm 53, a positive terminal 58 at one linear end of the linear positive arm 51, and a negative terminal 56 at one linear end of the linear negative arm 53.
[0048] Further reference Figure 3 The heating device 30 includes a positive electrode 32, a negative electrode 34, and a circuitous heating loop 36 electrically connected between them. When an appropriate voltage is applied between the positive electrode 32 and the negative electrode 34, the resulting current flows within the circuitous heating loop 36, thereby generating the required heat to heat the humidity-sensitive material layer 54. This causes the water vapor adhering to or within the humidity-sensitive material layer 54 to evaporate as the temperature gradually increases, thus ensuring that the sensing capacitor 50 is in a moisture-free state.
[0049] Preferably, one of the positive electrode 32 and the negative electrode 34 is a tantalum electrode, and the other electrode is a platinum electrode. The thickness of the tantalum electrode is preferably 0.01-0.5 micrometers, and the thickness of the platinum electrode is preferably 0.1-0.5 micrometers. Electrodes of this material and thickness provide better conductivity and stability.
[0050] More preferably, the humidity-sensitive material layer 54 is a polyimide material layer, and the thickness of the material layer is 1-5 micrometers.
[0051] Those skilled in the art will understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted. Furthermore, other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and solutions in the prior art that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted.
[0052] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.
Claims
1. A self-calibrating humidity sensor, characterized in that include: The substrate, a first insulating layer coated on the substrate, a heating device disposed on the first insulating layer, a second insulating layer coated on the heating device and separated from the first insulating layer, a reference capacitor disposed on the second insulating layer, and a moisture-sensitive capacitor disposed on the second insulating layer and simultaneously disposed above the heating device; the moisture-sensitive capacitor includes an interdigitated capacitor disposed on the second insulating layer and a moisture-sensitive material layer covering the interdigitated capacitor. Both the first insulating layer and the second insulating layer are silicon dioxide insulating films; The heating device includes a positive electrode, a negative electrode, and a circuitous heating loop electrically connected between the two. One of the positive and negative electrodes is a tantalum electrode, and the other electrode is a platinum electrode. The humidity-sensitive material layer is a polyimide material layer; A data acquisition unit, which is communicatively connected to the reference capacitor and the humidity sensing capacitor, is used to acquire the corresponding capacitance values of the reference capacitor and the humidity sensing capacitor. The system includes an analysis and processing unit, which is communicatively connected to the data acquisition unit and the heating device. The system compares the two capacitance values acquired by the data acquisition unit and, when the comparison results are different, controls the heating device to heat the humidity-sensitive capacitor for a predetermined period of time. After the heating process for the predetermined period of time is completed, the system continues to execute the steps of acquiring the reference capacitance and the corresponding capacitance values of the humidity-sensitive capacitor, as well as the steps of comparing the two capacitance values acquired by the data acquisition unit.
2. The self-calibrating humidity sensor according to claim 1, characterized in that: The thickness of both the first insulating layer and the second insulating layer is 100-400 nm.
3. The self-calibrating humidity sensor according to claim 1, characterized in that: The reference capacitor includes: a linear positive arm, a set of positive interdigitated fingers evenly spaced on the linear positive arm, a linear negative arm parallel to the linear positive arm, a set of negative interdigitated fingers evenly spaced on the linear negative arm, a positive terminal at one linear end of the linear positive arm, and a negative terminal at one linear end of the linear negative arm.
4. The self-calibrating humidity sensor according to claim 3, characterized in that: The interdigitated capacitor includes: a linear positive arm, a set of positive interdigitated fingers evenly spaced on the linear positive arm, a linear negative arm parallel to the linear positive arm, a set of negative interdigitated fingers evenly spaced on the linear negative arm, a positive terminal at one linear end of the linear positive arm, and a negative terminal at one linear end of the linear negative arm.
5. The self-calibrating humidity sensor according to claim 1, characterized in that: The thickness of the tantalum electrode is 0.01-0.5 micrometers, while the thickness of the platinum electrode is 0.1-0.5 micrometers.
6. The self-calibrating humidity sensor according to claim 1, characterized in that: The thickness of the humidity-sensitive material layer is 1-5 micrometers.
7. The self-calibrating humidity sensor according to claim 1, characterized in that: It further includes an output module, which is communicatively connected to the analysis and processing unit, for outputting the comparison result to the user when the comparison results of the two capacitance values are the same.