Method and device for measuring relative humidity of micron-sized space

Abstract

The invention discloses a method and device for measuring the relative humidity of a micron-sized space, and the method comprises the steps: building a standard relation graph between the form of the hyemaceae plant spore and the relative humidity by utilizing the characteristic that the hyemaceae plant spore has response to the change of the relative humidity, placing the hyemaceae plant spore in the micron-sized space, and measuring the relative humidity of the micron-sized space according to the relative humidity of the hyemaceae plant spore. And observing the morphological change of the spore of the equiseti plant, and combining with a relational graph of the spore and the relative humidity to obtain a corresponding relative humidity range, thereby realizing the measurement of the relative humidity in a micron-sized space such as a micro-fluidic chip. According to the method, the equiseti plant spores which are environment-friendly, non-toxic, easy to obtain, low in cost and reusable are utilized, the relative humidity of the micron-sized space can be simply and rapidly measured, and the method has important significance on related research and application needing to monitor the change of the relative humidity in the micron-sized space. The invention further provides an environment-friendly visual portable relative humidity measuring device which is applied to measuring the relative humidity of the skin.

Description

Technical Field

[0001] The present invention belongs to the technical field of humidity sensors, and more specifically, relates to a method and device for measuring micron-level spatial relative humidity. Background Art

[0002] Existing humidity sensors are more innovative in materials, and rarely pay more attention to the size of the space for measuring relative humidity. While improving materials, the size of sensors has also been reduced, but there is still no proposal to measure the relative humidity in micron-scale space. Detecting the relative humidity in micron-scale space, such as detecting changes in channel relative humidity in microfluidic organ chips (air-liquid interface lung model), has potential application value. The chip of the air-liquid interface lung model is an organ chip with a central chamber and flanking microchannels that can mimic the air-liquid interface of lung function. The airway model is created by co-culturing endothelial and epithelial cells. Changes in relative humidity levels in the chip environment can affect cell morphology, motility, and even gene expression. If the relative humidity in the chip channel can be obtained and changes in relative humidity can be detected, the control of relative humidity will help cell growth. Publication No. CN118007322A discloses a method for preparing a cellulose nanofiber membrane and a cellulose nanofiber / carbon nanotube composite membrane and a humidity sensor. Using pulp as a raw material, all-cellulose-based nanofibers (i.e., cellulose nanofibers) and cellulose nanofiber membranes are prepared by electrostatic spinning. The cellulose nanofibers are filament fibers with a diameter of about 200 to 1000 nm. The formed cellulose nanofiber membrane has the characteristics of ultra-thin (30 μm) and large pores (1 to 10 μm). Based on the above characteristics, the contact area between the cellulose nanofiber membrane and the wet air is increased, which accelerates the rapid combination and rapid separation of water molecules and cellulose, thereby improving the rapid moisture absorption and dehumidification performance of the cellulose nanofiber membrane, laying the foundation for high-performance fiber-based sensors. However, even synthetic nanofibers have disadvantages that cannot be ignored. Synthetic nanofibers are a layer of fiber membranes formed by disorderly stacking together. During the repeated measurement of temperature and humidity, due to the influence of temperature and humidity, the microstructure of the nanofiber membrane will collapse or deform locally, resulting in the unsatisfactory repeatability of its humidity sensor. Even though the existing humidity sensor preparation process is constantly developing towards miniaturization, the existing humidity sensor synthesis process is complex, has poor repeatability, is large in size, is costly, and fails to measure the relative humidity of micrometer-level space, and humidity sensors that measure the size of micrometer-level space have not been reported. Therefore, it is of great significance to provide a reusable, green, non-toxic and easily available method that can measure the relative humidity of micrometer-level space. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects and shortcomings in the prior art and provide a method for measuring micron-level spatial relative humidity.

[0004] A second object of the present invention is to provide a visual and portable relative humidity measuring device.

[0005] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0006] The present invention first provides a method for measuring micrometer-level space relative humidity, comprising the following steps:

[0007] S1. Record the morphology of spores of Equisetaceae plants under different relative humidity, and establish a standard relative humidity diagram corresponding to the morphology of spores of Equisetaceae plants and relative humidity;

[0008] S2. Fix the spores of the Equisetaceae plant in S1 in the micrometer-scale space to be measured, observe the morphology of the spores of the Equisetaceae plant, and obtain the relative humidity of the micrometer-scale space to be measured by comparing with the standard relative humidity chart of S1.

[0009] The Equisetaceae family only contains the genus Equisetum L., which is divided into two subgenera, namely Subgen. Equisetum and Subgen. Hippochaete (Milde) Baker. The spores of Equisetaceae plants can present different forms in response to changes in environmental relative humidity. So far, there has been no report on using the characteristics of their spores responding to changes in relative humidity to measure the relative humidity of a small space. The present invention utilizes the characteristic that the existing spores of Equisetaceae plants respond to changes in relative humidity, applies the spores of Equisetaceae to the measurement of relative humidity in micrometer-level space, and establishes a method for measuring relative humidity in micrometer-level space. The method establishes a relationship between spore morphology and relative humidity. Specifically, under different humidity conditions, the morphology of Equisetaceae spores changes regularly. When the relative humidity is between 50% and 60%, the distance between the elastic threads of the spores is far and stretched. With the increase of humidity, when the relative humidity reaches above 60%, the elastic threads of the spores gradually begin to bend and form an arc; when the relative humidity reaches above 80%, the elastic threads curl into a ball and surround the spores. Therefore, the real image of the spore state under different relative humidity conditions is recorded, and a standardized relative humidity card exclusive to the spores is formulated. By observing the morphology of the spores, the correct position is found from the established standardized relative humidity card, thereby obtaining the corresponding relative humidity range. By establishing such a relative humidity standard card for each spore, the reliability of the data can be ensured, thereby realizing the measurement of relative humidity in micrometer-level space such as microfluidic chips.

[0010] Furthermore, step S1 further includes recording the distances between adjacent elastic threads of spores of Equisetaceae plants under different relative humidities, and establishing a standard relative humidity table corresponding to the distances between adjacent elastic threads of spores of Equisetaceae plants and relative humidity.

[0011] Preferably, the adjacent elastic threads are two adjacent elastic threads that bend in the same direction when curled, and the distance is the farthest distance between the adjacent elastic threads.

[0012] Under different relative humidity conditions, the elastic threads of spores will bend to different degrees, and the distance between adjacent elastic threads will change. Therefore, it is also possible to establish a relationship table between the distance between spore elastic threads and relative humidity by recording different humidity conditions, and by measuring the distance between adjacent elastic threads of Equisetaceae spores in micrometer-level space, and comparing the established relationship table between the distance between spore elastic threads and relative humidity, the relative humidity of the current micrometer-level space can be obtained.

[0013] Furthermore, the Equisetum plant spore is one of Equisetum arvense spore and Equisetum ramosissimum spore.

[0014] Preferably, the Equisetaceae plant spores are Equisetum truncatum spores.

[0015] Furthermore, step S2 is to fix the spores of the Equisetaceae plant in the micrometer-scale space to be measured by magnetism.

[0016] Furthermore, a magnetic metal nanolayer is attached to the surface of the spores of the Equisetaceae plant.

[0017] Preferably, the magnetic metal nanolayer is attached to the surface of the spores of the Equisetaceae plant by sputtering metal.

[0018] Since the spores of the Equisetaceae plant are light and easily moved by airflow, the present invention sputters magnetic metal on the spores to attach a magnetic metal nanolayer on the surface of the spores, and then uses a magnetic device to better fix them on the carrier. Experimental verification shows that the morphological changes of the spores of the Equisetaceae plant sputtered with magnetic metal are not affected, and they still have the ability to respond to changes in different relative humidity.

[0019] Preferably, the magnetic metal is selected from one of iron and nickel.

[0020] Preferably, the magnetic metal is iron.

[0021] Furthermore, the micrometer-scale space is a microfluidic chip.

[0022] Preferably, the microfluidic chip is a cross-shaped microfluidic chip or a cell migration chip.

[0023] Furthermore, in step S1, a magnetic metal nanolayer is attached to the surface of the spores of the Equisetaceae plant.

[0024] Furthermore, step S2 is to fix the spores of the Equisetaceae plant by means of a magnetic field.

[0025] The present invention also provides a visual portable relative humidity measurement device, comprising an intelligent device with a camera, a portable microscope, and Equisetaceae plant spores; the portable microscope is fixed on the camera of the intelligent device, and the Equisetaceae plant spores are fixed on the objective lens surface of the portable microscope; the Equisetaceae plant spores contact an object to be measured, and the morphology of the Equisetaceae plant spores is observed and photographed by the intelligent device to detect the relative humidity of the object to be measured.

[0026] Furthermore, the smart device with a camera includes but is not limited to a smart phone.

[0027] Furthermore, the portable microscope is a mobile phone microscope.

[0028] Furthermore, the method for fixing the spores of the Equisetaceae plant on the objective surface of the portable microscope is: distributing the spores of the Equisetaceae plant on a filter membrane, covering the filter membrane with a transparent film to fix the spores of the Equisetaceae plant, and then fixing the filter membrane with the spores of the Equisetaceae plant fixed on the objective surface of the portable microscope.

[0029] Preferably, the method for using the device is: recording the morphological diagram of Equisetaceae plant spores or the distance between adjacent elastic threads under known different relative humidity environments, establishing a standardized relative humidity chart of Equisetaceae plant spores under different humidity, contacting the object to be measured with the Equisetaceae plant spores of the relative humidity measuring device, observing and photographing the morphology of the Equisetaceae plant spores with an intelligent device, and obtaining the relative humidity of the object to be measured according to the standardized relative humidity chart.

[0030] Furthermore, the visual portable relative humidity measuring device is used to detect changes in skin relative humidity.

[0031] The present invention utilizes the characteristic that the spores of the Equisetaceae plant can sense the change of relative humidity in the surrounding environment, and uses smart devices and portable microscopes, specifically a smart phone and a mobile phone microscope to make a portable relative humidity measuring device, which can detect the change of relative humidity of the skin. The spores of the Equisetaceae plant are fixed on the mobile phone microscope through a filter membrane, and the filter membrane can transfer the humidity of the outside to the surrounding of the spores. The morphology of the spores is observed through the camera of the mobile phone, so as to measure the relative humidity. Before the test, the spores are in an unfolded state. When the finger is close to the filter membrane, the humidity inside and outside the filter membrane is different. The humidity is transferred from the outside of the device to the inside of the device. The humidity of the finger is transferred to the surrounding of the spores through the filter membrane. As the humidity increases, the spores sense the change of relative humidity and curl up. Therefore, this device can be used in life to detect the change of relative humidity of the skin.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a method for measuring relative humidity in a micrometer-scale space. The method utilizes the characteristic that existing spores of Equisetaceae plants respond to changes in relative humidity, establishes a standard relationship diagram corresponding to the morphology of spores of Equisetaceae plants and relative humidity, and then places the spores of Equisetaceae plants in a micrometer-scale space. By observing the changes in the morphology of spores of Equisetaceae plants, the morphology of spores of Equisetaceae plants is compared with the established standard relationship diagram corresponding to the morphology of spores of Equisetaceae plants and relative humidity, and the range of relative humidity in the micrometer-scale space is obtained, thereby realizing the measurement of relative humidity in a micrometer-scale space such as a microfluidic chip; further, magnetic metal is sputtered on the surface of the spores, which has no effect on the response to the change in relative humidity, and the measurement of relative humidity in a micrometer-scale space can also be realized. The method utilizes green, environmentally friendly, non-toxic, easy to obtain, low-cost, and reusable spores of Equisetaceae plants. The method can simply and quickly realize the measurement of relative humidity in a micrometer-scale space, especially in a microfluidic chip, and has important significance for related research applications that need to monitor changes in relative humidity in a microfluidic chip. The present invention also provides a green, environmentally friendly, visual, portable relative humidity measurement device, which is used to measure the relative humidity of the skin. It can be further combined with a mini-program to capture images of spore morphology, measure the length of spores through data analysis, and directly display the current relative humidity range. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Diagram of the device for detecting the morphology of spores at different relative humidities.

[0035] Figure 2 is a relationship diagram corresponding to spore morphology and relative humidity; wherein, A is a standard relationship diagram between the spore spinning distances of three different spores and relative humidity at different relative humidities for spores not sputtered with iron, B is a standard relationship diagram between the spore spinning distances of three different spores and relative humidity at different relative humidities, C is a standardized relative humidity card of three different spores not sputtered with iron, and D is a standardized relative humidity card of three different spores sputtered with iron.

[0036] Figure 3 Diagram of the setup for magnetic characterization of iron-sputtered spores.

[0037] Figure 4The figures are the results of X-ray energy dispersive spectrometer (EDS) and magnetic characterization of spores before and after iron sputtering; A is the EDS image of spores before (a) and after (b) sputtering iron; B is the magnetic characterization of spores sputtered with iron, wherein a and b are the position and morphology of spores when airflow at a certain speed passes through the front and rear spores under the condition of no magnetic field, respectively; c and d are the position and morphology of spores when airflow at a certain speed passes through the front and rear spores under the condition of magnetic field.

[0038] Figure 5 These are the model verification and parameter analysis diagrams of the humidity changes of spores in the cross-shaped (A) and cell migration (B) microfluidic chip channels; wherein Aa is the cross-shaped chip diagram, Ab is the humidity distribution diagram of the cross-shaped microfluidic chip channel at t=0s, Ac is the humidity distribution diagram of the cross-shaped microfluidic chip channel at t=25s, Ba is the cell migration chip diagram, Bb is the humidity distribution diagram of the cell migration microfluidic chip channel at t=0s, and Bc is the humidity distribution diagram of the cell migration microfluidic chip channel at t=25s.

[0039] Figure 6 The figures are morphological diagrams of spores in response to changes in relative humidity in different microfluidic chips; A is a diagram showing the position of spores in a cross-shaped chip and the morphological diagrams of spores under low humidity (a) and high humidity (b); B is a diagram showing the position of spores in a cell migration chip and the morphological diagrams of spores under low humidity (a) and high humidity (b); C is a diagram showing the morphological diagrams of spores in the two chips under different humidity changes.

[0040] Figure 7 It is a portable relative humidity measuring device and a detection diagram of skin relative humidity; wherein, A is a 3D rendering of the portable relative humidity measuring device, B is the material for assembling the portable relative humidity measuring device, C is a diagram of spore morphology observed using the portable relative humidity measuring device, and D is a diagram of spore morphology for detecting changes in skin relative humidity using the portable relative humidity measuring device.

[0041] Figure 8 The present invention discloses the principle and related devices of preparing humidity sensors using spores of Equisetaceae plants; wherein A represents the morphological changes of spores in response to humidity changes, B represents the sputtering of magnetic metals by spores, C represents the humidity sensing of spores in a microenvironment, and D represents a skin humidity sensor. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0043] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0044] The spores of knotweed were obtained by planting by the inventor's team.

[0045] Example 1

[0046] like Figure 1 As shown, the present invention uses a 3D printer to print a total volume of about 10cm 3 The rectangular space is left empty at the bottom and glued to the slide, which is convenient for observing the morphology of spores under a microscope. A DHT22 temperature and humidity sensor with a measurement accuracy of ±2%RH and a resolution of 0.1%RH is placed on the left to measure the relative humidity around the spores. The cover glass is then used to maintain a closed space. At the bottom of this space, there is a 0.2×2×0.55cm rectangular parallelepiped that divides the bottom into two sides. Spores are placed on one side and hot water is placed on the other side. Hot water can create a high humidity environment. Place the spores on one side of the bottom and place the device under a microscope for observation, recording the current relative humidity of the air and the morphology of the spores. Add hot water to the other side of the bottom and cover the top with a slide to maintain a closed environment. At this time, the relative humidity in the closed space rises rapidly, and the spores curl up immediately. When the relative humidity no longer rises and the spore morphology no longer changes, record the phenomenon. As the observation time increases, the temperature of the hot water in the closed space slowly decreases, the relative humidity on one side of the spores also slowly decreases, and the spores slowly stretch from curling. Finally, slightly move the upper slide away to allow the relative humidity to drop to the same level as at the beginning. Finally, a graph of the relationship between spore morphology and relative humidity is obtained, and a standard relative humidity table is developed for each individual spore, that is, each spore can be standardized to obtain a spore standardized relative humidity card similar to the pH test paper color reference table, and the correct position is found from the established standardized relative humidity card to obtain the corresponding relative humidity range.

[0047] The relationship between the spore filament distance of the knotweed spores at different relative humidity and the relative humidity is shown in the figure below. Figure 2 As shown in A, the spore morphology of knotweed at different relative humidity and the spore standardized relative humidity scale corresponding to relative humidity are as follows Figure 2As shown in Figure C, the elastic threads of the spores of the knotweed show different shapes under different humidity conditions, which can reflect the humidity changes in the current environment. When the relative humidity is between 50% and 60%, the distance between the elastic threads of the spores is far and stretched out. As the humidity increases, when the relative humidity reaches above 60%, the elastic threads of the spores gradually begin to bend and form an arc. When the relative humidity reaches above 80%, the elastic threads curl into a ball and surround the spores. The elastic threads of the spores can respond to humidity changes and present different shapes because the elastic threads have a double-layer structure. The inner layer of the elastic thread is cellulose, which is tightly arranged and arranged longitudinally with a high density; the outer layer is composed of non-cellulose polysaccharides with a low density. Therefore, when the humidity of the surrounding environment changes, the outer layer of the elastic thread has a lower density and can accommodate more water molecules, so the volume becomes larger, thus reflecting better humidity sensitivity. Due to the different volume changes of the inner and outer layers of the elastic thread, the volume of the outer layer changes more, so the elastic thread bends toward the inner layer when it senses humidity changes. Observe the two elastic threads of the adjacent and curled-up spores of the knotweed grass that bend in the same direction, and measure the farthest distance between the two elastic threads in a certain state. The distance lengths between adjacent elastic threads of the knotweed grass spores are different under different relative humidity conditions. When the relative humidity is low, the elastic threads are in an extended state, and the distance between adjacent elastic threads is longer. When the relative humidity reaches above 85%, the elastic threads curl around the spores, and the distance length is shorter, less than 150μm. Therefore, first record the real images of the spore state under different relative humidity conditions, develop a standardized relative humidity card exclusive to the spores, and by observing the morphology of the spores, find the correct position from the established standardized relative humidity card to obtain the corresponding relative humidity range. By establishing such a relative humidity standard card for each spore, the reliability of the data can be ensured.

[0048] Similarly, the spore mycelium of Equisetum arvense, a plant of the Equisetaceae family, can also show regular morphological changes with changes in the relative humidity of the air, and a corresponding relative humidity standard card can be established.

[0049] Example 2

[0050] According to the results of Example 1, since the spores of the artemisia argyi are small and can respond to the relative humidity of the current surrounding environment, they can be used in microfluidic chips to indirectly measure the humidity in the channels of the microfluidic chips, which is impossible for other humidity sensors. However, when measuring the humidity in the channels of the microfluidic chips, it is necessary to input humid air at a certain speed into the channels. Since the spores of the artemisia argyi are light and easily blown away by airflow, iron is sputtered on the spores of the artemisia argyi by a magnetron sputtering instrument, and magnets are used to fix the spores of the artemisia argyi to prevent them from being blown away by airflow.

[0051] 1. The method of spore sputtering iron is as follows:

[0052] A 3D printer was used to print a square frame of 2×2×0.4cm and 0.2cm thick, which was glued to the coverslip to form a square groove. The spore spike of the knotweed was knocked on the top to sprinkle the spores on the coverslip. The role of the square frame is to prevent the airflow from blowing away the spores during sputtering. Finally, it was fixed on the turntable of the magnetron sputtering instrument and the magnetron sputtering instrument was turned on. First, pre-sputtering was performed at a current of 200mA for 60s, and then iron was deposited at a current of 300mA for 200s. The motor speed was 5. After the sputtering was completed, the spores were observed to turn black.

[0053] 2. A series of characterizations were performed on the spores of the knotweed sputtered with iron by magnetron sputtering, as follows:

[0054] (1) X-ray energy dispersive spectrometer (EDS): A small amount of spores were fixed with 1×1 cm conductive glue, and their surfaces were gold-sprayed before testing. Then, the microscopic morphology of the spores before and after sputtering iron was observed with a scanning electron microscope at a test voltage of 3 kV. The distribution of O, N, and Fe elements of the two spores was tested and analyzed using an X-ray energy dispersive spectrometer at a test voltage of 10 kV.

[0055] (2) Magnetic characterization: Cut a piece of white paper and stick it under a glass slide, and then place the glass slide on a magnet. Then place the spores on the glass slide and observe them under a coaxial light microscope, as shown in the schematic diagram. Figure 3 shown.

[0056] The characterization results are as follows:

[0057] In order to determine whether iron is successfully sputtered on the spores, the EDS spectrum mapping of spores without sputtered iron and spores with sputtered iron is scanned. The results are as follows Figure 4 As shown in A, it can be seen from the EDS spectrum that the iron element can be scanned on the spores with sputtered iron, with a relative content of 71.66%, and the relative content of iron on the spores without sputtered iron is 0%, indicating that iron is successfully sputtered on the elastic wire of the spores. The results show that iron was successfully sputtered on the spores of the knotweed by the magnetron sputtering instrument.

[0058] The spores were placed on a glass slide, a magnet was placed under the glass slide, and a piece of white paper was sandwiched between the glass slide and the magnet to better observe the morphology of the spores. Under the action of the magnetic field, the air above the spores was gently fanned by hand, and it was observed that the spores only rotated in position. Therefore, the spores splashed with iron have magnetic properties and can be fixed on the glass slide, thus avoiding the influence of airflow. When a certain speed of airflow passes through the spores, the position of the spores does not change, but only slightly rotates in direction, and the morphology of the spores does not change ( Figure 4 Bc, Bd). However, when there is no magnetic field, the spores move under the same conditions and even move out of the observation field ( Figure 4Ba, Bb). The results showed that the spores were magnetic, and further indicated that iron was successfully attached to the spores, and that magnets could be used to fix the spores of the knotweed to prevent them from being blown away by airflow in the channels of the microfluidic chip.

[0059] 3. The iron-sputtered spores of the knotweed were subjected to the same experimental conditions as in Example 1 to observe the morphology of the spores at different relative humidities and to establish a relationship diagram between the spore morphology and the relative humidity. The relationship diagram between the spore filament distance and the relative humidity of the knotweed spores at different relative humidities is shown in FIG. Figure 2 As shown in B, the spore morphology of knotweed at different relative humidity and the spore standardized relative humidity scale corresponding to relative humidity are as follows Figure 2 As shown in D, the results prove that the morphological changes of the spores of the knotweed sputtered with iron are not affected, and they still have the ability to respond to different relative humidity changes. The spores of the horsetail plant Equisetum arvense were sputtered with magnetic metal nickel, and they still have the ability to respond to different relative humidity changes.

[0060] Example 3

[0061] By observing the morphological changes of knotweed spores, it is possible to measure the relative humidity in the microfluidic chip channel, which is something other humidity sensors cannot measure.

[0062] Two microfluidic chips of different shapes were used, one was a cross-shaped chip and the other was a cell migration chip. Spores were sent into the channel of the microfluidic chip. At this time, the relative humidity of the channel was low, and the elastic wires of the spores were in an extended state. Air with a certain humidity was introduced, and the elastic wires of the spores felt the increase in the relative humidity in the channel, and the elastic wires became curled. A syringe pump was used to inject the humid air in the syringe into the channel at a certain speed. At this time, the relative humidity in the channel of the microfluidic chip became high. When the syringe pump was paused, the relative humidity in the channel slowly decreased. In the cross-shaped and cell migration microfluidic chip channels, the elastic wires of the spores gradually curled up due to the increase in relative humidity, and as the relative humidity decreased, the elastic wires slowly unfolded. This shape change is reversible, and the changes in relative humidity in the channel can be repeatedly measured.

[0063] Although simulation experiments cannot replace real experiments, they can help to better understand physical processes or phenomena and visualize experimental phenomena. Figure 5 As shown, in order to simulate the laminar flow process of compressible fluid through the channel, COMSOL Multiphysics software is needed. Select three-dimensional space when modeling. After the microfluidic chip model is established, select the material type as PDMS material, and the fluid in the channel is air. Add laminar flow and moisture transport in the air in the physical field part, set the initial relative humidity of the microfluidic chip channel, and the speed and relative humidity of air input.

[0064] The physical field laminar flow interface is used to calculate the velocity field and pressure field of single-phase fluid flow under laminar flow conditions. The Navier-Stokes equations are used to describe the changes in fluid pressure in microfluidic channels.

[0065]

[0066] Combining the two formulas, we can get

[0067]

[0068] Where u is the fluid velocity, p is the fluid pressure, ρ is the fluid density, μ is the dynamic viscosity of the fluid, I is the identity matrix, T is the temperature, and F is the external force acting on the fluid.

[0069] Solve it simultaneously with the continuity equation:

[0070]

[0071] By simulating the moisture transfer through vapor diffusion and convection in humid air, the moisture content changes through the vapor concentration c V The transmission representation is:

[0072]

[0073] Among them, M V is the molar mass of water vapor, c V is the vapor concentration, u is the fluid velocity, g is the gravitational acceleration, is the relative humidity, c sat is the vapor saturation concentration, D is the vapor diffusion coefficient in the air, and G is the humid air source.

[0074] The model verification and parameter analysis were carried out under the same experimental conditions. The initial relative humidity of the microfluidic chip channel was set to 50.9%, the air input speed was 0.11mm / s and the relative humidity was 54.6%, and the change of relative humidity in the pipeline was simulated and analyzed. When t = 0s, the humid air has not entered the channel yet, and the relative humidity in the channel is still 50.9%. When t = 25s, as the air with a relative humidity of 54.6% enters the channel, the relative humidity of the channel near the entrance increases rapidly. Overall, the relative humidity in the channel gradually increases, and there is a gradient change in relative humidity.

[0075] Use a microfluidic flat needle to transport the spores into the microfluidic chip channel, and place them under a biological microscope to observe the position and morphology of the spores. At this time, the relative humidity displayed by the DHT22 temperature and humidity sensor is 50.9%. Fill a 20mL syringe with water and push the water out, then pump it full of air. At this time, the air in the syringe is humid air. Use a syringe pump to slowly push the humid air into the channel at a speed of 0.11mm / s. Measure three times, and the relative humidity displayed by the DHT22 temperature and humidity sensor is 54.6%, 54.6%, and 54.5%, respectively. Take the average value, that is, the relative humidity of the humid air at this time is 54.6%. Observe the morphology of the spores in the microfluidic chip channel before and after the syringe pump is turned on and paused.

[0076] The study assumed that the gases were all ideal gases and was conducted under transient conditions. The results showed that when the injection pump was turned on, the relative humidity increased with time. The relative humidity in the pipeline after a certain period of time was compared with the morphology of the spores in the experimental phenomenon ( Figure 6 ), verifying that the model is correct. Therefore, the relative humidity at this time can be roughly measured based on the morphology of the spores in the channel.

[0077] Example 4

[0078] Production of portable relative humidity measurement device:

[0079] like Figure 7 As shown in A and 7B, the experimental supplies needed for this device are: double-sided tape, spores of knotweed, scissors, plastic wrap, filter membrane, mobile phone microscope, and mobile phone; the production method is as follows: first take a filter membrane, stick the double-sided tape on the filter membrane to form a quadrilateral with a blank in the middle, gently tap the sporangium spike of knotweed to make the spores scatter on the filter membrane, then cover the filter membrane with plastic wrap and cut off the excess part; then stick the mobile phone microscope on the mobile phone camera, first bring the mobile phone microscope close to the mobile phone camera, keep the aperture in the middle of the screen, and press it tightly; finally, stick the filter membrane with double-sided tape and stick it to the lens of the mobile phone microscope. At this time, be careful to lay it flat to avoid focusing.

[0080] Taking advantage of the fact that Artemisia spp. can sense changes in relative humidity in the surrounding environment, a portable relative humidity measuring device was made by combining a mobile phone and a mobile phone microscope, which can detect changes in skin relative humidity. Artemisia spp. spores were placed between plastic wrap and a filter membrane and glued to a mobile phone microscope. The filter membrane can transfer the external humidity to the area around the spores, and the morphology of Artemisia spp. can be observed through the mobile phone camera ( Figure 7C) to measure the relative humidity. Before testing, the spores are in an expanded state. When the finger is close to the filter membrane, the humidity inside and outside the filter membrane is different. The humidity is transferred from the outside of the device to the inside of the device. The humidity of the finger is transferred to the surrounding of the spores through the filter membrane. As the humidity increases, the spores sense the change in relative humidity and curl up. By comparing the humidity changes of the finger surface with and without gloves on the measuring device, the experimental results are as follows Figure 7 As shown in D, it shows that the changes in spores can be observed through the mobile phone camera. A portable relative humidity measurement device was successfully made using the spores of Artemisia argyi, which can be used in life to detect changes in skin relative humidity.

[0081] In combination with Examples 1 to 4, the present invention utilizes the characteristic that spores of the Equisetaceae family respond to changes in relative humidity, and further applies sputtered iron on their surfaces to achieve the measurement of relative humidity in a small space, and provides a green and environmentally friendly visual portable relative humidity measurement device, which is used to measure the relative humidity of the skin ( Figure 8 ).

Claims

1. A method for measuring relative humidity in micrometer-level space, characterized in that: The following steps are involved: S1. Record the morphology of spores of Equisetaceae plants under different relative humidity, and establish a standard relative humidity diagram corresponding to the morphology of spores of Equisetaceae plants and relative humidity; S2. Fix the spores of the Equisetaceae plant in S1 in the micrometer-scale space to be measured, observe the morphology of the spores of the Equisetaceae plant, and obtain the relative humidity of the micrometer-scale space to be measured by comparing with the standard relative humidity chart of S1.

2. The method according to claim 1, characterized in that: Step S1 also includes recording the distances between adjacent elastic threads of Equisetaceae spores at different relative humidities, and establishing a standard relative humidity table corresponding to the distances between adjacent elastic threads of Equisetaceae spores and relative humidity.

3. The method according to claim 1, characterized in that: The spores of the Equisetaceae plant in step S1 are spores of Herba Lycopodii.

4. The method according to claim 1, characterized in that: Step S2 is to fix the spores of the Equisetaceae plant in the micrometer-scale space to be measured by magnetism.

5. The method according to claim 4, characterized in that: A magnetic metal nanolayer is attached to the surface of the spores of the Equisetaceae plant.

6. The method according to claim 5, characterized in that: The magnetic metal is selected from one of iron and nickel.

7. The method according to claim 6, characterized in that: The magnetic metal is iron.

8. The method according to claim 1, characterized in that: The micron-scale space is a microfluidic chip.

9. The method according to claim 8, characterized in that: The microfluidic chip is a cross-shaped microfluidic chip or a cell migration chip.

10. A visual portable relative humidity measuring device based on the method according to any one of claims 1 to 9, characterized in that: The method comprises a smart device with a camera, a portable microscope, and spores of Equisetaceae plants; the portable microscope is fixed on the camera of the smart device, and the spores of Equisetaceae plants are fixed on the objective lens surface of the portable microscope; the spores of Equisetaceae plants contact the object to be tested, and the morphology of the spores of Equisetaceae plants is observed and photographed by the smart device to detect the relative humidity of the object to be tested.

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