Neural electrode device

Abstract

The present invention relates to a neural electrode device comprising: a first support layer including one surface and deformed according to designed external environmental conditions; an electrode pattern part disposed on the first support layer and partially exposed through one surface of the first support layer; and a second support layer disposed on the other surface corresponding to one surface of the first support layer and formed on the rear surface of the first support layer, wherein the shapes of the first support layer and the second support layer are deformed according to the designed external environmental conditions. The neural electrode device according to one embodiment of the present invention not only wraps around a nerve while the electrode is deformed by mechanical rigidity and pre-deformation caused by a designed external environment, but also has improved surface adhesion, so that a portion where the first support layer and the second support layer meet can be fixed while being bonded. In addition, the neural electrode device can acquire a biosignal through an electrode pattern partially exposed through the one surface of the first support layer.

Description

neural electrode device

[0001] Embodiments of the present invention relate to a neural electrode device.

[0002] In the field of medicine, technology involving the insertion of electrodes into specific parts of the human body to measure biological signals or deliver electrical stimulation is widely utilized. Electrodes are broadly classified into stimulating electrodes and measuring electrodes; stimulating electrodes are primarily used to stimulate body parts via electrical signals, while measuring electrodes are mainly used to detect signals generated from neural activity and transmit them externally.

[0003] Among these, cuff electrodes are used to wrap around peripheral nerves to measure nerve signals or regulate nerve activity. However, conventional cuff electrodes have limitations in their fixation methods, requiring additional devices such as surgical sutures or external actuators.

[0004] This fixation method can lead to potential risk factors and side effects, such as nerve damage and ischemia.

[0005] Therefore, in recent years, active research has been conducted to address these issues by improving electrode flexibility, stable contact and fixation strength, and integration with the tissue environment. In particular, electrode technology capable of self-fixation without external fixation devices while minimizing the difference in mechanical stiffness with neural tissue is attracting attention.

[0006] Embodiments of the present invention propose a technology capable of self-deforming and fixing by a specific temperature, and thereby aim to provide a neural electrode device capable of detecting and measuring nerve movements in a more multifaceted way.

[0007] In addition, embodiments of the present invention are designed so that the electrode can wrap around and fix the nerve at a specific temperature without external devices or surgical sutures, thereby providing a neural electrode device capable of precisely detecting nerve movement and stably recording nerve signals.

[0008] One embodiment of the present invention provides a neural electrode device comprising: a first support layer having one surface and deforming according to designed external environmental conditions; an electrode pattern portion disposed on the first support layer, with a portion of which is exposed through one surface of the first support layer; and a second support layer disposed on another surface corresponding to one surface of the first support layer and deforming according to designed external environmental conditions.

[0009] The neural electrode device according to an embodiment of the present invention is a neural interface device based on a shape memory polymer material capable of self-deforming and fixing by temperature, and can have a certain flexibility, strength, and elasticity by utilizing a shape memory polymer.

[0010] In addition, the neural electrode device according to the embodiment of the present invention can maintain its rolled shape after being rolled by temperature, and since the neural electrode device is fixed to the nerve by the adhesive force between the first support layer and the second support layer in a bent state, it does not require a separate fixing device.

[0011] Since the process of fixing the neural electrode device to the nerve does not require separate fixation, the fixation of the neural electrode device can be facilitated, and it is possible to attach to various types of nerves by adjusting the thickness of the first and second support layers.

[0012] Furthermore, the neural electrode device according to an embodiment of the present invention can stably record and measure electrical signals by adhering to the surface of biological tissue, and additionally, damage caused by mechanical / physical stimuli such as bending, folding, or twisting does not occur.

[0013] In addition, the neural electrode device according to the embodiment of the present invention can reduce the possibility of nerve damage and side effects through self-deformation and fixation at temperature, provide excellent integration with the biological environment, and significantly improve convenience in the medical field through a simple application process.

[0014] Of course, the scope of the present invention is not limited by these effects.

[0015] FIG. 1 is a perspective view illustrating a neural electrode device according to one embodiment of the present invention.

[0016] FIG. 2 is a plan view illustrating one embodiment of the electrode pattern portion of FIG. 1.

[0017] Figure 3 is a cross-sectional view taken along the line I-I' of Figure 1.

[0018] FIG. 4 is a diagram showing the process of forming a cuff of a neural electrode device according to one embodiment of the present invention.

[0019] FIG. 5 is a diagram showing a state in which a nerve electrode device according to one embodiment of the present invention is wrapped around a nerve.

[0020] FIG. 6 is a diagram showing the results of cuff formation of a neural electrode device according to the thickness and thickness ratio of a first support layer and a second support layer according to an embodiment of the present invention.

[0021] FIG. 7 is a cross-sectional view illustrating the process steps for manufacturing a neural electrode device according to one embodiment of the present invention.

[0022] FIGS. 8a to 8g are drawings illustrating the appearance of a neural electrode device according to one embodiment of the present invention after the completion of each manufacturing process.

[0023] One embodiment of the present invention provides a neural electrode device comprising: a first support layer having one surface and deforming according to designed external environmental conditions; an electrode pattern portion disposed on the first support layer, with a portion of which is exposed through one surface of the first support layer; and a second support layer disposed on another surface corresponding to one surface of the first support layer and deforming according to designed external environmental conditions.

[0024] In one embodiment of the present invention, at least one of the first support layer and the second support layer may include a shape memory polymer (SMP).

[0025] In one embodiment of the present invention, the first thickness of the first support layer and the second thickness of the second support layer may be the same.

[0026] In one embodiment of the present invention, the first thickness of the first support layer may be thicker than the second thickness of the second support layer.

[0027] In one embodiment of the present invention, the electrode pattern portion may include an electrode portion disposed on one side of the first support layer, a pad portion disposed on the other side of the first support layer, and a wire portion electrically connecting the electrode portion and the pad portion.

[0028] In one embodiment of the present invention, the electrode portion includes a plurality of electrodes, and the plurality of electrodes may be arranged to intersect the direction of the nerve.

[0029] In one embodiment of the present invention, the electrode portion and the pad portion may be exposed through one surface of the first support layer.

[0030] In one embodiment of the present invention, the wire portion may be disposed inside the first support layer.

[0031] In one embodiment of the present invention, the degree of deformation of the first support layer and the second support layer according to external environmental conditions and temperature conditions designed can be determined according to the ratio of the first thickness of the first support layer and the second thickness of the second support layer.

[0032] In one embodiment of the present invention, a method for manufacturing a neural electrode device may include: a step of forming a sacrificial layer on a substrate; a step of forming a shape memory polymer layer by applying and curing a first shape memory polymer having a first mixing ratio on the sacrificial layer; a step of forming a circuit pattern on the shape memory polymer layer through photolithography; a step of forming a metal thin film layer on the shape memory polymer layer on which the circuit pattern is formed; a step of forming an electrode pattern portion by removing a portion of the shape memory polymer layer and a portion of the metal thin film layer through a lift-off process; a step of forming a first support layer by applying and curing a shape memory polymer having the first mixing ratio on the electrode pattern portion to cover the electrode pattern portion and the shape memory polymer layer; a step of forming a second support layer by applying and curing a second shape memory polymer having a second mixing ratio on the first support layer; and a step of separating the substrate by removing the sacrificial layer.

[0033] In one embodiment of the present invention, the first mixing ratio and the second mixing ratio may be the same.

[0034] In one embodiment of the present invention, the first shape memory polymer may consist of a shape memory polymer with a molar ratio of 4.5 to 5.5 mol%, a solvent with a molar ratio of 10.5 to 11.5 mol%, and a curing agent with a molar ratio of 6.5 to 7.5 mol%.

[0035] In one embodiment of the present invention, the first shape memory polymer may be composed of poly(bisphenol a-co-epichlorohydrin) in a molar ratio of 4.5 to 5.5 mol%, neopentyl glycol diglycidyl ether in a molar ratio of 10.5 to 11.5 mol%, and EC301 in a molar ratio of 6.5 to 7.5 mol%.

[0036] In one embodiment of the present invention, the first mixing ratio and the second mixing ratio may be different from each other.

[0037] Other aspects, features, and advantages other than those described above will become clear from the following drawings, claims, and detailed description of the invention.

[0038] Hereinafter, the following embodiments will be described in detail with reference to the attached drawings. When describing with reference to the drawings, identical or corresponding components are given the same reference numerals, and redundant descriptions thereof will be omitted.

[0039] Since the embodiments are capable of various modifications, specific embodiments are illustrated in the drawings and described in detail in the detailed description. The effects and features of the embodiments and the methods for achieving them will become clear by referring to the details described below in conjunction with the drawings. However, the embodiments are not limited to those disclosed below and can be implemented in various forms.

[0040] In the drawings, parts unrelated to the explanation have been omitted to clearly explain the invention, and similar parts throughout the specification have been given similar reference numerals.

[0041] In the following embodiments, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0042] In the following examples, terms such as "include" or "have" mean that the features or components described in the specification are present, and do not preclude the possibility that one or more other features or components may be added.

[0043] In the following embodiments, when a part such as a unit, area, or component is described as being on or above another part, it includes not only cases where it is directly on top of another part, but also cases where another unit, area, or component is interposed in between.

[0044] In the following embodiments, terms such as "connect" or "combine" do not necessarily imply a direct and / or fixed connection or combination of two members unless the context clearly indicates otherwise, nor do they exclude the interposition of another member between the two members.

[0045] In the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, so the following embodiments are not necessarily limited to those illustrated.

[0046] FIG. 1 is a perspective view illustrating a neural electrode device according to one embodiment of the present invention, and FIG. 2 is a plan view illustrating one embodiment of the electrode pattern portion (20) of FIG. 1. FIG. 3 is a cross-sectional view taken along the line I-I' of FIG. 1.

[0047] Referring to FIGS. 1 to 3, a neural electrode device (1) according to one embodiment of the present invention includes a first support layer (10), an electrode pattern portion (20), and a second support layer (30).

[0048] Here, the neural electrode device (1) is a device that enables bidirectional information transmission by selectively measuring nerve signals from peripheral nerves and stimulating the nerve (T, see FIG. 5), and can be used to restore motor and sensory functions of amputee or paralyzed patients.

[0049] When the neural electrode device (1) is attached to a brain nerve, it can be used to measure brain waves to study how specific areas of the brain function, and to monitor brain diseases such as Alzheimer's, Parkinson's, and epilepsy. Alternatively, when the neural electrode device (1) is attached to a muscle nerve, it can measure electromyography to measure muscle diseases and muscle nerve damage.

[0050] The nerve electrode device (1) can be made in a cuff-type form to contact the nerve of a peripheral nerve to record nerve activity or to control the nerve.

[0051] The neural electrode device must be formed in a shape that wraps around the nerve to measure nerve signals or deliver electrical stimulation to the corresponding nerve.

[0052] Here, nerves refer to various nerves within the scope of peripheral nerves, such as the axillary nerve, vagus nerve, femoral nerve, spinal nerve, and sciatic nerve. However, since nerves vary in size depending on their location or individual, electrodes of various sizes have traditionally been required.

[0053] The present invention is characterized by using a single neural electrode device (1) comprising a shape memory polymer to wrap around various diameters to transmit neural stimulation or measure neural signals.

[0054] In one embodiment of the present invention, the neural electrode device (1) may be formed in a stacked structure in which a first support layer (10), an electrode pattern portion (20), and a second support layer (30) are stacked sequentially.

[0055] The first support layer (10) may include one side (110) and the other side (120) and may be deformed according to designed external environmental conditions. The first support layer (10) may function as a substrate that supports the neural electrode device (1).

[0056] The external environmental conditions designed in this specification may be various external environmental stimuli designed to cause deformation in the neural electrode device (1), and may include, for example, temperature, humidity, etc. That is, when the designed external environmental stimuli such as temperature, humidity, etc. are applied, the shape of the first support layer (10) is deformed according to the degree of stimulation and can wrap around the nerve tube.

[0057] In one embodiment, the first support layer (10) may be made of a material whose shape changes according to temperature. For example, the first support layer (10) may include a shape memory polymer (SMP).

[0058] In the present invention, a shape memory polymer refers to a polymer that has the property of returning to its original shape when the external environmental conditions designed are brought to a specific condition, even if the shape of an object changes after it has been made to have a certain shape under specific conditions.

[0059] The shape memory polymer may be any one of a polyurethane (PU)-based shape memory polymer, a polycaprolactone (PL)-based shape memory polymer, a polylactic acid (PLA)-based shape memory polymer, a poly(ethylene oxide) (PEO)-based shape memory polymer, a polyvinyl alcohol (PVA)-based shape memory polymer, a polylactic acid (PLA)-based shape memory polymer, or a poly(bisphenol α-co-epichlorohydrin)-based shape memory polymer.

[0060] In one embodiment, the first support layer (10) may include a shape memory polymer, which is poly(bisphenol a-co-epichlorohydrin).

[0061] The first support layer (10) may include a shape memory polymer, and may be formed with a pre-set mixing ratio of the shape memory polymer so that the mechanical strength of the first support layer (10) changes according to the conditions of the designed external environment as the temperature changes.

[0062] Specifically, the first support layer (10) can be rolled to have a bending shape at a specific temperature such as a temperature, and can be formed into a flat shape at a temperature lower than the specific temperature, for example, lower than 30°C.

[0063] Meanwhile, the electrode pattern portion (20) is made of an electrically conductive material and covers the outer wall of the nerve, and can perform the function of measuring and regulating the electrical signal of the nerve or regulating the nerve through electrical stimulation.

[0064] The electrode pattern portion (20) is harmless to the human body and can effectively transmit nerve signals, such as gold (Au), silver (Ag), platinum (Pt), titanium (Ti), graphene, carbon nanotubes (CNT), and metal-ceramic composites, and the type of electrode is not limited in the present invention.

[0065] Referring to FIGS. 2 and 3, the electrode pattern portion (20) may include an electrode portion (210), a pad portion (220), and a wire portion (230). Here, the electrode portion (210) and the wire portion (230) may be portions exposed through one side (110) of the first support layer (10). Meanwhile, one side (110) of the first support layer (10) may be a surface that comes into close contact with the nerve when the nerve electrode device (1) is bent.

[0066] The electrode portion (210) may be disposed on one side of the first support layer (10). The electrode portion (210) may perform the function of recording nerve signals by making direct contact with a nerve or stimulating the nerve.

[0067] The electrode portion (210) may be provided as a single unit, but may include multiple electrodes (211, 212) to receive various signals from nerves or to transmit stimulation signals.

[0068] In one embodiment, the electrode portion (210) may include a plurality of first electrodes (211) and a plurality of second electrodes (212).

[0069] A plurality of first electrodes (211) can be formed along a direction (x-direction) that intersects the bending direction (y-direction) of the first support layer (10) and the second support layer (30).

[0070] In detail, a plurality of first electrodes (211) may be extended in a direction parallel to the nerve during bending and may be spaced apart along the bending direction (y-direction).

[0071] Through the aforementioned arrangement structure, the multiple first electrodes (211) do not bend when in contact with the nerve, allowing for smoother control or measurement of the nerve.

[0072] A plurality of second electrodes (212) may be extended in a direction perpendicular to the nerve during bending, that is, in the bending direction (y-direction). Additionally, the second electrodes (212) may be placed at both ends of the first support layer (10) with a plurality of first electrodes (211) in between. A plurality of second electrodes (212) may be formed in a structure that wraps around the circumferential direction of the nerve, so that signals can be continuously applied or transmitted.

[0073] The pad portion (220) can be placed on the other side of the first support layer (10) and can be connected to an external device (B, see FIG. 6) to perform the function of transmitting nerve signals received from the electrode portion (210).

[0074] The pad portion (220) may be composed of a number corresponding to the number of electrodes. In one embodiment, when the electrode portion (210) includes one first electrode (212), the pad portion (220) may be provided with one pad (221). In another embodiment, as illustrated, the pad portion (220) may be provided with a number of pads (221, 222) corresponding to the number of electrodes (211, 212).

[0075] In one embodiment, the pad portion (220) may include a plurality of first pads (221) and a plurality of second pads (222). A plurality of first pads (221) may be electrically connected to each of a plurality of first electrodes (211), and a plurality of second pads (222) may be electrically connected to each of a plurality of second electrodes (212). A wire portion (230) electrically connects the electrode portion (210) and the pad portion (220) and can perform the function of transmitting a signal from the electrode portion (210) to the pad portion (220).

[0076] Unlike the electrode portion (210) and pad portion (220) which are exposed through one side (110) of the first support layer (10), the wire portion (230) can be placed inside the first support layer (10) so as not to be exposed. In other words, the wire portion (230) can be placed spaced apart from one side (110) of the first support layer (10). The wire portion (230) can be formed through the same process as the electrode portion (210) and pad portion (220).

[0077] The wire portion (230) may extend along the longitudinal direction (y-direction) of the neural electrode device (1). In one embodiment, the wire portion (230) may extend in a straight line. In another embodiment, as shown in FIGS. 1 and 2, the wire portion (230) may be formed in a zigzag shape or a wave shape. The present invention is not limited thereto, and the electrode portion (210) may be any structure having robust characteristics against bending stress that occurs when the neural electrode device (1) is bent.

[0078] The wire section (230) may be composed of a number corresponding to the electrodes. In one embodiment, when the electrode section (210) includes one first electrode (212), the wire section (230) may be provided with one wire (231). In another embodiment, as illustrated, the wire section (230) may be provided with a number of wires (231, 232) corresponding to the number of electrodes (211, 212).

[0079] In one embodiment, the wire section (230) may include a plurality of first wires (231) and a plurality of second wires (232). A plurality of first wires (231) may electrically connect each of a plurality of first electrodes (211) and a plurality of first pads (221), and a plurality of second wires (232) may electrically connect each of a plurality of second electrodes (212) and a plurality of second pads (222).

[0080] Meanwhile, the second support layer (30) is placed on the other side (120) corresponding to one side (110) of the first support layer (10) and can be deformed according to the designed external environmental conditions. The second support layer (30) performs the role of supporting the electrode pattern portion (20) so that it can be more closely attached to the nerve (T) when the first support layer (10) comes into contact with the nerve and rolls to form a cuff. The second support layer (30) can be deformed according to the designed external environmental conditions, and when designed external environmental stimuli such as temperature, light intensity, and humidity are applied, its shape is deformed according to the degree of stimulation so that it can wrap the nerve bundle together with the first support layer (10).

[0081] In one embodiment, the second support layer (30) may be made of a material whose shape changes according to temperature. For example, the second support layer (30) may include a shape memory polymer (SMP).

[0082] The shape memory polymer may be any one of a polyurethane (PU)-based shape memory polymer, a polycaprolactone (PL)-based shape memory polymer, a polylactic acid (PLA)-based shape memory polymer, a poly(ethylene oxide) (PEO)-based shape memory polymer, a polyvinyl alcohol (PVA)-based shape memory polymer, a polylactic acid (PLA)-based shape memory polymer, or a poly(bisphenol α-co-epichlorohydrin)-based shape memory polymer.

[0083] In one embodiment, the second support layer (30) may include a shape memory polymer such as poly(bisphenol a-co-epichlorohydrin).

[0084] The second support layer (30) may include a shape memory polymer, and may be formed with a pre-set mixing ratio of the shape memory polymer so that the mechanical strength of the second support layer (30) changes according to temperature change.

[0085] In one embodiment, the second support layer (30) may be formed with the same mixing ratio as the first support layer (10). However, the present invention is not limited thereto, and the mixing ratio of the shape memory polymer for forming the second support layer (30) may differ from the mixing ratio of the shape memory polymer for forming the first support layer (10). Specifically, the first support layer (10) and the second support layer (30) may have different thermal compression coefficients and elastic moduli, and as a result, the stress characteristics received when curing may differ.

[0086] As will be described later, in a neural electrode device (1) according to one embodiment of the present invention, due to the aforementioned difference in characteristics, the first support layer (10) expands while the second support layer (30) is curing on the first support layer (10), and when the curing of the second support layer (30) is completed, the first support layer (10) is cured in an expanded state, and the second support layer (30) and the first support layer (10) can be rolled using thermal deformation in which the first support layer (10) contracts.

[0087] FIG. 4 is a diagram showing the process of forming a cuff of a neural electrode device according to one embodiment of the present invention, and FIG. 5 is a diagram showing the state in which a neural electrode device according to one embodiment of the present invention is wrapped around a nerve.

[0088] Referring again to FIGS. 3, 4 and 5, a neural electrode device (1) according to one embodiment of the present invention may be divided into a first area (A1) where an electrode portion (210) is placed, a second area (A2) where a wire portion (230) is placed, and a third area (A3) where a pad portion (220) is placed.

[0089] The first region (A1) of the neural electrode device (1) may be a bending region or a nerve contact region that is deformed by temperature when inserted into the body. The third region (A3) of the neural electrode device (1) may be a region that is placed outside the body and where a pad portion (220) is placed and connected to an external device (B), such as a PCB.

[0090] A neural electrode device (1) according to one embodiment of the present invention can maintain a flat electrode shape as shown in FIG. 4 (a) at a temperature lower than a specific temperature at which a bending shape occurs. Additionally, when the neural electrode device (1) is inserted into the body as shown in FIG. 4 (b), the first support layer (10) and the second support layer (30) containing a shape memory polymer are deformed at a temperature and rolled, thereby allowing the neural (T) to wrap around itself.

[0091] The neural electrode device (1) is provided with a first support layer (10) and a second support layer (30) made of a shape memory polymer material, so that when a specific temperature condition is met, the first support layer (10) and the second support layer (30) spontaneously bend due to the difference in thermal stress, and the flexible polymer of the first support layer (10) wraps around the neural (T).

[0092] During the process of wrapping around the nerve (T), a temporarily strong bonding force is formed at the contact point, which can overcome the problem of electrode detachment caused by external forces and movement, and this structural feature enables the electrode to be stably fixed to the nerve without external actuators or sutures.

[0093] A neural electrode device (1) according to one embodiment of the present invention does not require electrode fixation work to measure neural signals, so damage to the nerves in the body can be minimized when measuring or transmitting neural signals.

[0094] FIG. 6 is a diagram showing the results of cuff formation of a neural electrode device according to the thickness and thickness ratio of a first support layer and a second support layer according to an embodiment of the present invention.

[0095] Referring again to FIGS. 3 and FIGS. 6, the degree to which the first support layer (10) and the second support layer (30) according to one embodiment of the present invention deform according to external environmental conditions can be determined according to the ratio of the thickness (t1) of the first support layer (10) and the second thickness (t2) of the second support layer (30). In other words, the neural electrode device (1) can set the degree of bending at a specific temperature differently by adjusting the ratio of the thicknesses of the first support layer (10) and the second support layer (30).

[0096] Referring to FIG. 6, the degree of cuff formation of the neural electrode device due to the thickness ratio and thickness difference between the first thickness (t1) of the first support layer (10) and the second thickness (t2) of the second support layer (30) can be determined.

[0097] In one embodiment of the present invention, the first thickness (t1) of the first support layer (10) and the second thickness (t2) of the second support layer (30) may be the same. At this time, referring to FIG. 6 (a) to (c), even if the ratio of the first thickness (t1) of the first support layer (10) and the second thickness (t2) of the second support layer (30) is the same, it can be confirmed that the degree of deformation of the neural electrode device (1) differs due to the difference in thickness.

[0098] In another embodiment, the first thickness (t1) of the first support layer (10) may be thicker than the second thickness (t2) of the second support layer (30). Referring to (d) and (e) of FIG. 6, the neural electrode device (1) can be made such that the first thickness (t1) of the first support layer (10) is thicker than the second thickness (t2) of the second support layer (30), and the degree of deformation varies depending on the thickness ratio.

[0099] In other words, the neural electrode device (1) according to one embodiment of the present invention can secure electrode bending conditions suitable for measuring neural signals by adjusting the thickness and thickness ratio of the first support layer (10) and the second support layer (30).

[0100] FIG. 7 is a cross-sectional view illustrating the process steps for manufacturing a neural electrode device according to one embodiment of the present invention, and FIG. 8a to 8g are drawings illustrating the appearance of the neural electrode device according to one embodiment of the present invention after the completion of each manufacturing process step.

[0101] A method for manufacturing a neural electrode device according to one embodiment of the present invention may include the steps of: forming a sacrificial layer on a substrate; applying and curing a first shape memory polymer having a first mixing ratio on the sacrificial layer to form a shape memory polymer layer; forming a circuit pattern on the shape memory polymer layer through photolithography; forming a metal thin film layer on the shape memory polymer layer on which the circuit pattern is formed; removing a portion of the shape memory polymer layer and a portion of the metal thin film layer through a lift-off process to form an electrode pattern portion; applying and curing a shape memory polymer having the first mixing ratio on the electrode pattern portion to cover the electrode pattern portion and the shape memory polymer layer to form a first support layer; applying and curing a second shape memory polymer having a second mixing ratio on the first support layer to form a second support layer; and removing the sacrificial layer to separate the substrate.

[0102] Referring to FIGS. 7 and FIGS. 8a to 8g, the manufacturing steps and manufacturing process of a neural electrode device (1) according to one embodiment are as follows.

[0103] Step (a) of FIG. 7 is a step of forming a sacrificial layer on a substrate, wherein a silicon oxide (SiO2) layer (50) is deposited on a silicon wafer substrate (40) to apply a sacrificial layer (60).

[0104] In step (b) of FIG. 7, a sacrificial layer (60) is formed on the silicon oxide (SiO2) layer (50). The appearance of the substrate after step (b) is completed may be as shown in FIG. 8 (a).

[0105] In one embodiment, the sacrificial layer (60) may be made of various materials such as aluminum (Al), copper (Cu), nickel (Ni), titanium (Ti), molybdenum (Mo), and chromium (Cr).

[0106] Step (c) of FIG. 7 is a step of forming a shape memory polymer layer by applying and curing a first shape memory polymer having a first mixing ratio onto the sacrificial layer prepared in Step (a) of FIG. 7. A shape memory polymer (SMP) is applied onto the sacrificial layer (60) via spin coating and then cured to form a shape memory polymer (SMP) layer (10'). The appearance of the substrate after completing Step (c) may be as shown in FIG. 8 (b).

[0107] Here, the shape memory polymer may be any one of a polyurethane (PU)-based shape memory polymer, a polycaprolactone (PL)-based shape memory polymer, a polylactic acid (PLA)-based shape memory polymer, a poly(ethylene oxide) (PEO)-based shape memory polymer, a polyvinyl alcohol (PVA)-based shape memory polymer, a polylactic acid (PLA)-based shape memory polymer, or a poly(bisphenol α-co-epichlorohydrin)-based shape memory polymer.

[0108] In one embodiment, the shape memory polymer layer (10') may be formed using a shape memory polymer, a solvent, and a curing agent having a predetermined mixing ratio. For example, the shape memory polymer layer (10') may be formed by mixing poly(bisphenol a-co-epichlorohydrin) at a molar ratio of 4.5 to 5.5 mol%, neopentyl glycol diglycidyl ether at a molar ratio of 10.5 to 11.5 mol%, and EC301, a curing agent, at a molar ratio of 6.5 to 7.5 mol%. This is merely one example, and the present invention is not limited thereto.

[0109] Steps (d) and (h) of Fig. 7 are steps of forming a circuit pattern on the shape memory polymer layer through photolithography.

[0110] In step (d) of Fig. 7, a photosensitive material is applied to the shape memory polymer (SMP) layer (10') to form a first photoresist layer (70).

[0111] In step (e) of Fig. 7, the first photoresist layer (70) is patterned to form a first photoresist pattern (PR pattern).

[0112] In step (f) of Fig. 7, the shape memory polymer (SMP) layer (10') is etched with the first photoresist pattern (PR pattern) formed in step (e).

[0113] A reactive ion etching (RIE) process can be utilized for the above etching.

[0114] A second photoresist layer (70') is formed by applying a photosensitive material once again onto the shape memory polymer layer (10') etched in step (g) of Fig. 7.

[0115] In step (h) of FIG. 7, a second photoresist layer (70') is patterned to form a second photoresist pattern (PR pattern). The appearance of the substrate after completing step (h) may be as shown in FIG. 8 (c), and the second photoresist pattern (PR pattern) is the same as the circuit pattern (C) for forming a metal thin film layer.

[0116] Step (i) of FIG. 7 is a step of forming a metal thin film layer on the shape memory polymer layer on which a circuit pattern is formed, and forming a metal thin film layer (20') to form an electrode pattern portion (20).

[0117] In one embodiment, the metal thin film layer (20') can be made of various metals such as gold (Au), titanium (Ti), chromium (Cr), and silver (Ag). The appearance of the substrate after completing step (i) may be as shown in (d) of FIG. 8.

[0118] Sputter and evaporator may be used in the above method for forming a metal thin film layer.

[0119] Step (j) of FIG. 7 is a step of forming an electrode pattern portion by removing a portion of the shape memory polymer layer and a portion of the metal thin film layer through a lift-off process. By removing the second photoresist layer (70') that was not etched in step (h) through a lift-off process using acetone, the shape memory polymer (SMP) layer (10') located below the second photoresist layer (70') and the metal thin film layer (20') located above the second photoresist layer (70') are removed together. Through this, an electrode pattern portion (20) can be formed in step (j) of FIG. 7.

[0120] Step (k) of FIG. 7 includes the step of forming a first support layer by applying and curing a shape memory polymer having the first mixing ratio on the electrode pattern portion to cover the electrode pattern portion and the shape memory polymer layer, and the step of forming a second support layer by applying and curing a second shape memory polymer having the second mixing ratio on the first support layer.

[0121] In detail, a first support layer (10) is formed by applying a shape memory polymer (SMP) by spin coating and then curing it, and then a second support layer (30) is formed by applying a shape memory polymer (SMP) in the same ratio as the first support layer (10) by spin coating and then curing it. The appearance of the substrate after the completion of step (k) may be as shown in (e) and (f) of FIG. 8.

[0122] In one embodiment, the first support layer (10) and the second support layer (30) may include the same material as the shape memory polymer layer (10') of step (c) of FIG. 7.

[0123] In step (k) above, the process of forming the first support layer (10) by applying the shape memory polymer (SMP) by spin coating and then curing it includes curing at a temperature of 100°C for 90 minutes and at 130°C for 60 minutes.

[0124] After the first support layer (10) is cured, a second support layer is formed in the same manner, and during this process, the shape memory polymer (SMP) included in the first support layer (10) is softened and expanded by high temperature, and the shape memory polymer (SMP) of the second support layer (30) is applied.

[0125] In one embodiment, the shape memory polymer constituting the first support layer (10) and the second support layer (30) may be formed using a shape memory polymer, a solvent, and a curing agent having a predetermined mixing ratio. For example, the shape memory polymer may be poly(bisphenol a-co-epichlorohydrin) with a molar ratio of 4.5 to 5.5 mol%, the solvent may be neopentyl glycol diglycidyl ether with a molar ratio of 10.5 to 11.5 mol%, and EC301, a curing agent with a molar ratio of 6.5 to 7.5 mol%, which may be mixed to form the shape memory polymer. This is merely one example, and the present invention is not limited thereto, and the first mixing ratio and the second mixing ratio may be the same or different depending on the type of electrode device being manufactured.

[0126] Subsequently, when the temperature rises during the curing process, the first support layer (10) is combined with the second support layer (30) in a stretched state, and when the temperature drops after the curing is finished, the mechanical rigidity increases. Through the mechanical rigidity described above, the first support layer (10) and the second support layer (30) can maintain a flat electrode shape even when the substrate (40) is separated as described later.

[0127] Additionally, due to the difference in bending stress between the first support layer (10) and the second support layer (30) disposed on the other side, a bending directionality toward one side can be formed at a temperature above a certain level. An electrode pattern portion (20) is disposed on one side of the first support layer (10), and when the neural electrode device (1) is inserted into the body, the side on which the electrode pattern portion (20) is disposed bends toward the nerve so that the electrode pattern portion (20) and the nerve can make fixed contact.

[0128] Step (l) of FIG. 7 is a step of separating the substrate by removing the sacrificial layer. By removing the sacrificial layer (60) through an etching solution, the substrate (40) can be separated from the first support layer (10) and the second support layer (30), and the neural electrode device (1) can be completed. The appearance of the substrate after completing step (l) may be as shown in FIG. 8 (g).

[0129] A neural electrode device (1) according to one embodiment of the present invention can easily form a structure in which a part of the electrode pattern portion (220) is exposed through one side of the first support layer (10) through the manufacturing method described above. In addition, the neural electrode device (1) can increase the adhesive force between the first support layer (10) and the second support layer (30) that is tensioned during the process of curing the second support layer (30) by first forming the first support layer (10) and then forming the second support layer (30) on the other side of the first support layer (10). When the neural electrode device (1) according to an embodiment of the present invention is inserted into a peripheral nerve, the mechanical strength of the first support layer (10), which is a shape memory polymer (SMP), is lowered by temperature, and the neural electrode device (1) can be rolled in a direction that wraps around the nerve by utilizing the thermal stress received by the first support layer (10), which includes the shape memory polymer (SMP), during the process.

[0130] In addition, the neural electrode device (1) can adjust the degree of cuff formation of the neural electrode device (1) by adjusting the thickness of the first support layer (10) and the second support layer (30), so that it can be customized for nerves of various thicknesses.

[0131] Accordingly, the neural electrode device (1) according to one embodiment of the present invention is not limited to one type of neural and can be used for various neural control, measurement, and stimulation by selectively adjusting the thickness of the first support layer (10) and the second support layer (30).

[0132] The neural electrode device (1) according to an embodiment of the present invention is maintained in a flat state at room temperature, making it easy to handle before application, and when it reaches a temperature, its mechanical rigidity changes to be similar to that of neural tissue, enabling harmonious integration with the nerve. Through this, the neural electrode device (1) can reduce unnecessary physical stress and enable stable measurement of neural signals over a long period.

[0133] The present invention has been described above with reference to preferred embodiments. Those skilled in the art will understand that the present invention can be implemented in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of the claims should be interpreted as being included in the invention.

[0134] Embodiments of the present invention relate to neural electrode devices and can be utilized in fields for stably recording and measuring electrical signals by adhering to the surface of biological tissue. However, the industrial applicability of the embodiments of the present invention is not limited to those described above.

Claims

1. A first support layer including one surface and deforming according to designed external environmental conditions; An electrode pattern portion disposed on the first support layer, wherein a portion thereof is exposed through one surface of the first support layer; and A neural electrode device comprising: a second support layer disposed on a surface corresponding to one surface of the first support layer and deformed according to designed external environmental conditions.

2. In Paragraph 1, A neural electrode device comprising at least one of the first support layer and the second support layer, wherein the first support layer and the second support layer comprise a shape memory polymer (SMP).

3. In Paragraph 2, A neural electrode device in which the first thickness of the first support layer and the second thickness of the second support layer are the same.

4. In Paragraph 2, A neural electrode device in which the first thickness of the first support layer is thicker than the second thickness of the second support layer.

5. In Paragraph 1, The above electrode pattern part An electrode portion disposed on one side of the first support layer; A pad portion disposed on the other side of the first support layer; and A neural electrode device comprising: a wire portion electrically connecting the electrode portion and the pad portion.

6. In Paragraph 5, The above electrode portion includes a plurality of electrodes, A neural electrode device in which the plurality of electrodes are arranged to intersect the direction of the nerve.

7. In Paragraph 5, A neural electrode device in which the electrode portion and the pad portion are exposed through one surface of the first support layer.

8. In Paragraph 5, The above wire portion is a neural electrode device disposed inside the first support layer.

9. In Paragraph 1, A neural electrode device in which the degree of deformation of the first support layer and the second support layer according to external environmental conditions designed is determined by the ratio of the first thickness of the first support layer and the second thickness of the second support layer.

10. A step of forming a sacrificial layer on a substrate; A step of forming a shape memory polymer layer by applying and curing a first shape memory polymer having a first mixing ratio on the sacrificial layer; A step of forming a circuit pattern on the shape memory polymer layer through photolithography; A step of forming a metal thin film layer on the shape memory polymer layer having the above circuit pattern formed thereon; A step of forming an electrode pattern portion by removing a portion of the shape memory polymer layer and a portion of the metal thin film layer through a lift-off process; A step of forming a first support layer by applying and curing a shape memory polymer having the first mixing ratio on the electrode pattern portion to cover the electrode pattern portion and the shape memory polymer layer; A step of forming a second support layer by applying and curing a second shape memory polymer having a second mixing ratio on the first support layer; and A method for manufacturing a neural electrode device comprising the step of removing the sacrificial layer to separate the substrate.

11. In Paragraph 10, A method for manufacturing a neural electrode device in which the first mixing ratio and the second mixing ratio are the same.

12. In Paragraph 11, The above-mentioned first shape memory polymer is, A method for manufacturing a neural electrode device comprising a shape memory polymer with a molar ratio of 4.5 to 5.5 mol%, a solvent with a molar ratio of 10.5 to 11.5 mol%, and a curing agent with a molar ratio of 6.5 to 7.5 mol%.

13. In Paragraph 12 The above-mentioned first shape memory polymer is, A method for manufacturing a neural electrode device comprising poly(bisphenol α-co-epichlorohydrin) in a molar ratio of 4.5 to 5.5 mol%, neopentyl glycol diglycidyl ether in a molar ratio of 10.5 to 11.5 mol%, and EC301 in a molar ratio of 6.5 to 7.5 mol%.

14. In Paragraph 10, A method for manufacturing a neural electrode device in which the first mixing ratio and the second mixing ratio are different.

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