Flexible and isotropically stretchable electrode device, and preparation method therefor and application thereof

Abstract

Disclosed in the present invention are a flexible and isotropically stretchable electrode device, and a preparation method therefor and the application thereof. The preparation method comprises the following steps: (1) preparing a silicone substrate, wherein the silicone substrate is an ecoflex 00-20 silicone substrate; (2) using a mask to prepare a patterned electrode on the silicone substrate by means of evaporation; (3) encapsulating a front end to complete the preparation of a flexible part of a device; and (4) connecting soft and hard interfaces and performing encapsulation to complete the preparation of the device. In the present invention, ecoflex 00-20 is used to prepare a silicone substrate of the device, and a patterned electrode is prepared by means of evaporation, thereby finally obtaining the flexible and isotropically stretchable electrode device. The device integrates multiple functions, has a resistance value increasing with tensile deformation, can serve as a deformation sensor to reflect the real-time capacity of a bladder, and further has good impedance stability and potential for long-term implantation.

Description

A flexible and uniformly stretchable electrode device and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a flexible isotropically stretchable electrode device, a preparation method thereof, and applications thereof. Background Art

[0002] Urination is one of the most important physiological processes in animals and is precisely controlled by the nervous system. Nervous system damage or disorders caused by trauma or systemic neurological diseases can lead to urinary dysfunction. Individuals with urinary dysfunction must rely on proper and adequate bladder management. For individuals who do not have a sense of bladder filling, untimely intermittent catheterization may lead to overfilling of the bladder, making accidents or serious complications more likely. Therefore, the development of monitoring systems that provide notification of the need to urinate and monitor the myoelectric signals of the detrusor muscle of the bladder wall during urination is crucial for patients with impaired bladder awareness. Current stimulation electrodes and monitoring devices are not flexible or comfortable enough.

[0003] Flexible electrode devices have been used in medical applications, such as skin patch electrodes used in fields such as electroencephalography (EEG), electrocardiography (ECG), and electromyography (EMG) to monitor bioelectric signals. These electrodes are usually made of flexible materials, such as medical glue and conductive materials. Unlike skin electrodes, bladder electrodes usually need to be inserted deep into the tissue rather than used for surface monitoring. Some similar technologies have also been used or have prospects for bladder monitoring or treatment, such as bladder charging technology or bladder pacemakers. Among them, bladder charging technology is used to measure the fluid pressure in the bladder. Bladder pacemakers are used to treat bladder dysfunction and usually involve implanting electrodes to transmit stimulation signals. These technologies usually involve implantable sensors or charging devices, and do not involve electrical stimulation. Unlike flexible and unidirectionally stretchable electrode devices, bladder pacemakers use rigid or semi-rigid electrodes.

[0004] Flexible stretchable electrodes are fabricated by combining conductive materials with flexible substrates. Conductive materials are inherently difficult to achieve ultrastretchability. Furthermore, achieving isotropic stretchability in two dimensions is much more challenging than achieving uniaxial stretchability in one dimension. For example, stretchable electrodes fabricated by blending conductive materials (such as graphene, carbon nanotubes, conductive polymers, and gold and silver nanowires) with flexible polymers are difficult to achieve isotropic stretchability in two dimensions. Stretchable electrodes with a microcracked gold mechanism develop crisscrossing cracks during isotropic stretching. When uniformly stretched beyond a certain limit (typically less than 2%), the gold film layer forms numerous disconnected islands of gold film, causing the electrode to lose electrical properties. Stretchable conductivity can also be achieved by structurally designing conductive materials. The most typical example is the widely used serpentine structure, but even this structure struggles to achieve perfect isotropic stretchability in two dimensions. In summary, methods for achieving stable, isotropic stretchable electrodes remain scarce.

[0005] Most reliable medical devices are rigid and single-function. Current approaches to achieving isotropically stretchable flexible electronics almost exclusively rely on isotropically pre-stretching the substrate. This increases the reproducibility of the fabricated electrodes, but results in uneven surfaces and pattern distortion across the majority of the flexible electrodes. Furthermore, pre-stretching the substrate is difficult to implement for large-scale electrode fabrication, as its performance and stability fall far short of the requirements for long-term, stable implantation.

[0006] Summary of the Invention

[0007] To address the above technical issues, the present invention provides a flexible, isotropically stretchable electrode device, its preparation method, and its application. The present invention utilizes a simple, one-step, high-temperature evaporation process to evaporate electrodes onto an ecoflex-20 substrate, producing a soft, isotropically stretchable electrode with excellent performance.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] In one aspect, the present invention provides a method for preparing a flexible isotropically stretchable electrode device, comprising the following steps:

[0010] (1) preparing a silicone substrate; the silicone substrate is an ecoflex 00-20 silicone substrate;

[0011] (2) preparing a patterned electrode on the silica gel substrate by evaporation using a mask;

[0012] (3) Encapsulating the front end to complete the flexible portion of the device;

[0013] (4) Connect the soft and hard interfaces and package to complete the device preparation.

[0014] As a preferred embodiment, in step (1), the specific steps of preparing the silicone substrate include: mixing component A and component B of ecoflex 00-20, coating the mixture on a flat substrate, and curing the mixture to obtain an ecoflex 00-20 thin film silicone substrate;

[0015] Preferably, the mass ratio of component A to component B is 1:1 to 1.5;

[0016] Preferably, the coating is spin coating;

[0017] Preferably, the spin coating speed is 200 to 500 rpm;

[0018] Preferably, the coating has a thickness of 200 to 500 microns;

[0019] Preferably, the curing is heat curing, the heating temperature is 50-70° C., and the heating time is 5-10 minutes.

[0020] As a preferred embodiment, in step (2), the evaporation rate is 1 to 2 nm / s;

[0021] Preferably, the vacuum degree of the evaporation is 1×10 -3 Pa~5×10 -3 Pa;

[0022] Preferably, the patterned electrode is selected from any one of gold, silver, and platinum, more preferably gold;

[0023] Preferably, the thickness of the patterned electrode is 250 to 350 nm;

[0024] Preferably, step (2) further includes a baking operation after the evaporation;

[0025] Preferably, the baking is performed at 50-70° C. for 30-60 minutes;

[0026] Preferably, the patterned electrode includes a bladder capacity detection module, an electrical stimulation module and an electromyographic signal acquisition module.

[0027] As a preferred embodiment, the packaging in step (3) is performed using ecoflex 00-20;

[0028] Preferably, the encapsulation step comprises spin coating ecoflex 00-20 and then heating and curing for encapsulation;

[0029] Preferably, the spin coating speed is 1500 to 3000 rpm;

[0030] Preferably, the spin coating has a thickness of 30 to 50 microns;

[0031] Preferably, the heating temperature is 100-120°C;

[0032] Preferably, the heating time is ≥ 1 h;

[0033] Preferably, before spin coating, a polyethylene terephthalate film is used to cover the bladder capacity detection module, the electrical stimulation module, the electromyographic signal acquisition module, and the soft and hard interface parts of the device; and before heat curing, the covering polyethylene terephthalate film is removed;

[0034] Preferably, the polyethylene terephthalate film has a thickness of 50 to 100 microns.

[0035] In certain specific embodiments, the specific operation of connecting the soft and hard interfaces in step (4) is: using a printed circuit board to connect the soft and hard interfaces, one end of the electrode channel on the printed circuit board is welded with a biological wire, and the other end is connected one-to-one with the electrode channel of the flexible part; the biological wire is a wire formed by insulating material wrapped with a metal material; the insulating material is a biocompatible material; and the metal material is preferably stainless steel.

[0036] In another aspect, the present invention provides an isotropically stretchable electrode device obtained by the above-mentioned preparation method.

[0037] In another aspect, the present invention provides a use of the flexible and unidirectionally stretchable electrode device in preparing a device for monitoring bladder information and electrically stimulating the bladder.

[0038] The above technical solution has the following advantages or beneficial effects:

[0039] This invention uses ecoflex 00-20 as the silicone substrate for the device and deposits patterned electrodes via vapor deposition, ultimately resulting in a flexible, isotropically stretchable electrode device. This multifunctional device increases its resistance with tensile deformation, making it suitable for use as a deformation sensor to reflect real-time bladder capacity.

[0040] The flexible isotropically stretchable electrode device prepared by the present invention has stable and large-window homogeneous stretching performance. The isotropic stretching ratio of the electrode is greater than 200% (the area change is 9 times the original), and the unidirectional stretching ratio is greater than 700%. In addition, under the condition of an area change of about 600%, the electrode can be stably stretched 5000 times. At various stretching rates and a stretching rate of 200%, the electrode can achieve 50,000 stable unidirectional stretching cycles. When the electrode sensing point area is 0.3mm 2 When the impedance is 1×10 5The electrode impedance remained unchanged after being immersed in PBS solution for several months, demonstrating its good impedance stability and potential for long-term implantation.

[0041] The device fabricated by this invention is the first to utilize implantable bladder electrodes to assess bladder filling status, monitor electromyography, and reduce neurogenic overactive bladder. Once the electrodes are fixed to the rat bladder, they deform due to the cyclical motion of the bladder wall, generating a continuously changing impedance that dynamically reflects bladder capacity. This provides an objective basis for determining catheterization timing and evaluating clinical drainage effectiveness. Furthermore, electrical stimulation suppresses DO and protects the upper urinary tract in rats with spinal cord injury. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG1 is a structural diagram of the flexible portion of the flexible isotropically stretchable electrode device prepared in Example 1 of the present invention.

[0043] FIG2 is a physical picture of the front end of the flexible and uniformly stretchable electrode device prepared in Example 1 of the present invention.

[0044] FIG3 is an overall physical picture of the flexible isotropically stretchable electrode device prepared in Example 1 of the present invention.

[0045] FIG4 is a stretching diagram of the flexible isotropically stretchable electrode device in Example 1 of the present invention and a microscopic morphology diagram before stretching.

[0046] FIG5 shows the uniaxial stretching performance of the prepared flexible uniaxially stretchable electrode device.

[0047] FIG6 is a graph showing the cycle performance of the flexible isotropically stretchable electrode device prepared in Example 1 of the present invention.

[0048] FIG7 is a comparison diagram of the impedance changes before and after stimulation of the flexible unidirectionally stretchable electrode device prepared in Example 1 of the present invention.

[0049] FIG8 is a diagram showing the electrode uniform stretching performance of the flexible uniform stretchable electrode device prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0050] The following embodiments are merely some of the embodiments of the present invention, rather than all of them. Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0051] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0052] Example 1:

[0053] This embodiment provides a flexible isotropically stretchable electrode device, the preparation method of which is as follows:

[0054] (1) Component A and component B of ecoflex 00-20 were mixed in a mass ratio of 1:1, placed in a mixing and degassing machine, mixed for one minute, and degassed for one minute; the resulting fluid mixture was spin-coated on an acrylic plate to form a film with a thickness of 300 μm at a speed of 300 revolutions per minute; and dried in an oven at 60° C. for 5 minutes to obtain a silicone flexible substrate for later use;

[0055] (2) A patterned gold electrode was prepared by evaporation on the silicone flexible substrate obtained in step (1) using a mask. The specific parameters of the evaporation were: evaporation rate 1 nm / s, gold film thickness 300 nm, vacuum degree 3×10 -3 Pa, the sample plate height is 60 mm; the patterned electrode includes a bladder capacity detection module, an electrical stimulation module, and an electromyographic signal acquisition module, as shown in Figure 1; after evaporation, it is baked in a 60°C oven for 60 minutes to enhance the adhesion of the gold electrode to the silicone flexible substrate;

[0056] (3) Use a 100 μm thick polyethylene terephthalate (PET) film to cover the electrical stimulation module, the electromyographic signal acquisition module, and the soft and hard interface parts of the device, and then spin-coat ecoflex 00-20 at a speed of 2,000 rpm to a thickness of 50 μm; remove the PET film used for covering, and then place it in a 120°C oven for curing for 1 hour to complete the preparation of the flexible part;

[0057] (4) Solder a biological wire to one end of the electrode channel of a 200-micron-thick printed circuit board, and align and connect the other end to the electrode channel of the flexible part; wrap it with sealing film to fix it, and then apply 734 glue to the entire printed circuit board and the interface of the flexible part and solidify it to ensure that the soft and hard interface parts of the device will not be infiltrated by liquid to prevent short circuit or open circuit.

[0058] A physical picture of the front end of the flexible uniformly stretchable electrode device prepared in this embodiment is shown in FIG2 , and a physical picture of the entire device is shown in FIG3 .

[0059] Figure 4 shows the stretching diagram of the flexible uniformly stretchable electrode device prepared in this embodiment and the microscopic morphology diagram before stretching. Figure 5 shows the stretching performance of the flexible uniformly stretchable electrode device prepared in this embodiment. It can be seen that the electrode has a maximum stretching conductivity of more than 700%. Figure 6 shows the cycle performance test diagram of the flexible uniformly stretchable electrode device prepared in this embodiment. The electrode has been tested for 3000 cycles at a stretching rate of 300% on the stretching machine test platform and the performance is still stable. Figure 7 shows a comparison diagram of the impedance change of the flexible uniformly stretchable electrode device prepared in this embodiment before and after electrical stimulation. The impedance of the electrode at a frequency of 1000 Hz is approximately 10 in a monitoring area of ​​1 square millimeter. 6 Ω, after electrical stimulation, the impedance decreases, indicating that the electrode is not damaged. Figure 8 shows the electrode uniform stretching performance of the flexible uniform stretchable electrode device prepared in this embodiment. It can be seen that when the electrode is 1×1 cm 2 Uniaxial stretching to 2×2cm 2 After that, it still conducts electricity, and the resistance value increases from more than 100Ω to more than 1000Ω.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A preparation method of a flexible and uniformly stretchable electrode device, characterized in that, It includes the following steps: (1) Prepare a silica gel substrate; the silica gel substrate is an ecoflex 00-20 silica gel substrate; (2) Use a mask template to prepare a patterned electrode on the silica gel substrate by evaporation coating; (3) Package the front end to complete the preparation of the flexible part of the device; (4) Connect and package the hard and soft interfaces to complete the preparation of the device.

2. The preparation method according to claim 1, wherein In step (1), the specific steps for preparing the silica gel substrate include: after mixing the A component and the B component of ecoflex 00-20, coat it on a planar substrate, and obtain an ecoflex 00-20 thin film silica gel substrate after curing.

3. The preparation method according to claim 2, characterized in that, In step (1), the mass ratio of the A component to the B component is 1:1 to 1.5; The coating is spin coating; The rotation speed of the spin coating is 200 to 500 revolutions per minute; The thickness of the coating is 200 to 500 microns; The curing is heat curing, the heating temperature is 50 to 70 °C, and the heating time is 5 to 10 minutes.

4. The preparation method according to claim 1, characterized in that, In step (2), the evaporation coating rate is 1 to 2 nm / s; The vacuum degree of the evaporation coating is 1×10 -3 Pa to 5×10 -3 Pa; The type of the patterned electrode is selected from any one of gold, silver, and platinum; The thickness of the patterned electrode is 250 to 350 nm.

5. The preparation method according to claim 4, wherein, The type of the patterned electrode is gold.

6. The preparation method according to claim 1, characterized in that, After the evaporation coating in step (2), a baking operation is further included.

7. The preparation method according to claim 6, characterized in that, The baking is at 50 to 70 °C for 30 to 60 min.

8. The preparation method according to claim 1, characterized in that, The patterned electrode includes a bladder capacity detection module, an electrical stimulation module, and an electromyogram signal acquisition module.

9. The preparation method according to claim 8, wherein The packaging in step (3) is carried out using ecoflex 00-20 for packaging.

10. The preparation method according to claim 9, characterized in that, The steps of the packaging are spin coating ecoflex 00-20 and then heat curing for packaging.

11. The preparation method according to claim 10, wherein The rotation speed of the spin coating is 1500 to 3000 revolutions per minute; The thickness of the spin coating is 30 to 50 microns; The heating temperature is 100 to 120 °C; The heating time is ≥1 h.

12. The preparation method according to claim 11, characterized in that, Before spin coating, a polyethylene terephthalate film is used to cover the bladder capacity detection module, the electrical stimulation module, the electromyogram signal acquisition module, and the hard and soft interface parts of the device; the covered polyethylene terephthalate film is removed before heat curing.

13. The preparation method according to claim 12, characterized in that, The thickness of the polyethylene terephthalate film is 50 to 100 microns.

14. The preparation method according to claim 1, characterized in that, The specific operation for connecting the hard and soft interfaces in step (4) is: use a printed circuit board to connect the hard and soft interfaces. One end of the electrode channel on the printed circuit board is welded to a biological wire, and the other end is connected to the electrode channel of the flexible part in one-to-one correspondence; the biological wire is a wire formed by wrapping a metal material with an insulating material; the insulating material is a material with biocompatibility; the metal material is stainless steel.

15. The uniformly stretchable electrode device obtained by the preparation method according to claim 1.

16. The application of the flexible uniformly stretchable electrode device according to claim 15 in the preparation of a device for monitoring bladder information and electrically stimulating the bladder.

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