A carbon-based electrode humidity sensing device, its fabrication method, carbon-based electrode humidity sensor, and its application.

Abstract

This invention provides a carbon-based electrode humidity sensing device, its fabrication method, a carbon-based electrode humidity sensor, and its applications, belonging to the field of humidity sensor technology. The carbon-based electrode humidity sensing device of this invention includes an electrolyte and a porous carbon-based electrode in contact with the electrolyte. The electrolyte is a first acid-modified polybenzimidazole material. The porous carbon-based electrode is either a hydrophilic or hydrophobic porous carbon-based electrode. The hydrophilic porous carbon-based electrode is obtained by laser processing of the first acid-modified polybenzimidazole material, while the hydrophobic porous carbon-based electrode is obtained by laser processing of either polybenzimidazole raw material or a second acid-modified polybenzimidazole material. The first and second acid-modified polybenzimidazole materials are obtained by modifying polybenzimidazole raw material with a first phosphoric acid solution and a second phosphoric acid solution, respectively, where the concentration of the first phosphoric acid solution is greater than the concentration of the second phosphoric acid solution. The carbon-based electrode humidity sensing device of this invention exhibits good signal repeatability and high sensitivity.

Description

Technical Field

[0001] This invention relates to the field of humidity sensor technology, and in particular to a carbon-based electrode humidity sensing element, its preparation method, a carbon-based electrode humidity sensor, and its applications. Background Technology

[0002] Humidity sensors are crucial components for detecting human respiration and skin surface humidity, and are closely related to health monitoring. To achieve efficient detection and avoid cross-infection during diagnosis, the development of multifunctional humidity sensors with features such as real-time tracking, wearable design, non-contact sensing, rapid and accurate response, and ultra-high sensitivity has become a trend. Furthermore, multifunctional humidity sensors have also found applications in living environment monitoring, wearable motion monitoring, agriculture, and chemical processes. Currently, publicly available multifunctional humidity sensors can detect humidity (e.g., CN 108918430 A, CN 109085204 A). However, due to insufficient research on humidity-sensing materials, existing humidity sensors suffer from low signal repeatability and poor sensitivity, thus failing to accurately sense the humidity environment. Summary of the Invention

[0003] The purpose of this invention is to provide a carbon-based electrode humidity sensing element, its preparation method, a carbon-based electrode humidity sensor, and its application. The carbon-based electrode humidity sensing element provided by this invention has good signal repeatability and high sensitivity.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a carbon-based electrode humidity sensing device, comprising an electrolyte and a porous carbon-based electrode in contact with the electrolyte, wherein the electrolyte is a first acid-modified polybenzimidazole material;

[0006] The porous carbon-based electrode is a hydrophilic porous carbon-based electrode or a hydrophobic porous carbon-based electrode. The hydrophilic porous carbon-based electrode is prepared by laser processing of a first acid-modified polybenzimidazole material, and the hydrophobic porous carbon-based electrode is prepared by laser processing of a polybenzimidazole raw material or a second acid-modified polybenzimidazole material.

[0007] Wherein, the first acid-modified polybenzimidazole material is obtained by modifying polybenzimidazole raw material with a first phosphoric acid solution, the second acid-modified polybenzimidazole material is obtained by modifying polybenzimidazole raw material with a second phosphoric acid solution, and the concentration of the first phosphoric acid solution is greater than the concentration of the second phosphoric acid solution.

[0008] Preferably, the carbon-based electrode humidity sensing element includes a resistive humidity sensing element or a capacitive humidity sensing element.

[0009] When the carbon-based electrode humidity sensing element is a resistive humidity sensing element, the porous carbon-based electrode is continuously distributed, and the porous carbon-based electrode is stacked with the electrolyte.

[0010] When the carbon-based electrode humidity sensing element is a capacitive humidity sensing element, the porous carbon-based electrode is an interdigitated electrode or a symmetrical electrode, and the electrolyte is disposed in the encapsulation region of the porous carbon-based electrode.

[0011] Preferably, the contact angle of the hydrophilic porous carbon-based electrode is <90°, and the contact angle of the hydrophobic porous carbon-based electrode is >90°; the porosity of both the hydrophilic and hydrophobic porous carbon-based electrodes is independently ≤50%, and their specific surface area is independently ≤1500 m². 2 / g.

[0012] Preferably, the volume swelling rate of the first acid-modified polybenzimidazole material is 20-122%, and the mass swelling rate is 5-30%.

[0013] This invention provides a method for fabricating the carbon-based electrode humidity sensing device described in the above technical solution.

[0014] (1) When the porous carbon-based electrode is a hydrophilic porous carbon-based electrode, the following steps are included:

[0015] The polybenzimidazole raw material was modified by immersing it in a first phosphoric acid solution to obtain a first acid-modified polybenzimidazole material.

[0016] Laser processing is performed on one side of the first acid-modified polybenzimidazole material to carbonize part of the first acid-modified polybenzimidazole material to form a hydrophilic porous carbon-based electrode, thereby obtaining a carbon-based electrode humidity sensing device.

[0017] (2) When the porous carbon-based electrode is a hydrophobic porous carbon-based electrode, the following steps are included:

[0018] The polybenzimidazole raw material was modified by immersing it in a second phosphoric acid solution to obtain a second acid-modified polybenzimidazole material.

[0019] A polybenzimidazole raw material or the second acid-modified polybenzimidazole material is laminated onto one side of the first acid-modified polybenzimidazole material, and then a hydrophobic porous carbon-based electrode is formed on the surface of the polybenzimidazole raw material or the second acid-modified polybenzimidazole material by laser processing, thereby obtaining a carbon-based electrode humidity sensing device.

[0020] Alternatively, a hydrophobic porous carbon-based electrode can be obtained by laser processing on the surface of the polybenzimidazole raw material or the second acid-modified polybenzimidazole material. Then, the hydrophobic porous carbon-based electrode is combined with the first acid-modified polybenzimidazole material to obtain a carbon-based electrode humidity sensing device.

[0021] Preferably, the concentration of the first phosphoric acid solution is 1 to 100 wt%, and the concentration of the second phosphoric acid solution is ≤5 wt%.

[0022] Preferably, the laser processing conditions for the hydrophilic porous carbon-based electrode and the hydrophobic porous carbon-based electrode independently include: the laser used is a carbon dioxide laser with a wavelength of 10.6 μm, a power of ≤10 W, a scanning speed of 1 to 12 inches / s, and an image density of 200 to 1000 PPI.

[0023] This invention provides a carbon-based electrode humidity sensor, comprising the carbon-based electrode humidity sensing element described in the above technical solution or the carbon-based electrode humidity sensing element prepared by the preparation method described in the above technical solution, a metal foil, and a conductive adhesive connecting the metal foil and the carbon-based electrode humidity sensing element; the metal foil is disposed at opposite ends of the porous carbon-based electrode in the carbon-based electrode humidity sensing element.

[0024] This invention provides the application of the carbon-based electrode humidity sensor described above in humidity sensing.

[0025] Preferably, when the carbon-based electrode humidity sensing element is a resistive humidity sensing element, the humidity detection range of the resistive humidity sensing element is RH 0% to RH 100%, the humidity sensing sensitivity is 0.1 to 0.319% / RH%, the response time is ≤100s, and the recovery time is ≤500s.

[0026] When the carbon-based electrode humidity sensing element is a capacitive humidity sensing element, the humidity detection range of the capacitive humidity sensing element is RH 0% to RH 100%, and the humidity sensing sensitivity is 1×10⁻⁶. 3 ~1.16×10 6 pF / RH%; response time ≤10s, response time ≤250s.

[0027] This invention provides a carbon-based electrode humidity sensing device, comprising an electrolyte and a porous carbon-based electrode in contact with the electrolyte. The electrolyte is a first acid-modified polybenzimidazole material. The porous carbon-based electrode is either a hydrophilic or a hydrophobic porous carbon-based electrode. The hydrophilic porous carbon-based electrode is prepared by laser processing of the first acid-modified polybenzimidazole material, and the hydrophobic porous carbon-based electrode is prepared by laser processing of either a polybenzimidazole raw material or a second acid-modified polybenzimidazole material. The first acid-modified polybenzimidazole material is obtained by modifying polybenzimidazole (PBI) raw material with a first phosphoric acid solution, and the second acid-modified polybenzimidazole material is obtained by modifying polybenzimidazole raw material with a second phosphoric acid solution, wherein the concentration of the first phosphoric acid solution is greater than the concentration of the second phosphoric acid solution. This invention utilizes the water absorption properties of polybenzimidazole raw material. The polybenzimidazole raw material is modified with a first phosphoric acid solution to obtain a first acid-modified polybenzimidazole material. Using this material as an electrolyte, a porous carbon-based electrode is formed by laser processing, giving it hydrophilic or hydrophobic properties. The resulting carbon-based electrode humidity sensing device has good signal repeatability and high sensitivity.

[0028] Furthermore, by adjusting the concentrations of the first and second phosphoric acid solutions and the laser processing conditions, the present invention enables carbon-based electrode humidity sensing devices to achieve humidity sensing performance with different sensitivities. Attached Figure Description

[0029] Figure 1 The diagram shows a resistive humidity sensing element (a), a capacitive humidity sensing element (b), and a physical image of the capacitive humidity sensing element (c) in the embodiments of the present invention.

[0030] Figure 2 This is a comparison of the dielectric constants of acid-modified polybenzimidazole materials prepared with phosphoric acid solutions of different concentrations in Example 1 under different frequency conditions.

[0031] Figure 3 This is a graph showing the test results of the continuous sensing signal of the capacitive humidity sensing element under test in different relative humidity environments in Example 1.

[0032] Figure 4 This is a linear fitting graph of the continuous sensing signal of the capacitive humidity sensing element under test in Example 1 under different relative humidity environments.

[0033] Figure 5 The graph shows the test results of the response time and recovery time of the capacitive humidity sensing element under test in Example 1 between 6% and 33% relative humidity.

[0034] Figure 6This is a comparison chart of the dielectric constants of acid-modified polybenzimidazole materials prepared with phosphoric acid solutions of different concentrations in Example 2 under different frequency conditions;

[0035] Figure 7 This is a graph showing the test results of the continuous sensing signal of the capacitive humidity sensing element under test in different relative humidity environments in Example 2;

[0036] Figure 8 This is a graph showing the test results of the resistance signal of the resistive humidity sensor under test in different relative humidity environments in Example 3;

[0037] Figure 9 The swelling changes of acid-modified polybenzimidazole materials obtained after modifying polybenzimidazole materials with phosphoric acid solutions of different concentrations (20-100 wt%) according to the method of Example 3 are shown in the figure.

[0038] Figure 10 This is a schematic diagram of the outer contour of the interdigitated carbon-based electrode etched using a polymethyl methacrylate plate in Example 4.

[0039] Figure 11 This is a graph showing the contact angle test results of the hydrophobic porous carbon-based electrode to be tested in Example 4;

[0040] Figure 12 This is a graph showing the test results of the continuous sensing signal of the capacitive humidity sensing element under test in different relative humidity environments in Example 4.

[0041] Figure 13 This is a graph showing the test results of the resistance signal of the resistive humidity sensor under test in different relative humidity environments in Example 5;

[0042] Figure 14 This is a graph showing the test results of the continuous sensing signal of the component under test in different relative humidity environments in Comparative Example 1;

[0043] Figure 15 The figure shows the test results of the continuous sensing signal of the component under test in Comparative Example 2 under different relative humidity environments. Detailed Implementation

[0044] This invention provides a carbon-based electrode humidity sensing device, comprising an electrolyte and a porous carbon-based electrode in contact with the electrolyte, wherein the electrolyte is a first acid-modified polybenzimidazole material;

[0045] The porous carbon-based electrode is a hydrophilic porous carbon-based electrode or a hydrophobic porous carbon-based electrode. The hydrophilic porous carbon-based electrode is prepared by laser processing of a first acid-modified polybenzimidazole material, and the hydrophobic porous carbon-based electrode is prepared by laser processing of a polybenzimidazole raw material or a second acid-modified polybenzimidazole material.

[0046] Wherein, the first acid-modified polybenzimidazole material is obtained by modifying polybenzimidazole raw material with a first phosphoric acid solution, the second acid-modified polybenzimidazole material is obtained by modifying polybenzimidazole raw material with a second phosphoric acid solution, and the concentration of the first phosphoric acid solution is greater than the concentration of the second phosphoric acid solution.

[0047] The carbon-based electrode humidity sensing device of the present invention includes an electrolyte, which is a first acid-modified polybenzimidazole material. The first acid-modified polybenzimidazole material is obtained by modifying polybenzimidazole raw material with a first phosphoric acid solution. In the present invention, the volume swelling rate of the first acid-modified polybenzimidazole material is preferably 20-122%, more preferably 50-122%, and even more preferably 100-122%; the mass swelling rate is preferably 5-30%, more preferably 10-30%, and even more preferably 25-30%. The specific preparation method of the first acid-modified polybenzimidazole material is described in detail below.

[0048] The carbon-based electrode humidity sensing device of this invention includes a porous carbon-based electrode in contact with the electrolyte. The porous carbon-based electrode is either a hydrophilic or hydrophobic porous carbon-based electrode. The hydrophilic porous carbon-based electrode is prepared by laser processing of a first acid-modified polybenzimidazole material. The hydrophobic porous carbon-based electrode is prepared by laser processing of a polybenzimidazole raw material or a second acid-modified polybenzimidazole material. The second acid-modified polybenzimidazole material is obtained by modifying a polybenzimidazole raw material with a second phosphoric acid solution, and the concentration of the first phosphoric acid solution is greater than the concentration of the second phosphoric acid solution. That is, this invention uses unmodified polybenzimidazole material (polybenzimidazole raw material) or polybenzimidazole material with a low degree of acid modification (second acid-modified polybenzimidazole material) as the hydrophobic porous carbon-based electrode via laser processing. The specific preparation method of the second acid-modified polybenzimidazole material is described in detail below.

[0049] In this invention, the carbon-based electrode humidity sensing element preferably includes a resistive humidity sensing element or a capacitive humidity sensing element. When the carbon-based electrode humidity sensing element is a resistive humidity sensing element, the porous carbon-based electrode is preferably continuously distributed, and the porous carbon-based electrode and the electrolyte are preferably stacked. In an embodiment of this invention, the porous carbon-based electrode in the resistive humidity sensing element is specifically as follows: Figure 1 As shown in a () Figure 1The acid-modified hygroscopic polymer is the first acid-modified polybenzimidazole material. When the carbon-based electrode humidity sensing element is a capacitive humidity sensing element, the porous carbon-based electrode is preferably an interdigitated electrode or a symmetrical electrode, and the electrolyte is preferably disposed in the encapsulation region of the porous carbon-based electrode; furthermore, the electrolyte can also preferably be disposed on the bottom surface of the porous carbon-based electrode; in the embodiments of the present invention, the porous carbon-based electrode in the capacitive humidity sensing element is specifically an interdigitated electrode, such as... Figure 1 As shown in b in the figure.

[0050] In this invention, the contact angle of the hydrophilic porous carbon-based electrode is preferably <90°, more preferably 0–20°; the contact angle of the hydrophobic porous carbon-based electrode is preferably >90°, more preferably 150°–180°. In this invention, the porosity of both the hydrophilic and hydrophobic porous carbon-based electrodes is preferably independently ≤50%, and their specific surface area is preferably independently ≤1500 m². 2 / g. Compared to non-porous electrodes like copper foil, the porous carbon-based electrode used in this invention can store moisture and charge, which is beneficial for improving the signal sensitivity of carbon-based electrode humidity sensing devices such as capacitive humidity sensing devices.

[0051] In this invention, from the perspective of the humidity sensing mechanism based on the materials: the first acid-modified polybenzimidazole material has the characteristics of absorbing water and acid, and water molecules have the obvious characteristic of forming hydrated hydrogen ions with hydrogen ions. This is the basis for the humidity sensing of the acid-modified polybenzimidazole material as the sensing area. Laser processing of the first acid-modified polybenzimidazole material results in a hydrophilic porous carbon-based electrode with a large number of phosphorus heteroatoms and pores that generate gas residues through phosphate free radical reactions, reducing the surface roughness of the material. Furthermore, the large number of phosphorus heteroatoms has good hydrophilic properties, promoting the absorption of moisture from the air. This invention prepares a hydrophobic porous carbon-based electrode with good hydrophobicity by laser processing of polybenzimidazole raw material or second acid-modified polybenzimidazole material. Specifically, the polybenzimidazole raw material or second acid-modified polybenzimidazole material has low water absorption capacity. During laser processing, the hydrophobic carbon-based material is doped with fewer phosphorus atoms, and even with a large number of pores, it can still form a hydrophobic material. The hydrophobic porous carbon-based electrode is combined with a first acid-modified polybenzimidazole material to obtain a carbon-based electrode humidity sensing device. Since the resistance of the hydrophobic porous carbon-based electrode is not affected by moisture, but only by the stretching and swelling of the electrolyte, the carbon-based electrode humidity sensing device has good stability (such as a resistive humidity sensing device).

[0052] The carbon-based electrode humidity sensing element described in this invention preferably includes resistive humidity sensing element and capacitive humidity sensing element. The humidity sensing mechanism will be explained below from the perspective of different configurations.

[0053] In this invention, the resistive humidity sensing device senses humidity through changes in resistance. The degree of humidity sensitivity of the phosphorus doped in the laser-processed porous carbon-based electrode and the first acid-modified polybenzimidazole material (i.e., the electrolyte) determines the overall resistance change of the resistive humidity sensing device. The first acid-modified polybenzimidazole material absorbs water and expands in volume, causing the electrolyte and porous carbon-based electrode to be pulled apart, reducing the contact of the conductive layer inside the porous carbon-based electrode and thus lowering the material's conductivity. Under the same temperature environment (humidity is easily affected by temperature), an increase in humidity leads to an increase in the resistance signal. Specifically, in the resistive humidity sensing device of this invention, the hydrophilic porous carbon-based electrode simultaneously serves as both the electrode and the sensing area to sense the humidity environment. Its humidity sensing mechanism has the following two aspects: 1) Utilizing the difference in water absorption capacity between the electrolyte and the hydrophilic porous carbon-based electrode to change the parallel resistance of the composite element; 2) The electrolyte undergoes volume swelling during water absorption, pulling the hydrophilic porous carbon-based electrode and causing changes in its internal conductive structure, thus altering the conductivity of the hydrophilic porous carbon-based electrode. The resistive humidity sensing device of the present invention can be further extended according to the humidity sensing mechanism as follows: Utilizing the difference in water absorption capacity between the electrolyte and the hydrophilic porous carbon-based electrode, the resistance signal of the humidity environment is further enhanced, thereby increasing the sensitivity of the resistive humidity sensing device. A hydrophobic porous carbon-based electrode is formed from polybenzimidazole raw material or second acid-modified polybenzimidazole through laser processing and then composited with a first acid-modified polybenzimidazole material. Through the difference in humidity sensitivity between the hydrophobic porous carbon-based electrode and the first acid-modified polybenzimidazole material, the resistance signal of the humidity environment is further enhanced, thereby increasing the sensitivity of the resistive humidity sensing device. The hydrophilic porous carbon-based electrode can achieve a superhydrophilic degree (contact angle below 20°), and the hydrophobic porous carbon-based electrode can achieve a superhydrophobic degree (contact angle above 150°).

[0054] In this invention, the capacitive humidity sensing device is a planar capacitor composed of interdigitated or symmetrical electrodes as porous carbon-based electrodes and a first acid-modified polybenzimidazole material as the electrolyte between the electrodes. The capacitive humidity sensing device senses humidity through changes in capacitance, wherein the capacitance change is related to both the electrolyte (i.e., the sensing material) and the porous carbon-based electrodes (i.e., the conductive material). Besides the electrolyte's inherent water absorption capacity, the dielectric constant of the electrolyte also increases significantly with increasing acid modification concentration and relative humidity. In the capacitive humidity sensing device of this invention, the electrolyte exhibits good insulation in a dry environment and conductivity and dielectric properties in a humid environment. Using the humid environment as a medium, rapid ion migration of the electrolyte between the porous carbon-based electrodes is achieved, obtaining a capacitance signal. For example, in an environment with relative humidity below 10%, its planar resistance can exceed 1 MΩ, even approaching complete insulation, while in a high humidity environment, its resistance can be as low as below 100 kΩ; the dielectric constant in a high humidity environment can reach 10. 7 The dielectric constant in low-humidity environments does not even exceed 1000. Furthermore, the hydrophilic porous carbon-based electrode can absorb moisture, promoting the further migration and accumulation of ions (mainly protons, hydrogen ions, or hydrated hydrogen ions formed by protons and water) within the electrolyte, thereby effectively enhancing the capacitive signal of the capacitive humidity sensing device and improving its humidity sensing performance. Specifically, the dielectric constant of polybenzimidazole material modified with 85wt% phosphoric acid solution can reach 10 at 100% relative humidity. 7 The dielectric constant of polybenzimidazole material modified with a lower concentration of phosphoric acid solution (10 wt%) is only 10 at a relative humidity of 20%. 3 The difference is on the order of magnitude, and the dielectric constant determines the magnitude of the capacitance signal. Electrolytes that absorb water and acid are analogous to the Grotthuss proton conduction theory: H₂O + H₃O + =H3O + The proton conduction mechanism of H2O and acid-modified polybenzimidazole materials: H3PO4 + PBI + H2O = H2PO4 - PBI - +H3O + The ability to transfer protons and moisture is the main reason for improving its dielectric constant. Furthermore, the phosphorus doping in the porous carbon-based electrode introduces porosity and hydrophilicity, providing space for the electrolyte to store moisture and transfer charge, further enhancing the charge storage capacity of the capacitive humidity sensor. This increases the capacitor's capacitance, thereby improving the distinguishability of capacitive signals in different humidity environments. Ultimately, the synergistic effect of the electrolyte and the porous carbon-based electrode enables a qualitative leap in the sensitivity performance of the capacitive humidity sensor.

[0055] This invention provides a method for fabricating the carbon-based electrode humidity sensing element described in the above technical solution. Depending on the specific type of the porous carbon-based electrode, different fabrication methods are employed. These are described in detail below.

[0056] In this invention, when the porous carbon-based electrode is a hydrophilic porous carbon-based electrode, the method for preparing the carbon-based electrode humidity sensing device includes the following steps:

[0057] The polybenzimidazole raw material was modified by immersing it in a first phosphoric acid solution to obtain a first acid-modified polybenzimidazole material.

[0058] Laser processing is performed on one side of the first acid-modified polybenzimidazole material to carbonize a portion of the first acid-modified polybenzimidazole material to form a hydrophilic porous carbon-based electrode, thereby obtaining a carbon-based electrode humidity sensing device.

[0059] This invention modifies polybenzimidazole raw material by immersing it in a first phosphoric acid solution to obtain a first acid-modified polybenzimidazole material. In this invention, the polybenzimidazole raw material is preferably a thin film material. In this invention, the concentration of the first phosphoric acid solution is preferably 1–100 wt%, more preferably 10–85 wt%, further preferably 30–85 wt%, even more preferably 50–80 wt%, and still more preferably 60–85 wt%. In this invention, the modification treatment temperature is preferably 10–40°C, more preferably 25–35°C; the time is preferably 24–72 h, more preferably 40–60 h, and even more preferably 48–50 h. In this invention, during the modification treatment, phosphoric acid (and water) molecules are inserted into the polybenzimidazole raw material to form an acid-modified polybenzimidazole material with hygroscopic effect. This invention preferably modifies the polybenzimidazole raw material under the above conditions, which enables the doping of polybenzimidazole material with phosphoric acid molecules, facilitating the acquisition of a carbon-based material with better hydrophilicity through laser processing.

[0060] After obtaining the first acid-modified polybenzimidazole material, the present invention performs laser processing on one side of the first acid-modified polybenzimidazole material to carbonize a portion of the first acid-modified polybenzimidazole material to form a hydrophilic porous carbon-based electrode, thereby obtaining a carbon-based electrode humidity sensing device. The present invention preferably uses this method to prepare a resistive humidity sensing device or a capacitive humidity sensing device with a hydrophilic porous carbon-based electrode. In the present invention, the laser processing conditions for the hydrophilic porous carbon-based electrode preferably include: the laser used is preferably a carbon dioxide laser; the wavelength of the carbon dioxide laser is preferably 10.6 μm; the power is preferably ≤10W, more preferably 0.4~8W, more preferably 1~6W, and even more preferably 2~5W; the scanning speed is preferably 1~12 inch / s, more preferably 2~4 inch / s; and the image density is preferably 200~1000 PPI, more preferably 100~500 PPI. The present invention preferably performs laser processing under the above conditions, which can preserve the rich pore structure on the surface while forming a structure with abundant chemical bonds such as PO and PH inside the porous carbon-based electrode. This structure forms hydrogen bonds with water molecules, forming an effective chemical structure for water molecule absorption, thereby making the surface of the porous carbon-based electrode more hydrophilic and more suitable for humidity monitoring.

[0061] The present invention preferably involves laser processing according to the specific shape of the hydrophilic porous carbon-based electrode. The present invention performs laser processing on one side of the first acid-modified polybenzimidazole material, causing a portion of the first acid-modified polybenzimidazole material to carbonize and form a hydrophilic porous carbon-based electrode. The remaining uncarbonized first acid-modified polybenzimidazole material serves as an electrolyte, together with the hydrophilic porous carbon-based electrode, constituting a carbon-based electrode humidity sensing device (including resistive humidity sensing devices or capacitive humidity sensing devices with hydrophilic porous carbon-based electrodes).

[0062] In this invention, when the porous carbon-based electrode is a hydrophobic porous carbon-based electrode, the method for preparing the carbon-based electrode humidity sensing device includes the following steps:

[0063] The polybenzimidazole raw material was modified by immersing it in a second phosphoric acid solution to obtain a second acid-modified polybenzimidazole material.

[0064] A polybenzimidazole raw material or the second acid-modified polybenzimidazole material is laminated onto one side of the first acid-modified polybenzimidazole material, and then a hydrophobic porous carbon-based electrode is formed on the surface of the polybenzimidazole raw material or the second acid-modified polybenzimidazole material by laser processing, thereby obtaining a carbon-based electrode humidity sensing device.

[0065] Alternatively, a hydrophobic porous carbon-based electrode can be obtained by laser processing on the surface of the polybenzimidazole raw material or the second acid-modified polybenzimidazole material. Then, the hydrophobic porous carbon-based electrode is combined with the first acid-modified polybenzimidazole material to obtain a carbon-based electrode humidity sensing device.

[0066] The present invention preferably prepares the first acid-modified polybenzimidazole material according to the method described in the above technical solution. Further details will not be elaborated here.

[0067] This invention modifies polybenzimidazole raw material by immersing it in a second phosphoric acid solution to obtain a second acid-modified polybenzimidazole material. In this invention, the concentration of the second phosphoric acid solution is preferably ≤5 wt%, more preferably 1–5 wt%. In this invention, the selectable range of modification conditions for preparing the second acid-modified polybenzimidazole material is preferably consistent with the selectable range of modification conditions for preparing the first acid-modified polybenzimidazole material, and will not be repeated here.

[0068] After obtaining the first acid-modified polybenzimidazole material and the second acid-modified polybenzimidazole material, this invention laminates the polybenzimidazole raw material or the second acid-modified polybenzimidazole material onto one side of the first acid-modified polybenzimidazole material. Then, a hydrophobic porous carbon-based electrode is formed on the surface of the polybenzimidazole raw material or the second acid-modified polybenzimidazole material by laser processing, resulting in a carbon-based electrode humidity sensing device. This invention preferably uses this method to prepare a resistive humidity sensing device with a hydrophobic porous carbon-based electrode. In this invention, the lamination method preferably includes hot pressing or bonding. In this invention, the selectable range of laser processing conditions for the hydrophobic porous carbon-based electrode is preferably consistent with the selectable range of laser processing conditions for the hydrophilic porous carbon-based electrode, and will not be elaborated further here. This invention preferably modifies the polybenzimidazole raw material with a second phosphoric acid solution of the above concentration, and then performs laser processing under the above conditions, which enables the obtained carbon-based material to have good hydrophobicity. In this invention, the temperature of the hot pressing is preferably 150-200°C, more preferably 170-180°C; the pressure is preferably 3-10 MPa, more preferably 4 MPa.

[0069] Alternatively, after obtaining the first acid-modified polybenzimidazole material and the second acid-modified polybenzimidazole material, the present invention uses laser processing on the surface of the polybenzimidazole raw material or the second acid-modified polybenzimidazole material to obtain a hydrophobic porous carbon-based electrode. Then, the hydrophobic porous carbon-based electrode is composited with the first acid-modified polybenzimidazole material to obtain a carbon-based electrode humidity sensing device. Preferably, the present invention uses this method to prepare a capacitive humidity sensing device with a hydrophobic porous carbon-based electrode. This invention preferably employs a masking sheet to assist in the fabrication of hydrophobic porous carbon-based electrodes. Specifically, this invention prepares a masking sheet according to the desired contour of the hydrophobic porous carbon-based electrode. The material of the masking sheet is preferably polymethyl methacrylate (PMMA, or acrylic glass). Laser processing is performed on the surface of the polybenzimidazole raw material or the second acid-modified polybenzimidazole material to obtain a hydrophobic porous carbon-based material. Then, the hydrophobic porous carbon-based material is cut according to the contour of the masking sheet to obtain a hydrophobic porous carbon-based electrode. The hydrophobic porous carbon-based electrode is then composited with the first acid-modified polybenzimidazole material to obtain a carbon-based electrode humidity sensing device. Preferably, this invention stacks the hydrophobic porous carbon-based electrode onto one side of the first acid-modified polybenzimidazole material to obtain a carbon-based electrode humidity sensing device. In this invention, the laser processing and composite methods are preferably consistent with the above technical solutions and will not be repeated here.

[0070] This invention provides a carbon-based electrode humidity sensor, comprising the carbon-based electrode humidity sensing element described in the above-described technical solution or prepared by the above-described preparation method, a metal foil, and a conductive adhesive connecting the metal foil and the carbon-based electrode humidity sensing element; the metal foil is disposed at both ends of the porous carbon-based electrode in the carbon-based electrode humidity sensing element. In this invention, the metal foil is preferably an aluminum foil, copper foil, or platinum foil; the conductive adhesive is preferably silver paste. Preferably, the metal foil is pasted onto both ends of the porous carbon-based electrode in the carbon-based electrode humidity sensing element. Specifically, the metal foil can be pasted onto the outer edge of the carbon-based electrode humidity sensing element and connected to an external circuit by bonding or soldering, and then used with other monitoring devices for humidity detection. In an embodiment of this invention, taking a capacitive humidity sensing element as an example, a physical image of the metal foil pasted onto the outer edge of the capacitive humidity sensing element is shown below. Figure 1 As shown in c. When the carbon-based electrode humidity sensing element is a resistive humidity sensing element, the bonding method and position of the metal foil are preferably the same as those of the capacitive humidity sensing element, and will not be described again here.

[0071] This invention provides the application of the carbon-based electrode humidity sensor described above in humidity sensing. In this invention, the carbon-based electrode humidity sensor is preferably used in the form of a resistive humidity sensor or a capacitive humidity sensor. Specifically, in the resistive humidity sensor, the carbon-based electrode humidity sensing element is a resistive humidity sensing element, and in the capacitive humidity sensor, the carbon-based electrode humidity sensing element is a capacitive humidity sensing element.

[0072] In this invention, when the carbon-based electrode humidity sensing element is a resistive humidity sensing element, the humidity detection range of the resistive humidity sensing element is preferably RH 0% (anhydrous, extremely dry) to RH 100% (saturated water vapor, extremely humid), the humidity sensing sensitivity is preferably 0.1 to 0.319% / RH%, more preferably 0.319% / RH% (resistance signal changes by 0.319% per relative humidity); the response time is preferably ≤100s, and the recovery time is preferably ≤500s.

[0073] In this invention, when the carbon-based electrode humidity sensing element is a capacitive humidity sensing element, the humidity detection range of the capacitive humidity sensing element is preferably RH 0% to RH 100%, and the humidity sensing sensitivity is preferably 1×10⁻⁶. 3 ~1.16×10 6 pF / RH%, more preferably 1.16×10 6 pF / RH% (capacitance signal change per relative humidity is 1.16 × 10⁻⁶) 6 The response time is preferably ≤100s, more preferably ≤10s, and even more preferably 5s; the response time is preferably ≤300s, more preferably ≤150s, even more preferably ≤50s, and even more preferably 19s; the linearity between the signal and relative humidity can reach 0.998.

[0074] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0075] Example 1

[0076] The steps for fabricating a hydrophilic electrode capacitive humidity sensing device are as follows:

[0077] (1) The polybenzimidazole material was placed in a phosphoric acid solution with a concentration of 60wt% or 85wt% and immersed for 40h at room temperature (25℃) to obtain acid-modified polybenzimidazole material.

[0078] (2) Using a carbon dioxide laser with a power of 8W and a wavelength of 10.6μm, at a scanning rate of 4inch / s and an image density of 500PPI, the acid-modified polybenzimidazole material is laser-processed, and the carbon dioxide laser is controlled to follow an interdigitated vector pattern ( Figure 1 Processing is carried out through path b) to form a porous carbon-based electrode with phosphorus doping and good superhydrophilic properties on the surface of the acid-modified polybenzimidazole material, thereby obtaining a hydrophilic electrode capacitive humidity sensing device.

[0079] Figure 2 This is a comparison chart of the dielectric constants of acid-modified polybenzimidazole materials prepared with phosphoric acid solutions of different concentrations in Example 1 under different frequency conditions. The results show that immersing the polybenzimidazole materials in phosphoric acid solutions of 60 wt% or 85 wt% results in acid-modified polybenzimidazole materials with extremely high dielectric constants at low frequencies. Specifically, the polybenzimidazole material modified with 85 wt% phosphoric acid has a dielectric constant close to 10 at 100 Hz. 7 It is nearly ten times the dielectric constant of polybenzimidazole material modified with 60wt% phosphoric acid.

[0080] The capacitive humidity sensing element prepared in Example 1 with a phosphoric acid solution concentration of 85 wt% was used as the capacitive humidity sensing element under test. It was connected to an external 50 Hz AC power supply and then placed in environments with different relative humidity levels (1–95% RH) to test the continuous sensing signal. Linear fitting was performed on the continuous sensing signal under different relative humidity conditions, and its sensitivity was calculated using Equation I.

[0081] S = ΔC / ΔRH% Equation I;

[0082] In Equation I, S represents sensitivity, in pF / RH%; ΔC represents the capacitance signal difference, in pF; and ΔRH% represents the humidity signal difference, in %.

[0083] Figure 3 This is a graph showing the test results of the continuous sensing signal of the capacitive humidity sensor under test in different relative humidity environments in Example 1. Figure 4 This is a linear fitting graph of the continuous sensing signal of the capacitive humidity sensor under test in different relative humidity environments in Example 1. Based on this, the sensitivity of the capacitive humidity sensor under test can be calculated to be 1.16 × 10⁻⁶ according to Equation I. 6 pF / RH%.

[0084] Figure 5The graph shows the test results of the response time and recovery time of the capacitive humidity sensor under test in Example 1 between 6% and 33% relative humidity. The results show that the capacitive humidity sensor under test exhibits good repeatability of humidity signal in a high relative humidity environment.

[0085] Example 2

[0086] The steps for fabricating a hydrophilic electrode capacitive humidity sensing device are as follows:

[0087] (1) The polybenzimidazole material was placed in a phosphoric acid solution with a concentration of 1 wt% or 30 wt% and immersed for 50 h at room temperature (25 °C) to obtain acid-modified polybenzimidazole material.

[0088] (2) A carbon dioxide laser with a power of 2W and a wavelength of 10.6μm is used to laser process the acid-modified polybenzimidazole material at a scanning rate of 4 inches / s and an image density of 500 PPI, and the carbon dioxide laser is controlled to follow an interdigitated vector pattern ( Figure 1 Processing is carried out through path b) to form a porous carbon-based electrode with phosphorus doping and hydrophilic properties on the surface of the acid-modified polybenzimidazole material, thereby obtaining a hydrophilic electrode capacitive humidity sensing device.

[0089] Figure 6 This is a comparison chart of the dielectric constants of acid-modified polybenzimidazole materials prepared with phosphoric acid solutions of different concentrations in Example 2 under different frequency conditions. The results show that immersing the polybenzimidazole materials in phosphoric acid solutions of 1 wt% or 30 wt% results in acid-modified polybenzimidazole materials with extremely high dielectric constants at low frequencies. Specifically, the polybenzimidazole material modified with 30 wt% phosphoric acid has a dielectric constant close to 10 at 100 Hz. 6 It is nearly a thousand times the dielectric constant of the phosphate-modified polybenzimidazole material with a concentration of 1 wt%.

[0090] The capacitive humidity sensing element prepared in Example 2 under the condition of 30wt% phosphoric acid solution concentration was used as the capacitive humidity sensing element under test. It was connected to an external 50Hz AC power supply and then placed in environments with different relative humidity (1~95%RH) to test the continuous sensing signal. The continuous sensing signal under different relative humidity conditions was linearly fitted, and then its sensitivity was calculated by Equation I. Figure 7 The graph shows the test results of the continuous sensing signal of the capacitive humidity sensor under test in different relative humidity environments in Example 2. Based on linear fitting and calculation according to Equation I, the sensitivity of the capacitive humidity sensor under test can reach 36342.09 pF / RH.

[0091] Example 3

[0092] The steps for fabricating a hydrophilic electrode resistive humidity sensing device are as follows:

[0093] (1) The polybenzimidazole material was placed in a 50wt% phosphoric acid solution and soaked for 48h at room temperature (25℃) to obtain the first acid modified polybenzimidazole material;

[0094] (2) A carbon dioxide laser with a power of 1W and a wavelength of 10.6μm is used to laser process the first acid-modified polybenzimidazole material at a scanning rate of 4 inches / s and an image density of 500 PPI, and the carbon dioxide laser is controlled to follow a vector pattern ( Figure 1 Processing is carried out through path a) to form a porous carbon-based electrode with phosphorus doping and hydrophilic properties on the surface of the first acid-modified polybenzimidazole material, thereby obtaining a hydrophilic electrode resistive humidity sensing device.

[0095] The resistive humidity sensing element prepared in Example 3 was used as the resistive humidity sensing element to be tested. It was connected to a resistance measuring instrument and then placed in environments with different relative humidity (13% to 90% RH) to test the change in resistance signal. Its sensitivity was calculated using Equation II.

[0096] S=ΔR / R 初始 / ΔRH% Formula II;

[0097] In Equation II, S represents sensitivity, measured in % / RH%, and ΔR represents the resistance signal difference. 初始 ΔRH% represents the initial resistance signal value, and ΔRH% represents the humidity signal difference.

[0098] Figure 8 The graph shows the resistance signal test results of the resistive humidity sensor under test in different relative humidity environments in Example 3. Based on this, the sensitivity of the resistive humidity sensor under test is calculated to be 0.308% / RH according to Equation II.

[0099] Because the first acid-modified polybenzimidazole material has swelling properties, the humidity sensing effect of the resistive humidity sensing device in Example 3 is affected by the swelling properties of the electrolyte (i.e., the first acid-modified polybenzimidazole material). Specifically, Figure 9The diagram shows the swelling changes of the first acid-modified polybenzimidazole material obtained by modifying the polybenzimidazole material with different concentrations of phosphoric acid solution (20-100 wt%) according to the method of Example 3. The "acid-modified material" specifically refers to the first acid-modified polybenzimidazole material, and the "dehydrated material" specifically refers to the first acid-modified polybenzimidazole material obtained by vacuum heating and dehydration. The results show that the higher the concentration of phosphoric acid solution during the acid modification process, the more obvious the surface swelling and volume swelling of the first acid-modified polybenzimidazole material.

[0100] Example 4

[0101] The steps for fabricating a hydrophobic electrode capacitive humidity sensing device are as follows:

[0102] (1) The polybenzimidazole material was placed in a phosphoric acid solution with a concentration of 85 wt% and immersed for 48 h at room temperature (25°C) to obtain an acid-modified polybenzimidazole material, which was designated as the first acid-modified polybenzimidazole material (used as an electrolyte for humidity sensing devices); the polybenzimidazole material was placed in a phosphoric acid solution with a concentration of 1 wt% and immersed for 48 h at room temperature (25°C) to obtain a polybenzimidazole material with a lower degree of acid modification, which was designated as the second acid-modified polybenzimidazole material.

[0103] (2) Using a flat plate made of polymethyl methacrylate (PMMA, or acrylic glass), the outer contour of the interdigitated carbon-based electrode is etched out (e.g., Figure 10 As shown, the electrode outline is the same as that of the capacitive humidity sensing element in Examples 1-2, and the PMMA material inside the outer outline of the interdigitated carbon-based electrode is removed to obtain a masking sheet.

[0104] (3) Using a carbon dioxide laser with a laser power of 0.4W and a wavelength of 10.6μm, the second acid-modified polybenzimidazole material is laser-processed at a scanning rate of 4inch / s and an image density of 500PPI to obtain a hydrophobic porous carbon-based material; then the hydrophobic porous carbon-based material is cut according to the outline of the masking sheet described in step (2) to obtain a hydrophobic porous carbon-based electrode.

[0105] (4) The hydrophobic porous carbonized electrode is placed on the surface of the first acid-modified polybenzimidazole material and hot-pressed composite is performed at a temperature of 170°C and a pressure of 4MPa to obtain a hydrophobic electrode capacitive humidity sensing element.

[0106] The hydrophobic porous carbon-based electrode prepared in Example 4 was used as the hydrophobic porous carbon-based electrode to be tested, and its contact angle was measured. Figure 11The image shows the contact angle test results of the hydrophobic porous carbon-based electrode under test in Example 4. The results show that the contact angle is 120.4°, indicating that the hydrophobic porous carbon-based electrode under test has a good hydrophobic effect.

[0107] The capacitive humidity sensing device prepared in Example 4 was used as the capacitive humidity sensing device under test. It was connected to an external 50Hz AC power supply and then placed in environments with different relative humidity (1-95%RH) to test the continuous sensing signal. The continuous sensing signal under different relative humidity conditions was linearly fitted, and its sensitivity was calculated by Equation I. Figure 12 The graph shows the test results of the continuous sensing signal of the capacitive humidity sensor under test in different relative humidity environments in Example 4. Based on linear fitting and calculation according to Equation I, the sensitivity of the capacitive humidity sensor under test can reach 1.47 × 10⁻⁶. 5 pF / RH%.

[0108] Example 5

[0109] The steps for fabricating a hydrophilic electrode resistive humidity sensing device are as follows:

[0110] (1) The polybenzimidazole material was placed in a 10wt% phosphoric acid solution and soaked for 48h at room temperature (25℃) to obtain acid-modified polybenzimidazole material.

[0111] (2) A carbon dioxide laser with a power of 1W and a wavelength of 10.6μm is used to laser process the acid-modified polybenzimidazole material at a scanning rate of 4 inches / s and an image density of 500 PPI, and the carbon dioxide laser is controlled to follow a vector pattern ( Figure 1 Processing is carried out through path a) to form a porous carbon-based electrode with phosphorus doping and hydrophilic properties on the surface of the acid-modified polybenzimidazole material, thereby obtaining a hydrophilic electrode resistive humidity sensing device.

[0112] The resistive humidity sensing element prepared in Example 5 was used as the resistive humidity sensing element to be tested. It was connected to a resistance measuring instrument and then placed in environments with different relative humidity (34% to 90% RH) to test the change in resistance signal. Its sensitivity was calculated by Equation II.

[0113] Figure 13 The graph shows the resistance signal test results of the resistive humidity sensor in Example 5 under different relative humidity environments. Based on this, the sensitivity of the capacitive humidity sensor was calculated to be 0.028% / RH% according to Equation II. Compared with the resistive humidity sensor prepared in Example 3, the sensitivity is reduced, indicating that the swelling characteristics of the electrolyte in the resistive humidity sensor will affect the sensitivity of the resistive humidity sensor.

[0114] Comparative Example 1

[0115] The procedure is the same as in Example 1, except that the step of acid modification of the polybenzimidazole material is omitted, i.e., the unmodified polybenzimidazole material is directly laser-processed.

[0116] The components prepared in Comparative Example 1 were used as the components under test, connected to an external 50Hz AC power supply, and then placed in environments with different relative humidity (1~95%RH) to test the continuous induction signal. Figure 14 The figure shows the test results of the component under test in Comparative Example 1, which continuously senses signals in different relative humidity environments. The results show that the component does not exhibit signal differentiation under different humidity environments and cannot be used as a humidity sensor.

[0117] Comparative Example 2

[0118] The procedure was performed according to Example 1, except that commercially available copper foil was used instead of the porous carbon-based electrode prepared by laser processing in Example 1. Specifically, interdigitated copper foil electrodes were used instead of the porous carbon-based electrode prepared by laser processing in Example 1 and adhered to the surface of the acid-modified polybenzimidazole material (the concentration of the phosphoric acid solution used was 85 wt%).

[0119] The components prepared in Comparative Example 2 were used as the components under test, connected to an external 50Hz AC power supply, and then placed in environments with different relative humidity (1~95%RH) to test the continuous induction signal. Figure 15 The graph shows the continuous sensing signal test results of the component under test in Comparative Example 2 under different relative humidity environments. The results show that the component has differentiation under conditions with large differences in humidity, but the capacitance signal is low, and it does not have differentiation for nearby humidity environments. This indicates that the porous carbon-based electrode used in this invention can store more moisture and charge through its porous structure, thereby improving the capacitance signal. With the participation of the porous carbon-based electrode, signal differentiation under different humidity conditions is achieved.

[0120] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A carbon-based electrode humidity sensing element, comprising an electrolyte and a porous carbon-based electrode in contact with the electrolyte, wherein the electrolyte is a first acid-modified polybenzimidazole material; The porous carbon-based electrode is a hydrophilic porous carbon-based electrode or a hydrophobic porous carbon-based electrode. The hydrophilic porous carbon-based electrode is prepared by laser processing of a first acid-modified polybenzimidazole material, and the hydrophobic porous carbon-based electrode is prepared by laser processing of a second acid-modified polybenzimidazole material. in, The first acid-modified polybenzimidazole material is obtained by modifying polybenzimidazole raw material with a first phosphoric acid solution, and the second acid-modified polybenzimidazole material is obtained by modifying polybenzimidazole raw material with a second phosphoric acid solution, wherein the concentration of the first phosphoric acid solution is greater than the concentration of the second phosphoric acid solution. The carbon-based electrode humidity sensing element is a capacitive humidity sensing element, the porous carbon-based electrode is an interdigitated electrode or a symmetrical electrode, and the electrolyte is disposed in the encapsulation region of the porous carbon-based electrode.

2. The carbon-based electrode humidity sensing element according to claim 1, characterized in that, The contact angle of the hydrophilic porous carbon-based electrode is <90°, and the contact angle of the hydrophobic porous carbon-based electrode is >90°; the porosity of both the hydrophilic and hydrophobic porous carbon-based electrodes is independently ≤50%, and their specific surface area is independently ≤1500 m². 2 / g.

3. The carbon-based electrode humidity sensing element according to claim 1, characterized in that, The volume swelling rate of the first acid-modified polybenzimidazole material is 20-122%, and the mass swelling rate is 5-30%.

4. The method for preparing the carbon-based electrode humidity sensing element according to any one of claims 1 to 3, (1) When the porous carbon-based electrode is a hydrophilic porous carbon-based electrode, the following steps are included: The polybenzimidazole raw material was modified by immersing it in a first phosphoric acid solution to obtain a first acid-modified polybenzimidazole material. Laser processing is performed on one side of the first acid-modified polybenzimidazole material to carbonize part of the first acid-modified polybenzimidazole material to form a hydrophilic porous carbon-based electrode, thereby obtaining a carbon-based electrode humidity sensing device. (2) When the porous carbon-based electrode is a hydrophobic porous carbon-based electrode, the following steps are included: The polybenzimidazole raw material was modified by immersing it in a second phosphoric acid solution to obtain a second acid-modified polybenzimidazole material. The second acid-modified polybenzimidazole material is laminated onto one side of the first acid-modified polybenzimidazole material, and then a hydrophobic porous carbon-based electrode is formed on the surface of the second acid-modified polybenzimidazole material by laser processing to obtain a carbon-based electrode humidity sensing device. Alternatively, a hydrophobic porous carbon-based electrode can be obtained by laser processing on the surface of the second acid-modified polybenzimidazole material, and then the hydrophobic porous carbon-based electrode can be combined with the first acid-modified polybenzimidazole material to obtain a carbon-based electrode humidity sensing device.

5. The preparation method according to claim 4, characterized in that, The concentration of the first phosphoric acid solution is 1~100wt%, and the concentration of the second phosphoric acid solution is ≤5wt%.

6. The preparation method according to claim 4, characterized in that, The laser processing conditions for the hydrophilic porous carbon-based electrode and the hydrophobic porous carbon-based electrode independently include: the laser used is a carbon dioxide laser with a wavelength of 10.6 μm, a power of ≤10 W, a scanning speed of 1~12 inch / s, and an image density of 200~1000 PPI.

7. A carbon-based electrode humidity sensor, comprising the carbon-based electrode humidity sensing element according to any one of claims 1 to 3 or the carbon-based electrode humidity sensing element prepared by the preparation method according to any one of claims 4 to 6, a metal foil, and a conductive adhesive connecting the metal foil and the carbon-based electrode humidity sensing element; wherein the metal foil is disposed at opposite ends of the porous carbon-based electrode in the carbon-based electrode humidity sensing element.

8. The application of the carbon-based electrode humidity sensor according to claim 7 in humidity sensing.

9. The application according to claim 8, characterized in that, The humidity detection range of the capacitive humidity sensing element is RH 0%~RH 100%, and the humidity sensing sensitivity is 1×10⁻⁶. 3 ~1.16×10 6 pF / RH%; response time ≤100s, reply time ≤300s.

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