A design method for curved micro-nano sensor wire structure

Abstract

The present invention relates to the field of flexible electronic technology, and specifically to a design method for a curved micro-nano sensor wire structure, wherein the wire structure is serpentine and is composed of a plurality of serpentine structural units connected in sequence, wherein each corner of the serpentine structural unit has a first cross-sectional dimension R1, and the connecting end between each corner of the serpentine structural unit has a second cross-sectional dimension R2, and the first cross-sectional dimension R1 is smaller than the second cross-sectional dimension R2. The present invention assists stress release by performing geometric compensation inside a single serpentine structural unit, which can further improve the ductility and durability of the wire; during the design process, stress compensation within a cycle is considered, and at the same time, the stress state and different elastic moduli of the flexible substrate are also considered in the parameter design, so that the design method can meet specific flexible application requirements.

Description

Technical Field

[0001] The invention relates to the field of flexible electronic technology, and in particular to a method for designing a curved surface micro-nano sensor wire structure. Background Art

[0002] With the continuous innovation and development of medical electronics, brain-computer interfaces, solar chips, industrial electronic products and other fields, as well as the increasing requirements of actual application scenarios, traditional planar electronic devices composed of rigid circuit boards are difficult to meet the requirements of actual applications, so flexible electronic technology came into being. Flexible electronics, also known as flexible circuits, is a technology that mounts electronic devices on flexible plastic substrates (such as polyimide, polyetheretherketone or polyethylene terephthalate, etc.) and uses special wire structures to assemble electronic circuits. Flexible electronics has a wide range of applications in industry, biology, medicine and other fields due to its unique stretchability, deformability and bendability.

[0003] The "flexibility" of flexible implantable devices is always accompanied by a cycle of deformation and recovery during use. In order to prevent mechanical failures such as bending, damage, or even breakage between components when the device is deformed, the wire structure must reduce stress concentration in order to improve durability. In order to improve the ductility and durability of the wire, the wire structure in flexible electronics often adopts a serpentine interconnect wire structure, in which the self-similar serpentine wire in the serpentine interconnect wire can be expanded in multiple stages when stretched.

[0004] However, conventional serpentine interconnect wires use a uniform cross-sectional size throughout the entire serpentine routing, and the stress distribution should be greater where the radius of curvature is smaller. Therefore, using a uniform cross-sectional size cannot adaptively release stress according to the stress distribution. Summary of the invention

[0005] The purpose of the present invention is to provide a method for designing a curved micro-nano sensor wire structure, which can further reduce stress concentration and improve the ductility and durability of the wire by performing geometric compensation inside a single serpentine structure unit to assist stress release, so as to solve the problems pointed out in the background technology.

[0006] The present invention is achieved through the following technical scheme: a method for designing a curved micro-nano sensor wire structure, wherein the wire structure is serpentine and is composed of a plurality of serpentine structure units connected in sequence, each corner of the serpentine structure unit has a first cross-sectional dimension R1, and the connecting ends between the corners of the serpentine structure unit have a second cross-sectional dimension R2, and the first cross-sectional dimension R1 is smaller than the second cross-sectional dimension R2.

[0007] According to a preferred embodiment, the serpentine structural unit is a primary serpentine structural unit.

[0008] According to a preferred embodiment, the cross-sectional dimensions from the connecting end to the corners of the serpentine structural unit vary in a gradient manner.

[0009] According to a preferred embodiment, the cross-sectional dimension reduction gradient from the connecting end to the corner between each corner of the serpentine structural unit matches the stress reduction gradient.

[0010] According to a preferred embodiment, the primary serpentine structure unit comprises a 180° arc-shaped curved wire in the middle and 90° arc-shaped curved wires on both sides, and the two corners of the 180° arc-shaped curved wire are respectively connected to the first ends of the 90° arc-shaped curved wires on both sides;

[0011] The corner of the 180° arc-bent wire and the first end of the 90° arc-bent wire have a first cross-sectional size R1, and the connecting end of the 180° arc-bent wire has a second cross-sectional size R2.

[0012] The design method comprises the following steps:

[0013] Determine the parameter of the first cross-sectional dimension R1 and the preset multiple of the parameter of the first cross-sectional dimension R1 and the parameter of the second cross-sectional dimension R2, and calculate the parameter of the second cross-sectional dimension R2;

[0014] Determine the cross-sectional size increase gradient, calculate and obtain a single-step cross-sectional size increment based on the parameter of the first cross-sectional size R1 and the cross-sectional size increase gradient, wherein the single-step cross-sectional size increment includes a single-step cross-sectional width increment and a single-step cross-sectional thickness increment;

[0015] Determine the radius of each arc-shaped bending wire of the primary serpentine structure unit, and draw a plan view of the primary serpentine structure unit;

[0016] The thickness of the primary serpentine structure unit is optimized and adjusted based on the flexible substrate material characteristics and stress state of the curved micro-nano sensor.

[0017] According to a preferred embodiment, the method further comprises determining the period of the primary serpentine structure unit based on the stress state of the flexible substrate of the curved micro-nano sensor, as follows:

[0018] Pre-stretching the flexible substrate after the oxygen plasma surface treatment and maintaining it for a post-treatment process;

[0019] After the post-treatment process, the flexible substrate is cooled to room temperature and the pre-stretching is released, and the periodic wrinkle parameters appearing on the surface of the flexible substrate are measured;

[0020] The period of the wire structure is determined based on the measured periodic corrugation parameters.

[0021] According to a preferred embodiment, the cross-sectional size increase gradient is determined according to the strain gradient from the two corners of the 180° arc-bent wire to the connection end and the strain gradient from the first end to the second end of the 90° arc-bent wire.

[0022] The technical solution of a curved micro-nano sensor wire structure design method provided by the present invention has at least the following advantages and beneficial effects: (1) geometric compensation is performed inside a single serpentine structure unit to assist stress release, thereby further improving the ductility and durability of the wire; (2) stress compensation within a cycle is considered during the design process, and the stress state and different elastic moduli of the flexible substrate are also taken into account in the parameter design. The design method can meet specific flexible application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of a curved micro-nano sensor wire structure provided in Example 1 of the present invention;

[0024] Figure 2 The design parameters of the curved micro-nano sensor wire structure provided in Example 2 of the present invention;

[0025] Figure 3 A schematic diagram of pre-stretching a flexible substrate provided in Example 2 of the present invention;

[0026] Figure 4 A schematic diagram of periodic wrinkles on the surface of a flexible substrate provided in Example 2 of the present invention;

[0027] Icon: 1-Primary serpentine structural unit. DETAILED DESCRIPTION

[0028] In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] Example 1

[0030] Figure 1 This is a schematic diagram of the structure of the curved micro-nano sensor wire structure provided by an embodiment of the present invention. Figure 1 As shown, the curved micro-nano sensor wire structure is serpentine and is composed of a number of serpentine structural units connected in sequence.

[0031] Specifically, each corner of the serpentine structure unit has a first cross-sectional size R1, and the connecting ends between the corners of the serpentine structure unit have a second cross-sectional size R2, wherein the corners refer to point a in the figure, and the connecting ends refer to point b in the figure.

[0032] Considering that the stress distribution should be greater where the radius of curvature is smaller, this embodiment performs geometric compensation inside a single serpentine structure unit according to the stress distribution, and adjusts the geometric dimensions of the serpentine structure unit to assist in stress release.

[0033] It should be noted that by making geometric compensation inside a single serpentine structure unit to assist stress release, the ductility and durability of the conductor can be further improved.

[0034] Specifically in this embodiment, it is found through ANSYS simulation that the stress level at point a is the lowest, the stress at point b is the largest, and the strain presents the same rule. Therefore, this embodiment adjusts the stress state of the serpentine structure unit through different cross-sectional dimensions, and performs geometric dimension design with the first cross-sectional dimension R1 being smaller than the second cross-sectional dimension R2. A larger cross-sectional dimension is used at point b where the stress is the largest to release stress, and the cross-sectional dimension from point a to point b is designed to change gradually, and the gradient of the cross-sectional dimension increase also matches the gradient of the stress increase.

[0035] In one implementation of the present embodiment, the above-mentioned serpentine structure unit is a primary serpentine structure unit 1; in the primary serpentine structure unit 1, the cross-sectional size from the connecting end to the corner between each corner changes gradiently, and the cross-sectional size reduction gradient from the connecting end to the corner between each corner matches the stress reduction gradient.

[0036] Specifically in this embodiment, the design of the primary serpentine structure unit 1 is as follows: the primary serpentine structure unit 1 includes a 180° arc-shaped curved wire in the middle and 90° arc-shaped curved wires on both sides, and the two end points of the 180° arc-shaped curved wire are respectively connected to the first ends of the 90° arc-shaped curved wires on both sides; the corner of the 180° arc-shaped curved wire and the first end of the 90° arc-shaped curved wire have a first cross-sectional size R1, and the connecting end of the 180° arc-shaped curved wire has a second cross-sectional size R2. It should be noted that the above is only an example, and the parameters of the arc bending can be adjusted according to specific needs, for example, the middle part is adjusted to a 225° arc-shaped curved wire, and the two sides are 67.5° arc-shaped curved wires, and no specific restrictions are made here.

[0037] Example 2

[0038] Based on the technical solution provided in Example 1, this embodiment provides a design method for a curved micro-nano sensor wire structure as in Example 1, comprising the following steps:

[0039] Step 1: Determine the parameters of the first cross-sectional dimension R1 and the preset multiples of the parameters of the first cross-sectional dimension R1 and the parameters of the second cross-sectional dimension R2, and calculate the parameters of the second cross-sectional dimension R2.

[0040] In this embodiment, the parameters of the first cross-sectional dimension R1 and the preset multiples can be directly given, for example, the width of the first cross-sectional dimension R1 is Set to 0.2mm, and set the preset multiple to 2.5 times; it should be noted that the preset multiple is preferably less than 3, at which time the stress state of the primary serpentine structure unit 1 is better; in addition, if the preset multiple is not limited by space, it can be larger, and no specific restriction is made here.

[0041] When the parameters of the first cross-sectional dimension R1 and the preset multiple are known, the parameters of the second cross-sectional dimension R2 can be calculated. For example, the width of the second cross-sectional dimension R2 can be calculated here: It is 0.5mm. Similarly, the section thickness can be calculated in the same way, which will not be elaborated here.

[0042] Step 2: Determine the cross-sectional size increase gradient, and calculate the single-step cross-sectional size increment based on the parameters of the first cross-sectional size R1 and the cross-sectional size increase gradient; in this embodiment, when the width of the first cross-sectional size R1 is When set to 0.2mm, the cross-sectional size increase gradient is set to 11, which is the width of the first cross-sectional size R1. The simulation and experiment results are obtained when the value is set to 0.2 mm. This is only for this scenario and there is no specific restriction on the value here. The single-step section size increment includes the single-step section width increment and the single-step section thickness increment.

[0043] In this embodiment, the cross-sectional size increase gradient of the primary serpentine structure unit 1 is determined according to the strain gradient from the connection end of the 180° arc-bent wire to the corner and the strain gradient from the first end to the second end of the 90° arc-bent wire. Specifically, in this embodiment, according to Determine, among which, represents the single-step stress increment from point a to point b, represents the maximum stress value at point b, Represents the stress value at point a.

[0044] Further, based on the width of the first cross-sectional dimension R1 And the section size increase gradient calculation to get the single-step section width increment, the expression is ,in Represents the single-step section width increment; similarly, the single-step section thickness increment is calculated in the same way, which will not be elaborated here.

[0045] Step 3: Determine the radius of each arc-shaped curved wire of the primary serpentine structure unit 1, and draw a plan view of the primary serpentine structure unit 1, see Figure 2As shown, the radius r of each arc-shaped curved wire can be determined according to the actual space size. In one implementation of this embodiment, r is 2.5 mm, the first cross-sectional dimension R1 is 0.1*2 mm, and the second cross-sectional dimension R2 is 0.25*2 mm.

[0046] Step 4: Optimize and adjust the thickness of the primary serpentine structure unit 1 based on the material characteristics and stress state of the curved micro-nano sensor flexible substrate, wherein the material characteristics of the curved micro-nano sensor flexible substrate include but are not limited to being light, thin, stretchable, corrosion-resistant, and resistant to high / low temperatures.

[0047] Step 5: Determine the period of the primary serpentine structure unit 1 based on the stress state of the flexible substrate of the curved micro-nano sensor .

[0048] In one implementation of this embodiment, PDMS is used as a flexible substrate for curved micro-nano sensors. The ratio of PDMS is determined according to the actual application scenario. If a larger elastic modulus is required, the proportion of curing agent is smaller. The thickness can be controlled by the rotation speed and time during spin coating, and then combined with the conventional curing process at 120 degrees Celsius and 60 minutes to form.

[0049] After the flexible substrate is prepared, oxygen plasma bombardment can be used to perform oxygen plasma surface treatment on the flexible substrate to enhance the bonding force between the interface of the flexible substrate and the coating. The oxygen plasma bombardment parameters can be selected as power 580W, flow rate 260ML / min, and time 10Min.

[0050] The flexible substrate after oxygen plasma surface treatment was pre-stretched by 20% and maintained. Figure 3 As shown, the parameter of the flexible substrate before pre-stretching is L, and the parameter after pre-stretching is L+L / 5; further, a post-processing process is performed, such as placing it in a coating chamber for film growth or performing a photolithography patterning process, and then depositing a layer of material to be coated on the flexible substrate film layer, followed by keeping warm for 2 hours and then cooling to room temperature.

[0051] After the post-processing process, the flexible substrate is cooled to room temperature and the pre-stretching is released, see Figure 4 As shown, due to the mismatch between the elastic modulus of the flexible substrate PDMS and the elastic modulus of the surface-plated metal, wrinkles will appear on the surface; and because the material of the entire upper surface is of the same type, the stress state of each point will be close, so the wrinkles on the surface are periodic.

[0052] Further, the periodic wrinkle parameters appearing on the surface of the flexible substrate are measured, and the period of the conductor structure is determined based on the measured periodic wrinkle parameters. , the calculation expression is ,in, is the measured periodic wrinkle parameter, is the pre-stretching amount, which is 0.2 in this embodiment and can be adjusted according to the actual application scenario.

[0053] It should be noted that during the design process, the intra-cycle stress compensation is considered, and the stress state and different elastic moduli of the flexible substrate are also taken into account in the parameter design. The design method can meet the specific flexible application requirements.

[0054] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for designing a curved micro-nano sensor wire structure, characterized in that: The wire structure is in a serpentine shape and is composed of a plurality of serpentine structural units connected in sequence. Each corner of the serpentine structural unit has a first cross-sectional size R1, and the connecting end between each corner of the serpentine structural unit has a second cross-sectional size R2, and the first cross-sectional size R1 is smaller than the second cross-sectional size R2; the serpentine structural unit is a primary serpentine structural unit (1); the cross-sectional size from the connecting end to the corner between each corner of the serpentine structural unit changes in a gradient; the cross-sectional size reduction gradient from the connecting end to the corner between each corner of the serpentine structural unit matches the stress reduction gradient; the primary serpentine structural unit (1) comprises a 180° arc-shaped curved wire in the middle and 90° arc-shaped curved wires on both sides, the two corners of the 180° arc-shaped curved wire are respectively connected to the first ends of the 90° arc-shaped curved wires on both sides; the corners of the 180° arc-shaped curved wire and the first end of the 90° arc-shaped curved wire have a first cross-sectional size R1, and the connecting end of the 180° arc-shaped curved wire has a second cross-sectional size R2; The design steps of the conductor structure are as follows: Determine the parameter of the first cross-sectional dimension R1 and the preset multiple of the parameter of the first cross-sectional dimension R1 and the parameter of the second cross-sectional dimension R2, and calculate the parameter of the second cross-sectional dimension R2; Determine the cross-sectional dimension reduction gradient from the connecting end to the corner between each corner of the serpentine structure unit, and calculate the single-step cross-sectional dimension increment based on the parameter of the first cross-sectional dimension R1 and the cross-sectional dimension increase gradient, wherein the single-step cross-sectional dimension increment includes a single-step cross-sectional width increment and a single-step cross-sectional thickness increment; Determine the radius of each arc-shaped curved wire of the primary serpentine structure unit (1), and draw a plan view of the primary serpentine structure unit (1); The thickness of the primary serpentine structural unit (1) is optimized and adjusted based on the flexible substrate material characteristics and stress state of the curved micro-nano sensor.

2. The method for designing a curved micro-nano sensor wire structure according to claim 1, characterized in that: The method also includes determining the period of the primary serpentine structure unit (1) based on the stress state of the flexible substrate of the curved micro-nano sensor, as follows: Pre-stretching the flexible substrate after the oxygen plasma surface treatment and maintaining it for a post-treatment process; After the post-treatment process, the flexible substrate is cooled to room temperature and the pre-stretching is released, and the periodic wrinkle parameters appearing on the surface of the flexible substrate are measured; The period of the wire structure is determined based on the measured periodic corrugation parameters.

3. The method for designing a curved micro-nano sensor wire structure according to any one of claims 1 to 2, characterized in that: The cross-sectional dimension increase gradient is determined according to the strain gradient from the two corners to the connection end of the 180° arc-bent wire and the strain gradient from the first end to the second end of the 90° arc-bent wire.

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