CN109573939B - Dual layer strained substrates and stretchable electronic devices - Google Patents
Dual layer strained substrates and stretchable electronic devices Download PDFInfo
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
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Abstract
The invention discloses a double-layer strain matrix, which comprises: a first base layer; a second base layer disposed on the first base layer; the first substrate has a hardness greater than the second substrate; the surface of the second base layer is wavy. According to the double-layer strain matrix provided by the embodiment of the invention, the first base layer with higher hardness is arranged below the second base layer with the wavy surface, so that the tensile property of the second base layer is maintained, the mechanical strength of the whole structure is improved, and the problem of insufficient strength of the existing mechanical system taking a single soft base layer as a support is solved.
Description
Technical Field
The invention relates to the technical field of biomedicine, in particular to a double-layer strain matrix and a stretchable electronic device.
Background
By providing a brittle film on a relatively thin, elastic substrate, the brittle material can be converted into a stretchable mechanical structure. However, mechanical systems consisting of a single soft base layer and a brittle film often have the disadvantage of insufficient mechanical strength, which makes it difficult to meet the requirements of practical applications. There is a need to develop a mechanical structure that maintains the stretch properties while providing strong, high strength.
Disclosure of Invention
Embodiments of the present invention provide a dual-layer strained-substrate and stretchable electronic device to solve the problem of insufficient strength of the existing mechanical system supported by a single soft substrate.
According to a first aspect, embodiments of the present invention provide a two-layer strained matrix comprising: a first base layer; a second base layer disposed on the first base layer; the first base layer has a hardness greater than the second base layer; the surface of the second base layer is wavy.
According to the double-layer strain matrix provided by the embodiment of the invention, the first base layer with higher hardness is arranged below the second base layer with the wavy surface, so that the tensile property of the second base layer is maintained, the mechanical strength of the whole structure is improved, and the problem of insufficient strength of the existing mechanical system taking a single soft base layer as a support is solved.
With reference to the first aspect, in a first embodiment of the first aspect, a ratio of a thickness of the second base layer to a wavelength of the undulation of the surface is greater than or equal to 12.
According to the double-layer strain matrix provided by the embodiment of the invention, the ratio of the thickness of the second base layer to the wave length of the wave shape on the surface of the second base layer is set to be a constant greater than or equal to 12, so that the structure formed by the two base layers and the structure formed by the second base layer only on the upper layer are basically the same in wavelength and amplitude, the functions of the two base layers can be decoupled, and the first base layer on the lower layer can be independently carried out in the aspects of material selection and design without affecting the overall tensile property of the device. Because the wave length and the amplitude of the wave-shaped structure generated on the surface of the second base layer above the double-layer strain matrix are not influenced by the first base layer at the lower layer, the first base layer at the lower layer can be made of a rigid protective material, a water-permeable and air-permeable material, a waterproof and chemical-corrosion-resistant material or a material with mechanical properties similar to that of human skin, so that the functions of the double-layer strain matrix are expanded, and the double-layer strain matrix can meet the requirements of different application occasions.
With reference to the first aspect or the first embodiment of the first aspect, in a second embodiment of the first aspect, the first base layer includes: a flexible matrix and a network of fibers disposed within the flexible matrix; the fiber network comprises a plurality of topological structures which are regularly arranged, all nodes of the topological structures are connected through a wavy microstructure, the wavy microstructure is provided with a preset width, and wave crests or wave troughs forming the wavy microstructure are provided with preset arc angles.
According to the double-layer strain matrix provided by the embodiment of the invention, the hard fiber network and the soft flexible matrix are combined in the first base layer, so that a bionic flexible biological structure is constructed, skin-like is realized, and the defect that the existing flexible matrix, skin and tissue are not matched with the mechanical property of the skin in the stretching process is overcome, so that the comfort degree of the first base layer and the double-layer strain matrix and stretchable electronic device formed by the first base layer in the wearing process can be greatly improved, and the mechanical invisibility of the first base layer and the double-layer strain matrix and stretchable electronic device formed by the first base layer in the skin tissue deformation process can be realized.
With reference to the second embodiment of the first aspect, in a third embodiment of the first aspect, the topological structure is a triangular topological structure, and each side of the triangular topological structure is the wavy microstructure.
According to the double-layer strain substrate provided by the embodiment of the invention, the fiber network in the first base layer is constructed through the triangular topological structure, so that the bionic flexible first base layer constructed by the hard fiber network and the soft flexible substrate has mechanical properties similar to those of skin, and the problem of low wearing comfort of the existing biological integrated electronic device or stretchable electronic device is solved.
With reference to the second embodiment of the first aspect, in the fourth embodiment of the first aspect, the topology is a honeycomb topology, and each side of the honeycomb topology is the wavy microstructure.
According to the double-layer strain substrate provided by the embodiment of the invention, the fiber network in the first base layer is constructed through the honeycomb-shaped topological structure, so that the bionic flexible first base layer constructed by the hard fiber network and the soft flexible substrate has mechanical properties similar to those of skin, and the problem of low wearing comfort of the existing biological integrated electronic device or stretchable electronic device is solved.
With reference to the second implementation manner of the first aspect, in a fifth implementation manner of the first aspect, the topological structure is a Kagome topological structure, each side of the Kagome topological structure is the wavy microstructure, and a space is formed between each two Kagome topological structures.
According to the double-layer strain matrix provided by the embodiment of the invention, the fiber network in the first base layer is constructed through the Kagome topological structure, so that the bionic flexible first base layer constructed by the hard fiber network and the soft flexible matrix has mechanical properties similar to those of skin, and the problem of low wearing comfort of the existing biological integrated electronic device or stretchable electronic device is solved.
With reference to the second implementation manner of the first aspect, in a sixth implementation manner of the first aspect, the topological structure is a square topological structure, and each side of the square topological structure is the wavy microstructure.
According to the double-layer strain substrate provided by the embodiment of the invention, the fiber network in the first base layer is constructed through the square topological structure, so that the bionic flexible first base layer constructed by the hard fiber network and the soft flexible substrate has mechanical properties similar to those of skin, and the problem of low wearing comfort of the existing biological integrated electronic device or stretchable electronic device is solved.
With reference to the second implementation manner of the first aspect, in a seventh implementation manner of the first aspect, the topological structure is a rhombus topological structure, each side of the rhombus topological structure is the wavy microstructure, and a space is formed between the rhombus topological structures.
According to the double-layer strain substrate provided by the embodiment of the invention, the fiber network in the first base layer is constructed through the diamond topological structure, so that the bionic flexible first base layer constructed by the hard fiber network and the soft flexible substrate has mechanical properties similar to those of skin, and the problem of low wearing comfort of the existing biological integrated electronic device or stretchable electronic device is solved.
According to a second aspect, embodiments of the present invention provide a stretchable electronic device comprising: the bi-layer strained matrix of the first aspect or any embodiment of the first aspect.
Embodiments of the present invention provide a stretchable electronic device with enhanced mechanical strength due to the dual-layer strained matrix as described in the first aspect or any of the embodiments of the first aspect.
With reference to the second aspect, in a first embodiment of the second aspect, the stretchable electronic device further comprises: a sensor layer disposed on the bi-layer strain matrix.
According to the stretchable electronic device provided by the embodiment of the invention, the sensor layer is arranged on the double-layer strain substrate, so that the stretchable electronic device has a signal acquisition function.
With reference to the first embodiment of the second aspect, in the second embodiment of the second aspect, the sensor layer is a rigid film, and a surface of the rigid film is in a wave shape and is attached to the second base layer in the two-layer strain matrix.
According to the stretchable electronic device provided by the embodiment of the invention, the sensor layer is designed into the wavy rigid film, so that the stretching of the sensor layer is realized, and the performance of the sensor layer is ensured. Due to the wavy design of the sensor layer, the sensor layer can be made of high-performance electronic materials containing fragile materials such as silicon and the like, and compared with flexible organic thin film materials, the electrical performance is remarkably improved.
With reference to the first embodiment of the second aspect, in a third embodiment of the second aspect, the sensor layer is in an island bridge structure, and the island bridge structure includes: the device comprises an island structure formed by sensors and a metal bridge connected with the island structure, wherein the metal bridge is in a wave-shaped configuration and is attached to a second base layer in the double-layer strain matrix.
According to the stretchable electronic device provided by the embodiment of the invention, the sensor layer is designed into the island bridge structure, so that the stretching of the sensor layer is realized, and the performance of the sensor layer is ensured. Due to the island bridge structure design of the sensor layer, the island structure can be made of high-performance electronic materials containing fragile materials such as silicon, and compared with flexible organic thin film materials, the electrical performance is remarkably improved.
With reference to any one of the first to third embodiments of the second aspect, in a fourth embodiment of the second aspect, the stretchable electronic device further comprises a soft encapsulation layer disposed on the sensor layer.
The stretchable electronic device provided by the embodiment of the invention has the characteristics of water resistance, chemical corrosion resistance, heat resistance and the like due to the arrangement of the soft packaging layer, so that the function of the stretchable electronic device is further promoted.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 shows a schematic structural diagram of one specific example of a two-layer strained substrate in an embodiment of the invention;
FIG. 2 is a graph showing the wavelength ratio and amplitude ratio of a single base layer to a double layer strained substrate for different Young's modulus ratios;
FIG. 3 is a graph showing the variation of the wavelength ratio and amplitude ratio of a single base layer to a double-layer strained base corresponding to the ratio of the thickness of a different second base layer to the wavelength of the undulations of its surface;
FIG. 4 shows a structural drawing of a biopolymer;
FIG. 5 shows a schematic structural diagram of one specific example of a fiber network in a first substrate in an embodiment of the invention;
FIG. 6 shows an enlarged view of a wavy microstructure in an embodiment of the present invention;
FIG. 7 shows a schematic structure diagram of a triangular topology in an embodiment of the invention;
FIG. 8 shows a schematic structural diagram of a honeycomb topology in an embodiment of the present invention;
FIG. 9 shows a schematic structure diagram of a Kagome topology in an embodiment of the invention;
FIG. 10 shows a schematic structural diagram of a square topology in an embodiment of the invention;
FIG. 11 illustrates a schematic structural diagram of a diamond topology in an embodiment of the present invention;
FIG. 12 shows stress-strain plots of a first base layer of different topologies;
FIG. 13 shows stress-strain plots of the first base layer in the x-direction and the y-direction;
FIG. 14 shows stress-strain curves corresponding to different wave-shaped microstructure arc angles;
FIG. 15 shows stress-strain curves for different widths of undulating microstructure;
FIG. 16 shows stress-strain curves corresponding to different thicknesses of undulating microstructures;
FIG. 17 shows a plot of tangential modulus change for different undulating microstructure thicknesses;
FIG. 18 shows a stress-strain curve of the first substrate and a stress-strain curve of the real skin of a human body at a corresponding location;
fig. 19 shows a schematic structural view of one specific example of a stretchable electronic device in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic structural diagram of a dual-layer strained substrate according to an embodiment of the present invention, where the dual-layer strained substrate may include: a first base layer 1 and a second base layer 2 disposed on the first base layer 1. Specifically, the first base layer 1 has a hardness greater than that of the second base layer 2, and the surface of the second base layer 2 is wavy. Because the first base layer arranged at the lower part of the double-layer strain matrix has higher hardness, the mechanical strength of the double-layer strain matrix is enhanced, the mechanical strength of the whole structure is improved, and the problem of insufficient strength of the existing mechanical system taking a single soft base layer as a support is solved. In addition, the surface of the second base layer disposed on the upper portion of the dual-layer strained substrate is wavy, so that the stretchable property of the second base layer in the dual-layer strained substrate is maintained, and thus the dual-layer strained substrate provided by the embodiment of the invention can be applied to the design of a stretchable electronic device, and the corresponding stretchable electronic device has strong mechanical strength while maintaining the stretchable property.
The dual-layer strained substrate provided by embodiments of the present invention may be fabricated using pre-strain. Firstly, transferring a rigid film onto a flat pre-strained double-layer strain substrate, wherein the pre-strain direction of the double-layer strain substrate is a horizontal direction; second, the pre-strain of the bi-layer strained substrate is released and the bi-layer strained substrate is allowed to return to its original length, at which point the rigid film and the second base layer on top of the bi-layer strained substrate are bent into a wave-like geometry, thereby allowing the bi-layer strained substrate to provide an effective horizontal tensile force.
Through the analysis of the mechanical properties of the structure formed by the second base layer alone and the double-layer strained substrate, the double-layer strained substrate provided by the embodiment of the invention is found to have substantially the same wavelength and amplitude when the ratio of the thickness of the second base layer 2 to the waved wavelength of the surface of the second base layer is greater than or equal to 12, which indicates that the functions of the two-layer substrate materials in the double-layer strained substrate provided by the embodiment of the invention can be decoupled, and the first base layer of the lower layer can be independently performed in terms of the selection and design of the materials without affecting the overall tensile properties of the device. The specific mechanical properties were analyzed as follows:
the elastic energy of the bilayer matrix can be determined by the edge values. First using uiAnd wiDenotes the displacement in the x and z directions, where i ═ 1 and 2 denote the top and bottom layers of the substrate, respectively. The equilibrium equation can be expressed in terms of displacement:
wherein v isiIs the poisson's ratio of each substrate layer. Let z be 0 denote the top surface of the substrate. Continuity of displacement between the film and the substrate is required
w1|z＝0＝w0＝Acos(kx)
Because the film is much stiffer than both substrate layers, the shear at the film/substrate interface is negligible,
displacement and stress continuity requirements
Solving the equation can obtain the elastic energy of the double-layer matrix
Wherein L is0Is the length of the substrate in the original unstretched state, and is related to the length L of the film in the original unstretched state0(1+pre)；
Is the in-plane strain modulus of the top substrate layer, and furthermore v for the incompressible matrix material1＝v2When g is 0.5, g may be represented as
Wherein r ═ Es1/Es2Is the ratio of the Young's moduli of the top and bottom substrate layers, η ═ 2khsIs a dimensionless parameter that represents the ratio of the thickness of the top substrate layer to the wavelength of the undulations formed in its surface.
Bending energy U of external device filmbAnd tensile energy Um
The total energy of the system can be written as Utotal＝Ub+Um+UsMinimum required energy
The expression of wavelength and amplitude can be obtained
The wavelength and the amplitude of the single-layer aggregate are subjected to non-dimensionalization to obtain the corresponding non-dimensionalized wavelength and amplitude
The results of the variation of the dimensionless wavelength and amplitude with respect to the Young's modulus ratio and the thickness-wavelength ratio of the upper and lower layers are shown in FIGS. 2 and 3. From the results, it can be seen that when η0>12, the wavelength and amplitude of the two layers of substrates are basically the same as the result of only the upper layer material, which shows that the functions of the two layers of substrate materials can be decoupled, and the selection and design of the lower layer substrate material can be carried out independently without affecting the whole deviceThe stretchability of (a). Therefore, the lower-layer substrate material can be designed by using a skin-like and nonlinear bionic substrate, so that the matching with the mechanical properties of the skin in the stretching deformation process is completed.
The composite material consisting of hard and soft structures found in biology provides inspiration for constructing novel synthetic materials. Fig. 4 is a schematic structural view of a biopolymer. As shown in fig. 4, the solid lines connecting the solid points represent collagen and elastin in the biological system, which are filled in the biological tissue to impart elasticity to the biological tissue. The flexible bionic structure can be constructed by simulating the structure of the biological tissue, so that the simulation of the mechanical property of the skin or the biological tissue is realized, and the flexible bionic structure can be matched with the nonlinear stretching property of the skin or the biological tissue.
In order to enable the first base layer in the dual-layer strained substrate provided by the embodiment of the invention to be matched with the mechanical properties of the skin, thereby improving the wearing comfort of the dual-layer strained substrate and the stretchable electronic device constructed by the dual-layer strained substrate, the first base layer may be designed into a structure including a flexible substrate and a fiber network disposed in the flexible substrate. In one embodiment, the two-dimensional fiber network of polyimide filaments may be disposed within a flexible matrix by photolithography, and the flexible matrix may be selected from a matrix having a degree of softness similar to that of skin. Fig. 5 is a schematic structural diagram of a fiber network in a first substrate according to an embodiment of the present invention. As shown in fig. 5, the solid lines connecting the solid points represent fiber networks that fill the first substrate to provide the first substrate with mechanical properties similar to skin. The fiber network shown in fig. 5 includes a plurality of topologies arranged regularly, and the nodes of each topology are connected by a wavy microstructure. Fig. 6 is an enlarged view of a wavy microstructure constituting a fiber network provided in an embodiment of the present invention, as shown in fig. 6, the wavy microstructure has a predetermined width w, and peaks or valleys constituting the wavy microstructure have a predetermined arc angle θ.
The composite structure of the first substrate described above has non-linear characteristics similar to those of skin at various locations. Here, the approach of designing the composite structure is first introduced to improve the comfort of the first substrate during wear by precisely matching the stress-strain characteristics to the skin. The wavy microstructure, like collagen and elastin in biological systems, can uniquely define the mechanical properties of the first substrate. The wavy microstructure may be represented by three dimensionless parameters, namely arc angle θ, normalized width w, and normalized thickness t.
Next, the first substrate may be mechanically evaluated using finite element simulations. In a specific embodiment, the topology of the fiber network in the first substrate may be a triangular topology, a honeycomb topology, or a Kagome topology. Due to the six-fold symmetry of the topology, a fiber network made of the topology can provide isotropic elastic properties under small strains. Fig. 7 to 9 are schematic structural diagrams of a triangular topology, a honeycomb topology, or a Kagome topology, respectively. As shown in fig. 7, each side constituting the triangular topological structure is a wavy microstructure, and the structure in the dashed frame is a triangular topological structure; as shown in fig. 8, each side constituting the honeycomb-shaped topological structure is a wavy microstructure, and the structure in the dotted frame is a honeycomb-shaped topological structure; as shown in fig. 9, each side of the Kagome topological structure is a wavy microstructure, a space is formed between the Kagome topological structures, and the structure in the dashed box is a Kagome topological structure.
In another embodiment, the topology of the fiber network in the first substrate may be a square topology or a diamond topology, and the fiber network composed of the square topology or the diamond topology can provide an anisotropic elastic response. Fig. 10 and fig. 11 are schematic structural diagrams of a square topology or a diamond topology, respectively. As shown in fig. 10, each side constituting the square topological structure is a wave-shaped microstructure, and the structure in the dashed frame is a square topological structure; as shown in fig. 11, each edge constituting the rhombus topological structure is a wave-shaped microstructure, and a space is formed between the rhombus topological structures, and the structure in the dashed box is a rhombus topological structure.
The relative density, defined by the ratio of the mass density of the fiber network to the mass density of the corresponding flexible matrix, is approximately linearly proportional to the width of the undulating microstructure, as shown in equations (1) to (3):
wherein,
and
respectively representing the relative densities of the triangular topology, the honeycomb topology and the Kagome topology; theta and w respectively represent the arc angle and the width of the wavy microstructure constituting each topology.
For a given relative density (e.g. relative density)
) The stress-strain curves for the first substrate with a triangular topology, a honeycomb topology, or a Kagome topology are shown in fig. 12. In fig. 12, curve 91 represents the stress-strain curve for a first base layer having a triangular topology, curve 92 represents the stress-strain curve for a first base layer having a honeycomb topology, and curve 93 represents the stress-strain curve for a first base layer having a Kagome topology. Among them, the first base layer having a triangular topology exhibits the most prominent strain limiting behavior. Taking the first base layer with triangular topological structure as an example, other design parameters (such as wavy micro-junctions) are analyzedThe arc angle, width, and thickness of the structure) has an effect on the mechanical properties of the first substrate. For the first base layer with the triangular topological structure, the arc angle of the wavy microstructure is set to be 180 degrees, the thickness of the wavy microstructure is set to be 0.15 mu m, and stress-strain curves of the wavy microstructure in the x direction and the y direction are drawn. As shown in fig. 13, a curve 101 represents a stress-strain curve in the x direction of the first base layer having a triangular topology and composed of the wavy microstructure, and a curve 102 represents a stress-strain curve in the y direction of the first base layer having a triangular topology and composed of the wavy microstructure. As can be seen in fig. 13, the first base layer has isotropic characteristics for stretch within 40%, but at greater strain stretch, the first base layer requires moderate anisotropy.
Taking the first base layer with a triangular topology as an example, when the wavy microstructure has a predetermined width (for example, the width w is 0.15 μm), the stress-strain curve of the first base layer is changed by the different arc angles θ of the wavy microstructure, as shown in fig. 14. In fig. 14, a curve 111 represents a stress-strain curve of the first base layer corresponding to an arc angle θ of the wavy microstructure of 90 °; curve 112 represents a stress-strain curve of the first base layer corresponding to an arc angle θ of the wavy microstructure of 120 °; curve 113 represents a stress-strain curve of the first base layer corresponding to an arc angle θ of 150 ° in the wavy microstructure; curve 114 represents a stress-strain curve of the first base layer corresponding to an arc angle θ of 180 ° of the wavy microstructure; curve 115 shows the stress-strain curve of the first base layer corresponding to an arc angle θ of 200 ° of the wavy microstructure. Still taking the first base layer with a triangular topology as an example, when the wavy microstructure has a predetermined radian (e.g., the radian θ is 180 °), the stress-strain curve of the first base layer is changed by the difference of the width w of the wavy microstructure, as shown in fig. 15. In fig. 15, a curve 121 represents a stress-strain curve of the first base layer corresponding to a width w of the wavy microstructure of 0.25 μm; curve 122 represents the stress-strain curve of the first base layer corresponding to the width w of the wavy microstructure being 0.20 μm; curve 123 represents the stress-strain curve of the first base layer corresponding to the width w of the wavy microstructure being 0.15 μm; curve 124 represents the stress-strain curve of the first base layer corresponding to the width w of the wavy microstructure being 0.10 μm; curve 125 shows the stress-strain curve of the first base layer corresponding to the width w of the wavy microstructure being 0.05 μm. Fig. 14 to 15 show that the arc angle of the wavy microstructure controls the transition from low tangent modulus to high tangent modulus (i.e. transition strain), and the width of the wavy microstructure defines how fast the transition is.
Fig. 16 shows the effect of the thickness t of the wavy microstructure on the mechanical properties of the first substrate. Taking the first base layer with a triangular topology as an example, when the wavy microstructure has a predetermined width and a predetermined arc angle (for example, the width w is 0.15 μm, and the arc angle θ is 180 °), the stress-strain curve of the first base layer is changed by the difference in the thickness t of the wavy microstructure, as shown in fig. 16. In fig. 16, a curve 131 represents a stress-strain curve of the first base layer corresponding to a thickness t of 80 μm of the wavy microstructure; curve 132 represents the stress-strain curve of the first base layer corresponding to the thickness t of the wavy microstructure being 55 μm; curve 133 shows the stress-strain curve of the first base layer for a wavy microstructure having a thickness t of 20 μm. Fig. 16 shows that a decrease in thickness of the undulating microstructure results in an increase in the slope of the stress-strain curve across the transition strain, i.e. the thickness of the undulating microstructure enhances the degree of rapidity of the transition. The thickness of the undulating microstructure has a relatively small effect on the first base layer compared to the parameters of fig. 14-15. FIG. 17 shows the tangent modulus variation curves corresponding to the thicknesses of different wavy microstructures. In fig. 17, a curve 141 shows a tangent modulus variation curve corresponding to a thickness t of 80 μm of the wavy microstructure; curve 142 represents the tangent modulus variation curve corresponding to the thickness t of the wavy microstructure being 55 μm; curve 143 shows the tangent modulus variation curve for a wavy microstructure having a thickness t of 20 μm. FIG. 17 shows that as the strain increases, the tangent modulus increases slowly and then increases sharply until the strain increasespeakMaximum reached at 60% and then decrease. In the first substrate, for any given fiber network, there is a critical thickness below which stretching to a peak at the first substrate occurspeakBuckling will occur.
In one embodiment, a first substrate is made using a soft, breathable, thin elastomer (about 100 μm thick) as the flexible matrix, with a fiber network (about 20 μm to 50 μm thick) of polyimide made by laser cutting or photolithography or the like embedded therein, which can accurately reproduce the stress-strain curves of real human skin at different areas of the body. In one embodiment, a first base layer with a triangular topological structure is used to simulate the mechanical performance of skin on the back of a human body (the stress-strain curve of the skin on the back of the human body is shown as curve 151' in fig. 18), the width w of the wavy microstructure in the first base layer is set to be 0.15 μm, the arc angle θ is set to be 110 ° and the radius R is set to be 400 μm, and the stress-strain curve is shown as curve 151 in fig. 18; the mechanical performance of the skin at another position on the back of the human body is simulated by using the first base layer with a triangular topological structure (the stress-strain curve of the skin at another position on the back of the human body is shown as a curve 152' in fig. 18), the width w of the wave-shaped microstructure in the first base layer is set to be 0.11 μm, the arc angle theta is set to be 150 ° and the radius R is set to be 400 μm, and the stress-strain curve is shown as a curve 152 in fig. 18; the mechanical properties of the skin of the human abdomen are simulated by using the first base layer with a triangular topological structure (the stress-strain curve of the skin of the human abdomen is shown as a curve 153' in fig. 18), the width w of the wave-shaped microstructure in the first base layer is set to be 0.12 μm, the arc angle θ is set to be 200 ° and the radius R is set to be 400 μm, and the stress-strain curve is shown as a curve 153 in fig. 18. Fig. 18 shows that the stress-strain curves of the three first substrates are respectively matched with the stress-strain curves of the real human skin at the corresponding positions, thereby confirming that the first substrate provided by the embodiment of the invention has similar mechanical properties with the skin or biological tissues.
The first base layer provided by the embodiment of the invention combines the hard fiber network with the soft flexible base body, so that a bionic flexible biological structure is constructed to realize skin-like, and the defect that the existing flexible base body, skin and tissue are not matched with the mechanical property of the skin in the stretching process is overcome, so that the comfort degree of the first base layer and the bio-integrated electronic device formed by the first base layer in the wearing process can be greatly improved, and the mechanical invisibility of the first base layer, the double-layer strain base body and the stretchable electronic device in the skin tissue deformation process can be realized.
Embodiments of the present invention also provide a stretchable electronic device, as shown in fig. 19, which includes any one of the two-layer strain matrices 3 in the above embodiments, and a sensor layer 4 and/or a soft encapsulation layer 5 may be further disposed on the two-layer strain matrix 3. Due to the soft packaging layer 5, the stretchable electronic device has the characteristics of water resistance, chemical corrosion resistance, heat resistance and the like, so that the function of the stretchable electronic device is further promoted.
In one embodiment, the sensor layer 4 may be a rigid film having a corrugated surface that is attached to the second substrate of the two-layer strain matrix 3. In another embodiment, the sensor layer 4 is in the form of an island bridge structure comprising: the sensor comprises an island structure formed by the sensor and a metal bridge connected with the island structure, wherein the metal bridge is in a wave-shaped configuration and is attached to a second base layer in the double-layer strain matrix 3. By designing the sensor layer 4 into a wave-shaped or island-bridge structure, the sensor layer 4 can be stretched, and the electrical performance of the sensor layer 4 is ensured. Due to the wave-shaped or island-bridge structural design of the sensor layer 4, the rigid film forming the wave-shaped sensor layer or the island structure in the island-bridge structure can be made of high-performance electronic materials containing fragile materials such as silicon and the like, and compared with flexible organic film materials, the electrical performance is remarkably improved.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.
Claims (12)
1. A bi-layer strained substrate, comprising:
a first base layer;
a second base layer disposed on the first base layer; the first base layer has a hardness greater than the second base layer; the surface of the second base layer is wavy;
the first base layer includes: a flexible matrix and a network of fibers disposed within the flexible matrix;
the fiber network comprises a plurality of topological structures which are regularly arranged, all nodes of the topological structures are connected through a wavy microstructure, the wavy microstructure is provided with a preset width, and wave crests or wave troughs forming the wavy microstructure are provided with preset arc angles.
2. The dual layer strained substrate of claim 1, wherein the ratio of the thickness of the second base layer to the wavelength of the waviness of the surface is greater than or equal to 12.
3. The dual-layer strained substrate of claim 1, wherein the topology is a triangular topology, and each side of the triangular topology is the wave-shaped microstructure.
4. The dual layer strained substrate of claim 1, wherein the topology is a honeycomb topology, each side of the honeycomb topology being the undulating microstructure.
5. The dual-layer strained substrate of claim 1, wherein the topology is a Kagome topology, each side of the Kagome topology is the wavy microstructure, and a space is formed between each Kagome topology.
6. The dual layer strained substrate of claim 1, wherein the topology is a square topology, and each side of the square topology is the waved microstructure.
7. The dual-layer strained substrate of claim 1, wherein the topological structure is a diamond topological structure, each side of the diamond topological structure is the wavy microstructure, and a space is formed between the diamond topological structures.
8. A stretchable electronic device, comprising: the bi-layer strained matrix of any one of claims 1-7.
9. A stretchable electronic device in accordance with claim 8, further comprising: a sensor layer disposed on the bi-layer strain matrix.
10. A stretchable electronic device according to claim 9, wherein the sensor layer is a rigid film having a surface that undulates and conforms to the second base layer of the bi-layer strained matrix.
11. A stretchable electronic device according to claim 9, wherein the sensor layer is in an island bridge structure comprising: the device comprises an island structure formed by sensors and a metal bridge connected with the island structure, wherein the metal bridge is in a wave-shaped configuration and is attached to a second base layer in the double-layer strain matrix.
12. A stretchable electronic device according to any of claims 9 to 11, further comprising a soft encapsulation layer disposed on the sensor layer.
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| CN114171497B (en) * | 2021-11-30 | 2023-02-03 | 中国农业大学 | Malleable electronic devices, flexible substrates, and methods of making the same |
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Effective date of registration: 20221201 Address after: 215163 Suzhou 88 high tech Zone, Jiangsu science and Technology City Patentee after: Suzhou Guoke medical technology development (Group) Co.,Ltd. Patentee after: Cheng Huanyu Address before: 321300 8th floor, Jinzu building, headquarters center, Yongkang City, Jinhua City, Zhejiang Province Patentee before: YONGKANG GUOKE REHABILITATION ENGINEERING TECHNOLOGY Co.,Ltd. Patentee before: Cheng Huanyu |