Microstructure composite dielectric layer and preparation method and application thereof

Abstract

The invention relates to the technical field of dielectric layers, in particular to a microstructure composite dielectric layer and a preparation method and application thereof. The preparation method comprises the following steps: S1, scanning a PI film by using laser to serve as an LIG template; s2, slowly adding the carbon nanotube dispersion liquid into the polydimethylsiloxane prepolymer, fully stirring and dispersing, then adding a curing agent, and continuously stirring to obtain a stable SWCNT / PDMS composite solution; and S3, uniformly spreading the SWCNT / PDMS composite solution on the surface of the LIG template, carrying out thermosetting treatment, cooling to room temperature, and stripping a formed SWCNT / PDMS film to obtain the microstructure composite dielectric layer. The novel method for manufacturing the capacitive pressure sensor is adjustable in structural parameters, simple and convenient in preparation process, high in repeatability, suitable for large-area preparation of the flexible substrate and capable of achieving high sensitivity, low detection limit and excellent cycle stability.

Description

Technical Field

[0001] The present invention relates to the technical field of dielectric layers, and in particular to a microstructured composite dielectric layer and a preparation method and application thereof. Background Art

[0002] Flexible pressure sensors, key components in these devices, can convert external pressure signals into electrical signals, enabling real-time monitoring of physiological signals. Capacitive pressure sensors have become a research hotspot due to their simple structure, low energy consumption, and lack of temperature drift. Their basic structure typically consists of two electrodes and a flexible dielectric layer, sensing pressure changes by measuring the capacitance change between the electrodes.

[0003] The design and material selection of the dielectric layer have a significant impact on sensor performance. By rationally regulating the structure of the dielectric layer, the sensitivity, response speed, and durability of the sensor can be significantly improved, thereby promoting the development of new materials and advanced manufacturing processes. In capacitive sensors, the dielectric layer is typically made of an elastomeric material with good elasticity and compressibility. Its structure and properties directly affect the overall performance of the sensor. However, the viscoelastic properties of the elastomer can lead to hysteresis effects and long relaxation times, thereby limiting the dynamic response capability of the sensor. To improve sensing performance, reducing the viscoelasticity of the dielectric layer can effectively shorten the relaxation time.

[0004] Constructing appropriate microstructures can increase the gap between electrodes, making the dielectric layer more deformable, thereby reducing viscoelastic behavior and improving its compressibility and response speed. Common surface microstructure shapes include micro-pyramids, micro-columns, and micro-domes. These surface microstructures are primarily manufactured using methods such as laser direct writing, 3D printing, and etching. However, traditional manufacturing methods are technically complex and costly, limiting their widespread application and reproducibility.

[0005] In contrast, template-assisted methods are gaining popularity due to their simplicity, low cost, and scalability. Natural templates (such as mimosa leaves, silk, and sandpaper) can be used to effectively construct a variety of surface microstructures, significantly reducing costs and improving sensor sensitivity. However, these natural templates still face challenges in structural uniformity, repeatability, and geometric accuracy control. Summary of the Invention

[0006] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a microstructured composite dielectric layer and a preparation method and application thereof.

[0007] The first object of the present invention is to provide a method for preparing a microstructured composite dielectric layer, comprising the following steps:

[0008] S1, using laser scanning to form a porous laser-induced graphene layer with a wavy convex structure on the surface of the PI film as a template;

[0009] S2. Slowly add the carbon nanotube dispersion to the polydimethylsiloxane prepolymer, stir and disperse thoroughly, then add the curing agent, and continue stirring to obtain a stable SWCNT / PDMS composite solution;

[0010] S3. Evenly spread the SWCNT / PDMS composite solution on the surface of the LIG template, perform a thermal curing treatment, cool to room temperature, and peel off the formed SWCNT / PDMS film to obtain the microstructured composite dielectric layer.

[0011] Furthermore, the laser power is 900-2000 mW, the ablation speed is 1.2-2 mm / s, and the filling density is 4-8.

[0012] Furthermore, the carbon nanotubes are mixed into the polydimethylsiloxane prepolymer at a mass fraction of 0.2% to 0.6%.

[0013] Furthermore, the obtained wavy protrusion structure of the microstructured composite dielectric layer has a protrusion height of 50-55 μm and a top width of 95-105 μm; the thickness of the LIG template is 250 μm.

[0014] The second object of the present invention is to provide a microstructured composite dielectric layer prepared by the above-mentioned preparation method.

[0015] The third object of the present invention is to provide a wearable flexible pressure sensor, comprising the above-mentioned microstructured composite dielectric layer, an upper electrode and a lower electrode, wherein the microstructured composite dielectric layer is bonded to the upper and lower electrodes.

[0016] Furthermore, the upper electrode and the lower electrode are silver electrodes.

[0017] Furthermore, a microelectronic printer is used to print a silver electrode with a preset pattern on a clean PET flexible substrate. After printing, the PET substrate with the electrode pattern is placed on a hot plate, heat-treated at 80°C to 120°C for 15 to 30 minutes, and then naturally cooled to obtain the silver electrode.

[0018] Compared with the existing technology, the present invention has the following beneficial effects:

[0019] 1. The microstructure template is highly adjustable and has good repeatability. This invention uses laser induction technology to prepare a microstructured graphene template on the surface of a PI film. By adjusting the laser power, scanning speed, and filling density, the morphological parameters of the microstructure can be flexibly controlled, achieving high-fidelity and controllable replication of the dielectric layer's microstructure features, effectively improving the consistency and repeatability of the sensor.

[0020] 2. The dielectric layer has a stable morphology and excellent response performance. The use of SWCNT / PDMS composite elastic material as the dielectric layer not only improves the conductivity and mechanical elasticity of the composite material, but also maintains the stability of the surface microstructure. The microstructure design effectively adjusts the nonlinear characteristics of the capacitance change with pressure, making the sensor highly sensitive in the low-pressure range (maximum 1.38kPa-1) and with a detection limit as low as 0.2Pa, meeting the needs of monitoring small force changes.

[0021] 3. Simple packaging and excellent overall device flexibility. Silver electrodes are fabricated using microelectronic printing technology and bonded to the microstructured dielectric layer through alignment and lamination. The complete sensor unit is then encapsulated using medical tape. This simple and reliable packaging method enables rapid assembly, resulting in a device with excellent flexibility, stability, and wearability.

[0022] 4. Wide range of applications and high practical value. The developed flexible capacitive pressure sensor can achieve real-time detection of various physiological signals (such as pulse, respiration, vocal cord vibration, swallowing movements, etc.), with good response speed and signal-to-noise ratio. It shows broad application prospects and market potential in smart wearables, health monitoring, human-computer interaction and other fields.

[0023] In summary, the present invention has developed a new method for manufacturing capacitive pressure sensors with adjustable structural parameters, simple preparation process, high repeatability, suitable for large-area preparation of flexible substrates, and capable of achieving high sensitivity, low detection limit, and excellent cyclic stability. While ensuring sensing performance, it simplifies the preparation process and improves manufacturing consistency, providing a feasible path for the large-scale application of high-performance flexible electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a real picture of laser processing;

[0025] Figure 2 This is a diagram of laser-induced graphene structure characterization and analysis;

[0026] Figure 3 is the size relationship corresponding to graphene;

[0027] Figure 4 (ac) SEM of graphene surface; (df) SEM of graphene cross section;

[0028] Figure 5 The figure is a process diagram for preparing the dielectric layer;

[0029] Figure 6 is the cross-sectional SEM of SWCNT / PDMS;

[0030] Figure 7 is the XRD pattern of graphene and SWCNT / PDMS;

[0031] Figure 8 This is a real photo of the flexible sensor;

[0032] Figure 9 (a) Low-pressure sensitivity test results; (b) High-pressure sensitivity test results;

[0033] Figure 10 (a) Performance comparison of different CNT doping contents; (b) Performance comparison of 0-50kPa and pure PDMS;

[0034] Figure 11 This is the response time test diagram of SWCNT / PDMS capacitive sensor;

[0035] Figure 12 This is the repeatability test diagram of SWCNT / PDMS capacitive sensor;

[0036] Figure 13 This is the pulse signal test diagram;

[0037] Figure 14 This is the finger bending signal test diagram;

[0038] Figure 15 It is a respiratory monitoring chart;

[0039] Figure 16 For vocal cord and swallowing monitoring chart;

[0040] Figure 17 This is the basic sound response test chart. DETAILED DESCRIPTION

[0041] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0042] Example 1

[0043] Dielectric layer preparation of laser-induced graphene (LIG) template

[0044] A method for constructing a tunable microstructure template using laser-induced graphene (LIG) technology is used to replicate the flexible dielectric layer of capacitive sensors. This method features a simple preparation process, controllable parameters, and strong template replication capability, making it suitable for large-scale production. The preparation method includes the following steps:

[0045] (1) Substrate treatment: Polyimide (PI) film was chosen as the substrate material. The pre-cut PI film was placed in anhydrous ethanol and ultrasonically cleaned for 10 minutes to remove surface impurities. Then it was transferred to deionized water and cleaned for another 10 minutes to further remove residual ethanol. Finally, the cleaned PI film was placed in a constant temperature drying oven at 60°C for 6 hours to obtain a clean and dry PI film, providing a stable basis for subsequent laser processing.

[0046] (2) Laser pattern design: According to the required microstructure form (such as stripe array, corrugated structure, etc.), the laser scanning path was designed using the laser engraving machine supporting software (such as Laser 2.0.6) or CAD software, and the laser ablation pattern was drawn.

[0047] (3) Laser ablation processing: The treated PI film was fixed on an acrylic plate, and PI tape was used to paste its edges to ensure that the film was flat and not curled. The laser head was adjusted to focus on the surface of the PI film, and the designed laser pattern was loaded for processing.

[0048] (4) Structure formation and template acquisition: After laser scanning, a porous laser-induced graphene (LIG) layer with three-dimensional protruding structure was formed on the surface of the PI film. The LIG layer was arranged in a regular wave-like micro-platform structure, with good mechanical strength and morphology stability, which could be used as a concave mold for constructing the microstructure of the flexible dielectric layer.

[0049] (5) Laser parameter regulation and verification: During the laser ablation process, in order to obtain the optimal structure performance, the key parameters of laser processing need to be optimized, including laser power, ablation speed and filling density.

[0050] Through cross-experiment of laser power (range: 35-60%) and ablation speed (range: 30%-65%), resistance test was conducted on the laser-induced graphene sample, and the experimental results are shown in Table 2. The experimental results show that too low power leads to incomplete conversion on the surface of PI, resulting in large resistance; too high power or too slow speed can easily cause PI film to be ablated too much, bend and deform, or graphene layer to fall off. Considering the structure integrity and conductivity, the laser power of 45% and the ablation speed of 60% were selected as the optimal parameters.

[0051] The laser marking machine used was DJ6, with a laser head power of 3W and a maximum scanning speed of 3mm / s. The main parameters are shown in Table 1:

[0052] Table 1 Main parameters of laser marking machine

[0053]

[0054]

[0055] Table 2 Resistance of graphene formed by different laser parameters

[0056]

[0057]

[0058] After fixing the laser power and speed, the filling density (i.e., the scanning line spacing) is further adjusted to control the microstructure spacing and morphology. Figure 2 This is the topography reconstruction obtained from white-light interferometry measurements. The red portion represents the graphene protrusions, and the blue portion represents the grooves left after laser ablation. As the packing density increases, the spacing between the graphene protrusions decreases, but the overall structure height decreases. This is primarily due to the destructive effect of secondary ablation on the existing graphene structure, resulting in a decrease in height.

[0059] Laser-induced graphene structure characterization and analysis

[0060] The spacing and height data show that as the filling density increases, the graphene spacing decreases, and the overall height change shows a decreasing trend. When the filling density is high, the reciprocating motion of the laser head causes the graphene produced initially within the spot radius to undergo secondary ablation. This secondary ablation destroys its structure, resulting in a decrease in the overall height. Figure 3 The graphene formed by laser ablation is regularly arranged in a wavy micro-terrace. This structure can be used as a concave mold for constructing the micro-terrace structure, and it also has a certain control range.

[0061] The prepared graphene was characterized by SEM. After laser ablation of the PI film, wavy graphene was formed, in which the gullies were on the side with deeper laser ablation, such as Figure 4 (a) shows the raised part is the layered graphene, and its surface is a porous and loose carbon nanotube stacking structure. Figure 4 (b) is the microstructure of the top of a single protrusion. Figure 4 (c) voids on raised surfaces, Figure 4 (d), (e) and (f) show the neatly arranged graphene wave array in cross section, and the height of its protrusions is measured to be about 50 μm.

[0062] Example 2

[0063] Replication and preparation of microstructured dielectric layers

[0064] By introducing carbon nanotubes (SWCNTs) into a PDMS matrix, a SWCNT / PDMS composite dielectric layer is prepared. The surface microstructure is replicated using the LIG template formed in the first step, thereby obtaining a flexible dielectric layer with a micro-table array structure. This flexible dielectric layer can be used to construct the core functional layer of a highly sensitive capacitive pressure sensor. The preparation process is as follows: Figure 5 As shown, it mainly includes the following steps:

[0065] (1) Preparation of SWCNT / PDMS composite material: First, accurately weigh the polydimethylsiloxane (PDMS) prepolymer and its curing agent and preliminarily mix them in a mass ratio of 10:1. Then, slowly add the SWCNT dispersion prepared according to the preset ratio to the PDMS prepolymer and stir it thoroughly using a mechanical or magnetic stirring device for 30 minutes to ensure that the SWCNTs are evenly dispersed in the PDMS matrix. After mixing, add the PDMS curing agent and continue stirring for 30 minutes to obtain a stable SWCNT / PDMS composite solution.

[0066] (2) LIG template preparation and film formation: A 5 cm × 5 cm PI film was prepared after the treatment in step 1). The surface of the PI film was laser-written to form a LIG pattern with a three-dimensional terraced or corrugated microstructure, which could be directly used as a flexible mold for microstructure formation.

[0067] (3) Formation of SWCNT / PDMS composite dielectric layer: The prepared SWCNT / PDMS mixture was evenly spread on the surface of the LIG template. To control the film thickness and ensure surface consistency, a four-sided preparation device was used for scraping, and the target thickness was controlled to be 250 μm.

[0068] (4) Thermal curing and demolding: The composite film coated with the LIG template was placed in a 90°C constant temperature drying oven for thermal curing for 2 hours. After curing, it was cooled to room temperature and the formed SWCNT / PDMS film was slowly peeled off. The surface of the film completely retained the microstructure of the LIG template and could be used as a flexible dielectric layer to construct a pressure sensor.

[0069] (5) Sample cutting and pretreatment: After demolding, the composite dielectric film was cut into 10 mm × 10 mm square samples and surface treated with anhydrous ethanol to remove residual stress and dust. This standard size facilitates subsequent electrode loading and device packaging, as well as performance testing such as sensitivity.

[0070] The cross section of the dielectric layer of the prepared SWCNT / PDMS structure was characterized by SEM, as shown in Figure 6 As shown, its wavy protrusion structure can be clearly observed, which is basically consistent with the size of the laser-induced graphene template. The protrusion height is 52.78um and the top width is 102.89um. At the same time, the structure of PDMS does not change significantly during the demolding process, and has good consistency.

[0071] The prepared dielectric layer was characterized by XRD, and the X-ray diffraction (XRD) curve of laser-induced graphene (LIG) was shown in Figure 7 After laser treatment, LIG ​​was successfully formed on the surface of the PI film. When comparing pure PDMS and SWCNT-doped PDMS samples, the latter showed a relatively obvious bulge at 2θ = 23°, confirming that a trace amount of SWCNT was doped into the PDMS. Compared with normally grown SWCNT / PDMS, the SWCNT / PDMS grown on the LIG template had a more obvious bulge at 2θ = 23°, indicating that some layered graphene was attached to the PDMS surface. However, no obvious peak was observed at 2θ = 26.381°, further confirming that the internal structure of the prepared LIG is stable and the dielectric layer has good stability. It is possible that a trace amount of layered graphene was introduced to the surface during the PDMS molding process.

[0072] Example 3

[0073] Electrode layer preparation and sensor packaging

[0074] By constructing conductive electrodes on the upper and lower surfaces of the microstructured dielectric layer and encapsulating them as a whole, a complete capacitive sensor unit that can be used for flexible pressure sensing is formed. The actual capacitive sensor unit is as follows: Figure 8 The following are the steps for preparing the electrode layer and the overall packaging of the sensor:

[0075] (1) Silver electrode pattern design and printing: Use a microelectronics printer to print a preset pattern of silver electrodes on a clean PET flexible substrate. The electrode pattern design must match the size of the dielectric layer (10 mm × 10 mm) and reserve an area for external lead connection.

[0076] (2) Heat treatment and curing of silver electrodes: After printing is completed, the PET substrate with the electrode pattern is placed on a hot plate and heat treated at a set temperature (e.g., 80°C to 120°C) for 15-30 minutes to improve the conductivity, structural integrity, and adhesion stability of the silver electrodes.

[0077] (3) External lead connection and package reinforcement: Use silver glue to connect the signal end of the electrode to the external wire, and stick copper tape at the lead interface to prevent damage caused by lead dragging or electrode falling off.

[0078] (4) Sensor unit packaging: The SWCNT / PDMS dielectric layer with completed microstructure replication is cut to match the size of the silver electrodes. The dielectric layer is precisely contacted with the upper and lower electrodes by laminating them together. Subsequently, medical-grade flexible tape is used to seal the edges, resulting in a complete capacitive pressure sensing unit with excellent flexibility and capacitive response performance.

[0079] Example 4

[0080] Characterization of the graphene microstructure revealed that the spacing and height of the micro-mesa structures formed by low-power laser ablation are related to the packing density. Graphene with packing densities ranging from 1 to 10 was first fabricated. At packing densities of 8-10, the overall structure of the graphene was too compact, making it unsuitable for PDMS demolding and difficult to stably control. Therefore, pure PDMS dielectric layers were fabricated using graphene with packing densities of 1-7 as templates to analyze the impact of the microstructure on the dielectric layer's sensitivity.

[0081] After sensitivity testing, the highest sensitivity of the dielectric layer is 0.941kPa under the condition of filling density of 6. -1 (0.21kPa-0.75kPa), 0.178kPa -1 (0.75kPa-2.94kPa), 0.006kPa -1 (2.94kPa-150kPa), such as Figure 9 (a) and (b) are the sensitivity tests at low and high pressures, respectively. It can be concluded that excessive packing density is detrimental to the compression of the dielectric layer, while too low a packing density results in low compression deformation of the dielectric layer.

[0082] Example 5

[0083] PDMS doped with SWCNT and with graphene micro-platform structure were tested separately. Flexible pressure sensing units were made based on microelectronic printing technology using flexible PET as the substrate. On this basis, the two parts were combined to obtain the dielectric layer preparation process with the best performance.

[0084] A capacitive flexible pressure sensing unit made of SWCNT / PDMS was fabricated using parameters such as a laser power density of 45%, a speed of 60%, and a packing density of 6. Within a certain range, the relationship between capacitance and pressure can be approximately considered linear. The SWCNT / PDMS dielectric layer fabricated with a graphene template was tested, and the highest sensitivity was 1.38 kPa when the SWCNT doping content was 0.5%. -1 (0-1.42kPa), 0.7kPa -1 (1.42-3.33kPa), 0.22kPa -1 (3.33kPa-11.76kPa), Figure 10 (a) Comparison of the performance of PDMS with different SWCNT doping contents. The sensitivity of pure PDMS is 0.066 kPa -1 (0-5.27kPa), 0.004kPa -1 (5.27-28.91kPa), 0.001kPa -1 (28.91kPa-50kPa), Figure 10(b) Performance comparison of SWCNT / PDMS with a doping concentration of 0.5% and pure PDMS.

[0085] Response time and stability test

[0086] After applying external stimuli, the time required from the beginning of the change to reaching a steady state is called the response time of the sensor. This parameter has a great influence on the real-time detection of dynamic signals. Figure 11 As shown in the data, when a vertical load is applied to the sensor and the force is quickly removed after reaching a steady state, the sensor unit fabricated with a micro-table structure, SWCNT / PDMS, has a fast response time of 73ms and a recovery time of 141ms from the loaded state. The increased elasticity of PDMS by doping with SWCNTs allows the sensor unit with microstructured contacts to quickly recover to its initial state. This process produces sensor units with excellent response characteristics.

[0087] Flexible sensors need to have good stability and durability. Repeatability tests are conducted on them. Figure 12 The dielectric layer elastic material was pressurized and unloaded three times continuously at 1kPa, 10kPa, 30kPa, 50kPa, and 100kPa. The capacitance response was basically the same in the three repeated experiments, and it was able to return to its original initial state before and after pressurization and unloading, indicating that the prepared dielectric layer has good repeatability in use.

[0088] Wearable flexible pressure sensing application testing

[0089] like Figure 13 As shown, the sensor's ability to monitor low-voltage pulse signals was demonstrated. The sensor was fixed to the wrist to monitor the radial artery pulse and successfully recorded the pulse signal. Based on the test results, the subject's pulse rate was estimated to be approximately 67 beats per minute, which is within the normal resting heart rate range of a healthy adult. Furthermore, the pulse signal captured by the sensor clearly displayed three typical peaks in each cycle: the systolic wave (P wave), the tidal wave (T wave), and the diastolic peak (D wave), indicating that the sensor has good potential for real-time pulse signal monitoring and medical testing.

[0090] like Figure 14 As shown in the figure, when the sensor is integrated into the finger joint, the changes in the capacitance signal at different bending angles (30°, 60°, 90°, 120°) show obvious differentiation, indicating that the sensor can accurately sense the degree of finger bending. This feature has application value in gesture recognition, human-computer interaction, rehabilitation training and other scenarios.

[0091] Figure 15A schematic diagram shows how the sensor is attached to a mask to monitor nasal exhaled airflow. During the test, volunteers took three deep breaths and then breathed normally. The results showed that each signal peak corresponded to a respiratory cycle, with capacitance increasing rapidly during exhalation and changing more slowly during inhalation. This periodic signal change reflects respiratory rate and can be used to assess a person's health. For example, abnormal respiratory rate and intensity can be used to detect early symptoms of asthma, shock, or allergies.

[0092] Figure 16 The sensor, applied to the throat, accurately captured pressure fluctuations generated by two distinct physiological activities: swallowing and drinking. Comparing the characteristic waveforms of swallowing and drinking revealed two distinct peaks during swallowing, reflecting the upward movement and retraction of the hyoid bone, which induces significant pressure fluctuations. This feature-based differentiation mechanism provides an accurate and practical method for monitoring throat movements, with potential applications in medical and health monitoring. Furthermore, the sensor demonstrated excellent performance in sound and speech detection.

[0093] Figure 17 The vocal cord vibration signal is displayed. Different tones (do, re, mi, fa, sol, la, si) produce unique capacitance response curves. Each note produces a different characteristic waveform, and the sensor is able to identify these note characteristics, demonstrating its potential in speech recognition and vocal cord rehabilitation training.

[0094] Any matters not mentioned above shall be subject to the existing technology.

[0095] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in similar ways, but they will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a microstructured composite dielectric layer, characterized in that: The process includes the following steps: S1, using laser scanning to form a porous laser-induced graphene layer with a wavy convex structure on the surface of the PI film as a LIG template; S2. Slowly add the carbon nanotube dispersion to the polydimethylsiloxane prepolymer, stir and disperse thoroughly, then add the curing agent, and continue stirring to obtain a stable SWCNT / PDMS composite solution; S3. Evenly spread the SWCNT / PDMS composite solution on the surface of the LIG template, perform a thermal curing treatment, cool to room temperature, and peel off the formed SWCNT / PDMS film to obtain the microstructured composite dielectric layer.

2. The preparation method according to claim 1, wherein The laser power is 900-2000mW, the ablation speed is 1.2-2mm / s, and the filling density is 4-8.

3. The preparation method according to claim 1, wherein The carbon nanotubes are mixed into the polydimethylsiloxane prepolymer at a mass fraction of 0.2% to 0.6%.

4. The preparation method according to claim 1, wherein The obtained wavy protrusion structure of the microstructured composite dielectric layer has a protrusion height of 50-55 μm and a top width of 95-105 μm; the thickness of the LIG template is 250 μm.

5. A microstructured composite dielectric layer prepared by the preparation method according to any one of claims 1 to 4.

6. A wearable flexible pressure sensor, characterized in that: The device comprises the microstructured composite dielectric layer according to claim 5, an upper electrode and a lower electrode, wherein the microstructured composite dielectric layer is bonded to the upper and lower electrodes.

7. A wearable flexible pressure sensor according to claim 6, characterized in that: The upper and lower electrodes are silver electrodes.

8. A wearable flexible pressure sensor according to claim 7, characterized in that: A microelectronic printer is used to print a silver electrode with a preset pattern on a clean PET flexible substrate. After printing, the PET substrate with the electrode pattern is placed on a hot plate, heat-treated at 80° C. to 120° C. for 15 to 30 minutes, and then naturally cooled to obtain the silver electrode.

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