Low-coupling flexible self-powered multi-mode sensor and preparation method and application thereof

Abstract

The invention provides a low-coupling flexible self-powered multi-mode sensor and a preparation method and application thereof, and belongs to the technical field of flexible electronic materials. Comprising a temperature sensing layer, a pressure sensing layer and a humidity sensing layer which are stacked in sequence. The temperature sensing layer is made of a PEDOT: PSS / MWCNT composite material and outputs a temperature response signal through resistance change; the pressure sensing layer is formed by combining a PDMS layer with a micro-nano structure and a PET layer, and outputs a pressure response voltage signal based on a triboelectric effect; the humidity sensing layer is composed of PVA / CA composite matrix and EGaIn liquid metal, and humidity response signals are output through hygroscopicity induced resistance change. The sensor realizes simultaneous detection of three physical quantities of temperature, pressure and humidity, has low coupling degree among the sensing units, and can be applied to the fields of robot interaction, wearable health monitoring and environment monitoring.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible electronic materials, and in particular to a low-coupling flexible self-powered multimodal sensor and a preparation method and application thereof. Background Art

[0002] With the rapid development of human-computer interaction, wearable health monitoring, and environmental sensing technologies, multimodal sensors, as key devices for acquiring multiple physical parameters, have attracted widespread attention. In particular, in the field of flexible electronics, sensors that can simultaneously sense multiple environmental parameters such as temperature, pressure, and humidity have important application value.

[0003] Currently, research on multimodal sensors focuses primarily on the integration of multiple sensing functions and signal decoupling. For example, CN116147796B discloses a self-powered flexible sensor based on pressure and temperature. This sensor generates a potential difference through a thermoelectric self-powered layer, and combines the resistance changes of a thermal resistance sensing layer and an interlocking pressure-sensitive layer to achieve pressure and temperature decoupling. CN117607216A proposes a flexible humidity and pressure sensor that is resistant to cross-interference. This sensor uses a humidity sensing unit to provide a humidity-resistance signal, and a pressure sensing unit to provide a pressure-voltage signal, thereby reducing cross-interference.

[0004] Regarding temperature and pressure dual-mode sensing, CN116499522B discloses a highly sensitive flexible temperature and pressure dual-mode decoupling and sensor. This sensor consists of a first flexible electrode, a pressure sensing layer, a second flexible electrode, and a temperature sensing layer stacked in sequence. Material selection and structural design prevent crosstalk between the temperature and humidity sensing layers. CN115490912B proposes a method for resisting temperature interference in flexible piezoresistive sensing materials. This method utilizes conductive nanowires and conductive nanoparticles to form a special composite conductive network, and applies a hydrophobic coating to the surface to suppress temperature and humidity interference.

[0005] In the area of ​​self-powered multimodal sensing, CN111786590A discloses a triboelectric nanogenerator and flexible sensor that can simultaneously detect temperature and pressure. This sensor uses a single-electrode triboelectric nanogenerator to detect pressure and utilizes the temperature-dependent variation of electrode resistance to detect temperature. This design achieves self-powering without the need for an external power source and exhibits excellent flexibility and stability.

[0006] However, the multimodal sensors in the existing technology still have the following problems: First, there is obvious coupling interference between the sensing signals of most sensors, and complex algorithms are needed for signal decoupling, which not only increases the energy consumption and computational burden of the system, but also reduces the sensing accuracy; second, most sensors are overly dependent on external power supply, which limits their application in portable and wearable devices; third, the existing multimodal sensors are often complex in structural design and the preparation process is cumbersome, making it difficult to achieve large-scale production; fourth, when simultaneously sensing the three parameters of temperature, pressure and humidity, the existing technology makes it difficult to achieve low signal coupling while ensuring high sensitivity of each parameter.

[0007] Therefore, there is an urgent need to develop a flexible multimodal sensor with a simple structure, controllable preparation process, low signal coupling characteristics and self-powered, so as to meet the requirements of wearable devices for lightweight, flexibility and long-term stability, and improve the reliability and accuracy of practical applications. Summary of the Invention

[0008] In order to solve the problems of mutual interference among the sensing signals of multimodal sensors, the need for complex algorithm decoupling, high energy consumption and computational burden, and excessive dependence on external power supplies, and realize a flexible multimodal sensor with self-powered, low signal coupling interference and high reliability, the present invention provides a low-coupling flexible self-powered multimodal sensor and its preparation method and application.

[0009] To achieve the above object, the present invention provides the following solutions:

[0010] A low-coupling flexible self-powered multimodal sensor comprises a temperature sensing layer, a pressure sensing layer, and a humidity sensing layer stacked in sequence, wherein:

[0011] The temperature sensing layer is made of a conductive composite material and outputs a temperature response signal through resistance changes;

[0012] The pressure sensing layer is composed of a flexible polymer layer with a micro-nano structure and a base material layer, and outputs a pressure response voltage signal based on the triboelectric effect;

[0013] The humidity sensing layer is composed of hydrophilic conductive hydrogel and outputs a humidity response signal by inducing resistance change through hygroscopicity.

[0014] Preferably, the temperature sensing layer and the humidity sensing layer serve as the positive and negative electrodes of the pressure sensing layer respectively, and the impedance level of the temperature sensing layer is lower than the total impedance level of the pressure sensing layer.

[0015] Preferably, the temperature sensing layer is made of a conductive polymer / carbon nanotube composite material and has a negative temperature coefficient sensitivity in the range of 25 to 80°C.

[0016] Preferably, the conductive polymer / carbon nanotube composite material is a PEDOT:PSS / MWCNT composite material, the temperature sensitivity of which is improved by adding a polar solvent, and is prepared by a solution coating process.

[0017] Preferably, the flexible polymer layer of the pressure sensing layer is a PDMS layer, the base material layer is a PET layer, and the pressure sensing layer has segmented pressure sensitivity within the range of 0.2 to 120 kPa.

[0018] Preferably, the micro-nano structure of the PDMS layer is replicated by a sandpaper template method to enhance the triboelectric effect and improve the pressure sensing ability.

[0019] Preferably, the hydrophilic conductive hydrogel of the humidity sensing layer comprises a hydrophilic polymer matrix and a liquid metal conductive filler, and the resistance change rate is linearly correlated with the humidity within the range of 40% to 95% RH.

[0020] Preferably, the hydrophilic polymer matrix is ​​a PVA / CA composite matrix, and the liquid metal conductive filler is EGaIn.

[0021] The present invention also provides a method for preparing the above-mentioned low-coupling flexible self-powered multimodal sensor, comprising the following steps:

[0022] S1, dispersing carbon nanotubes and a polar solvent in a conductive polymer solution, coating the solution on a base material layer using a solution coating process and curing the solution to obtain the temperature sensing layer;

[0023] S2. forming a micro-nano structure on the surface of the flexible polymer by a sandpaper template method, and then compounding it with a base material layer to obtain the pressure sensing layer;

[0024] S3, mixing and dispersing the hydrophilic polymer solution and the liquid metal, and then solidifying and forming the mixture to obtain the humidity sensing layer;

[0025] S4. Using the humidity sensing layer as a substrate, compounding the pressure sensing layer and the temperature sensing layer in sequence, and connecting electrodes to obtain a low-coupling flexible self-powered multimodal sensor.

[0026] The present invention also provides an application of the above-mentioned low-coupling flexible self-powered multimodal sensor in robot interaction, wearable health monitoring and environmental monitoring.

[0027] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0028] (1) Through the physical separation design of the three functional layers, the self-decoupling of the three sensor signals of temperature, pressure, and humidity is achieved, avoiding the problem of mutual interference between traditional multimodal sensor signals. Various types of signals can be directly distinguished without complex algorithms, and the detection error is controlled within 2.5%, which greatly reduces the complexity and computational burden of signal processing.

[0029] (1) The triboelectric effect is used to achieve self-powered pressure detection. The temperature and humidity detection is based on the principle of passive resistance change. The entire device can work continuously without an external power supply, solving the problem of traditional sensors being overly dependent on external power and reducing system energy consumption.

[0030] (3) Through the synergistic effect of PEDOT:PSS / MWCNTs composite material, micro-nanostructured PDMS triboelectric layer and PVA / CA / EGaIn hydrogel layer, high sensitivity and wide range of multimodal sensing are achieved, and the temperature detection sensitivity reaches -0.055℃ -1 , pressure detection covers 0.2~120kPa, and humidity detection responds linearly in the range of 40%~95%RH.

[0031] (4) The multi-layer structure constructed based on flexible materials such as PDMS and PVA gives the sensor excellent flexibility and reliability. The bending radius is less than 5 mm, and it can be conformally attached to human skin or the surface of a robot. After 2000 pressure cycles and 25 temperature cycle tests, the signal attenuation is less than 5%, meeting the needs of long-term stable operation.

[0032] (5) The modular design enables simultaneous detection of temperature, pressure, and humidity, and can be widely used in electronic skin, wearable health monitoring equipment, and human-machine collaborative robots, meeting the application requirements of lightweight, flexibility, and long-term stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 A schematic structural diagram of a low-coupling, flexible, self-powered multimodal sensor provided in Example 1 of the present invention;

[0035] Figure 2 Schematic diagram of the sensing mechanism of the low-coupling flexible self-powered multimodal sensor provided in Example 1 of the present invention;

[0036] Figure 3Flow chart for preparing the PEDOT:PSS / MWCNTs temperature sensing layer provided in Example 2 of the present invention;

[0037] Figure 4 This is a scanning electron microscope image of the PEDOT:PSS / MWCNTs temperature sensing layer provided in Example 2 of the present invention;

[0038] Figure 5 This is a scanning electron microscope image of the micro-nanostructure on the PDMS surface provided in Example 2 of the present invention;

[0039] Figure 6 Flow chart for preparing the PVA / CA / EGaIn humidity-sensitive hydrogel provided in Example 2 of the present invention;

[0040] Figure 7 A voltage response curve diagram of the pressure sensing layer to different pressures provided in Example 2 of the present invention;

[0041] Figure 8 A sensitivity curve diagram of the pressure sensing layer provided in Example 2 of the present invention;

[0042] Figure 9 A sensitivity curve diagram of the temperature sensing layer provided in Example 2 of the present invention;

[0043] Figure 10 A curve showing the change in relative resistance ΔR / R0 of the humidity sensing layer provided in Example 2 of the present invention at different humidity gradients;

[0044] Figure 11 This is a comparison chart of the stability performance of the low-coupling flexible self-powered multimodal sensor under different conditions provided by Example 2 of the present invention; wherein, Figure 11 Figure a is a comparison of the stability performance of the low-coupling flexible self-powered multimodal sensor under 2000 pressure cycles. Figure 11 Figure b is a comparison of the stability performance of the low-coupling flexible self-powered multimodal sensor under 25 temperature cycles. Figure 11 Figure c is a comparison chart of the stability performance of the low-coupling flexible self-powered multimodal sensor under 5 humidity cycles.

[0045] Figure 12 This is a graph showing the pressure response of the pressure sensing layer to different bending angles of the finger provided in Example 3 of the present invention;

[0046] Figure 13 A curve showing the change in relative resistance ΔR / R0 of the temperature sensing layer under normal human breathing provided by Example 3 of the present invention;

[0047] Figure 14 A curve showing the change in relative resistance ΔR / R0 of the humidity sensing layer provided in Example 3 of the present invention when monitoring the humidity of human skin;

[0048] Figure 15 This is a graph showing the simultaneous detection of temperature, pressure and humidity in the environment by a low-coupling flexible self-powered multimodal sensor provided in Example 3 of the present invention attached to a manipulator.

[0049] Description of reference numerals:

[0050] 1. Temperature sensing layer; 2. Pressure sensing layer; 3. Humidity sensing layer. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] Example 1

[0054] like Figure 1 and Figure 2 As shown, this embodiment provides a low-coupling flexible self-powered multimodal sensor including a temperature sensing layer 1, a pressure sensing layer 2, and a humidity sensing layer 3 stacked in sequence.

[0055] The temperature sensing layer 1 is made of a conductive polymer / carbon nanotube composite material, specifically a PEDOT:PSS / MWCNT composite material. This composite material is prepared using a solution coating process by adding a polar solvent to increase temperature sensitivity. The temperature sensing layer 1 has a negative temperature coefficient of sensitivity in the range of 25-80°C and a sensitivity of -0.055°C in the range of 2-40°C. -1 , the sensitivity is -0.004℃ in the range of 40~80℃ -1 That is, as the temperature increases, the resistance value decreases, so that a temperature response signal can be output through the resistance change.

[0056] The pressure sensing layer 2 consists of a flexible polymer layer with a micro-nano structure and a base material layer. The flexible polymer layer is a PDMS layer, and the base material layer is a PET layer. The micro-nano structure of the PDMS layer is replicated by the sandpaper template method. This micro-nano structure can enhance the triboelectric effect and improve the pressure sensing ability. The pressure sensing layer 2 has a segmented pressure sensitivity in the range of 0.2 to 120 kPa, a sensitivity of 8.254 V / kPa in the range of 0.2 to 5 kPa, and a sensitivity of 0.063 V / kPa in the range of 5 to 120 kPa. It outputs a pressure response voltage signal based on the triboelectric effect. When external pressure acts on the sensor surface, the contact area between the micro-nanostructured PDMS layer and the PET layer changes, generating a corresponding tribovoltage signal.

[0057] The humidity sensing layer 3 is composed of a hydrophilic conductive hydrogel, which contains a hydrophilic polymer matrix and a liquid metal conductive filler. The hydrophilic polymer matrix is ​​a PVA / CA composite matrix, and the liquid metal conductive filler is EGaIn. The humidity sensing layer 3 exhibits a resistance change rate ΔR / R0 that is linearly correlated with humidity within the RH range of 40% to 95%. This layer outputs a humidity response signal through hygroscopically induced resistance changes. As ambient humidity increases, the hydrophilic hydrogel absorbs moisture, causing its resistance to change, thereby enabling humidity sensing.

[0058] In the structural design of this multimodal sensor, the temperature sensing layer 1 and the humidity sensing layer 3 serve as the positive and negative electrodes for the pressure sensing layer 2, respectively. The impedance of the temperature sensing layer 1 (in the MΩ range) is lower than the total impedance of the pressure sensing layer 2 (in the GΩ range). This design enables the three sensing functions to operate in the same device with low coupling, meaning that the sensing signals have minimal mutual interference and can independently output their respective response signals.

[0059] This low-coupling, flexible, self-powered multimodal sensor achieves simultaneous detection of three parameters: temperature, pressure, and humidity through a layered structural design. The temperature sensing layer 1 is based on the resistive thermal effect, the pressure sensing layer 2 is based on the triboelectric effect, and the humidity sensing layer 3 is based on the resistance change caused by moisture absorption. These three different working mechanisms enable the sensor to distinguish different environmental stimuli and output corresponding electrical signals. Because the pressure sensing layer 2 is based on the triboelectric effect, it can generate a voltage signal without the need for an external power supply, thus achieving self-powered characteristics. At the same time, the overall construction of flexible materials gives the sensor good flexibility and conformability, making it suitable for multi-parameter monitoring on various curved surfaces and in dynamic environments.

[0060] Example 2

[0061] This embodiment provides a method for fabricating a low-coupling, flexible, self-powered, multimodal sensor. The sensor fabricated by this method includes a temperature sensing layer, a pressure sensing layer, and a humidity sensing layer stacked in sequence. This sensor has the same structure as the low-coupling, flexible, self-powered, multimodal sensor described in Example 1, and shares the same functional characteristics and operating principles.

[0062] S1. Dispersing carbon nanotubes and polar solvents in a conductive polymer solution, coating the solution on a base material layer and curing the solution to obtain a temperature sensing layer.

[0063] Specifically, refer to Figure 3 First, PEDOT:PSS / MWCNTs were synthesized: 80 mg of multi-walled carbon nanotubes (MWCNTs) and 40 mg of TritonX-100 (40 mg) were dispersed in 20 ml of deionized water, and then ultrasonically stirred for 2.5 h. 0.1 g of dimethyl sulfoxide (DMSO) was added as a polar solvent to 2 g of PEDOT:PSS solution. Secondly, the PET film was pretreated: 1.5×2.5 cm cut PET films were treated with ethanol, deionized water and acetone, respectively. The PET film was then cleaned at a power of 20 W for 30 seconds using an O2 plasma cleaner. Finally, the dispersion was evenly coated on the PET substrate by a spin coating process, and dried at 60°C for 2 hours to complete curing, thereby obtaining a temperature sensing layer with a negative temperature coefficient effect. The temperature sensing layer exhibits good temperature response characteristics in the range of 25 to 80°C. As Figure 4 As shown, the uniform and non-aggregated dispersion of MWCNTs in the PEDOT:PSS matrix indicates that MWCNTs are fully mixed with PEDOT:PSS.

[0064] like Figure 9 As shown in the figure, the sensitivity curve of the temperature sensing layer presents a segmented characteristic. In the range of 20-40℃, ΔR / R0 decreases rapidly with increasing temperature, and the corresponding sensitivity factor is -0.055 / ℃; after entering the range of 40-80℃, the decrease of ΔR / R0 slows down, and the sensitivity factor is -0.004 / ℃, which clearly shows that the temperature sensing layer has different sensitivities in different temperature ranges, reflecting its response characteristics to temperature changes. It can sensitively reflect temperature changes in a wide temperature range (20-80℃) according to the differences in temperature ranges, and adapt to the needs of different temperature detection scenarios.

[0065] S2. Forming a micro-nanostructure on the surface of a flexible polymer using a sandpaper template method, and then compounding it with a base material layer to obtain a pressure sensing layer:

[0066] Take an appropriate amount of PDMS prepolymer and curing agent and mix them in a ratio of 10:1. After stirring thoroughly, pour the mixture on the pre-treated sandpaper surface (sandpaper particle size is 600 mesh), vacuum the PDMS for 30 minutes and then pour it onto the sandpaper surface, and then cure it at 80°C for 2 hours. After the PDMS is completely cured, carefully peel off the sandpaper to obtain a PDMS film with a micro-nano structure on the surface. The PDMS film is compounded with the PET base material layer to form a pressure sensing layer based on the triboelectric effect. The pressure sensing layer has segmented pressure sensitivity in the range of 0.2 to 120 kPa. Figure 5 As shown, the multi-level wrinkling structure of sandpaper was replicated onto the PDM film by a simple casting method, which effectively enhanced the surface roughness of the triboelectric layer.

[0067] like Figure 7 As shown in the figure, when the pressure sensing layer is subjected to different pressures, the voltage changes in a pulsed manner. The greater the pressure, the higher the pulse peak value. This intuitively shows that it can sensitively reflect the pressure size by voltage in a wide range from small to high pressure. Secondly, as Figure 8 As shown in the figure, the sensitivity curve of the pressure sensing layer presents a segmented characteristic. In the low pressure range (about 0-5kPa), the voltage rises rapidly with the increase of pressure, and the corresponding sensitivity reaches 8.254V / kPa; after entering the high pressure range (about 5-120kPa), the voltage growth trend slows down, and the sensitivity is 0.063V / kPa, which clearly shows that the pressure sensing layer has different sensitivities in different pressure ranges, corresponding to the characteristic of 0.2-120kPa segmented pressure sensitivity.

[0068] S3. Mixing and dispersing the hydrophilic polymer solution and the liquid metal, and then solidifying and forming the mixture to obtain a humidity sensing layer.

[0069] like Figure 6 As shown, 1 g of polyvinyl alcohol (PVA) was dissolved in deionized water and stirred at 90°C for 2 h to prepare a PVA solution. 0.4 g of cellulose acetate (CA) was then dissolved in 1 ml of deionized water and slowly added to the PVA solution with continuous stirring. The solution was cooled to 60°C for 30 min. EGaIn was then dispersed in the PVA / CA solution using an ultrasonic cell disruptor for 2 h to form a suspension with the EGaIn. The mixture was then poured into a mold and maintained at 50°C for 12 h. Finally, the PVA / CA / EGaIn film was carefully peeled from the mold to obtain a hydrophilic conductive hydrogel humidity sensing layer. The resistance change rate of this humidity sensing layer was linearly correlated with humidity within the 40% to 95% RH range.

[0070] Specifically, such as Figure 10As shown, the relative resistance ΔR / R0 of the humidity sensing layer changes over time (seconds) under different humidity gradients (RH = 40% to 90%). As the humidity gradually increases from 40% to 90%, ΔR / R0 shows an overall downward trend, and the curve segments corresponding to different humidity levels are clearly distinguished. When the corresponding humidity environment switches, ΔR / R0 responds quickly and tends to be stable, clearly demonstrating that the humidity sensing layer can sensitively reflect differences in ambient humidity through changes in relative resistance. This verifies that it has the ability to effectively sense humidity changes and output corresponding resistance response signals within the 40% to 90% RH humidity range, adapting to the needs of humidity detection applications.

[0071] S4. Use the humidity sensing layer as the substrate, and sequentially compound the pressure sensing layer and the temperature sensing layer, and connect the electrodes to obtain a low-coupling flexible self-powered multimodal sensor:

[0072] The humidity sensing layer prepared in S3 serves as the base substrate, upon which the pressure sensing layer prepared in S2 and the temperature sensing layer prepared in S1 are sequentially stacked. Conductive silver paste is used to connect copper electrodes to the surfaces of the temperature and humidity sensing layers, respectively, forming a complete circuit connection. Finally, the entire sensor is encapsulated and protected with a flexible encapsulation material, resulting in a low-coupling, flexible, self-powered, multimodal sensor.

[0073] Reference Figure 11 The a in the figure shows the initial, 1000 cycle, and 2000 cycle states respectively. It can be seen that under different cycle numbers, the voltage pulse pattern is highly consistent, and the peak value and frequency have no obvious attenuation, which shows that after a large number of cycles, the pressure sensing layer has a stable and reliable signal output based on the triboelectric effect, and can continuously and accurately respond in long-term dynamic pressure detection scenarios. Figure 11 As shown in Figure b, as the temperature changes periodically, ΔR / R0 shows regular pulse fluctuations, and the curve shape and change amplitude in 25 cycles have a high degree of overlap, indicating that the resistance-temperature response characteristics of the temperature sensing layer are stable, and the sensitivity and linearity are not easy to drift during repeated temperature measurements, which is suitable for long-term temperature monitoring needs. Figure 11 As shown in Figure c, the humidity switches between 50% RH and 95% RH. Each time the humidity increases, ΔR / R0 decreases rapidly; when the humidity decreases, ΔR / R0 recovers simultaneously. The curves for the five cycles are highly consistent, verifying the excellent reversibility of moisture absorption and desorption in the humidity sensing layer. The consistent response during repeated testing demonstrates its ability to stably cope with variable humidity environments, ensuring the reliability of long-term humidity monitoring.

[0074] Through this fabrication method, the temperature sensing layer and humidity sensing layer serve as the two electrodes of the pressure sensing layer, respectively. The impedance of the temperature sensing layer is significantly lower than the combined impedance of the pressure sensing layer, achieving low coupling between the three sensing functions. The resulting multimodal sensor can simultaneously detect changes in temperature, pressure, and humidity in the environment and output corresponding electrical signals. Constructed from fully flexible materials, the sensor exhibits excellent flexibility and conformability, making it suitable for multi-parameter monitoring on various curved surfaces and in dynamic environments.

[0075] Example 3

[0076] This embodiment provides an application of a low-coupling flexible self-powered multimodal sensor in robot interaction, wearable health monitoring, and environmental monitoring.

[0077] The basic structure of this low-coupling, flexible, self-powered multimodal sensor is the same as that of Example 1, comprising a temperature sensing layer, a pressure sensing layer, and a humidity sensing layer stacked in sequence. The temperature sensing layer is constructed from a PEDOT:PSS / MWCNT composite material, the pressure sensing layer comprises a micro-nanostructured PDMS layer and a PET layer, and the humidity sensing layer comprises a hydrophilic conductive hydrogel composed of a PVA / CA composite matrix and EGaIn liquid metal conductive filler.

[0078] In robotic interaction applications, this multimodal sensor can be installed on the robot's fingers, palms, and other contact areas to simultaneously sense the temperature, pressure, and humidity of the object it touches. By acquiring this multimodal information, the robot can more accurately determine the material, state, and characteristics of the object it touches, enabling more intelligent object grasping and manipulation. For example, when grasping fragile objects, the sensor can monitor the applied pressure in real time to avoid excessive squeezing; when handling temperature-sensitive items, the handling strategy can be adjusted based on temperature feedback; and when handling slippery objects, the gripping force can be adjusted based on humidity information. This multimodal sensing capability enables robots to interact with their environment more naturally, just like humans, through tactile information.

[0079] like Figure 15 As shown in the figure, the low-coupling, flexible, self-powered, multimodal sensor attached to a manipulator simultaneously detects ambient temperature, pressure, and humidity. Temperature sensing: ΔR / R0 decreases when approaching hot water (i) and increases when moving away (ii). Corresponding changes occur when holding (v) and releasing (vi) the hot water cup, demonstrating its sensitive detection of temperature fluctuations. Pressure sensing: The voltage rises sharply when holding the hot water cup (iii) and decreases when releasing (iv), reflecting its response to pressure. Humidity sensing: ΔR / R0 changes with ambient humidity during operations such as approaching hot water, verifying its humidity detection capability. Combined with the manipulator holding different water cups, the sensor's multimodal simultaneous monitoring capabilities are demonstrated, adapting to complex environmental perception tasks and providing multi-dimensional data for the manipulator's environmental interaction.

[0080] like Figure 12 As shown in the figure, the pressure sensing layer of the low-coupling flexible self-powered multimodal sensor responds to pressure at different finger bending angles (30°, 45°, and 90°). As the finger bending angle increases from 30° to 90°, the voltage pulse peak gradually increases, and the pulse pattern remains stable at each angle. Combined with the diagram of the glove finger in the corresponding bending state, it is intuitively demonstrated that the pressure sensing layer can accurately capture the pressure differences caused by slight changes in the finger angle. The sensitive reflection of the voltage signal verifies its ability to detect dynamic and multi-posture pressure, making it suitable for application scenarios such as gesture recognition and human-computer interaction that require the perception of subtle pressure changes.

[0081] In wearable health monitoring applications, this sensor can be integrated into smart bracelets, smart clothing, or medical patches. The sensor adheres to the surface of human skin and simultaneously monitors surface temperature, contact pressure, and skin moisture, providing multi-dimensional data for health assessment. Surface temperature can be used to monitor fever and detect abnormalities in thermoregulation; pressure sensing can be used for motion posture monitoring and sleep quality assessment; and humidity monitoring can be used to monitor sweat secretion and assist in assessing exercise intensity and metabolic status. Because the sensor is self-powered, it requires no frequent charging, making it suitable for long-term wear and monitoring. Its flexibility allows it to conform to the curves of the human body, improving wearer comfort and signal acquisition stability.

[0082] like Figure 13 As shown in the figure, the temperature sensing layer of the low-coupling flexible self-powered multimodal sensor responds to the relative resistance ΔR / R0 during normal human breathing. The curve fluctuates regularly with the respiratory cycle (inhalation-expiration cycle): during inhalation, due to factors such as airflow temperature, ΔR / R0 changes to a positive value and then falls back; during exhalation, ΔR / R0 continues to decrease to a trough, and the curve shape is highly consistent within multiple respiratory cycles. This intuitively demonstrates that the temperature sensing layer can accurately capture subtle temperature changes caused by airflow temperature, heat exchange, etc. during the breathing process, and sensitively reflect the respiratory rhythm through relative resistance changes. It verifies that it has the ability to detect tiny temperature fluctuations and output stable response signals in application scenarios related to biological signs (such as respiratory monitoring), and can be used to assist in tasks such as health monitoring.

[0083] like Figure 14The figure shows the relative resistance ΔR / R0 variation characteristics of the humidity sensing layer of a low-coupling flexible self-powered multimodal sensor for monitoring human skin humidity. Initially, skin humidity corresponds to a certain ΔR / R0 value. After washing hands, ΔR / R0 further changes due to increased skin moisture. After applying hand cream, skin humidity changes, and ΔR / R0 again fluctuates accordingly. Combined with the skin and humidity display in different states, the figure intuitively demonstrates that the humidity sensing layer can accurately capture the difference in humidity of human skin before and after daily activities (washing hands, applying skin care products), and sensitively reflects skin humidity changes through relative resistance changes. This verifies its ability to sense tiny humidity fluctuations and output stable response signals in application scenarios such as wearable health monitoring (such as real-time skin humidity detection), providing effective technical support for skin condition monitoring.

[0084] In environmental monitoring applications, this sensor can be deployed indoors and outdoors to build a distributed environmental parameter monitoring network. The sensor simultaneously monitors ambient temperature, air pressure changes, and humidity, providing data support for meteorological monitoring, smart homes, and industrial environmental monitoring. In agricultural greenhouses, it can be used to precisely control the growing environment; in cultural relic protection sites, it can monitor the stability of the preservation environment; and in industrial production environments, it can monitor equipment operating status and environmental safety parameters. The sensor's self-powered nature reduces battery replacement and maintenance costs, making it suitable for large-scale deployment. Its flexibility allows it to be installed on a variety of irregular surfaces, expanding its application scenarios.

[0085] Through applications in the above three fields, this low-coupling flexible self-powered multimodal sensor fully demonstrates its technical advantages of simultaneous multi-parameter detection, self-powered and flexible bonding, providing new technical solutions for intelligent interaction, health monitoring and environmental perception.

[0086] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0087] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A low-coupling flexible self-powered multimodal sensor, characterized in that: It includes a temperature sensing layer, a pressure sensing layer and a humidity sensing layer stacked in sequence, wherein: The temperature sensing layer is made of a conductive composite material and outputs a temperature response signal through resistance changes; The pressure sensing layer is composed of a flexible polymer layer with a micro-nano structure and a base material layer, and outputs a pressure response voltage signal based on the triboelectric effect; The humidity sensing layer is composed of hydrophilic conductive hydrogel and outputs a humidity response signal by inducing resistance change through hygroscopicity.

2. A low-coupling flexible self-powered multimodal sensor according to claim 1, characterized in that: The temperature sensing layer and the humidity sensing layer serve as positive and negative electrodes of the pressure sensing layer respectively, and the impedance level of the temperature sensing layer is lower than the total impedance level of the pressure sensing layer.

3. The low-coupling flexible self-powered multimodal sensor according to claim 1, characterized in that: The temperature sensing layer adopts a conductive polymer / carbon nanotube composite material and has a negative temperature coefficient sensitivity within the range of 25 to 80°C.

4. The low-coupling flexible self-powered multimodal sensor according to claim 3, characterized in that: The conductive polymer / carbon nanotube composite material is a PEDOT:PSS / MWCNT composite material, the temperature sensitivity of which is improved by adding a polar solvent, and is prepared by a solution coating process.

5. The low-coupling flexible self-powered multimodal sensor according to claim 1, characterized in that: The flexible polymer layer of the pressure sensing layer is a PDMS layer, the base material layer is a PET layer, and the pressure sensing layer has segmented pressure sensitivity within the range of 0.2 to 120 kPa.

6. The low-coupling flexible self-powered multimodal sensor according to claim 5, characterized in that: The micro-nano structure of the PDMS layer is replicated by a sandpaper template method to enhance the triboelectric effect and improve the pressure sensing ability.

7. The low-coupling flexible self-powered multimodal sensor according to claim 1, characterized in that: The hydrophilic conductive hydrogel of the humidity sensing layer comprises a hydrophilic polymer matrix and a liquid metal conductive filler, and the resistance change rate is linearly correlated with the humidity within the range of 40% to 95% RH.

8. The low-coupling flexible self-powered multimodal sensor according to claim 1, characterized in that: The hydrophilic polymer matrix is ​​a PVA / CA composite matrix, and the liquid metal conductive filler is EGaIn.

9. A method for preparing a low-coupling flexible self-powered multimodal sensor according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, dispersing carbon nanotubes and a polar solvent in a conductive polymer solution, coating the solution on a base material layer using a solution coating process and curing the solution to obtain the temperature sensing layer; S2. forming a micro-nano structure on the surface of the flexible polymer by a sandpaper template method, and then compounding it with a base material layer to obtain the pressure sensing layer; S3, mixing and dispersing the hydrophilic polymer solution and the liquid metal, and then solidifying and forming the mixture to obtain the humidity sensing layer; S4. Using the humidity sensing layer as a substrate, compounding the pressure sensing layer and the temperature sensing layer in sequence, and connecting electrodes to obtain a low-coupling flexible self-powered multimodal sensor.

10. Application of the low-coupling flexible self-powered multimodal sensor according to any one of claims 1 to 8 in robot interaction, wearable health monitoring and environmental monitoring.

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