A PDMS substrate with micro-island bridge array clamped support and a preparation method thereof

Abstract

The application discloses a PDMS substrate with a micro-island bridge array fixed support and a preparation method thereof, belongs to the field of aviation intelligent skin and sensing technology, and aims at solving the problems of easy failure of curved surface attachment and self-repairing of damage of a pasting interface of an existing flexible array type pressure sensor.The PDMS substrate comprises three gradient modulus PDMS structure layers arranged from bottom to top, and the three gradient modulus PDMS structure layers are respectively a bottom layer, a middle layer and a top layer.The bottom layer is a viscous PDMS layer with double-component repair microcapsules embedded therein; the middle layer is a transition layer formed by compounding PDMS and nano clay; and the top layer is a stiffness PDMS layer provided with a micro-island bridge array.A PVDF sensitive film is fixedly supported on the micro-island bridge array to form a beam film structure; a graphene resistor is integrated on the upper surface of the PVDF sensitive film corresponding to the micro-island fixed support area; and the back surface of the graphene resistor is pre-coated with a PDMS flexible protective layer.The application is used for a flexible array type pressure sensor.

Description

Technical Field

[0001] This invention relates to a PDMS substrate with a micro-island bridge array fixed support and its fabrication method, belonging to the field of aerospace smart skin and sensing technology. Background Technology

[0002] Modern aircraft aerodynamic design heavily relies on precise monitoring of wing surface pressure distribution. Wind tunnel testing, as a core verification method, requires the deployment of hundreds of pressure measurement points on the wing surface. Traditional methods use drilled holes to embed pressure scanning valves, resulting in a 15%-20% loss of wing surface structural strength, and discrete measurement points cannot invert the overall pressure distribution. Flexible array sensors integrate a sensitive element array onto a flexible substrate and attach it to the aircraft wing surface, achieving non-destructive global monitoring, lightweight design, and real-time dynamic pressure field mapping. While flexible array pressure sensors can achieve non-destructive global monitoring, they suffer from two major bottlenecks:

[0003] 1. Insufficient dynamic monitoring capability: The frequency response of the piezoresistive sensing unit made of carbon materials such as graphene and carbon nanotubes is <100Hz, which cannot capture turbulent transient fluctuations (≥1kHz).

[0004] 2. Failure of curved surface bonding: Abrupt curvature of the wing leading edge (R≤50mm) requires high-precision bonding process. Curved surfaces are prone to causing bubbles / wrinkles, which prevents the sensor from conforming to the curved surface. The bonding strength is reduced in the high-speed wind tunnel, making the sensor unusable. High-speed airflow (pulsating pressure ≥8kHz) and sand impact cause microcracks to propagate, and traditional bonding cannot self-repair. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of easy failure of curved surface adhesion and inability to self-repair damage at the bonding interface in existing flexible array pressure sensors, and to provide a PDMS substrate with micro-island bridge array support and its preparation method.

[0006] The present invention discloses a PDMS substrate with micro-island bridge array support, which includes: three gradient modulus PDMS structure layers arranged from bottom to top, the three gradient modulus PDMS structure layers being a bottom layer, a middle layer, and a top layer;

[0007] The bottom layer is a viscous PDMS layer embedded with two-component repair microcapsules;

[0008] The intermediate layer is a transition layer formed by PDMS and nano-clay composite;

[0009] The top layer is a stiff PDMS layer with a micro-island bridge array;

[0010] The micro-island bridge array is fixed with a PVDF sensitive membrane, forming a beam-membrane structure;

[0011] The PVDF sensitive film has a graphene resistor integrated on its upper surface corresponding to the micro-island fixed region;

[0012] The graphene resistor has a PDMS flexible protective layer pre-coated on its back.

[0013] Preferably, the PVDF sensitive membrane senses dynamic pressure signals through the piezoelectric effect;

[0014] The graphene resistor senses static pressure signals through the piezoresistive effect.

[0015] Preferably, the thickness of the bottom layer is 500 μm, and it is formed by the addition curing reaction of the main agent A and the curing agent B;

[0016] The mass ratio of main agent A to curing agent B is 13:1;

[0017] The main agent A is a vinyl-containing polydimethylsiloxane;

[0018] The curing agent B is a hydrogen-containing polydimethylsiloxane.

[0019] Preferably, the two-component repair microcapsules are uniformly distributed in the bottom layer;

[0020] The dual-component repair microcapsule comprises microcapsule A and microcapsule B;

[0021] The shell material of microcapsule A is polymethyl methacrylate (PMMA), and the core material is a mixture containing alicyclic epoxy resin and a photoinitiator.

[0022] The shell material of the microcapsule B is polymethyl methacrylate (PMMA), and the core material is dimethyl silicone oil.

[0023] Each bicomponent repair microcapsule has a diameter of 20 μm. When the wing surface deforms and causes wrinkles or cracks, the bicomponent repair microcapsule ruptures and releases the bicomponent repair material.

[0024] Preferably, the intermediate layer is prepared from a composite material of PDMS and nanoclay, with a Young's modulus of 1 MPa; it is used to bond two layers of materials with different moduli to buffer abrupt changes in modulus and suppress interfacial delamination.

[0025] Preferably, the micro-island bridge array includes multiple spaced micro-islands and micro-bridges connecting adjacent micro-islands;

[0026] The micro-island has a height of 300 μm, a diameter of 100 μm, and a center-to-center distance of 150 μm between adjacent micro-islands.

[0027] Preferably, the micro-island bridge array is fabricated using 3D printing or screen printing technology.

[0028] Preferably, the top layer includes a substrate layer and an array of micro-island bridges disposed on the surface of the substrate layer;

[0029] The substrate layer is formed of a high-hardness polymer;

[0030] The high-hardness polymer contains PDMS and silica filler dispersed therein, with the silica filler content being 10 wt%.

[0031] The present invention discloses a method for fabricating a PDMS substrate with a micro-island bridge array support, the method specifically comprising:

[0032] S1. Prepare a high-viscosity PDMS prepolymer with embedded two-component repair microcapsules, and obtain the bottom layer after casting.

[0033] S2. Prepare a mixed prepolymer of PDMS and nano-clay on the upper surface of the bottom layer, cast it to form an intermediate layer, and then crosslink the intermediate layer with the bottom layer.

[0034] S3. Construct a micro-island bridge array mold cavity on the upper surface of the intermediate layer using 3D printing or screen printing technology, and inject high-rigidity PDMS prepolymer. After curing, it forms the top layer and micro-island bridge array structure.

[0035] S4. The PVDF sensitive membrane is bonded and fixed onto the top layer of the micro-island bridge array;

[0036] S5. In the region corresponding to the micro-island fixed branch on the PVDF sensitive film, a graphene resistor is integrated by laser direct writing or transfer printing process.

[0037] S6. A flexible PDMS prepolymer is coated on the back of the PVDF sensitive film that integrates graphene resistors and cured to form a flexible PDMS protective layer.

[0038] Preferably, the preparation method of the two-component repair microcapsules includes:

[0039] S1. Preparation of microcapsule A: The capsule core A containing alicyclic epoxy resin and photoinitiator is mixed with methyl methacrylate (MMA) monomer to form an oil phase, and the oil phase is emulsified in an aqueous solution containing emulsifier to form an emulsion; then an initiator is added, and a polymerization reaction is carried out at 70°C to polymerize MMA at the oil-water interface to form a PMMA shell, and microcapsule A is obtained after post-treatment.

[0040] S2. Preparation of microcapsule B: The core B containing dimethyl silicone oil is mixed with methyl methacrylate (MMA) monomer to form an oil phase, and the oil phase is emulsified in an aqueous solution containing an emulsifier to form an emulsion; then an initiator is added, and a polymerization reaction is carried out at 70°C to polymerize MMA at the oil-water interface to form a PMMA shell, and microcapsule B is obtained after post-treatment.

[0041] S3. Mix microcapsule A and microcapsule B at a mass ratio of 1:1 to obtain a two-component repair microcapsule.

[0042] Advantages of this invention: This invention proposes a PDMS substrate with micro-island bridge array fixed support and its preparation method, which is used for pressure monitoring of aircraft wing surfaces and is mainly applied in wind tunnel experiments.

[0043] A three-layer gradient modulus flexible PDMS substrate is employed. The bottom layer is a high-viscosity PDMS layer with embedded two-component repair microcapsules. When structural damage occurs during bonding due to bubbles, wrinkles, or high-speed airflow impact, the microcapsules rupture to release a repair agent, achieving self-repair. The middle layer is a PDMS + nano-clay composite transition layer, balancing flexibility and structural stability. The top layer is a high-stiffness micro-island bridge array PDMS layer used to support the PVDF sensitive membrane. The PVDF membrane forms a beam-membrane structure through island bridges, utilizing the piezoelectric effect to measure dynamic pressure. A graphene resistor (pre-coated with a flexible PDMS layer on the back) is integrated on the upper surface of the PVDF micro-island support, achieving static pressure monitoring through the piezoresistive effect.

[0044] By using a gradient modulus substrate coupled with a multiphysics sensing mechanism, the problems of dynamic and static separation, environmental adaptability and long-term reliability in airfoil pressure testing can be solved simultaneously. Using 3D printing or screen printing technology, mass-produced engineering products can be easily realized. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of a PDMS substrate with micro-island bridge array fixed support as described in this invention;

[0046] Figure 2 This is a schematic diagram of the two-component repair microcapsules described in this invention under ultraviolet light irradiation conditions;

[0047] Figure 3 This is a process flow diagram of a method for fabricating a PDMS substrate with micro-island bridge array support as described in this invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0051] Example 1:

[0052] The following is combined with Figure 1 This embodiment describes a PDMS substrate with a micro-island bridge array support, which includes three gradient modulus PDMS structural layers arranged from bottom to top, namely a bottom layer, a middle layer, and a top layer;

[0053] The bottom layer is a viscous PDMS layer embedded with two-component repair microcapsules;

[0054] The intermediate layer is a transition layer formed by PDMS and nano-clay composite;

[0055] The top layer is a stiff PDMS layer with a micro-island bridge array;

[0056] The micro-island bridge array is fixed with a PVDF sensitive membrane, forming a beam-membrane structure;

[0057] The PVDF sensitive film has a graphene resistor integrated on its upper surface corresponding to the micro-island fixed region;

[0058] The graphene resistor has a PDMS flexible protective layer pre-coated on its back.

[0059] Furthermore, the PVDF sensitive membrane senses dynamic pressure signals through the piezoelectric effect;

[0060] The graphene resistor senses static pressure signals through the piezoresistive effect.

[0061] Furthermore, the thickness of the bottom layer is 500 μm, and it is formed by the addition curing reaction of the main agent A and the curing agent B;

[0062] The mass ratio of main agent A to curing agent B is 13:1;

[0063] The main agent A is a vinyl-containing polydimethylsiloxane;

[0064] The curing agent B is a hydrogen-containing polydimethylsiloxane.

[0065] Furthermore, the two-component repair microcapsules are uniformly distributed in the bottom layer;

[0066] The dual-component repair microcapsule comprises microcapsule A and microcapsule B;

[0067] The shell material of microcapsule A is polymethyl methacrylate (PMMA), and the core material is a mixture containing alicyclic epoxy resin and a photoinitiator.

[0068] The shell material of the microcapsule B is polymethyl methacrylate (PMMA), and the core material is dimethyl silicone oil.

[0069] Each bicomponent repair microcapsule has a diameter of 20 μm. When the wing surface deforms and causes wrinkles or cracks, the bicomponent repair microcapsule ruptures and releases the bicomponent repair material.

[0070] Furthermore, the intermediate layer is prepared using a composite material of PDMS and nano-clay with a Young's modulus of 1 MPa; it is used to bond two layers of materials with different moduli to buffer abrupt changes in modulus and suppress interfacial delamination.

[0071] Furthermore, the micro-island bridge array includes multiple spaced micro-islands and micro-bridges connecting adjacent micro-islands;

[0072] The micro-island has a height of 300 μm, a diameter of 100 μm, and a center-to-center distance of 150 μm between adjacent micro-islands.

[0073] Furthermore, the micro-island bridge array is fabricated using 3D printing or screen printing technology.

[0074] Furthermore, the top layer includes a substrate layer and an array of micro-island bridges disposed on the surface of the substrate layer;

[0075] The substrate layer is formed of a high-hardness polymer;

[0076] The high-hardness polymer contains PDMS and silica filler dispersed therein, with the silica filler content being 10 wt%.

[0077] In this embodiment, the bottom layer is a self-healing adhesive layer, which is an adhesion layer made of high-viscosity PDMS with pre-embedded two-component microcapsules. Its adhesive properties ensure a tight, bubble-free bond with the airfoil surface. When wrinkles, bubbles, or high-speed airflow in the wind tunnel cause the membrane layer to peel off during the bonding process, the microcapsules rupture due to mechanical compression, and the released repair agent can quickly fill the defects and restore structural integrity. This design significantly improves the sensor's survivability in complex airflow environments and reduces the need for manual maintenance.

[0078] The bottom layer is 500 μm thick, with a high-viscosity PDMS main agent A (vinyl polydimethylsiloxane) and curing agent B (hydrogen-containing polydimethylsiloxane) (A:B=13:1), dispersing two-component microcapsules with a diameter of 20 μm (microcapsule preparation method is as follows). When the wing surface deformation causes wrinkles or microcracks, the capsules rupture and release self-healing material.

[0079] In this embodiment, the intermediate layer is a transition layer, consisting of PDMS and nanoclay. The nanoclay enhances the mechanical strength of the PDMS while maintaining the bending adaptability of the flexible substrate. This layer acts as a stress buffer, effectively dispersing the local stress generated by the deformation of the airfoil, preventing interface peeling or signal distortion caused by the mismatch between the substrate and the sensitive element's modulus, and ensuring the long-term stability of dynamic and static pressure tests.

[0080] The intermediate layer has a thickness of 50 μm and a modulus of 1 MPa. It is a PDMS / nanoclay composite material that buffers the modulus abrupt change between the adhesion layer and the support layer, suppresses interfacial peeling, and achieves mechanical transition.

[0081] In this embodiment, the top layer is a micro-island bridge array support layer, employing a high-stiffness PDMS micro-island bridge array. The island bridge structure mechanically supports the PVDF membrane, forming a stable beam-membrane structure, and physical isolation prevents mechanical crosstalk. This design allows the PVDF to undergo controllable deformation under dynamic pressure, improving the sensitivity of the piezoelectric signal. Simultaneously, a graphene + PDMS composite resistive layer is integrated at the micro-island support, utilizing the piezoresistive effect to achieve high-precision static pressure measurement. The gradient modulus design causes the substrate modulus to gradually increase from the flexible bonding layer to the rigid sensing layer, ensuring conformal bonding with the airfoil while achieving high-precision mechanical constraints on the sensitive element, overcoming the technical bottleneck of the "rigid-flexible contradiction" in traditional single-layer substrates.

[0082] The top layer is 500 μm thick. A micro-island bridge array with a diameter of 100 μm, a height of 300 μm, and a spacing of 150 μm is constructed on the surface of high-hardness PDMS (A:B=7:1, with 10 wt% added silica). The top of the micro-island bearing area is coated with high-viscosity PDMS (A:B=13:1) to support the sensitive element and form a beam-membrane sensitive structure.

[0083] In this embodiment, the flexible pressure sensor PDMS substrate includes a three-layer functional structure, from the wing adhesion layer to the sensitive element support layer, to achieve precise control of function and mechanical properties.

[0084] In this embodiment, the microcapsules in the adhesion layer achieve "pressure-triggered self-repair": when the stress in the bubble area is >0.5MPa, the microcapsule ruptures and releases the microcapsule repair components, which are then cured by ultraviolet light; at the support layer micro-island bridge support, the PVDF piezoelectric sensitive membrane is suspended, forming a suspended beam membrane structure, and a graphene piezoresistive resistor is constructed at the top of the micro-island bearing area to simultaneously sense static pressure.

[0085] Example 2:

[0086] The following is combined with Figure 2 and Figure 3 This embodiment describes a method for fabricating a PDMS substrate with a micro-island bridge array support. The method specifically includes:

[0087] S1. Prepare a high-viscosity PDMS prepolymer with embedded two-component repair microcapsules, and obtain the bottom layer after casting.

[0088] S2. Prepare a mixed prepolymer of PDMS and nano-clay on the upper surface of the bottom layer, cast it to form an intermediate layer, and then crosslink the intermediate layer with the bottom layer.

[0089] S3. Construct a micro-island bridge array mold cavity on the upper surface of the intermediate layer using 3D printing or screen printing technology, and inject high-rigidity PDMS prepolymer. After curing, it forms the top layer and micro-island bridge array structure.

[0090] S4. The PVDF sensitive membrane is bonded and fixed onto the top layer of the micro-island bridge array;

[0091] S5. In the region corresponding to the micro-island fixed branch on the PVDF sensitive film, a graphene resistor is integrated by laser direct writing or transfer printing process.

[0092] S6. A flexible PDMS prepolymer is coated on the back of the PVDF sensitive film that integrates graphene resistors and cured to form a flexible PDMS protective layer.

[0093] Furthermore, the preparation method of the two-component repair microcapsules includes:

[0094] S1. Preparation of microcapsule A:

[0095] The core A containing alicyclic epoxy resin and photoinitiator is mixed with methyl methacrylate (MMA) monomer to form an oil phase, and the oil phase is emulsified in an aqueous solution containing an emulsifier to form an emulsion.

[0096] Then an initiator was added, and a polymerization reaction was carried out at 70°C to polymerize MMA at the oil-water interface to form a PMMA shell. After post-treatment, microcapsule A was obtained.

[0097] S2. Preparation of microcapsules B:

[0098] The core B containing dimethyl silicone oil is mixed with methyl methacrylate (MMA) monomer to form an oil phase, and the oil phase is emulsified in an aqueous solution containing an emulsifier to form an emulsion.

[0099] Then an initiator was added, and a polymerization reaction was carried out at 70°C to polymerize MMA at the oil-water interface to form a PMMA shell. After post-treatment, microcapsules B were obtained.

[0100] S3. Mix microcapsule A and microcapsule B at a mass ratio of 1:1 to obtain a two-component repair microcapsule.

[0101] In this embodiment, core A is composed of alicyclic epoxy resin CN104 (99.5 wt%) and photoinitiator TPO (0.5 wt%), mixed evenly.

[0102] Core B: Dimethyl silicone oil (purity ≥99%).

[0103] Shell material: PMMA (polymethyl methacrylate).

[0104] Auxiliary materials: emulsifier (Span 80), MMA monomer, initiator AIBN (azobisisobutyronitrile), deionized water.

[0105] Preparation of microcapsule A:

[0106] Step 1: Emulsion Preparation

[0107] The capsule core A (CN104+TPO) was mixed with MMA monomer at a mass ratio of 1:1, and emulsifier Span 80 (accounting for 2wt% of the oil phase) was added and stirred to form the oil phase.

[0108] The oil phase was slowly added to deionized water (containing 0.5 wt% emulsifier) ​​and homogenized at high speed (10,000 rpm, 10 min) to form a stable emulsion.

[0109] Step 2: Interface Aggregation

[0110] Add initiator AIBN (1 wt% of MMA monomer) to the emulsion and heat to 70°C to initiate polymerization.

[0111] Continue stirring for 4 hours to allow MMA to polymerize at the oil-water interface and form a PMMA shell.

[0112] Cool to room temperature, filter, wash, and dry to obtain microcapsules A (particle size 10-50 μm).

[0113] Preparation of microcapsule B:

[0114] Repeat the preparation steps of microcapsule A, but replace the core with dimethyl silicone oil, keeping other parameters unchanged, to obtain microcapsule B.

[0115] Mixing and coating:

[0116] Microcapsules A and B were mixed at a mass ratio of 1:1 and uniformly dispersed in the PDMS adhesive layer.

[0117] Triggering conditions:

[0118] Light source: Ultraviolet light (wavelength 365nm, intensity 10-20mW / cm²).

[0119] Time: 30 seconds of irradiation.

[0120] Reaction process:

[0121] Step 1: Microcapsule rupture

[0122] When cracks or damage occur in the adhesive layer, microcapsules A and B rupture simultaneously due to stress, releasing core A (CN104+TPO) and core B (dimethyl silicone oil).

[0123] Step 2: Photoinitiated polymerization

[0124] Under ultraviolet light irradiation, TPO absorbs energy and decomposes into free radicals (phosphate ester free radicals and benzoyl free radicals).

[0125] Free radicals initiate the ring-opening polymerization of the epoxy groups of CN104, forming a three-dimensional cross-linked polymer structure.

[0126] Step 3: Collaborative Repair

[0127] Dimethyl silicone oil acts as an inert diluent, reducing the viscosity of the repair agent and promoting the flow and penetration of CN104 in the crack.

[0128] Cross-linked polymers fill cracks, and silicone oil forms a flexible interface layer to relieve residual stress and restore mechanical properties.

[0129] In this invention, the preparation method is as follows:

[0130] Step 1: Pre-curing of the adhesive layer

[0131] Microcapsule-containing PDMS was coated onto a deep silicon etched mold A with microstructures and pre-cured at 60°C for 20 minutes (30% cross-linking degree to maintain microcapsule activity).

[0132] Step 2: Spin coating of transition layer

[0133] A PDMS / nanoclay (Laponite RD) slurry (50 μm thick) was spin-coated onto the surface of the adhesion layer to resolve the modulus mismatch of the heterogeneous layer.

[0134] Step 3: Support Lamination Imprinting

[0135] High-modulus PDMS (containing 30% SiO2) is pressed into a deep silicon etching mold A, and a mold B with micropillar protrusions is pressed onto A. The mold is shaped at 70℃ for 10 minutes and then vacuum rolled (0.5MPa, 60℃) to ensure the complete transfer of the micropillar protrusion structure.

[0136] Step 4: Integration of Sensitive Components

[0137] A graphene / PVDF composite sensor array is attached to the micro-island support and then vacuum rolled (0.5MPa).

[0138] Final curing regime: 60℃ / 30min → 80℃ / 1h → 100℃ / 30min (avoid damaging microcapsules at >120℃).

[0139] This invention, through the design of a "sandwich-style" PDMS structure, achieves conformal application to highly viscous curved surfaces, solves the problem of self-healing damage at the bonding interface in engineering applications, and simultaneously constructs a high-elasticity modulus PDMS support structure to address the issue of simultaneous monitoring of dynamic and static pressure.

[0140] Compared with traditional PDMS composite membranes:

[0141] Existing technology (CN109603569A): focuses on low-temperature continuous coating process, but does not solve the problems of interface delamination and dynamic damage repair;

[0142] This application introduces a two-component microcapsule repair + transition layer modulus buffer, which is suitable for self-repair of micro-cracks in large structures and is easy to implement in engineering.

[0143] Comparison with flexible sensor patents:

[0144] Existing technology (CN116642608A): Employs PEDOT:PSS / rGO foam sensing layer, suitable for human tactile monitoring (strain >10%).

[0145] This application proposes a micro-island bridge fixed support structure for the support layer, which enables PVDF / graphene to form a beam-membrane structure suitable for monitoring fields where high-frequency dynamic pressure and static pressure coexist.

[0146] Compared with gradient materials patents:

[0147] Existing technology (PDMS / SiC functionally graded substrate): enhances the mechanical properties of PDMS with SiC, but does not integrate sensing functions;

[0148] This application: The three-layer gradient design simultaneously achieves the integration of "attachment-buffering-sensing", and the micro-island bridge structure is precisely controlled by silicon micro MEMS technology, resulting in a larger number of sensitive units per unit area, which is easy to implement in engineering.

[0149] In this invention, a novel architecture based on a three-layer gradient PDMS substrate is used to achieve, for the first time, a flexible array pressure sensor:

[0150] Self-healing and highly reliable bonding: The microcapsule self-healing mechanism significantly improves environmental adaptability and reduces the risk of sensor failure in wind tunnel experiments;

[0151] Decoupling of dynamic and static pressure: The gradient modulus substrate and the beam-film-piezoresistive composite sensing structure enable synchronous high-precision measurement of dynamic pressure (piezoelectric) and static pressure (piezoresistive).

[0152] Structure-function integration: The micro-island bridge array simultaneously performs multiple functions such as fixed support, isolation and hydrostatic sensing, simplifying the fabrication process and improving integration.

[0153] The present invention proposes a PDMS substrate with micro-island bridge array fixed support and its preparation method, which provides a highly adaptable and long-life solution for the testing of aerodynamic parameters of aircraft and has significant market application prospects.

[0154] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A PDMS substrate with a micro-island bridge array fixed support, characterized in that, It includes: The structure consists of three gradient modulus PDMS layers arranged from bottom to top, namely the bottom layer, the middle layer, and the top layer. The bottom layer is a viscous PDMS layer embedded with two-component repair microcapsules; The intermediate layer is a transition layer formed by PDMS and nano-clay composite; The top layer is a stiff PDMS layer with a micro-island bridge array; The micro-island bridge array is fixed with a PVDF sensitive membrane, forming a beam-membrane structure; The PVDF sensitive film has a graphene resistor integrated on its upper surface corresponding to the micro-island fixed region; The graphene resistor has a PDMS flexible protective layer pre-coated on its back.

2. The PDMS substrate with micro-island bridge array support according to claim 1, characterized in that, The PVDF sensitive membrane senses dynamic pressure signals through the piezoelectric effect; The graphene resistor senses static pressure signals through the piezoresistive effect.

3. A PDMS substrate with micro-island bridge array support according to claim 1, characterized in that, The thickness of the bottom layer is 500 μm, and it is formed by the addition curing reaction of the main agent A and the curing agent B. The mass ratio of main agent A to curing agent B is 13:1; The main agent A is a vinyl-containing polydimethylsiloxane; The curing agent B is a hydrogen-containing polydimethylsiloxane.

4. A PDMS substrate with micro-island bridge array support according to claim 1 or 3, characterized in that, The two-component repair microcapsules are uniformly distributed in the bottom layer; The dual-component repair microcapsule comprises microcapsule A and microcapsule B; The shell material of microcapsule A is polymethyl methacrylate (PMMA), and the core material is a mixture containing alicyclic epoxy resin and a photoinitiator. The shell material of the microcapsule B is polymethyl methacrylate (PMMA), and the core material is dimethyl silicone oil. Each bicomponent repair microcapsule has a diameter of 20 μm. When the wing surface deforms and causes wrinkles or cracks, the bicomponent repair microcapsule ruptures and releases the bicomponent repair material.

5. A PDMS substrate with micro-island bridge array support according to claim 1, characterized in that, The intermediate layer is prepared from a composite material of PDMS and nanoclay with a Young's modulus of 1 MPa; it is used to bond two layers of materials with different moduli to buffer abrupt changes in modulus and suppress interfacial delamination.

6. A PDMS substrate with micro-island bridge array support according to claim 1, characterized in that, The micro-island bridge array includes multiple spaced micro-islands and micro-bridges connecting adjacent micro-islands; The micro-island has a height of 300 μm and a diameter of 100 μm; The center-to-center distance between adjacent micro-islands is 150 μm.

7. A PDMS substrate with micro-island bridge array support according to claim 1, characterized in that, The micro-island bridge array is fabricated using 3D printing or screen printing technology.

8. A PDMS substrate with micro-island bridge array support according to claim 1, characterized in that, The top layer includes a substrate layer and a micro-island bridge array disposed on the surface of the substrate layer; The substrate layer is formed of a high-hardness polymer; The high-hardness polymer contains PDMS and silica filler dispersed therein, with the silica filler content being 10 wt%.

9. A method for fabricating a PDMS substrate with a micro-island bridge array support, characterized in that, The preparation method specifically includes: S1. Prepare a high-viscosity PDMS prepolymer with embedded two-component repair microcapsules, and obtain the bottom layer after casting. S2. Prepare a mixed prepolymer of PDMS and nano-clay on the upper surface of the bottom layer, cast it to form an intermediate layer, and then crosslink the intermediate layer with the bottom layer. S3. Construct a micro-island bridge array mold cavity on the upper surface of the intermediate layer using 3D printing or screen printing technology, and inject high-rigidity PDMS prepolymer. After curing, it forms the top layer and micro-island bridge array structure. S4. The PVDF sensitive membrane is bonded and fixed onto the top layer of the micro-island bridge array; S5. In the region corresponding to the micro-island fixed branch on the PVDF sensitive film, a graphene resistor is integrated by laser direct writing or transfer printing process. S6. A flexible PDMS prepolymer is coated on the back of the PVDF sensitive film that integrates graphene resistors and cured to form a flexible PDMS protective layer.

10. A method for fabricating a PDMS substrate with a micro-island bridge array support according to claim 9, characterized in that, The preparation method of the two-component repair microcapsules includes: S1. Preparation of microcapsule A: A core A containing alicyclic epoxy resin and a photoinitiator is mixed with methyl methacrylate (MMA) monomer to form an oil phase, and the oil phase is emulsified in an aqueous solution containing an emulsifier to form an emulsion. Then an initiator was added, and a polymerization reaction was carried out at 70°C to polymerize MMA at the oil-water interface to form a PMMA shell. After post-treatment, microcapsule A was obtained. S2. Preparation of microcapsules B: The core B containing dimethyl silicone oil is mixed with methyl methacrylate (MMA) monomer to form an oil phase, and the oil phase is emulsified in an aqueous solution containing an emulsifier to form an emulsion. Then an initiator was added, and a polymerization reaction was carried out at 70°C to polymerize MMA at the oil-water interface to form a PMMA shell. After post-treatment, microcapsules B were obtained. S3. Mix microcapsule A and microcapsule B at a mass ratio of 1:1 to obtain a two-component repair microcapsule.

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