Ultrahigh-sensitivity integrated capacitive multifunctional sensor and preparation method thereof

Abstract

The invention provides an integrated capacitive multifunctional sensor with ultrahigh sensitivity and a preparation method thereof, belongs to the technical field of flexible sensors, and aims to solve the technical problem that the multifunctional sensor is low in integration level and sensitivity. The integrated capacitive multifunctional sensor comprises a top-layer electrode, a microstructure dielectric layer and a bottom-layer electrode which are stacked from top to bottom, wherein the top-layer electrode and the bottom-layer electrode are provided with conductive leading-out belts; a hole-shaped electrode array consisting of hole-shaped electrode units is arranged on the top layer electrode; the hole-shaped electrode unit comprises an internal annular electrode, an external annular electrode and a connecting electrode; and the internal annular electrode is positioned in the external annular electrode and is communicated with the external annular electrode through the connecting electrode. According to the invention, three measurement functions are integrated in a single sensor, and the sensor has the advantages of high sensitivity, simple structure, low preparation cost, high adaptability and the like. In addition, the three signals can be effectively decoupled and distinguished, and extra circuits and algorithms are not needed.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible sensors, and particularly relates to a capacitive multifunctional sensor. Background Art

[0002] In the past few decades, the research on flexible pressure tactile sensors has achieved great success. Researchers have adopted a series of measures to improve the performance of pressure sensors, such as the microstructure engineering of dielectric layers. However, with the increasing integration and complexity of intelligent devices, pressure sensors require higher sensitivity to capture subtle signals and fast response times to adapt to flexible application scenarios. Therefore, it is an urgent need to achieve pressure sensors with higher sensing performance. Temperature sensors are an important part of flexible sensors other than pressure sensors and play an indispensable role in diagnosing diseases, avoiding accidents, and providing information about the surrounding environment. However, the temperature sensors studied in the past usually require additional sensing materials, have complex manufacturing processes, and low sensitivity, making it difficult to integrate them with other types of sensors. Therefore, it is urgent to design a simple, highly sensitive, and integrated temperature sensor to meet the integrated and diversified development of intelligent robots.

[0003] Despite the significant progress in tactile sensing technology, proximity sensing technology still has great potential and has not been fully developed. Proximity sensing technology that can obtain information without physical contact has become an ideal choice for scenarios where physical contact is impossible. For example, in human-machine interaction, the perception of visual and tactile information is crucial for safely grasping objects. If the robot's vision is in a close-range detection environment blocked by the manipulator, a proximity sensor is needed to replace the visual system to detect information within a few centimeters of the contact surface to achieve the position of the object to be grasped, prevent collisions, and improve safety. However, the characteristics of traditional proximity sensors, such as large volume, slow response, small detection distance, high production cost, and lack of flexibility, severely limit their application in the field of wearable electronic skin. Flexible proximity sensors, with their flexible characteristics, are smaller in volume and have a wider detection range than traditional proximity sensors, gradually attracting the attention of researchers. It is particularly important to manufacture a flexible wearable multifunctional sensor with high-sensitivity proximity sensing capabilities.

[0004] In addition, in the current field of sensor technology, although remarkable progress has been made in science and technology, integrating multiple functions such as proximity, pressure transmission, and temperature into a single sensor while ensuring excellent sensing performance remains a highly challenging task. The working principles and mechanisms of different sensors vary. For example, proximity sensors usually detect the approach of objects based on electromagnetic induction, the photoelectric effect, or capacitance changes; pressure sensors measure pressure using piezoresistive effects, piezoelectric effects, etc.; temperature sensors rely on principles such as thermistors and thermocouples to sense temperature. Therefore, integrating these sensors with different principles not only requires solving the complexity of circuit design but also overcoming the problem of signal interference that may occur between different sensors. In addition, achieving high integration in a limited space also poses extremely high requirements for manufacturing processes and material selection. It is necessary to ensure that the sizes of individual sensor elements are tiny while also ensuring their stable and reliable operation. In terms of performance, each sensor has specific requirements for accuracy, sensitivity, and response time. Meeting these performance indicators simultaneously after integration is even more difficult. Patent Publication No. CN115290229A discloses a graphene-based highly sensitive flexible multifunctional sensor and its preparation method. The sensor includes a temperature sensor layer, a capacitive pressure sensor microstructural dielectric layer, a humidity sensor layer, and a PDMS encapsulation layer. The temperature sensor layer is located at the bottom layer, the PDMS encapsulation layer is located at the top layer, and the capacitive pressure sensor microstructural dielectric layer is between the temperature sensor layer and the humidity sensor layer. The humidity sensor silver electrodes, the capacitive pressure sensor microstructural dielectric layer, and the temperature sensor silver electrodes are vertically aligned and stacked to form four capacitive pressure sensors with different detection ranges. Currently, multifunctional sensors mainly achieve their functional diversification by integrating multiple sensing elements. However, this integration method brings a series of intractable problems, making it difficult to further optimize and improve the key performance indicators of sensors such as size, sensitivity, and reliability. Summary of the Invention

[0005] Aiming at the technical problems of low integration and sensitivity of multifunctional sensors, the present invention proposes an ultra-high-sensitivity integrated capacitive multifunctional sensor and its preparation method, and presents a highly sensitive proximity sensing electrode structure, a non-contact dynamic finger trajectory recognition method, and a preparation process for a highly sensitive pressure and temperature sensing dielectric layer.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] An ultra-high sensitivity integrated capacitive multi-functional sensor, characterized in that it includes a top electrode, a micro-structured dielectric layer, and a bottom electrode stacked from top to bottom, and the top electrode and the bottom electrode are provided with conductive lead strips; a hole-shaped electrode array composed of hole-shaped electrode units is provided on the top electrode; the hole-shaped electrode unit includes an inner circular electrode, an outer circular electrode, and a connecting electrode; the inner circular electrode is located inside the outer circular electrode and is connected through the connecting electrode.

[0008] The hole-shaped electrode array is composed of 16 hole-shaped electrode units arranged in a 4×4 array. The structure and size of each hole-shaped electrode unit are the same. The adjacent hole-shaped electrode units are arranged at intervals and are connected to the conductive lead strip.

[0009] The outer diameter of each hole-shaped electrode unit of the top electrode is 2-6 mm, the inner hole diameter is 0.5-2 mm, and the distance between adjacent two electrodes is 1-4 mm. The size of the hole-shaped electrode unit can be adjusted according to the actual situation.

[0010] Preferably, the outer diameter of each hole-shaped electrode unit of the top electrode is 4 mm, the inner hole diameter is 1 mm, and the distance between adjacent two electrodes is 2.5 mm. Through the array design, the effective contact area between the electrode and the outside world is increased, and the external signal can be sensed more sensitively. The regular arrangement is convenient for unified control and signal processing. The arrangement at intervals reduces the signal interference between adjacent units, and the conductive lead strip is responsible for transmitting the sensed electrical signal. This structure improves the detection sensitivity and accuracy of the sensor to external signals, and ensures the stability and reliability of signal transmission.

[0011] A circular electrode array composed of circular electrode units is provided on the bottom electrode. It provides another way to sense signals for the sensor. Cooperating with the hole-shaped electrode array, it can sense the changes of external physical quantities from different angles and ways, enhancing the functional diversity of the sensor. It enriches the detection dimension of the sensor, enabling the sensor to more comprehensively perceive the changes in the external environment.

[0012] The circular electrode array is composed of 16 circular electrode units arranged in a 4×4 array. The structure and size of each circular electrode unit are the same, and the diameter is 4 mm. The distance between adjacent circular electrode units is 2.5 mm and is connected to the conductive lead strip. The arrangement of the electrode units in the circular electrode array and the hole-shaped electrode array can be adjusted according to actual needs.

[0013] The top electrode and the bottom electrode include a substrate and a conductive layer provided on the substrate. The substrate plays a role of support and insulation, enabling the conductive layer to exist stably and be isolated from other components; the conductive layer is responsible for conducting charges and realizing the transmission and induction of electrical signals. It ensures the stability and functionality of the electrode structure, providing the basic conditions for the normal operation of the sensor.

[0014] The substrate is a flexible polyimide (PI) or polyethylene terephthalate film; the preferred substrate is PI, which has good mechanical properties, insulation properties and high temperature resistance, can stably support the conductive layer in various environments, and endows the sensor with a certain flexibility; the material of the conductive layer is metal; the metal is copper (Cu) or gold. Preferably, the metal is copper. As the conductive layer material, Cu has excellent electrical conductivity, can efficiently transmit charges, ensures the stable operation of the electrode in a complex environment, and improves the efficiency and stability of electrical signal transmission. The electrode array is formed by depositing a metal target with a thickness of 10 - 30 μm onto a substrate with a thickness of 40 - 80 μm.

[0015] The microstructured dielectric layer is an ion gel film, and the ion gel film is provided with microcone structures having a bottom diameter of 100 - 500 μm and a height of 100 - 300 μm. The ion gel film has unique dielectric properties and can be polarized under the action of an electric field to change the capacitance characteristics; the microcone structures can generate more obvious deformations when stressed, thereby more sensitively changing the capacitance. This improves the detection sensitivity of the sensor to changes in physical quantities such as pressure and electric field, and enhances the sensing performance of the sensor.

[0016] A preparation method of an ultra-high sensitivity integrated capacitive multi-functional sensor, characterized by comprising the following steps:

[0017] (1) Deposit a conductive layer and a conductive lead-out strip on a substrate in sequence to prepare a top electrode and a bottom electrode;

[0018] (2) Prepare a microstructured dielectric layer;

[0019] (3) Place the ion gel film between the top electrode and the bottom electrode and perform encapsulation.

[0020] The preparation method of the microstructured dielectric layer is to add an ionic liquid to a polymer solution to prepare a gel solution, and pour the gel solution into a mold for curing to obtain an ion gel film.

[0021] The ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]); the polymer in the polymer solution is polyvinyl alcohol (PVA); the ionic liquid in the gel solution accounts for 30 - 60 wt% of the sum of the masses of the polymer and the ionic liquid. [EMIM][TFSI] is an imidazole-based room temperature ionic liquid. Imidazole-based ionic liquids have low viscosity and high conductivity, and their conductivity can reach up to 10 -2S / cm, with advantages such as low viscosity, low melting point, and high conductivity. PVA is a non-toxic and biodegradable polymer material and an ideal candidate for preparing functional gels. Its side chains are rich in hydroxyl groups, which can endow the gel with excellent mechanical properties. Most importantly, hydrogen bonds can be formed between the hydroxyl groups of PVA and the strongly electronegative atoms (N, F, and O) of the ionic groups in the ionic liquid, and there are electrostatic interactions between a large number of anionic and cationic groups. In addition, materials such as polyvinylidene fluoride copolymer P(VDF-HFP) can also be used in gel selection.

[0022] Advantages of the present invention:

[0023] (1) Based on the capacitive edge field effect, a new type of hole-shaped sensing electrode is proposed, and combined with the array method, effectively enhancing the sensitivity and detection distance of proximity sensing.

[0024] (2) An ionic gel dielectric layer is prepared by a simple, efficient, green and environmentally friendly method without the need for toxic solvents, cross-linking agents and initiators. IL and PVA are spontaneously polymerized by stirring at room temperature, with high flexibility and universality. At the same time, the hole-shaped sensing electrode and the microcone structure dielectric layer cooperate with each other to significantly improve the detection sensitivity.

[0025] (3) The designed multifunctional sensor has a highly integrated and integrated structure and excellent sensing performance. It has ultra-high proximity sensitivity (the maximum capacitance drop for a human hand is 0.54 pF, and the detection distance is 30 mm) and excellent stability. When used as a pressure sensor, the sensitivity reaches 4.822 kPa in the pressure range of 0 - 5 kPa -1 . As a temperature sensor, it has ultra-high temperature sensitivity (80.6 %C -1 , 25 - 80 °C), and can be effectively decoupled and distinguished from the pressure signal without the need for additional decoupling algorithms and processing circuits.

[0026] (4) Seven materials are distinguished in a non-contact manner, providing a new solution for the recognition of short-distance dynamic finger sliding trajectories. The ultra-high sensitivity pressure and temperature sensing performance provides great potential applications for obtaining weak physiological signals and real-time temperature detection. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1Exploded view of the components of the integrated capacitive multi-functional sensor of the present invention;

[0029] Figure 2 Schematic diagram of the top electrode of the integrated capacitive multi-functional sensor of the present invention;

[0030] In the figure, 1 is the top electrode; 2 is the micro-structured dielectric layer; 3 is the bottom electrode; 4 is the conductive lead-out strip; 100 is the hole-shaped electrode array; 101 is the internal circular electrode; 102 is the external circular electrode; 103 is the connection electrode for connection.

[0031] Figure 3 Schematic diagram of the top electrode; (a) Size of the hole-type top electrode array; (b) Physical diagram of the integrated capacitive multi-functional sensor.

[0032] Figure 4 Schematic diagrams of three electrode structures and corresponding simulation diagrams of the edge electric field intensity distribution.

[0033] Figure 5 Result diagram of the performance characterization of the integrated capacitive proximity sensor of the present invention.

[0034] Figure 6 Result diagram of the dynamic finger trajectory recognition of the integrated capacitive proximity energy sensor of the present invention.

[0035] Figure 7 Result diagram of the non-contact material recognition of the integrated capacitive proximity energy sensor of the present invention.

[0036] Figure 8 Result diagram of the influence of the ionic liquid mass fraction on the performance of the integrated capacitive pressure sensor of the present invention.

[0037] Figure 9 Result diagram of the sensitivity performance of the integrated capacitive pressure sensor of the present invention.

[0038] Figure 10 Result diagram of the pulse signal monitoring of the integrated capacitive pressure sensor of the present invention.

[0039] Figure 11 Result diagram of the sensitivity performance of the integrated capacitive temperature sensor of the present invention.

[0040] Figure 12 Result diagram of the decoupling of temperature and pressure signals of the integrated capacitive temperature sensor of the present invention. Detailed implementation manners

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] Embodiment 1

[0043] An ultra-high-sensitivity integrated capacitive multi-functional sensor, as Figure 1 shown, includes a top electrode 1, a micro-structured dielectric layer 2, and a bottom electrode 3 stacked from top to bottom. The top electrode 1 and the bottom electrode 3 are provided with conductive lead-out strips 4; the conductive wires are bonded to the conductive lead-out strips 4 and connected to the signal measurement interface. The top electrode 1 is provided with a hole-shaped electrode array 100 composed of hole-shaped electrode units; as Figure 2 shown, the hole-shaped electrode unit includes an inner circular electrode 101, an outer circular electrode 102, and a connecting electrode 103; the inner circular electrode 102 is located inside the outer circular electrode 101 and is connected through the connecting electrode 103.

[0044] The output of the integrated capacitive multi-functional sensor can be calculated according to the formula of a parallel-plate capacitor C = ε 0 ε r A / d, where A is the overlapping area of the two electrodes, ε 0 is the permittivity of vacuum, ε r is the relative permittivity of the dielectric material between the electrodes, and d is the distance between the electrodes. The key to the operation of a capacitive proximity sensor is the capacitive coupling between the edge field of the sensor and the approaching object. When a finger approaches the upper surface of the sensor, part of the edge field will be intercepted by the finger and point to the finger instead of returning to the top electrode 1, resulting in a decrease in the capacitance value between the two electrodes. When the distance between the approaching object and the device decreases or the interaction area increases, the edge field near the approaching object continuously strengthens, the capacitive coupling is also stronger, the capacitance of the proximity sensor drops more significantly, and the sensitivity increases.

[0045] Further, the hole-shaped electrode array 100 is composed of 16 hole-shaped electrode units arranged in a 4×4 array. The structure and size of each hole-shaped electrode unit are the same. The adjacent hole-shaped electrode units are arranged at intervals and are connected to the conductive lead-out strip 4. The bottom electrode 3 is provided with a circular electrode array composed of circular electrode units. The circular electrode array is composed of 16 circular electrode units arranged in a 4×4 array. The structure and size of each circular electrode unit are the same. The adjacent circular electrode units are arranged at intervals and are connected to the conductive lead-out strip 4.

[0046] The preparation method of the above-mentioned ultra-high-sensitivity integrated capacitive multi-functional sensor includes the following steps:

[0047] (1) Preparation of the micro-structured dielectric layer: First, dissolve 1 g of PVA powder in deionized water at a ratio of 1:9, and stir magnetically at 95 °C for 3 h until the PVA powder is completely dissolved. Wait for the mixed solution to cool to room temperature, then add 0.67 g of [EMIM][TFSI] (40 wt%), and stir for 2 h to promote the spontaneous polymerization of IL and PVA, named PVA-IL. Clean the PTFE mold with absolute ethanol to remove impurities, then ultrasonically clean for 10 min, pour the mixture into the PTFE mold, degas for 20 min, and cure at room temperature for 24 h to obtain a soft ion gel film with a microcone structure having a bottom diameter of 300 um and a height of 200 um.

[0048] (2) Preparation of the electrode array: Deposit 20 um of copper (Cu) on a 60 um polyimide (PI) film substrate as a flexible electrode. The hole-shaped electrode array is the upper electrode. As Figure 3 shown, a 4×4 electrode array is arranged, the outer diameter of each electrode unit is 4 mm, the inner diameter is 1 mm, and the distance between adjacent electrode units is 2.5 mm. The circular electrode array is the lower electrode, and a 4×4 electrode array is arranged. Laminate the PVA-IL film between the two electrodes, and encapsulate the sensor using an ultra-thin double-sided tape. The entire sensor area is 25×25 mm 2 .

[0049] Example 2

[0050] An ultra-high-sensitivity integrated capacitive multi-functional sensor, the difference from Example 1 is that the proportion of [EMIM][TFSI] in the micro-structured dielectric layer is 50 wt%, and other structures are the same.

[0051] Example 3

[0052] An ultra-high-sensitivity integrated capacitive multi-functional sensor, the difference from Example 1 is that the proportion of [EMIM][TFSI] in the micro-structured dielectric layer is 60 wt%, and other structures are the same.

[0053] Comparative Example 1

[0054] A capacitive multi-functional sensor, the difference from Example 1 is that the hole-shaped electrode unit in the top electrode is changed to a circular electrode unit, and the circular electrode unit is a circular structure, and other structures are the same as those in Example 1.

[0055] Comparative Example 2

[0056] A capacitive multi-functional sensor, which is different from that of Embodiment 1 in that the hole-shaped electrode unit in the top layer electrode is changed to a ring-shaped electrode unit. The ring-shaped electrode unit is a hollow ring structure, and other structures are the same as those of Embodiment 1.

[0057] Figure 4 Figs. 1 and 2 are schematic diagrams of three electrode structures of Embodiment 1 and Comparative Examples 1 and 2 and the corresponding edge electric field intensity distributions. Comparing the hole-shaped electrode with the circular and ring-shaped electrodes, when an object gradually approaches the sensor, the edge field of the hole-shaped electrode will be enhanced due to the multiple electrode spacings. Compared with the other two electrode structures, the hole-shaped electrode shows a stronger edge electric field, and the capacitive coupling with the approaching object is more obvious.

[0058] The integrated capacitive multi-functional sensor prepared in Embodiment 3 was tested and characterized for applications, such as Figures 5 - 12 .

[0059] Such as Figure 5 and 6 As shown, the maximum capacitance drop generated by the hole-shaped electrode structure for the human hand is 0.54 pF, and the farthest detection distance reaches 30 mm. Since the surface charges of different objects are different, the capacitive coupling effect with the edge field will be different, thus affecting the capacitive output response of the proximity sensor. Based on this phenomenon, the sensor shows different capacitive responses when different material objects approach. The proximity capacitive responses of the sensor to 7 materials including copper, iron, polyimide, acrylic, glass, cardboard, and the human hand were tested. It can be found that the proximity capacitive response of the conductor material is higher than that of the non-conductor, and the proximity capacitive response of the human hand is the largest. This unique sensing performance is expected to provide new ideas for non-contact material identification.

[0060] Such as Figure 7 As shown, the highly sensitive proximity sensing function can also be used for dynamic finger trajectory recognition. When a finger continuously slides on the surface of the top layer electrode 1 of the capacitive sensor array along a preset geometric trajectory ("L" shape, rectangle, and triangle), the sensor unit can detect the transient drop phenomenon of the local capacitance signal in real time. By synchronously recording and processing these signals through a high-precision signal acquisition interface circuit, a three-dimensional mapping histogram of the capacitance value generated during the finger movement and a capacitance value graph changing with time can be obtained. Taking the "L" shaped trajectory as an example, the finger slides over the sensing units 1-2-3-4-8-12-16 in sequence. Each time it slides over a sensing unit, it will cause a drop in the capacitance value of that sensing unit. In this way, a drop signal will appear in the time-domain graph of the capacitance changing with time. According to the obtained capacitance value output curve, the movement trajectory of the finger can be effectively identified.

[0061] A double-layer effect will form at the contact interface between the microstructured dielectric layer and the electrode. This is because the ionic liquid contains a large number of cations and anions. When a voltage is applied, the cations and anions are attracted to the cathode and anode respectively, and ion-electron pairs with nanoscale spacing will form on the surfaces of the electrode and the dielectric layer. The working mechanism of this sensor depends on the change in the contact area between the electrode and the dielectric layer. When pressure is applied, the contact area increases, and more cations or anions are attracted to the contact surface, thus increasing the capacitance.

[0062] As Figure 8 shown, the mixing ratio of the ionic liquid in polyvinyl alcohol in Examples 1-3 will affect the sensitivity and linearity of the integrated capacitive pressure sensor. With the increase in the mixing ratio of the ionic liquid, the sensitivity and measurement range of the capacitive pressure sensor to external pressure increase significantly.

[0063] As Figure 9 shown, when 60 wt% of the ion gel is mixed in the dielectric layer, the integrated capacitive pressure sensor exhibits the highest sensitivity, measurement range, and linearity in the pressure range of 0-5 kPa, which are 4.822 kPa -1 , 200 kPa, and 99.6% respectively. At the same time, these excellent performance parameters also confirm that a capacitive pressure sensor with ultra-high sensitivity can be obtained through a simple manufacturing process. Although for pressure ranges exceeding 5 kPa, the sensitivity decreases due to the flattening of the microcone structure, it is sufficient to meet the application requirements in most scenarios.

[0064] As Figure 10 shown, the ion gel microcone structure pressure sensing unit adopted in the microstructured dielectric layer of the present invention endows the pressure sensor with ultra-high tactile sensitivity and micro-strain perception ability, and can accurately capture and collect the characteristics of vascular pulsation. A 24-year-old healthy adult male volunteer was selected for the test. In the experiment, the sensor was accurately positioned at the radial artery detection site using a medical band-aid and a moderate pre-tightening force was provided to ensure the close fit between the sensor and the skin. In terms of the detection system configuration, the output end of the sensing unit was connected to a high-precision LCR impedance analysis system, and the time-frequency domain analysis of the capacitance signal was realized through the MATLAB data acquisition platform. Periodic pulse signals can be clearly observed from the figure, and from the waveform analysis of the enlarged figure, it shows that a single pulse contains characteristic components such as percussion wave (P wave), tidal wave (T wave), and diastolic wave (D wave). These time-varying characteristics respectively correspond to key physiological events such as left ventricular ejection, peripheral resistance change, and aortic valve closure, providing a multi-parameter diagnostic window for the quantitative assessment of cardiovascular function.

[0065] Temperature affects the conductivity of ions. As the temperature increases, ion dissociation is activated at high temperatures, increasing the charge carriers and thus enhancing the conductivity of the IL. The temperature sensitivity can be calculated according to the formula where C 0 is the initial capacitance value at room temperature, ΔC represents the change in capacitance due to temperature change, and ΔT represents the change in sensor temperature.

[0066] As Figure 11 shown, to accurately evaluate the sensitivity of the integrated capacitive temperature sensor, a series of increasing temperature changes are applied to the sensor during the experiment, and the corresponding capacitance changes are accurately measured. From these data, a relationship curve between temperature change and capacitance change can be plotted. The slope of this curve is the sensitivity of the sensor, which directly reflects the sensitivity of the sensor to temperature changes. The test temperature is set with 25°C at room temperature as the initial temperature, and the temperature of the constant temperature heating plate is controlled to rise gradually. The fitting curve within 25 - 80°C shows that the temperature sensitivity of the sensor reaches 80.6% / °C -1 , and this high-sensitivity temperature response enables it to accurately measure the temperature changes of objects during the grasping operation of intelligent robots, contributing to a rapid response to the temperature of the grasped object and avoiding damage caused by high temperatures.

[0067] Since the acquisition of contact temperature signals is often accompanied by the coupling of pressure signals, these two physical quantities are interrelated and jointly affect the state or behavior of an object. For example, when a flexible sensor is integrated into a robotic gripper for object grasping, the sensor not only needs to sense temperature changes to monitor the object's temperature but also needs to sense pressure changes to monitor the magnitude of the tactile force.

[0068] As Figure 12 shown, a static force of 0.16 kPa is applied to the sensor at room temperature of 25°C for 20 s. At this time, the capacitance change of the sensor will output a step signal (the first stage), while the temperature remains unchanged, that is, the temperature is not sensitive to the pressure signal. Subsequently, in the second stage, the temperature begins to rise, and the capacitance change of the sensor rises rapidly. When the temperature reaches 35°C, the temperature begins to drop slowly, and the capacitance output curve of the sensor follows suit. In the third stage, the same pressure is applied again during the temperature cooling process, and the capacitance change output of the sensor is the same as that in the first stage, indicating that the pressure signal is not sensitive to temperature fluctuations.

[0069] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An ultra-high-sensitivity integrated capacitive multifunctional sensor, characterized in that: It includes a top electrode, a microstructured dielectric layer and a bottom electrode stacked from top to bottom, and the top electrode and the bottom electrode are provided with conductive lead-out strips; the top electrode is provided with a hole-shaped electrode array composed of hole-shaped electrode units; the hole-shaped electrode unit includes an inner circular ring electrode, an outer circular ring electrode and a connecting electrode; the inner circular ring electrode is located inside the outer circular ring electrode and is connected through the connecting electrode.

2. The ultra-high sensitivity integrated capacitive multifunctional sensor according to claim 1, characterized in that: The hole-shaped electrode array is composed of 16 hole-shaped electrode units arranged in a 4×4 array, each hole-shaped electrode unit has the same structure and size, and adjacent hole-shaped electrode units are arranged at intervals and connected to the conductive lead-out belt.

3. The ultra-high sensitivity integrated capacitive multifunctional sensor according to claim 1 or 2, characterized in that: A circular electrode array consisting of circular electrode units is arranged on the bottom electrode.

4. The ultra-high sensitivity integrated capacitive multifunctional sensor according to claim 3, characterized in that: The circular electrode array is composed of 16 circular electrode units arranged in a 4×4 array, each circular electrode unit has the same structure and size, and adjacent circular electrode units are arranged at intervals and connected to the conductive lead-out belt.

5. The ultra-high sensitivity integrated capacitive multifunctional sensor according to claim 1, characterized in that: The top electrode and the bottom electrode include a substrate and a conductive layer arranged on the substrate.

6. The ultra-high-sensitivity integrated capacitive multifunctional sensor according to claim 5, characterized in that: The substrate is a polyimide or polyethylene terephthalate film; the conductive layer is made of metal; and the metal is copper or gold.

7. The ultra-high sensitivity integrated capacitive multifunctional sensor according to claim 1, characterized in that: The microstructure dielectric layer is an ion gel film, and a microcone structure is arranged on the ion gel film.

8. The method for preparing the ultra-high sensitivity integrated capacitive multifunctional sensor according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) depositing a conductive layer and a conductive lead-out tape on a substrate to sequentially prepare a top electrode and a bottom electrode; (2) preparing a microstructured dielectric layer; (3) The ion gel film is placed between the top electrode and the bottom electrode and encapsulated.

9. The method for preparing the ultra-high sensitivity integrated capacitive multifunctional sensor according to claim 8, characterized in that: The preparation method of the microstructure dielectric layer comprises adding an ionic liquid into a polymer solution to prepare a gel solution, pouring the gel solution into a mold and solidifying it to obtain an ion gel film.

10. The method for preparing the ultra-high sensitivity integrated capacitive multifunctional sensor according to claim 9, characterized in that: The ionic liquid is 1-ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide; the polymer in the polymer solution is polyvinyl alcohol; the ionic liquid in the gel solution accounts for 30-60 wt % of the sum of the mass of the polymer and the ionic liquid.

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