Strain regulation system, method and applications based on flexible sensors and actuators

Abstract

The present disclosure relates to the technical field of flexible sensor and actuator, and proposes a strain adjustment system, method and application based on flexible sensor and actuator. The strain adjustment system based on flexible sensor and actuator comprises a flexible bending sensor, a flexible actuator and a processor, the flexible bending sensor and the flexible actuator are arranged on the surface of an object to be detected respectively; the bending of the surface of the object is detected by the flexible bending sensor; the processor controls the flexible actuator to generate corresponding bending strain according to the bending detection result. The present disclosure improves the performance of the flexible bending sensor and the flexible actuator by improving the preparation method of the flexible bending sensor and the flexible actuator, and combines the flexible bending sensor and the flexible actuator to form an integrated system, which can realize integrated operation from signal monitoring to feedback control.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of flexible sensor and actuator, and particularly, to a strain adjustment system, method and application based on flexible sensor and actuator. BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute the prior art.

[0003] In modern sensor technology, flexible bending sensors and flexible actuators show broad application prospects in many fields due to their unique performance. Flexible bending sensors can convert strain into electrical signals, have soft and stretchable characteristics, and are suitable for various complex use scenarios. However, there are still many problems in the actual application of flexible bending sensors in the prior art: first, the sensitivity of flexible bending sensors is low under small strain, and the resistance change rate is not high, which limits their application in precision measurement. Second, the preparation process of such sensors is relatively complex, and the required materials are expensive, making it difficult to achieve large-area production. In addition, poor environmental adaptability is also a significant drawback, as the sensor is difficult to work stably in various complex environments, and the flexible bending sensor cannot closely adhere to the surface of the monitored object, affecting its measurement accuracy and stability.

[0004] Flexible actuators can transform external stimuli (such as electrical stimuli) into alloy lattice changes, thereby causing strain, and are widely used in various intelligent devices and systems. However, existing flexible actuators also face many technical bottlenecks. For example, they are usually unable to complete the corresponding strain through small current stimulation, limiting their application in low-power devices. Flexible actuators made by existing chemical preparation methods are difficult to withstand large loads, and the generated strain is too small, limiting the application environment. Currently, most existing flexible sensors can only be used for monitoring signals, and the range of actuator movement and the type of strain are also greatly limited, which cannot meet the diversified application needs.

[0005] In summary, the existing flexible bending sensors and flexible actuators have obvious deficiencies in sensitivity, preparation process, cost, environmental adaptability, and functional integration. Although flexible bending sensors and flexible actuators have wide applications, there is a lack of systems that combine the two in the prior art. SUMMARY

[0006] The present disclosure proposes a strain adjustment system, method and application based on a flexible sensor and an actuator to solve the above problems. The performance of the flexible bending sensor and the flexible actuator is improved by improving the preparation method of the flexible bending sensor and the flexible actuator, and the flexible bending sensor and the flexible actuator are combined to form an integrated system, and the integrated operation from signal monitoring to feedback control is realized innovatively.

[0007] In order to achieve the above object, the present disclosure adopts the following technical solutions:

[0008] One or more embodiments provide a strain adjustment system based on a flexible sensor and an actuator, comprising: a flexible bending sensor, a flexible actuator and a processor, the flexible bending sensor and the flexible actuator are arranged on the surface of an object to be detected respectively;

[0009] The bending of the surface of the object is detected by the flexible bending sensor; the processor controls the flexible actuator to generate a corresponding bending strain after judging the bending detection result.

[0010] One or more embodiments provide a strain adjustment method of a strain adjustment system based on a flexible sensor and an actuator, comprising the following steps:

[0011] The bending of the surface of the object is detected based on the flexible sensor;

[0012] The detection result is compared with a set threshold value;

[0013] The actuator is controlled to generate a corresponding bending strain according to the comparison result of the detection data.

[0014] One or more embodiments provide an application of the strain adjustment system based on the above flexible sensor and actuator in an auxiliary plant growth system;

[0015] The flexible bending sensor is attached to the upper surface of the leaf, and the flexible bending sensor generates a resistance change when the leaf generates a bending strain, and then a voltage change signal is obtained;

[0016] The flexible actuator is attached to the back of the leaf, and generates a bending strain when an electric stimulus is obtained.

[0017] Compared with the prior art, the present disclosure has the following beneficial effects:

[0018] This disclosure presents a sensing and feedback actuation system by combining a highly sensitive, low-hysteresis, and flexible bending sensor that adapts to the surface of an object with a flexible actuator that can generate large bending strain with a small current stimulus and withstand a large load. The system determines the bending by setting a threshold value for the sensor signal change. When the detected bending exceeds the threshold, the processor outputs high and low level signals via a relay, rapidly controlling the flexible actuator to generate the corresponding bending strain. This closed-loop control mechanism ensures that the system can respond and adjust quickly, maintaining the desired bending state of the object's surface.

[0019] By organically combining flexible bending sensors with flexible actuators, not only is the performance of individual devices improved, but efficient and precise strain regulation is also achieved through a closed-loop control system, demonstrating significant technological advantages and broad application potential.

[0020] The advantages of this disclosure, as well as its additional advantages, will be described in detail in the following specific embodiments. Attached Figure Description

[0021] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute a limitation thereof.

[0022] Figure 1 This is a flowchart illustrating the fabrication process of a flexible bending sensor provided in one or more embodiments of this disclosure;

[0023] Figure 2 This is a schematic diagram of the three-layer structure of a flexible bending sensor provided in one or more embodiments of this disclosure;

[0024] Figure 3 This is a SEM (scanning electron microscope) image of the electrode layer of a flexible bending sensor provided in one or more embodiments of this disclosure;

[0025] Figure 4 This describes the rate of change of resistance under bending strain of a flexible bending sensor provided in one or more embodiments of this disclosure.

[0026] Figure 5 This refers to the response time and recovery time of the flexible bending sensor provided in one or more embodiments of this disclosure;

[0027] Figure 6 This is the minimum detection limit of the flexible bending sensor provided in one or more embodiments of this disclosure;

[0028] Figure 7 This describes the spatial variation of strain in the flexible actuator provided in Embodiment 3 of this disclosure when it contracts under energization.

[0029] Figure 8This describes the temperature change over time of the flexible actuator provided in Embodiment 3 of this disclosure during the initial power-on activation and secondary activation processes.

[0030] Figure 9 This describes the change in surface temperature of the flexible actuator provided in Embodiment 3 of this disclosure as a function of the applied current.

[0031] Figure 10 This refers to the bending angle of the flexible actuator provided in Embodiment 3 of this disclosure when different currents are applied;

[0032] Figure 11 This is the maximum load to which the flexible actuator provided in Embodiment 3 of this disclosure applies different currents;

[0033] Figure 12 This is a schematic diagram of a sensing feedback-assisted plant growth system composed of a flexible bending sensor and an actuator, as provided in Embodiment 1 of this disclosure. Detailed Implementation

[0034] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0035] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0036] It should be noted that the terminology used herein is for descriptive purposes only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. It should be noted that, without conflict, the various embodiments and features within those embodiments can be combined with each other. The embodiments will now be described in detail with reference to the accompanying drawings.

[0037] To address some of the technical problems existing in the background art, this disclosure presents a method for fabricating a flexible bending sensor and a flexible actuator. The flexible bending sensor of this disclosure has high sensitivity, low hysteresis, and is flexible enough to adapt to object surfaces; the flexible actuator can generate large bending strain with small current stimulation and can withstand large loads. Both devices overcome some of the aforementioned limitations, broadening their application scenarios. Furthermore, this disclosure combines the two into a strain regulation system based on the flexible sensor and actuator, realizing sensing and feedback execution. The sensor is responsible for the sensing function. After the microcontroller collects the sensing signal, the 80C51 processor judges the data, setting the sensor signal change as a threshold for judgment. The judgment result is used by the 80C51 processor to control the high and low level output of a relay to control the flexible actuator. Specific embodiments are described below.

[0038] Example 1

[0039] In one or more of the technical solutions disclosed in the embodiments, such as Figures 1 to 12 As shown, a strain regulation system based on a flexible sensor and actuator includes: a flexible bending sensor, a flexible actuator, and a processor, wherein the flexible bending sensor and the flexible actuator are respectively disposed on the surface of the object to be detected;

[0040] The bending of the object's surface is detected by a flexible bending sensor; after the processor judges the bending detection result, it controls the flexible actuator to generate the corresponding bending strain.

[0041] Further technical solutions, flexible bending sensors, include:

[0042] From bottom to top, the layers are: bottom film, electrode film, and top film.

[0043] The bottom layer is a TPU film used as an adhesive tape; the electrode film is a silver electrode film; the top layer is a TPU / CNTs spun film, which is a TPU spun film wrapped with a carbon nanotube film.

[0044] The bottom layer, TPU film, is an encapsulation layer mainly used to fix the object being applied and achieve adhesion with the sensor. The TPU sticker is very thin and will not affect the strain range, thus avoiding inflexible strain.

[0045] The electrode film, or electrode layer, is fixed at both ends of the underlying film. This design allows for flexible changes; the uneven microstructure design improves sensitivity to different strains. SEM images of the electrode surface are shown below. Figure 3 As shown; it also improves the sensitivity to small-range strains and reduces the detection limit, as shown in the test results. Figure 4 At the same time, the sensitivity of the three-layer membrane also improves the response speed, such as Figure 5 As shown.

[0046] The flexible bending sensor provided in this embodiment employs a three-layer film structure, where the bottom TPU film, electrode film, and top TPU / CNTs spun film work together to ensure extremely high sensitivity, accuracy, and a very fast response time. The silver electrode film with a sandpaper-like microstructure and the three-dimensional tubular carbon nanotubes with excellent electrical properties further enhance the sensor's detection capabilities. This high-sensitivity design enables the sensor to accurately detect minute bending changes, ensuring the system provides precise data when monitoring the bending of object surfaces in real time.

[0047] The flexible bending sensor in this embodiment can adapt to a variety of surfaces and environments: its flexibility and high adaptability allow it to be applied to various complex surfaces, without being limited by specific shapes or materials. This characteristic makes the system promising for a wide range of applications in multiple fields, such as medical devices, robotics, wearable devices, and electronic skin.

[0048] A further technical solution, a flexible actuator, includes: a nickel-titanium shape memory alloy as a substrate, and a flexible material wrapped around the substrate;

[0049] Optionally, the flexible material used for wrapping is silicone rubber;

[0050] In this embodiment, the flexible actuator uses a nickel-titanium shape memory alloy as the matrix and is wrapped with flexible silicone rubber, making the actuator more flexible when generating bending strain. The SMA shape memory alloy can recover its predetermined shape when heated; the SMA shape memory alloy can provide a large force under small DC stimulation that does not affect the external environment, enabling the actuator to be applied to multiple load-bearing scenarios and provide a stable actuation effect.

[0051] A further technical solution involves attaching a flexible sensor and a flexible actuator to both sides of the object in the orthogonal direction of bending. The flexible sensor can identify the bending condition in real time when the object bends, while the flexible actuator assists in actuating the bending strain.

[0052] Furthermore, the strain adjustment method based on the strain adjustment system of the aforementioned flexible sensor and actuator includes the following steps:

[0053] Detecting the curvature of an object's surface using flexible sensors;

[0054] Compare the search results with the set threshold;

[0055] The actuator is controlled to generate corresponding bending strain based on the comparison results of the test data.

[0056] In this embodiment, the flexible sensor can accurately detect the curvature of an object's surface in real time, providing high-precision curvature data. This real-time detection capability ensures the system can respond quickly to external changes. By comparing the detection results with preset thresholds, the system can automatically determine whether strain adjustment is needed. This automated judgment and adjustment process reduces manual intervention and improves work efficiency. Precise control is achieved; the system controls the actuator to generate corresponding bending strain based on the comparison results of the detection data, ensuring the accuracy and reliability of the adjustment process. The actuator can precisely adjust the degree of curvature as needed, allowing the object's surface to reach the expected curvature state. By precisely controlling strain adjustment, excessive or insufficient curvature is avoided, protecting the object being adjusted.

[0057] Example 2

[0058] Based on Example 1, this example provides a method for fabricating a flexible bending sensor as described in Example 1, such as... Figures 1 to 6 As shown, it includes the following steps:

[0059] Step 1: Dissolve TPU in an organic solvent, stir magnetically, pour into a petri dish, and place in an oven to dry the surface solvent, obtaining a TPU elastic adhesive film as the bottom film;

[0060] Step 2: Dissolve polyurethane in an organic solvent and prepare TPU spun film using electrospinning process. After hydrophilic treatment, place it in a well dispersed multi-walled carbon nanotube solution so that carbon nanotube conductive material is wrapped in the TPU spun film to obtain TPU / CNTs spun film.

[0061] Step 3: Prepare a silicone rubber film with a microporous structure, and deposit a layer of silver as a silver electrode by magnetron sputtering;

[0062] Step 4: Attach two silver electrodes to the bottom film, and then cover the two silver electrodes with a TPU / CNTs spun film to obtain the prepared flexible bending sensor.

[0063] In this embodiment, the TPU spun film exhibits excellent breathability and does not react when applied to an object surface. By winding TPU nanospun fiber structures with conductive carbon nanotubes, both breathability and sensitivity are improved. Furthermore, the electrospinning process is simple and allows for large-area fabrication.

[0064] Step 1 is the preparation of the bottom layer film, which includes: dissolving TPU in an organic solvent, stirring it thoroughly with magnetic force, pouring it into a glass petri dish, and placing it in an oven to dry the surface solvent, thereby obtaining a TPU elastic adhesive film as the bottom layer film;

[0065] Specifically, the organic solvent can be any one or a mixture of several organic solvents selected from N,N-dimethylformamide, tetrahydrofuran, and acetone;

[0066] Optionally, the oven temperature can be 60 degrees Celsius;

[0067] Step 2, the method for preparing the TPU / CNTs spun film for the functional layer, includes:

[0068] Step 21, Preparation of conductive solution: Place multi-walled carbon nanotubes into a glass bottle, add an oily dispersant for carbon nanotubes, add deionized water to cover the powder, seal the glass bottle and then perform ultrasonic treatment to obtain a well-dispersed multi-walled carbon nanotube solution.

[0069] Optionally, the glass bottle can be sealed with sealing adhesive;

[0070] One drop of the carbon nanotube oily dispersant can be added to the glass bottle.

[0071] Optionally, the ultrasonic treatment can be performed by placing a sealed glass bottle in an ultrasonic bath and ultrasonically treating it for 60 minutes, followed by ultrasonic treatment with a pulse signal for 30 minutes.

[0072] Step 22: Prepare the spinning solution by dissolving polyurethane (TPU) in an organic solvent and stirring it magnetically until dissolved. Prepare a TPU spinning film using electrospinning process on the obtained spinning solution and then treat the surface of the spinning film with ions to make it hydrophilic.

[0073] Specifically, the organic solvent is the same as in step 1, and can be any one or a mixture of several organic solvents selected from N,N-dimethylformamide, tetrahydrofuran, and acetone;

[0074] The thickness of the spun film can be prepared to be 100 μm;

[0075] Optionally, the TPU spun film can be treated with a polydopamine solution to make it hydrophilic;

[0076] An achievable technical solution, a method for preparing a TPU spinning solution, specifically involves using granular polyurethane (1185A) as a solute to obtain a solution with a concentration of 8-28wt%, magnetically stirring at 200-500rpm for 8h to obtain a spinning solution, with the temperature controlled at 60-90℃.

[0077] Preferably, the concentration of the TPU spinning solution is 18 wt%.

[0078] An achievable technical solution for preparing TPU spun film is as follows: TPU fiber film is prepared by electrospinning, with a spinning speed of 1-1.5 ml / h, a voltage of 12KV-18KV, a receiving distance of 12-18 cm, and a spinning duration of 2-6 h.

[0079] TPU polyurethane is non-toxic after spinning and has good biocompatibility. It is breathable and does not easily cause moisture problems when worn or applied to objects for a long time. The TPU film prepared by electrospinning has a unique three-dimensional skeleton. The microstructure prepared by this process has a porous three-dimensional skeleton, which provides excellent breathability, facilitates the exchange of heat and cold between the applied object and the external environment, and improves the comfort of the application. At the same time, the preparation cost of this microstructure is low, the preparation area can be large, and the process is simple and widely used, which can realize substantial mass application.

[0080] Step 23: Immerse the hydrophilically treated TPU spun film in an ultrasonically dispersed multi-walled carbon nanotube solution, seal the bottle opening with sealing glue, and perform ultrasonic treatment to obtain a TPU / CNTs spun film as a functional layer.

[0081] Specifically, the hydrophilically treated TPU spun film is immersed in multi-walled carbon nanotube (CNT) solutions of different concentrations and subjected to ultrasonic treatment for 30-60 minutes, so that the multi-walled carbon nanotubes are wound around the TPU spun film to obtain a TPU / CNTs spun film.

[0082] One specific implementation example, a method for preparing TPU / CNTs spun films from TPU spun films, is as follows:

[0083] (a) Quantitatively dilute multi-walled carbon nanotubes to obtain multi-walled carbon nanotube solutions of different concentrations;

[0084] (b) Soak the hydrophilically treated TPU spun film in multi-walled carbon nanotube solutions of different concentrations and sonicate for 2-6 hours for later use;

[0085] (c) The soaked TPU spun film was ultrasonically treated in a multi-walled carbon nanotube solution for 45 min with a 10 min interval, and repeated twice for later use.

[0086] (d) Soak the TPU film after ultrasonic treatment in step (c) for another 45 minutes to obtain a TPU / CNTs nanofiber membrane.

[0087] In the above scheme, the TPU spun film immersed in the multi-walled carbon nanotube solution is placed in an ultrasonic environment, through which conductive materials can be permeated;

[0088] In step 4, for electrode preparation, silicone rubber is stirred evenly in a 1:1 ratio and spin-coated onto a sandpaper template and dried to obtain a silicone rubber film with a microporous structure. A layer of silver is deposited by magnetron sputtering to serve as a silver electrode.

[0089] Specifically, the A and B agents of silicone rubber (PDMS) are mixed in a 1:1 mass ratio and stirred evenly. The mixture is then dripped into a glass petri dish and spin-coated evenly. After the surface dries, a 200nm layer of silver is magnetron sputtered.

[0090] The specific process for preparing the silver electrode in step 4 is as follows:

[0091] (a) Mix PDMS A and B components in a 1:1 ratio and stir thoroughly with a dropper;

[0092] (b) Place the PDMS mixture in a vacuum chamber to remove inner air bubbles and keep the solution homogeneous for later use;

[0093] (c) Cut an appropriate size of 800-grit sandpaper, lay it flat on the glass plate, and slowly pour in the PDMS mixture;

[0094] (d) Using a spin coating process, with a spin coating speed of 200 m / s and a spin coating time of 30 s, the sandpaper surface was evenly coated with the mixture and then placed in a 60℃ oven to dry for 1 hour.

[0095] (e) A silver target was sputtered onto the PDMS surface using a magnetron sputtering process with a power of 40W and a sputtering time of 10min. After sputtering, a soft silver electrode with a microstructure on the surface was obtained.

[0096] The flexible bending sensor prepared by the above method includes, from bottom to top, a bottom film, an electrode film and a top film; the bottom film is a TPU film used as an adhesive tape, the electrode film is a silver electrode film, and the top film is a spun carbon nanotube film.

[0097] The three-layer film prepared above is assembled, with a TPU film as the bottom layer, electrodes as the middle layer, and a TPU / CNTs spun film as the top layer. This assembled device not only ensures high sensitivity under high and low strain conditions, but its design is also more suitable for various application scenarios.

[0098] In the aforementioned flexible bending sensor, the strain distance at both ends is larger than that in the middle under small strain, resulting in a better response. Therefore, with electrodes at both ends, the protruding parts of the electrodes first contact the functional layer under small strain, forming a conductive path and generating a resistance change signal. Under large strain, most of the protruding parts of the electrodes contact the TPU / CNTs spun film. As the bending angle increases, the recessed silver electrodes within the microstructure contact the TPU / CNTs spun film, forming more conductive paths and further reducing the resistance. The sandpaper-like microstructure on the electrode surface, the electrospun three-dimensional microstructure, and the overall structural design of the sensor all contribute to improving the sensor's sensitivity.

[0099] Example 3

[0100] This embodiment provides a method for preparing a flexible actuator as described in Embodiment 1, such as... Figures 7 to 11 As shown, it includes the following steps:

[0101] Step 1: Mix reagent A and reagent B of PDMS at a ratio of 1:10, stir well, place in a vacuum chamber, remove air bubbles by vacuuming, and obtain PDMS solution.

[0102] Step 2: Using nickel-titanium shape memory alloy as the substrate, encapsulate it with PDMS solution, and dry it to obtain an SMA actuator with a soft outer shell.

[0103] In step 1, PDMS A and B reagents are doped at a ratio of 1:10, stirred for 10 minutes, and then placed in a vacuum chamber to remove air bubbles.

[0104] Nickel-titanium shape memory alloy (SMA) is a material with a shape memory effect;

[0105] In some embodiments, the nickel-titanium shape memory alloy can be selected with a diameter of 0.8 mm and a cutting length of 5 cm;

[0106] In step 2, the method for encapsulating the PDMS solution with the nickel-titanium shape memory alloy is as follows:

[0107] Step 21: Spin-coat the prepared PDMS solution onto a culture dish to a thickness of 0.8-1.6 mm;

[0108] Step 22: Before the PDMS on the petri dish is completely cured, a nickel-titanium shape memory alloy is laid on top. Then, in the same way as in step 21, a layer of PDMS is spin-coated on the other side of the nickel-titanium shape memory alloy to obtain a nickel-titanium shape memory alloy encapsulating the PDMS solution. The alloy is then dried in a 60°C oven to obtain an SMA actuator with a soft outer shell.

[0109] In this embodiment, a nickel-titanium shape memory alloy that can be subjected to external stimuli to change stress is used as the matrix. It can remember the corresponding shape in various application scenarios and achieve strain that conforms to the scenario.

[0110] In some embodiments, the method for setting the memory shape of nickel-titanium shape memory alloy can be: bending martensitic SMA at room temperature into a specific shape, keeping the shape unchanged, and annealing it at 200°C for 20 seconds under a hot heat gun to obtain an actuator SMA substrate with memory shape.

[0111] The annealing temperature and annealing time can be determined according to specific circumstances.

[0112] In other embodiments, the SMA wire can be bent into a U-shape and heated uniformly at 300°C for 5-8 seconds with a hot air gun, so that the SMA wire remembers the U-shape.

[0113] After the PDMS coats the SMA evenly, the drying method can be: put it in a 60℃ oven and dry for 40 minutes to obtain an SMA actuator with a soft outer shell.

[0114] In the above scheme, the principle of the SMA actuator is that the SMA metal wire, after being heated and electrically stimulated, undergoes strain contraction, restoring its original memory shape to the state it was in when bending the object, thereby achieving the purpose of assisting the strain of flexible objects. The flexible actuator in this embodiment is also simple to manufacture, can be mass-produced, and its thickness can be changed according to the application.

[0115] The performance of flexible actuators depends on application requirements. The actuator needs to undergo bending strain. The load capacity and the relationship between power supply and strain rate can be determined by testing. Compared with chemical actuators, SMA actuators have a larger strain range and stronger load capacity, which can greatly broaden the application scenarios.

[0116] There are various types and fabrication methods for flexible actuators. Using SMA (Silicone Magnetite) as the actuating element, based on the mature industrialization of SMA wire, rather than chemical methods, is highly suitable for applications on biological surfaces such as plants. To visually represent the changes in actuator strain, such as... Figure 6 The diagram illustrates the spatial changes before and after the actuator response. Based on the characteristics of SMA (Strained Machining Matrix), the magnitude of the DC current has a significant impact on the strain rate of the SMA metal, such as... Figure 7 As shown. To achieve the performance of assisted strain on plant leaves, the actuator thickness was varied, and the maximum load under different DC currents was tested, such as... Figure 8 As shown.

[0117] Example 4

[0118] Based on Example 2, this example provides a specific implementation scheme of the fabrication method of the flexible bending sensor of Example 2, including the following steps:

[0119] (A1) Preparation of TPU spinning solution: Particulate polyurethane (1185A) was used as solute to obtain a solution with a concentration of 8-28wt%. The solution was magnetically stirred at 200-500rpm for 8h to obtain a spinning solution. The temperature was set to 60-90℃ to obtain a uniform spinning solution.

[0120] (A2) Preparation of TPU spinning film: TPU spinning film was prepared by electrospinning at a spinning speed of 1-1.5 ml / h, a voltage of 12KV-18KV, a receiving distance of 12-18 cm, and a spinning duration of 4 h.

[0121] (A3) Hydrophilic treatment of TPU spinning film: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, and disperse it by ultrasonication for 30min. Immerse the TPU spinning film prepared in (A2) in the buffer solution, sonicate for 20min, and soak for 4h. Then take it out and dry it in a dryer at 60℃ for later use.

[0122] (A4) Preparation of TPU / CNTs spinning film: Weigh 30mg of CNTs powder and add 24ml of deionized water. Disperse the film by ultrasonication for 30min. Then, soak the TPU spinning film in multi-walled carbon nanotube solution and sonicate it for 45min. Repeat the process twice with a 10min interval to obtain TPU / CNTs nanofiber film.

[0123] (A5) Electrode preparation: Mix PDMS A and B agents in a 1:1 ratio and stir evenly with a dropper. Place the PDMS mixture in a vacuum chamber to remove inner air bubbles and keep the solution uniform. Lay sandpaper flat on a glass plate and slowly pour the PDMS mixture onto it. Use a spin coating process at a speed of 200 m / s for 30 s to spin coat the mixture evenly on the sandpaper surface. Place it in a 60℃ oven to dry for 1 h. Use a magnetron sputtering process to sputter silver target material onto the PDMS surface at a power of 40 W for 10 min. After sputtering, a soft silver electrode with microstructure on the surface is obtained.

[0124] In this embodiment, the performance differences of the flexible sensor obtained by changing the preparation conditions are as follows: the spinning time of the TPU spinning film is 4 hours; the resulting flexible sensor has a moderate thickness and a small tensile modulus.

[0125] Based on Example 3, this example provides a specific implementation of the method for fabricating a flexible actuator according to Example 3, including the following steps:

[0126] (B1) Select SMA metal with a diameter of 0.8mm and cut it to a length of 5cm. Bend the SMA metal wire into a U-shape and heat it evenly at 300℃ for 5-8 seconds with a hot air gun to make the SMA memory U-shape.

[0127] (B2) Mix PDMS A and B agents at a ratio of 1:10, stir evenly with a dropper, put the PDMS mixture into a vacuum chamber to remove inner air bubbles, keep the solution uniform, weigh 2-6g of PDMS to coat the SMA evenly, put it into a 60℃ oven to dry for 40min, and you will get an SMA actuator with a soft outer shell.

[0128] Example 5

[0129] Based on Example 2, this example provides a specific implementation scheme of the fabrication method of the flexible bending sensor of Example 2, including the following steps:

[0130] (A1) Preparation of TPU spinning solution: Particulate polyurethane (1185A) was used as solute to obtain a solution with a concentration of 8%-28%Wt. The solution was magnetically stirred at 200-500rpm for 8h to obtain a spinning solution. The temperature was set to 60-90℃ to obtain a uniform spinning solution.

[0131] (A2) Preparation of TPU spun film: TPU fiber film was prepared by electrospinning at a spinning speed of 1-1.5 ml / h, a voltage of 12KV-18KV, a receiving distance of 12-18 cm, and a spinning duration of 4 h.

[0132] (A3) Hydrophilic treatment of TPU spinning film: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, and ultrasonically disperse for 30min. Immerse the TPU spinning film prepared in (A2) in the buffer solution, ultrasonically for 20min, and after soaking for 4h, take it out and dry it in a dryer at 60℃ for later use.

[0133] (A4) Preparation of TPU / CNTs spinning film: Weigh 30mg of CNTs powder and add 12ml of deionized water. Disperse the film by ultrasonication for 30min. Then, soak the TPU spinning film in multi-walled carbon nanotube solution and sonicate it for 45min. Repeat the process twice with a 10min interval to obtain TPU / CNTs nanofiber film.

[0134] (A5) Electrode preparation: Mix PDMS A and B agents in a 1:1 ratio and stir evenly with a dropper. Place the PDMS mixture in a vacuum chamber to remove inner air bubbles and keep the solution uniform. Lay sandpaper flat on a glass plate and slowly pour the PDMS mixture onto it. Use a spin coating process at a speed of 200 m / s for 30 s to spin coat the mixture evenly on the sandpaper surface. Place it in a 60℃ oven to dry for 1 h. Use a magnetron sputtering process to sputter silver target material onto the PDMS surface at a power of 40 W for 10 min. After sputtering, a soft silver electrode with microstructure on the surface is obtained.

[0135] Compared to Example 4, in this example, during the preparation of the TPU / CNTs spinning film, 30 mg of CNTs powder was weighed and 12 ml of deionized water was used to prepare the solution. The CNTs solution concentration was higher, and under the same ultrasonic preparation time, the conductivity was better and the initial resistance was reduced, which is beneficial to improving the sensitivity.

[0136] The TPU tape is attached to the underlying substrate, the electrodes prepared in (A5) are placed at both ends, and the TPU / CNTs film prepared in (A4) is covered on the electrodes to fix the electrodes at both ends.

[0137] Example 6

[0138] Based on Example 2, this example provides a specific implementation scheme of the fabrication method of the flexible bending sensor of Example 2, including the following steps:

[0139] (A1) Preparation of TPU spinning solution: Particulate polyurethane (1185A) was used as solute to obtain a solution with a concentration of 8-28wt%. The solution was magnetically stirred at 200-500rpm for 8h to obtain a spinning solution. The temperature was set to 60-90℃ to obtain a uniform spinning solution.

[0140] (A2) Preparation of TPU spinning film: TPU spinning film was prepared by electrospinning at a spinning speed of 1-1.5 ml / h, a voltage of 12KV-18KV, a receiving distance of 12-18 cm, and a spinning duration of 4 h.

[0141] (A3) Hydrophilic treatment of TPU spinning film: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, and ultrasonically disperse for 30min. Immerse the TPU spinning film prepared in (A2) in the buffer solution, ultrasonically for 20min, and after soaking for 4h, take it out and dry it in a dryer at 60℃ for later use.

[0142] (A4) Preparation of TPU / CNTs spinning film: Weigh 30mg of CNTs powder and add 6ml of deionized water. Disperse the film by ultrasonication for 30min. Then, soak the TPU spinning film in multi-walled carbon nanotube solution and sonicate it for 45min. Repeat the process twice with a 10min interval to obtain TPU / CNTs nanofiber film.

[0143] (A5) Electrode preparation: Mix PDMS A and B agents 1:1, stir evenly with a dropper, put the PDMS mixture into a vacuum chamber to remove inner air bubbles and keep the solution uniform, lay sandpaper flat on a glass plate, slowly pour the PDMS mixture into the glass plate, use a spin coating process at a speed of 200m / s for 30s, spin coat the mixture evenly on the sandpaper surface, put it into a 60℃ oven to dry for 1h, and use a magnetron sputtering process to sputter silver target material onto the PDMS surface at a power of 40W for 10min. After sputtering, a soft silver electrode with microstructure on the surface is obtained.

[0144] Compared to Examples 4 and 5, in this example, during the preparation of the TPU / CNTs spinning film, 30 mg of CNTs powder was weighed and added to 6 ml of deionized water to prepare a solution. As the concentration of the CNTs solution increased, the CNTs agglomerated and were not easily dispersed, resulting in a drastic change in resistance in a short period of time during the stretching of the spinning film.

[0145] Example 7

[0146] Based on Example 2, this example provides a specific implementation scheme of the fabrication method of the flexible bending sensor of Example 2, including the following steps:

[0147] (A1) Preparation of TPU spinning solution: Particulate polyurethane (1185A) was used as solute to obtain a solution with a concentration of 8%Wt. The solution was magnetically stirred at 200-500rpm for 8h to obtain a spinning solution. The temperature was set to 60-90℃ to obtain a uniform spinning solution.

[0148] (A2) Preparation of TPU spinning film: TPU spinning film was prepared by electrospinning at a spinning speed of 1-1.5 ml / h, a voltage of 12KV-18KV, a receiving distance of 12-18 cm, and a spinning duration of 4 h.

[0149] (A3) Hydrophilic treatment of TPU fiber membrane: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, and disperse it by ultrasonication for 30min. Immerse the TPU spun film prepared in (A2) in the buffer solution, sonicate for 20min, and soak for 4h. Then take it out and dry it in a dryer at 60℃ for later use.

[0150] (A4) Preparation of TPU / CNTs spinning film: Weigh 30mg of CNTs powder and add 24ml of deionized water. Disperse the film by ultrasonication for 30min. Then, soak the TPU spinning film in multi-walled carbon nanotube solution and sonicate it for 45min. Repeat the process twice with a 10min interval to obtain TPU / CNTs nanofiber film.

[0151] (A5) Electrode preparation: Mix PDMS A and B agents 1:1, stir evenly with a dropper, put the PDMS mixture into a vacuum chamber to remove inner air bubbles and keep the solution uniform, lay sandpaper flat on a glass plate, slowly pour the PDMS mixture into the glass plate, use a spin coating process at a speed of 200m / s for 30s, spin coat the mixture evenly on the sandpaper surface, put it into a 60℃ oven to dry for 1h, and use a magnetron sputtering process to sputter silver target material onto the PDMS surface at a power of 40W for 10min. After sputtering, a soft silver electrode with microstructure on the surface is obtained.

[0152] Compared to Examples 4 to 6, in this example, particulate polyurethane (1185A) is used as a solute in the preparation of the TPU spinning solution to obtain a solution with a concentration of 8% wt. The effect is that the spun film has good flexibility, which is suitable for the application environment of micro-stretching and reduces the constraint of the sensor on the object being used.

[0153] Example 8

[0154] Based on Example 2, this example provides a specific implementation scheme of the fabrication method of the flexible bending sensor of Example 2, including the following steps:

[0155] (A1) Preparation of TPU spinning solution: Particulate polyurethane (1185A) was used as solute to obtain a solution with a concentration of 18%Wt. The solution was magnetically stirred at 200-500rpm for 8h to obtain a spinning solution. The temperature was set to 60-90℃ to obtain a uniform spinning solution.

[0156] (A2) Preparation of TPU spun film: TPU fiber film was prepared by electrospinning at a spinning speed of 1-1.5 ml / h, a voltage of 12KV-18KV, a receiving distance of 12-18 cm, and a spinning duration of 4 h.

[0157] (A3) Hydrophilic treatment of TPU spinning film: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, and ultrasonically disperse for 30min. Immerse the TPU spinning film prepared in (A2) in the buffer solution, ultrasonically for 20min, and after soaking for 4h, take it out and dry it in a dryer at 60℃ for later use.

[0158] (A4) Preparation of TPU / CNTs spinning film: Weigh 30mg of CNTs powder and add 24ml of deionized water. Disperse the film by ultrasonication for 30min. Then, soak the TPU spinning film in multi-walled carbon nanotube solution and sonicate it for 45min. Repeat the process twice with a 10min interval to obtain TPU / CNTs nanofiber film.

[0159] (A5) Electrode preparation: Mix PDMS A and B agents 1:1, stir evenly with a dropper, put the PDMS mixture into a vacuum chamber to remove inner air bubbles and keep the solution uniform, lay sandpaper flat on a glass plate, slowly pour the PDMS mixture into the glass plate, use a spin coating process at a speed of 200m / s for 30s, spin coat the mixture evenly on the sandpaper surface, put it into a 60℃ oven to dry for 1h, and use a magnetron sputtering process to sputter silver target material onto the PDMS surface at a power of 40W for 10min. After sputtering, a soft silver electrode with microstructure on the surface is obtained.

[0160] Compared to Examples 4 to 7, in this example, particulate polyurethane (1185A) is used as a solute in the preparation of the TPU spinning solution to obtain a solution with a concentration of 18% wt, which achieves a balance between mechanical properties and soft stretchability.

[0161] Example 9

[0162] Based on Example 2, this example provides a specific implementation scheme of the fabrication method of the flexible bending sensor of Example 2, including the following steps:

[0163] (A1) Preparation of TPU spinning solution: Particulate polyurethane (1185A) was used as solute to obtain a solution with a concentration of 28%Wt. The solution was magnetically stirred at 200-500rpm for 8h to obtain a spinning solution. The temperature was set to 60-90℃ to obtain a uniform spinning solution.

[0164] (A2) Preparation of TPU spinning film: TPU spinning film was prepared by electrospinning at a spinning speed of 1-1.5 ml / h, a voltage of 12KV-18KV, a receiving distance of 12-18 cm, and a spinning duration of 4 h.

[0165] (A3) Hydrophilic treatment of TPU spinning film: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, and disperse it by ultrasonication for 30min. Immerse the TPU spinning film prepared in (A2) in the buffer solution, sonicate for 20min, and soak for 4h. Then take it out and dry it in a dryer at 60℃ for later use.

[0166] (A4) Preparation of TPU / CNTs spinning film: Weigh 30mg of CNTs powder and add 6ml of deionized water. Disperse the film by ultrasonication for 30min. Then, soak the TPU spinning film in multi-walled carbon nanotube solution and sonicate it for 45min. Repeat the process twice with a 10min interval to obtain TPU / CNTs nanofiber film.

[0167] (A5) Electrode preparation: Mix PDMS A and B agents in a 1:1 ratio and stir evenly with a dropper. Place the PDMS mixture in a vacuum chamber to remove inner air bubbles and keep the solution uniform. Lay sandpaper flat on a glass plate and slowly pour the PDMS mixture onto it. Use a spin coating process at a speed of 200 m / s for 30 s to spin coat the mixture evenly on the sandpaper surface. Place it in a 60℃ oven to dry for 1 h. Use a magnetron sputtering process to sputter silver target material onto the PDMS surface at a power of 40 W for 10 min. After sputtering, a soft silver electrode with microstructure on the surface is obtained.

[0168] Compared to Examples 4 to 8, in this example, particulate polyurethane (1185A) is used as a solute in the preparation of the TPU spinning solution to obtain a solution with a concentration of 28% wt. The effect is to obtain a spinning film with stronger mechanical properties and stronger resistance to damage during stretching.

[0169] Example 9

[0170] The strain regulation system of Example 1 can be applied to various aspects such as human body, plant, animal, and human-computer interaction. It has high sensitivity under small strain conditions and is suitable for monitoring minute changes.

[0171] Based on Example 1, this example provides the application of the strain regulation system based on flexible sensors and actuators described in Example 1 in an assisted plant growth system, as shown in Figures 12 and 13.

[0172] A flexible bending sensor is attached to the upper surface of the blade. The flexible bending sensor can generate a change in resistance when the blade undergoes bending strain, and thus obtain a voltage change signal.

[0173] The flexible actuator is attached to the back of the blade, such as... Figure 10 As shown, bending strain is generated when the device is stimulated by an electrical source.

[0174] Furthermore, it also includes a data acquisition circuit. This circuit acquires voltage change signals, and when the transmitted signal reaches a threshold indicating abnormal bending, it executes a judgment. To assist plant growth, the actuator responds, lifting the leaves to their normal position, thus promoting plant growth. The overall plant bending sensing and feedback execution system, such as… Figure 9 As shown.

[0175] In this embodiment, the controller of the acquisition circuit can be an 80C51 microcontroller. It can identify bending signals by acquiring sensor signals and setting thresholds, and at the same time, it can open or close the relay by sending switch signals, thereby controlling the power supply of the actuator and providing targeted feedback to the plant.

[0176] Voltage acquisition is performed using the built-in ADC0804 module of the 80C51 series microcontroller platform, which can achieve 8-bit high-precision signal acquisition. The voltage signal acquired by the ADC0804 is judged by a threshold. The signal that exceeds the voltage threshold, i.e. the bending strain that requires actuator auxiliary compensation, is transmitted to the relay as a switching signal. The relay controls whether the power supply circuit is open.

[0177] Compared to existing application system designs, most application systems can only achieve sensor acquisition and recognition, and can only reflect the values ​​collected by the sensors. However, the sensing feedback-assisted plant growth system composed of flexible bending sensors and flexible actuators can achieve acquisition, recognition and feedback. It processes the acquired signal data, and the actuator adjusts the bending strain of the applied object according to the feedback of abnormal signals, thereby achieving auxiliary adjustment for plant growth.

[0178] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

[0179] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A strain regulation system based on flexible sensors and actuators, characterized in that, include: The system includes a flexible bending sensor, a flexible actuator, and a processor. The flexible bending sensor and the flexible actuator are respectively disposed on the surface of the object to be detected. The bending of the object's surface is detected by a flexible bending sensor; after the processor judges the bending detection result, it controls the flexible actuator to generate the corresponding bending strain. From bottom to top, the layers are: bottom film, electrode film, and top film; the bottom film is a TPU film used as the adhesive tape film. The electrode film is a silver electrode film; the top layer film is a TPU / CNTs spun film, which is a TPU spun film wrapped with carbon nanotubes. The fabrication method of the flexible bending sensor includes the following steps: TPU was dissolved in an organic solvent, magnetically stirred, and then poured into a petri dish. The dish was then placed in an oven to dry the surface solvent, resulting in a TPU elastic adhesive film as the bottom layer. Polyurethane was dissolved in an organic solvent, and a TPU spun film was prepared using an electrospinning process. After hydrophilic treatment, the film was placed in a well-dispersed multi-walled carbon nanotube solution, causing the carbon nanotube conductive material to entangle in the TPU spun film, resulting in a TPU / CNTs spun film. A silicone rubber film with a microporous structure was prepared, and a layer of silver was deposited by magnetron sputtering as a silver electrode. Two silver electrodes were attached to the bottom layer film, and then the TPU / CNTs spun film was covered on the two silver electrodes to obtain the prepared flexible bending sensor. The organic solvent is any one or a mixture of several organic solvents selected from N,N-dimethylformamide, tetrahydrofuran, and acetone; The method for preparing TPU spinning solution by dissolving polyurethane in an organic solvent is as follows: using particulate polyurethane as a solute to obtain a solution with a concentration of 8-28wt%, and magnetically stirring at 200-500rpm for 8h to obtain a spinning solution, with the temperature controlled at 60-90℃. The preparation of TPU spun film is as follows: TPU fiber film is prepared by electrospinning, with a spinning speed of 1-1.5 ml / h, a voltage of 12KV-18KV, a receiving distance of 12-18 cm, and a spinning duration of 2-6 h. The specific process for preparing the silver electrode is as follows: Mix PDMS A and B agents in a 1:1 ratio and stir evenly with a dropper; place the PDMS mixture in a vacuum chamber to remove inner air bubbles and keep the solution uniform, and set aside; cut sandpaper of a set size, lay it flat on a glass plate, and slowly pour the PDMS mixture into it; use a spin coating process with a spin coating speed of 200 m / s and a spin coating time of 30 s to spin coat the sandpaper surface evenly with the mixture, and place it in a 60℃ oven to dry for 1 h; use a magnetron sputtering process to sputter the silver target onto the PDMS surface with a power of 40 W and a sputtering time of 10 min. After sputtering, a soft silver electrode with a microstructure on the surface is obtained.

2. The strain regulation system based on a flexible sensor and actuator as described in claim 1, characterized in that, The flexible actuator comprises a nickel-titanium shape memory alloy as a substrate and a flexible material encapsulating the substrate.

3. The strain regulation system based on a flexible sensor and actuator as described in claim 1, characterized in that: The flexible sensor and the flexible actuator are respectively attached to both sides of the object in the orthogonal direction of bending. The flexible sensor can identify the bending status in real time when the object bends, while the flexible actuator assists in actuating the bending strain.

4. A strain regulation method based on the strain regulation system based on a flexible sensor and actuator as described in any one of claims 1-3, characterized in that: Detecting the curvature of an object's surface using flexible sensors; Compare the search results with the set threshold; The actuator is controlled to generate corresponding bending strain based on the comparison results of the test data.

5. The strain adjustment method of the strain adjustment system based on flexible sensors and actuators as described in claim 4, characterized in that, The method for fabricating a flexible actuator includes the following steps: PDMS A and B reagents were mixed at a ratio of 1:10, stirred evenly, and then placed in a vacuum chamber. The vacuum chamber was evacuated to remove air bubbles, and a PDMS solution was obtained. A nickel-titanium shape memory alloy is used as the matrix, encapsulated in PDMS solution, and dried to obtain an SMA actuator with a soft outer shell.

6. The strain adjustment method of the strain adjustment system based on flexible sensors and actuators as described in claim 5, characterized in that: The method for encapsulating PDMS solution with nickel-titanium shape memory alloy is as follows: Step 21: Spin-coat the prepared PDMS solution onto a culture dish to a thickness of 0.8-1.6 mm; Step 22: Before the PDMS on the petri dish is completely cured, a nickel-titanium shape memory alloy is laid on top. Then, in the same way as in step 21, a layer of PDMS is spin-coated on the other side of the nickel-titanium shape memory alloy to obtain a nickel-titanium shape memory alloy encapsulating the PDMS solution. The alloy is then dried in a 60°C oven to obtain an SMA actuator with a soft outer shell.

7. The application of the strain regulation system based on flexible sensors and actuators as described in any one of claims 1-3 in an assisted plant growth system; A flexible bending sensor is attached to the upper surface of the blade. The flexible bending sensor can generate a change in resistance when the blade undergoes bending strain, and thus obtain a voltage change signal. The flexible actuator is attached to the back of the blade and generates bending strain when it is powered.

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