A triboelectric humidity and pressure dual-mode sensor and its testing method

Abstract

This invention discloses a triboelectric humidity and pressure dual-modal sensor and its testing method. The dual-modal sensor comprises a humidity sensing unit and a pressure sensing unit. The humidity sensing unit comprises a microstructured PVA ion gel and a PET substrate. A wire connected to the PVA ion gel outputs a signal to monitor humidity changes. The pressure sensing unit comprises two upper and lower copper electrodes, with a dielectric layer of magnetic fiber fluff sprayed with PVA ion gel positioned between the two electrodes. When subjected to pressure, the contact area between the fiber fluff and the electrodes increases, generating different electrical signals as the pressure changes. This invention can achieve real-time monitoring of surface pressure and humidity, and has the advantages of high measurement accuracy and long service life. It provides a new approach for intelligent sorting and motion detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to a triboelectric humidity and pressure dual-mode sensor and a testing method thereof. Background Art

[0002] Flexible electronic devices, due to their softness and strong conformability, have attracted widespread attention in numerous fields, including personal health monitoring, health assessment, and activity monitoring. Flexible sensors, as a key technology in this field, have been hailed as the key to unlocking a new digital world, greatly expanding their potential application scenarios and significantly enhancing user interaction experiences. Currently, flexible sensors have demonstrated significant impact in key application areas such as smart homes, health monitoring systems, and wearable devices. Among these sensors, pressure sensors have garnered particular attention due to their wide range of applications, including on-skin electronic devices, robotic human-machine interfaces, and biomedicine. Furthermore, humidity, a critical variable in our daily lives, can provide valuable information about our living environment, medical conditions, and personal health status. Despite this, research on humidity sensors is relatively limited, primarily because changes in humidity often affect sensor sensitivity, limiting their performance.

[0003] Common composite sensors usually integrate multiple sensing units into one sensor, with each sensing unit performing its own function. When working, the values ​​of different physical quantities can be obtained by detecting the signals of each sensing unit, thus realizing the function of detecting multiple physical quantities and having good detection performance. A flexible array humidity and pressure sensor (CN114858339A) implemented by inkjet printing technology integrates humidity and pressure measurement units at the same time without interfering with each other. However, the composite sensor has a multi-layer structure and is therefore relatively complex. Moreover, since the sensor is based on the LC resonance principle, a relatively expensive network analyzer is required as testing equipment. ZnS:Mn and reduced graphene oxide are incorporated into an elastomer to obtain a temperature, humidity and pressure sensor (CN110793676A), which has the advantages of high integration, high resolution and high sensitivity. However, the preparation of the sensor requires processes such as photolithography in semiconductor production, resulting in a complex process and high cost. Moreover, when the sensor detects humidity, the response time takes tens of seconds, the reaction is slow, and the sensitivity of measuring humidity is low, less than 10MΩ / %RH. The principle of detecting humidity by this sensor is based on the increase of graphene oxide capacitance with increasing humidity, but the elastomer PDMS also causes capacitance changes with increasing pressure, which causes the accuracy of the sensor in measuring humidity to decrease in the presence of pressure. The existing temperature and humidity pressure sensor (CN106568539A) also requires processes such as photolithography in semiconductor production for manufacturing. The existing preparation method has prepared porous PDMS flexible pressure sensors with a variety of pore sizes and pore structures. The maximum pressure sensitivity of the capacitive porous PDMS flexible pressure sensor is 0.0658KPa. -1 The use of conductive fillers or increasing the flexibility of the pore structure can increase the pressure sensitivity of porous PDMS flexible pressure sensors, but the sensitivity does not exceed 1.7529KPa. -1 .

[0004] The pressure sensitivity of the graphene-filled flexible pressure sensor (CN114479469A) does not exceed 76.321 kPa -1 , and as the pressure increases, the sensitivity decreases. When the conductive filler is conductive nano-carbon black, carbon nanotubes, graphene, Ag powder, Au powder or silver-coated copper powder, its pressure sensitivity does not exceed 7.29kPa-1. A conductive fabric (CN111609954A) formed of 3,4-ethylenedioxythiophene (EDOT) / sodium polystyrene sulfonate (PSS) is attached to a PDMS substrate to obtain a pressure sensor, but the sensitivity is low. The flexible capacitive pressure sensor (CN115096480A) is filled with carbon nanotubes and MXene, but the pressure sensitivity is also low. The pressure sensitivity of the multilayer composite pressure sensor (CN110501095A) does not exceed 507kPa -1, which is currently the most sensitive pressure sensor. The above existing pressure sensors have limited sensitivity or complex processes when adding temperature and humidity sensing functions.

[0005] Therefore, there is an urgent need to develop a flexible sensor that can effectively detect pressure and humidity, and at the same time has the characteristics of high sensitivity and fast response time, so as to provide a basis for the industrialization of flexible sensing. Summary of the Invention

[0006] The present invention aims to provide a flexible sensor with a simple structure, high sensitivity, fast response time, and strong durability that can effectively detect pressure and humidity, meeting the needs of flexible electronic devices in the fields of intelligent sorting and motion detection. Specifically, the present invention provides a triboelectric humidity-pressure dual-modal sensor and its testing method, which can achieve real-time monitoring of ambient humidity and pressure.

[0007] The present invention is achieved through at least one of the following technical solutions.

[0008] A triboelectric humidity and pressure dual-modal sensor comprises a humidity sensing unit and a pressure sensing unit. The humidity sensing unit comprises a PVA ion gel with a microstructure and a PET substrate. The PVA ion gel with the microstructure is connected to the PET substrate, wherein a wire is connected to the PVA ion gel with the microstructure for outputting an electrical signal. The pressure sensing unit comprises an upper electrode, magnetic fiber fluff sprayed with the PVA ion gel, and a lower electrode. Wires are connected to the upper and lower electrodes for outputting an electrical signal.

[0009] Furthermore, the humidity sensing unit is made of PDMS, and the thickness of the humidity sensing unit is 50 μm-70 μm.

[0010] Furthermore, the PVA ion gel with microstructure is prepared by spin-coating polydimethylsiloxane on a stretched silicone substrate, and releasing the pre-stretching after solidification to naturally form a surface microstructure.

[0011] Furthermore, the PVA ion gel with microstructure and the PET substrate are connected via a silicone adhesive.

[0012] Furthermore, the pressure sensing unit has a thickness of 5 mm to 8 mm.

[0013] Furthermore, the upper electrode and the lower electrode are made of copper.

[0014] Furthermore, the bottom of the magnetic fiber fluff sprayed with PVA ion gel is connected to the lower electrode through a silicone adhesive; the upper electrode is placed on the upper part of the magnetic fiber fluff sprayed with PVA ion gel, and the whole is packaged into a pressure sensing unit using PI film.

[0015] Furthermore, the PET substrate and the upper electrode are connected via a silicone adhesive.

[0016] Furthermore, the resistance of the PVA ion gel with microstructures decreases with the increase of ambient humidity;

[0017] When subjected to pressure, the contact area between the magnetic fiber hairs sprayed with PVA ion gel and the upper electrode increases, generating different electrical signals as the pressure changes.

[0018] A method for testing a triboelectric humidity-pressure dual-modal sensor according to any one of the preceding claims comprises the following steps:

[0019] Step S1: using an electrostatic collection device to record the electrical signal generated by the triboelectric humidity and pressure dual-modal sensor, and converting the original sinusoidal signal into a square wave signal through a signal processing module to improve the signal stability and reduce the complexity of the detection signal;

[0020] Step S2: using a humidity detector to record the ambient humidity, and a pressure detector to record the external pressure applied to the triboelectric humidity-pressure dual-modal sensor;

[0021] Step S3: Based on the output electrical signal and the recorded humidity and pressure, the ambient humidity is represented by voltage change, and the external pressure is represented by capacitance.

[0022] Compared with the existing technology, the testing method of the triboelectric humidity and pressure dual-modal sensor of the present invention has the following beneficial effects:

[0023] (1) In the sensor proposed in the present invention, when the ambient humidity changes, the resistance of the humidity sensing unit changes, and the output voltage signal changes synchronously with the change in humidity. Therefore, by collecting and summarizing the voltage values ​​of different ambient humidity, the functional relationship between ambient humidity and voltage can be obtained.

[0024] (2) The pressure sensing unit of the sensor proposed in the present invention is realized by covering the surface of the fiber hair with an ion gel layer. Therefore, as the pressure increases, the contact area increases, and the capacitance value of the electrode interface also increases. The change in capacitance is directly converted into an electrical signal, enabling the sensor to sense and respond to smaller pressure changes. Since the fiber hair is made of silicone and has elasticity, it has an extremely long service life and extremely high stability, as well as the advantages of self-driven sensing, a wide detection range, and high measurement accuracy.

[0025] (3) The present invention has the characteristics of miniaturization and integration, and can be applied to various scenarios to realize real-time monitoring of humidity and pressure without hindering the movement of objects, providing a theoretical and experimental basis for the development of new flexible electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the structural schematic of the triboelectric humidity and pressure dual-mode sensor of this embodiment;

[0027] Figure 2 Schematic diagram of the working principle of the triboelectric humidity and pressure dual-modal sensor of this embodiment;

[0028] Figure 3 4 is a response diagram of the humidity sensing unit in the triboelectric humidity and pressure dual-modal sensor of this embodiment to the detection of the ambient humidity signal;

[0029] Figure 4 This is a result diagram showing the effect of ambient humidity on the sensitivity of the humidity sensing unit in the triboelectric humidity and pressure dual-modal sensor of this embodiment;

[0030] Figure 5 1 is a diagram showing the results of a durability test of the humidity sensing unit in the triboelectric humidity and pressure dual-modal sensor of this embodiment;

[0031] Figure 6 Graph showing signal test results at different frequencies for the pressure sensing unit in the triboelectric humidity and pressure dual-modal sensor of this embodiment;

[0032] Figure 7 This is a result diagram showing the effect of pressure on the sensitivity of the pressure sensing unit in the triboelectric humidity and pressure dual-modal sensor of this embodiment;

[0033] Figure 8 1 is a graph showing the results of a durability test of a pressure sensing unit in the triboelectric humidity and pressure dual-modal sensor of this embodiment;

[0034] Explanation of the reference numerals: 1 - humidity sensing unit; 11 - PVA ion gel with microstructure; 12 - PET substrate; 2 - pressure sensing unit; 21 - upper electrode; 22 - magnetic fiber fluff sprayed with PVA ion gel; 23 - lower electrode. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application are clearly and completely described. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings:

[0037] like Figure 1The structure of the triboelectric humidity and pressure dual-modal sensor of this embodiment is shown in FIG. The triboelectric humidity and pressure dual-modal sensor includes a humidity sensing unit 1 and a pressure sensing unit 2. The humidity sensing unit 1 includes a microstructured polyvinyl alcohol (PVA) ion gel 11 and a polyethylene terephthalate (PET) substrate 12. The microstructured PVA ion gel 11 and the PET substrate 12 are connected by a silicone adhesive. The microstructured PVA ion gel 11 is connected to a wire for outputting an electrical signal to monitor humidity changes. The pressure sensing unit 2 includes an upper electrode 21, a magnetic fiber fluff 22 sprayed with PVA ion gel, and a lower electrode 23. The upper and lower electrodes 21 and 23 are connected to wires for outputting electrical signals. The magnetic fiber fluff 22 sprayed with PVA ion gel acts as a dielectric layer. When subjected to pressure, the contact area between the fiber fluff and the electrode increases, generating different electrical signals as the pressure changes.

[0038] The PVA ion gel 11 with microstructure is obtained by spin-coating polyvinyl alcohol (PVA) on a pre-stretched substrate (silicone sheet), and releasing the pre-stretched naturally formed surface microstructure after solidification.

[0039] The specific preparation steps of the microstructured PVA ion gel 11 of this embodiment include: dissolving PVA with a molecular weight of 145,000 and a mass of 3g in deionized water, and stirring at 90°C for 2 hours to completely dissolve it. After cooling to 50°C, 2.5 ml of 85% phosphoric acid was added as a crosslinking agent to promote the formation of a stable three-dimensional polymer network. After stirring for 1 hour to thoroughly mix, the PVA solution was coated on a PET substrate to a thickness of approximately 50-70μm, and then cured in a constant temperature oven at 50°C for 8 hours to form the ion gel.

[0040] The specific preparation steps of the magnetic fiber fluff 22 are as follows: 10 ml of polydimethylsiloxane (PDMS) is prepared in a ratio of 1:1 between substrate and curing agent, and after stirring evenly, 6 g of hydroxy iron nanoparticles (500 nm in diameter) and 1 g of neodymium iron boron nanoparticles (2000 mesh) are added. After being thoroughly stirred with an electric stirrer, the mixture is spin-coated on a PET film with a thickness of 0.2 mm. After the spin-coated solution stabilizes, the PET film containing PDMS is placed on top of a strong magnet, and magnetic fiber fluff will grow under the action of the magnetic field. After waiting for 24 hours at room temperature for the PDMS to completely solidify, the fiber fluff can be removed from the PET film. Then, a spray gun is used to spray the PVA solution on the surface of the magnetic fiber fluff 22, and the mixture is placed in a constant temperature oven at 50°C for 8 hours to cure to form an ion gel.

[0041] The bottom of the magnetic fiber fluff 22 sprayed with PVA ion gel is connected to the lower electrode 23 through a silicone adhesive; the upper electrode 21 is placed on the upper part of the magnetic fiber fluff 22 sprayed with PVA ion gel, and the whole is packaged with PI film to form a pressure sensing unit 2.

[0042] The PET substrate 12 is connected to the upper electrode 21 via a silicone adhesive. As humidity increases, the resistance of the microstructured PVA ion gel 11 decreases, causing the electrical signal to vary with humidity. When subjected to pressure, the contact area between the magnetic fiber hairs 22, coated with the PVA ion gel, and the upper electrode 21 increases, generating varying electrical signals as pressure changes.

[0043] As an embodiment, the PVA ion gel 11 with microstructure has an outer dimension of 10 mm×10 mm and a thickness of 50-70 μm. The pressure sensing unit 2 has an overall outer dimension of 10 mm×10 mm and a thickness of 5-8 mm.

[0044] As an embodiment, the upper electrode 21 and the lower electrode 23 are made of copper.

[0045] like Figure 2 As shown, the testing method of the triboelectric humidity and pressure dual-modal sensor specifically includes the following steps:

[0046] Step S1: Using an electrostatic collection device to record the electrical signal generated by the triboelectric humidity and pressure dual-modal sensor, the signal was transmitted to a computer through a programmable electrometer (6514, Keithley, USA) and a data acquisition system (PCI-6289, National Instruments, USA). The original sinusoidal signal was converted into a square wave signal using LabVIEW to improve signal stability and reduce the complexity of the detection signal;

[0047] Step S2: repeatedly placing a weight of a fixed weight on the surface of the triboelectric humidity-pressure dual-modal sensor of this embodiment to apply pressure, and using a humidity detector and a pressure detector to record the ambient humidity and the applied external pressure;

[0048] In step S2, the ambient humidity is recorded using a humidity detection device, and the applied ambient pressure is recorded by a pressure sensor;

[0049] Step S3: Based on the output electrical signal and the recorded humidity and pressure, the ambient humidity is represented by voltage change, and the external pressure is represented by capacitance.

[0050] like Figure 3 FIG. 1 is a schematic diagram of the electrical signal output of the humidity sensor unit of this embodiment at different relative humidity. As the humidity decreases, the voltage signal increases.

[0051] like Figure 4 As shown in the figure, the sensitivity of the humidity sensor unit described in this embodiment is affected by the ambient humidity. When the relative humidity increases from 13.8% to 92%, the voltage sensitivity of the sensor decreases by 26.6 times. It can be seen from the figure that the determination coefficient R 2 Close to 1, showing good linearity.

[0052] like Figure 5 As shown in FIG, the results of the durability test of the humidity sensing unit in the triboelectric humidity and pressure dual-modal sensor of the present invention are shown. Figure 5 a is the test result on the first day under the environment of relative humidity of 80±2%. Figure 5 b is the test result on the second day under the environment of relative humidity of 80±2%. Figure 5 C is the test result in an environment with a relative humidity of 80±2%. The test results show that during the three-day test in the same humidity environment, the voltage change of the electrical signal is stable and there is no obvious attenuation, reflecting the ultra-long service life of this design.

[0053] like Figure 6 As shown in the figure, the signal test results of the pressure sensing unit in the triboelectric humidity and pressure dual-modal sensor described in the present invention at different frequencies are shown. It can be seen that the change amplitude of the capacitor output signal at different frequencies is basically the same, and the frequency has no significant effect on the sensor signal output.

[0054] like Figure 7 As shown in FIG. 1 , the sensitivity of the pressure sensing unit of the present invention is affected by pressure, and the capacitance sensitivity S has good linearity.

[0055] like Figure 8 As shown, Figure 8 FIG. b is a result diagram of the durability test of the pressure sensing unit according to the present invention. Figure 8 a is the signal amplification diagram in the initial stage, Figure 8 Figure c is an amplified view of the final stage signal. Experimental results show that after one hour of continuous pressing, the capacitor output voltage amplitude remains stable at 8.8V, showing no significant attenuation, demonstrating the exceptionally long service life of this design.

[0056] The triboelectric humidity and pressure dual-modal sensor and its testing method proposed in the embodiments of the present invention are characterized by miniaturization and integration. They can detect ambient humidity and pressure without affecting the movement of the host device, providing a theoretical and experimental basis for the development of new flexible electronic devices.

[0057] The specific embodiments described above further illustrate the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is merely a specific embodiment of the present invention and is not intended to limit the present invention. It can also be a reasonable combination of the features described in the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A triboelectric humidity and pressure dual-modal sensor, characterized by: The invention comprises a humidity sensing unit (1) and a pressure sensing unit (2), wherein the humidity sensing unit (1) comprises a PVA ion gel (11) with a microstructure and a PET substrate (12), wherein the PVA ion gel (11) with a microstructure is connected to the PET substrate (12), wherein a wire is connected to the PVA ion gel (11) with a microstructure for outputting an electrical signal; and the pressure sensing unit (2) comprises an upper electrode (21), magnetic fiber hairs (22) sprayed with the PVA ion gel, and a lower electrode (23), wherein wires are connected to the upper electrode (21) and the lower electrode (23) for outputting an electrical signal. The PVA ion gel (11) with microstructure is prepared by spin-coating polydimethylsiloxane on a stretched silica gel substrate, and releasing the pre-stretching after solidification to naturally form a surface microstructure.

2. The triboelectric humidity and pressure dual-modal sensor according to claim 1, characterized in that: The material of the humidity sensing unit (1) is PDMS, and the thickness of the humidity sensing unit (1) is 50 μm-70 μm.

3. The triboelectric humidity and pressure dual-modal sensor according to claim 1, characterized in that: The PVA ion gel (11) with a microstructure and the PET substrate (12) are connected via a silicone adhesive.

4. The triboelectric humidity and pressure dual-modal sensor according to claim 1, characterized in that: The pressure sensing unit (2) has a thickness of 5 mm to 8 mm.

5. The triboelectric humidity and pressure dual-modal sensor according to claim 1, characterized in that: The upper electrode (21) and the lower electrode (23) are made of copper.

6. The triboelectric humidity and pressure dual-modal sensor according to claim 1, characterized in that: The bottom of the magnetic fiber fluff (22) sprayed with PVA ion gel is connected to the lower electrode (23) through a silicone adhesive; the upper electrode (21) is placed on the upper part of the magnetic fiber fluff (22) sprayed with PVA ion gel, and the whole is packaged with a PI film to form a pressure sensing unit (2).

7. The triboelectric humidity and pressure dual-modal sensor according to claim 1, characterized in that: The PET substrate (12) and the upper electrode (21) are connected via a silicone adhesive.

8. The triboelectric humidity and pressure dual-modal sensor according to claim 1, characterized in that: As the ambient humidity increases, the resistance of the PVA ion gel (11) with microstructure decreases; When subjected to pressure, the contact area between the magnetic fiber hairs (22) sprayed with PVA ion gel and the upper electrode (21) increases, and different electrical signals are generated as the pressure changes.

9. A method for testing a triboelectric humidity-pressure dual-modal sensor according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step S1: using an electrostatic collection device to record the electrical signal generated by the triboelectric humidity and pressure dual-modal sensor, and converting the original sinusoidal signal into a square wave signal through a signal processing module to improve the signal stability and reduce the complexity of the detection signal; Step S2: using a humidity detector to record the ambient humidity, and a pressure detector to record the external pressure applied to the triboelectric humidity-pressure dual-modal sensor; Step S3: Based on the output electrical signal and the recorded humidity and pressure, the ambient humidity is represented by voltage change, and the external pressure is represented by capacitance.

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